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-------------------------------------------------------------------------------
-- 
-- RapidIO IP Library Core
-- 
-- This file is part of the RapidIO IP library project
-- http://www.opencores.org/cores/rio/
-- 
-- Description
-- Containing the transmission channel independent parts of the LP-Serial
-- Physical Layer Specification (RapidIO 2.2, part 6).
-- 
-- To Do:
-- -
-- 
-- Author(s): 
-- - Magnus Rosenius, magro732@opencores.org 
-- 
-------------------------------------------------------------------------------
-- 
-- Copyright (C) 2013 Authors and OPENCORES.ORG 
-- 
-- This source file may be used and distributed without 
-- restriction provided that this copyright statement is not 
-- removed from the file and that any derivative work contains 
-- the original copyright notice and the associated disclaimer. 
-- 
-- This source file is free software; you can redistribute it 
-- and/or modify it under the terms of the GNU Lesser General 
-- Public License as published by the Free Software Foundation; 
-- either version 2.1 of the License, or (at your option) any 
-- later version. 
-- 
-- This source is distributed in the hope that it will be 
-- useful, but WITHOUT ANY WARRANTY; without even the implied 
-- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
-- PURPOSE. See the GNU Lesser General Public License for more 
-- details. 
-- 
-- You should have received a copy of the GNU Lesser General 
-- Public License along with this source; if not, download it 
-- from http://www.opencores.org/lgpl.shtml 
-- 
-------------------------------------------------------------------------------
 
 
-------------------------------------------------------------------------------
-- RioSerial
--
-- Generics
-- --------
-- TIMEOUT_WIDTH - The number of bits to be used in the portLinkTimeout signal.
-- NUMBER_WORDS - The number of parallell words that the data symbols can
-- contain. This sizes the data buses. It can be used to increase the bandwidth
-- of the core. Note that it cannot be larger than 4. This is since two
-- packets may be completed at the same tick and the interface to the
-- packetBuffer cannot handle more than one packets in one tick.
--
-- Signals
-- -------
-- System signals.
-- clk - System clock.
-- areset_n - System reset. Asynchronous, active low. 
--
-- Configuration signals. These are used to change the runtime behaviour.
-- portLinkTimeout_i - The number of ticks to wait for a packet-accepted before
--   a timeout occurrs.
-- linkInitialized_o - Indicates if a link partner is answering with valid
--   status-control-symbols. 
-- inputPortEnable_i - Activate the input port for non-maintenance packets. If
--   deasserted, only non-maintenance packets are allowed.
-- outputPortEnable_i - Activate the output port for non-maintenance packets.
--   If deasserted, only non-maintenance packets are allowed.
--
-- This interface makes it possible to read and write ackId in both outbound
-- and inbound directions. All input signals are validated by localAckIdWrite.
-- localAckIdWrite_i - Indicate if a localAckId write operation is ongoing.
--   Usually this signal is high one tick. 
-- clrOutstandingAckId_i - Clear outstanding ackId, i.e. reset the transmission
--   window. The signal is only read if localAckIdWrite_i is high.
-- inboundAckId_i - The value to set the inbound ackId (the ackId that the
--  next inbound packet should have) to. This signal is only read if localAckIdWrite
--  is high.
-- outstandingAckId_i - The value to set the outstanding ackId (the ackId
--   transmitted but not acknowledged) to. This signal is only read if localAckIdWrite
--   is high.
-- outboundAckId_i - The value to set the outbound ackId (the ackId that the
--   next outbound packet will have) to. This signal is only read if localAckIdWrite
--   is high.
-- inboundAckId_o - The current inbound ackId.
-- outstandingAckId_o - The current outstanding ackId.
-- outboundAckId_o - The current outbound ackId.
--
-- This is the interface to the packet buffering sublayer. 
-- The window signals are used to send packets without removing them from the
-- memory storage. This way, many packet can be sent without awaiting
-- packet-accepted symbols and if a packet-accepted gets lost, it is possible
-- to revert and resend a packet. This is achived by reading readWindowEmpty
-- for new packet and asserting readWindowNext when a packet has been sent.
-- When the packet-accepted is received, readFrame should be asserted to remove the
-- packet from the storage. If a packet-accepted is missing, readWindowReset is
-- asserted to set the current packet to read to the one that has not received
-- a packet-accepted.
-- readFrameEmpty_i - Indicate if a packet is ready in the outbound direction.
--   Once deasserted, it is possible to read the packet content using
--   readContent_o to update readContentData and readContentEnd.
-- readFrame_o - Assert this signal for one tick to discard the oldest packet.
--   It should be used when a packet has been fully read, a linkpartner has
--   accepted it and the resources occupied by it should be returned to be
--   used for new packets.
-- readFrameRestart_o - Assert this signal to restart the reading of the
--   current packet. readContentData and readContentEnd will be reset to the
--   first content of the packet. 
-- readFrameAborted_i - This signal is asserted if the current packet was
--   aborted while it was written. It is used when a transmitter starts to send a
--   packet before it has been fully received and it is cancelled before it is
--   completed. A one tick asserted readFrameRestart signal resets this signal.
-- readWindowEmpty_i - Indicate if there are more packets to send.
-- readWindowReset_o - Reset the current packet to the oldest stored in the memory.
-- readWindowNext_o - Indicate that a new packet should be read. Must only be
--   asserted if readWindowEmpty is deasserted. It should be high for one tick.
-- readContentEmpty_i - Indicate if there are any packet content to be read.
--   This signal is updated directly when packet content is written making it
--   possible to read packet content before the full packet has been written to
--   the memory storage.
-- readContent_o - Update readContentData and readContentEnd.
-- readContentEnd_i - Indicate if the end of the current packet has been
--   reached. When asserted, readContentData is not valid.
-- readContentData_i - The content of the current packet.
-- writeFrameFull_i - Indicate if the inbound packet storage is ready to accept
--   a new packet.
-- writeFrame_o - Indicate that a new complete inbound packet has been written.
-- writeFrameAbort_o - Indicate that the current packet is aborted and that all
--   data written for this packet should be discarded. 
-- writeContent_o - Indicate that writeContentData is valid and should be
--   written into the packet content storage. 
-- writeContentData_o - The content to write to the packet content storage.
--
-- This is the interface to the PCS (Physical Control Sublayer). Four types of
-- symbols exist, idle, control, data and error.
-- Idle symbols are transmitted when nothing else can be transmitted. They are
-- mainly intended to enforce a timing on the transmitted symbols. This is
-- needed to be able to guarantee that a status-control-symbol is transmitted
-- at least once every 256 symbol.
-- Control symbols contain control-symbols as described by the standard.
-- Data symbols contains a 32-bit fragment of a RapidIO packet.
-- Error symbols indicate that a corrupted symbol was received. This could be
-- used by a PCS layer to indicate that a transmission error was detected and
-- that the above layers should send link-requests to ensure the synchronism
-- between the link-partners.
-- The signals in this interface are:
-- portInitialized_i - An asserted signal on this pin indicates that the PCS
--   layer has established synchronization with the link and is ready to accept
--   symbols. 
-- outboundSymbolEmpty_o - An asserted signal indicates that there are no
--   outbound symbols to read. Once deasserted, outboundSymbol_o will be
--   already be valid. This signal will be updated one tick after
--   outboundSymbolRead_i has been asserted.
-- outboundSymbolRead_i - Indicate that outboundSymbol_o has been read and a
--   new value could be accepted. It should be active for one tick. 
-- REMARK: Update this comment...
-- outboundSymbol_o - The outbound symbol. It is divided into two parts,
--   symbolType and symbolContent.
--   symbolType - The two MSB bits are the type of the symbol according to
--   table below:
--     00=IDLE, the rest of the bits are not used.
--     01=CONTROL, the control symbols payload (24 bits) are placed in the MSB
--       part of the symbolContent.
--     10=ERROR, the rest of the bits are not used.
--     11=DATA, all the remaining bits contain the number of valid words and
--     the payload of the symbol.
--   symbolContent - The rest of the bits are symbol content. If there are
--     multiple words in the symbols they must be set to zero. The first
--     received word is placed in the MSB part of this field.
-- inboundSymbolFull_o - An asserted signal indicates that no more inbound
--   symbols can be accepted.
-- inboundSymbolWrite_i - Indicate that inboundSymbol_i contains valid
--   information that should be forwarded. Should be active for one tick.
-- inboundSymbol_i - The inbound symbol. See outboundSymbol_o for formating.
-------------------------------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use work.rio_common.all;
 
 
-------------------------------------------------------------------------------
-- Entity for RioSerial.
-------------------------------------------------------------------------------
entity RioSerial is
  generic(
    TIMEOUT_WIDTH : natural := 20;
    NUMBER_WORDS : natural range 1 to 4 := 1);
  port(
    -- System signals.
    clk : in std_logic;
    areset_n : in std_logic;
 
    -- Status signals for maintenance operations.
    portLinkTimeout_i : in std_logic_vector(TIMEOUT_WIDTH-1 downto 0);
    linkInitialized_o : out std_logic;
    inputPortEnable_i : in std_logic;
    outputPortEnable_i : in std_logic;
 
    -- Support for portLocalAckIdCSR.
    localAckIdWrite_i : in std_logic;
    clrOutstandingAckId_i : in std_logic;
    inboundAckId_i : in std_logic_vector(4 downto 0);
    outstandingAckId_i : in std_logic_vector(4 downto 0);
    outboundAckId_i : in std_logic_vector(4 downto 0);
    inboundAckId_o : out std_logic_vector(4 downto 0);
    outstandingAckId_o : out std_logic_vector(4 downto 0);
    outboundAckId_o : out std_logic_vector(4 downto 0);
 
    -- Outbound frame interface.
    readFrameEmpty_i : in std_logic;
    readFrame_o : out std_logic;
    readFrameRestart_o : out std_logic;
    readFrameAborted_i : in std_logic;
    readWindowEmpty_i : in std_logic;
    readWindowReset_o : out std_logic;
    readWindowNext_o : out std_logic;
    readContentEmpty_i : in std_logic;
    readContent_o : out std_logic;
    readContentEnd_i : in std_logic;
    readContentData_i : in std_logic_vector(2+(32*NUMBER_WORDS-1) downto 0);
 
    -- Inbound frame interface.
    writeFrameFull_i : in std_logic;
    writeFrame_o : out std_logic;
    writeFrameAbort_o : out std_logic;
    writeContent_o : out std_logic;
    writeContentData_o : out std_logic_vector(2+(32*NUMBER_WORDS-1) downto 0);
 
    -- PCS layer signals.
    portInitialized_i : in std_logic;
    outboundSymbolEmpty_o : out std_logic;
    outboundSymbolRead_i : in std_logic;
    outboundSymbol_o : out std_logic_vector(((2+32)*NUMBER_WORDS-1) downto 0);
    inboundSymbolFull_o : out std_logic;
    inboundSymbolWrite_i : in std_logic;
    inboundSymbol_i : in std_logic_vector(((2+32)*NUMBER_WORDS-1) downto 0));
end entity;
 
 
-------------------------------------------------------------------------------
-- Architecture for RioSerial.
-------------------------------------------------------------------------------
architecture RioSerialImpl of RioSerial is
 
  component RioFifo1 is
    generic(
      WIDTH : natural);
    port(
      clk : in std_logic;
      areset_n : in std_logic;
 
      empty_o : out std_logic;
      read_i : in std_logic;
      data_o : out std_logic_vector(WIDTH-1 downto 0);
 
      full_o : out std_logic;
      write_i : in std_logic;
      data_i : in std_logic_vector(WIDTH-1 downto 0));
  end component;
 
  component RioTransmitter is
    generic(
      TIMEOUT_WIDTH : natural;
      NUMBER_WORDS : natural range 1 to 4 := 1);
    port(
      clk : in std_logic;
      areset_n : in std_logic;
 
      portLinkTimeout_i : in std_logic_vector(TIMEOUT_WIDTH-1 downto 0);
      portEnable_i : in std_logic;
 
      localAckIdWrite_i : in std_logic;
      clrOutstandingAckId_i : in std_logic;
      outstandingAckId_i : in std_logic_vector(4 downto 0);
      outboundAckId_i : in std_logic_vector(4 downto 0);
      outstandingAckId_o : out std_logic_vector(4 downto 0);
      outboundAckId_o : out std_logic_vector(4 downto 0);
 
      portInitialized_i : in std_logic;
      txFull_i : in std_logic;
      txWrite_o : out std_logic;
      txType_o : out std_logic_vector(1 downto 0);
      txData_o : out std_logic_vector(31 downto 0);
 
      txControlEmpty_i : in std_logic;
      txControlSymbol_i : in std_logic_vector(12 downto 0);
      txControlUpdate_o : out std_logic;
      rxControlEmpty_i : in std_logic;
      rxControlSymbol_i : in std_logic_vector(12 downto 0);
      rxControlUpdate_o : out std_logic;
 
      linkInitialized_i : in std_logic;
      linkInitialized_o : out std_logic;
      ackIdStatus_i : in std_logic_vector(4 downto 0);
 
      readFrameEmpty_i : in std_logic;
      readFrame_o : out std_logic;
      readFrameRestart_o : out std_logic;
      readFrameAborted_i : in std_logic;
      readWindowEmpty_i : in std_logic;
      readWindowReset_o : out std_logic;
      readWindowNext_o : out std_logic;
      readContentEmpty_i : in std_logic;
      readContent_o : out std_logic;
      readContentEnd_i : in std_logic;
      readContentWords_i : in std_logic_vector(1 downto 0);
      readContentData_i : in std_logic_vector(32*NUMBER_WORDS-1 downto 0));
  end component;
 
  component RioReceiver is
    generic(
      NUMBER_WORDS : natural range 1 to 4 := 1);
    port(
      clk : in std_logic;
      areset_n : in std_logic;
 
      portEnable_i : in std_logic;
 
      localAckIdWrite_i : in std_logic;
      inboundAckId_i : in std_logic_vector(4 downto 0);
      inboundAckId_o : out std_logic_vector(4 downto 0);
 
      portInitialized_i : in std_logic;
      rxEmpty_i : in std_logic;
      rxRead_o : out std_logic;
      rxType_i : in std_logic_vector(2*NUMBER_WORDS-1 downto 0);
      rxData_i : in std_logic_vector(32*NUMBER_WORDS-1 downto 0);
 
      txControlWrite_o : out std_logic_vector(NUMBER_WORDS-1 downto 0);
      txControlSymbol_o : out std_logic_vector(12*NUMBER_WORDS downto 0);
      rxControlWrite_o : out std_logic_vector(NUMBER_WORDS-1 downto 0);
      rxControlSymbol_o : out std_logic_vector(12*NUMBER_WORDS downto 0);
 
      ackIdStatus_o : out std_logic_vector(4 downto 0);
      linkInitialized_o : out std_logic;
 
      writeFrameFull_i : in std_logic;
      writeFrame_o : out std_logic;
      writeFrameAbort_o : out std_logic;
      writeContent_o : out std_logic;
      writeContentWords_o : out std_logic_vector(1 downto 0);
      writeContentData_o : out std_logic_vector(32*NUMBER_WORDS-1 downto 0));
  end component;
 
  signal linkInitializedRx : std_logic;
  signal linkInitializedTx : std_logic;
  signal ackIdStatus : std_logic_vector(4 downto 0);
 
  signal txControlWrite : std_logic_vector(NUMBER_WORDS-1 downto 0);
  signal txControlWriteSymbol : std_logic_vector(12*NUMBER_WORDS downto 0);
  signal txControlReadEmpty : std_logic_vector(NUMBER_WORDS-1 downto 0);
  signal txControlRead : std_logic_vector(NUMBER_WORDS-1 downto 0);
  signal txControlReadSymbol : std_logic_vector(12*NUMBER_WORDS downto 0);
 
  signal rxControlWrite : std_logic_vector(NUMBER_WORDS-1 downto 0);
  signal rxControlWriteSymbol : std_logic_vector(12*NUMBER_WORDS downto 0);
  signal rxControlReadEmpty : std_logic_vector(NUMBER_WORDS-1 downto 0);
  signal rxControlRead : std_logic_vector(NUMBER_WORDS-1 downto 0);
  signal rxControlReadSymbol : std_logic_vector(12*NUMBER_WORDS downto 0);
 
  signal outboundFull : std_logic;
  signal outboundWrite : std_logic;
  signal outboundType : std_logic_vector(1 downto 0);
  signal outboundData : std_logic_vector(32*NUMBER_WORDS-1 downto 0);
  signal outboundSymbol : std_logic_vector(2+(32*NUMBER_WORDS-1) downto 0);
 
  signal inboundEmpty : std_logic;
  signal inboundRead : std_logic;
  signal inboundType : std_logic_vector(1 downto 0);
  signal inboundData : std_logic_vector(32*NUMBER_WORDS-1 downto 0);
  signal inboundSymbol : std_logic_vector(((2+32)*NUMBER_WORDS-1) downto 0);
 
begin
 
  linkInitialized_o <=
    '1' when ((linkInitializedRx = '1') and (linkInitializedTx = '1')) else '0';
 
  -----------------------------------------------------------------------------
  -- Serial layer modules.
  -----------------------------------------------------------------------------
 
  Transmitter: RioTransmitter
    generic map(
      TIMEOUT_WIDTH=>TIMEOUT_WIDTH,
      NUMBER_WORDS=>NUMBER_WORDS)
    port map(
      clk=>clk, areset_n=>areset_n,
      portLinkTimeout_i=>portLinkTimeout_i,
      portEnable_i=>outputPortEnable_i,
      localAckIdWrite_i=>localAckIdWrite_i,
      clrOutstandingAckId_i=>clrOutstandingAckId_i,
      outstandingAckId_i=>outstandingAckId_i,
      outboundAckId_i=>outboundAckId_i,
      outstandingAckId_o=>outstandingAckId_o,
      outboundAckId_o=>outboundAckId_o,
      portInitialized_i=>portInitialized_i,
      txFull_i=>outboundFull, txWrite_o=>outboundWrite,
      txType_o=>outboundType, txData_o=>outboundData,
      txControlEmpty_i=>txControlReadEmpty(0), txControlSymbol_i=>txControlReadSymbol,
      txControlUpdate_o=>txControlRead(0),
      rxControlEmpty_i=>rxControlReadEmpty(0), rxControlSymbol_i=>rxControlReadSymbol,
      rxControlUpdate_o=>rxControlRead(0),
      linkInitialized_o=>linkInitializedTx,
      linkInitialized_i=>linkInitializedRx, ackIdStatus_i=>ackIdStatus,
      readFrameEmpty_i=>readFrameEmpty_i, readFrame_o=>readFrame_o,
      readFrameRestart_o=>readFrameRestart_o, readFrameAborted_i=>readFrameAborted_i,
      readWindowEmpty_i=>readWindowEmpty_i,
      readWindowReset_o=>readWindowReset_o, readWindowNext_o=>readWindowNext_o,
      readContentEmpty_i=>readContentEmpty_i, readContent_o=>readContent_o,
      readContentEnd_i=>readContentEnd_i,
      readContentWords_i=>readContentData_i(2+(32*NUMBER_WORDS-1) downto 1+(32*NUMBER_WORDS-1)),
      readContentData_i=>readContentData_i(32*NUMBER_WORDS-1 downto 0));
 
  SymbolFifo: for i in 0 to NUMBER_WORDS-1 generate
    TxSymbolFifo: RioFifo1
      generic map(WIDTH=>13)
      port map(
        clk=>clk, areset_n=>areset_n,
        empty_o=>txControlReadEmpty(i),
        read_i=>txControlRead(i),
        data_o=>txControlReadSymbol(12*(i+1) downto 12*i),
        full_o=>open,
        write_i=>txControlWrite(i),
        data_i=>txControlWriteSymbol(12*(i+1) downto 12*i));
 
    RxSymbolFifo: RioFifo1
      generic map(WIDTH=>13)
      port map(
        clk=>clk, areset_n=>areset_n,
        empty_o=>rxControlReadEmpty(i),
        read_i=>rxControlRead(i),
        data_o=>rxControlReadSymbol(12*(i+1) downto 12*i),
        full_o=>open,
        write_i=>rxControlWrite(i),
        data_i=>rxControlWriteSymbol(12*(i+1) downto 12*i));
  end generate;
 
  Receiver: RioReceiver
    generic map(NUMBER_WORDS=>NUMBER_WORDS)
    port map(
      clk=>clk, areset_n=>areset_n,
      portEnable_i=>inputPortEnable_i,
      localAckIdWrite_i=>localAckIdWrite_i,
      inboundAckId_i=>inboundAckId_i,
      inboundAckId_o=>inboundAckId_o,
      portInitialized_i=>portInitialized_i,
      rxEmpty_i=>inboundEmpty, rxRead_o=>inboundRead,
      rxType_i=>inboundType, rxData_i=>inboundData,
      txControlWrite_o=>txControlWrite, txControlSymbol_o=>txControlWriteSymbol,
      rxControlWrite_o=>rxControlWrite, rxControlSymbol_o=>rxControlWriteSymbol,
      ackIdStatus_o=>ackIdStatus,
      linkInitialized_o=>linkInitializedRx,
      writeFrameFull_i=>writeFrameFull_i,
      writeFrame_o=>writeFrame_o, writeFrameAbort_o=>writeFrameAbort_o,
      writeContent_o=>writeContent_o,
      writeContentWords_o=>writeContentData_o(2+(32*NUMBER_WORDS-1) downto 1+(32*NUMBER_WORDS-1)),
      writeContentData_o=>writeContentData_o(32*NUMBER_WORDS-1 downto 0));
 
  -----------------------------------------------------------------------------
  -- PCS layer FIFO interface.
  -----------------------------------------------------------------------------
 
  outboundSymbol <= outboundType & outboundData;
  OutboundSymbolFifo: RioFifo1
    generic map(WIDTH=>2+32*NUMBER_WORDS)
    port map(
      clk=>clk, areset_n=>areset_n,
      empty_o=>outboundSymbolEmpty_o, read_i=>outboundSymbolRead_i, data_o=>outboundSymbol_o,
      full_o=>outboundFull, write_i=>outboundWrite, data_i=>outboundSymbol);
 
  inboundType <= inboundSymbol(2+(32*NUMBER_WORDS-1) downto 1+(32*NUMBER_WORDS-1));
  inboundData <= inboundSymbol(32*NUMBER_WORDS-1 downto 0);
  InboundSymbolFifo: RioFifo1
    generic map(WIDTH=>2+32*NUMBER_WORDS)
    port map(
      clk=>clk, areset_n=>areset_n,
      empty_o=>inboundEmpty, read_i=>inboundRead, data_o=>inboundSymbol,
      full_o=>inboundSymbolFull_o, write_i=>inboundSymbolWrite_i, data_i=>inboundSymbol_i);
 
end architecture;
 
 
 
-------------------------------------------------------------------------------
-- RioTransmitter
-------------------------------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use work.rio_common.all;
 
 
-------------------------------------------------------------------------------
-- Entity for RioTransmitter.
-------------------------------------------------------------------------------
entity RioTransmitter is
  generic(
    TIMEOUT_WIDTH : natural;
    NUMBER_WORDS : natural range 1 to 4 := 1);
  port(
    -- System signals.
    clk : in std_logic;
    areset_n : in std_logic;
 
    -- Status signals used for maintenance.
    portLinkTimeout_i : in std_logic_vector(TIMEOUT_WIDTH-1 downto 0);
    portEnable_i : in std_logic;
 
    -- Support for localAckIdCSR.
    localAckIdWrite_i : in std_logic;
    clrOutstandingAckId_i : in std_logic;
    outstandingAckId_i : in std_logic_vector(4 downto 0);
    outboundAckId_i : in std_logic_vector(4 downto 0);
    outstandingAckId_o : out std_logic_vector(4 downto 0);
    outboundAckId_o : out std_logic_vector(4 downto 0);
 
    -- Port output interface.
    portInitialized_i : in std_logic;
    txFull_i : in std_logic;
    txWrite_o : out std_logic;
    txType_o : out std_logic_vector(2*NUMBER_WORDS-1 downto 0);
    txData_o : out std_logic_vector(32*NUMBER_WORDS-1 downto 0);
 
    -- Control symbols aimed to the transmitter.
    txControlEmpty_i : in std_logic;
    txControlSymbol_i : in std_logic_vector(12 downto 0);
    txControlUpdate_o : out std_logic;
 
    -- Control symbols from the receiver to send.
    rxControlEmpty_i : in std_logic;
    rxControlSymbol_i : in std_logic_vector(12 downto 0);
    rxControlUpdate_o : out std_logic;
 
    -- Internal signalling from the receiver part.
    linkInitialized_o : out std_logic;
    linkInitialized_i : in std_logic;
    ackIdStatus_i : in std_logic_vector(4 downto 0);
 
    -- Frame buffer interface.
    readFrameEmpty_i : in std_logic;
    readFrame_o : out std_logic;
    readFrameRestart_o : out std_logic;
    readFrameAborted_i : in std_logic;
    readWindowEmpty_i : in std_logic;
    readWindowReset_o : out std_logic;
    readWindowNext_o : out std_logic;
    readContentEmpty_i : in std_logic;
    readContent_o : out std_logic;
    readContentEnd_i : in std_logic;
    readContentWords_i : in std_logic_vector(1 downto 0);
    readContentData_i : in std_logic_vector(32*NUMBER_WORDS-1 downto 0));
end entity;
 
 
-------------------------------------------------------------------------------
-- Architecture for RioTransmitter.
-------------------------------------------------------------------------------
architecture RioTransmitterImpl of RioTransmitter is
 
  constant NUMBER_STATUS_TRANSMIT : natural := 15;
  constant NUMBER_LINK_RESPONSE_RETRIES : natural := 2;
 
  component RioTransmitterCore is
    generic(
      NUMBER_WORDS : natural range 1 to 4 := 1);
    port(
      -- System signals.
      clk : in std_logic;
      areset_n : in std_logic;
 
      -- Status signals used for maintenance.
      portEnable_i : in std_logic;
 
      -- Port output interface.
      portInitialized_i : in std_logic;
      txFull_i : in std_logic;
      txWrite_o : out std_logic;
      txType_o : out std_logic_vector(2*NUMBER_WORDS-1 downto 0);
      txData_o : out std_logic_vector(32*NUMBER_WORDS-1 downto 0);
 
      -- Control symbols aimed to the transmitter.
      txControlEmpty_i : in std_logic;
      txControlSymbol_i : in std_logic_vector(13*NUMBER_WORDS-1 downto 0);
      txControlUpdate_o : out std_logic;
 
      -- Control symbols from the receiver to send.
      rxControlEmpty_i : in std_logic;
      rxControlSymbol_i : in std_logic_vector(13*NUMBER_WORDS-1 downto 0);
      rxControlUpdate_o : out std_logic;
 
      -- Internal signalling from the receiver part.
      linkInitialized_o : out std_logic;
      linkInitialized_i : in std_logic;
      ackIdStatus_i : in std_logic_vector(4 downto 0);
 
      -- Internal core variables for cascading.
      timeSentSet_o : out std_logic;
      timeSentReset_o : out std_logic;
      timeSentExpired_i : in std_logic;
      operational_i : in std_logic;
      operational_o : out std_logic;
      ackId_i : in std_logic_vector(4 downto 0);
      ackId_o : out std_logic_vector(4 downto 0);
      bufferStatus_i : in std_logic_vector(4 downto 0);
      bufferStatus_o : out std_logic_vector(4 downto 0);
      statusReceived_i : in std_logic;
      statusReceived_o : out std_logic;
      numberSentLinkRequests_i : in std_logic_vector(1 downto 0);
      numberSentLinkRequests_o : out std_logic_vector(1 downto 0);
      outputErrorStopped_i : in std_logic;
      outputErrorStopped_o : out std_logic;
      fatalError_i : in std_logic;
      fatalError_o : out std_logic;
      recoverActive_i : in std_logic;
      recoverActive_o : out std_logic;
      recoverCounter_i : in std_logic_vector(4 downto 0);
      recoverCounter_o : out std_logic_vector(4 downto 0);
      ackIdWindow_i : in std_logic_vector(4 downto 0);
      ackIdWindow_o : out std_logic_vector(4 downto 0);
      frameState_i : in std_logic_vector(6 downto 0);
      frameState_o : out std_logic_vector(6 downto 0);
      frameWordCounter_i : in std_logic_vector(1 downto 0);
      frameWordCounter_o : out std_logic_vector(1 downto 0);
      frameContent_i : in std_logic_vector(32*NUMBER_WORDS-1 downto 0);
      frameContent_o : out std_logic_vector(32*NUMBER_WORDS-1 downto 0);
      counter_i : in std_logic_vector(3 downto 0);
      counter_o : out std_logic_vector(3 downto 0);
      symbolsTransmitted_i : in std_logic_vector(7 downto 0);
      symbolsTransmitted_o : out std_logic_vector(7 downto 0);
 
      -- Frame buffer interface.
      readFrameEmpty_i : in std_logic;
      readFrame_o : out std_logic;
      readFrameRestart_o : out std_logic;
      readFrameAborted_i : in std_logic;
      readWindowEmpty_i : in std_logic;
      readWindowReset_o : out std_logic;
      readWindowNext_o : out std_logic;
      readContentEmpty_i : in std_logic;
      readContent_o : out std_logic;
      readContentEnd_i : in std_logic;
      readContentWords_i : in std_logic_vector(1 downto 0);
      readContentData_i : in std_logic_vector(32*NUMBER_WORDS-1 downto 0));
  end component;
 
  component MemorySimpleDualPortAsync is
    generic(
      ADDRESS_WIDTH : natural := 1;
      DATA_WIDTH : natural := 1;
      INIT_VALUE : std_logic := 'U');
    port(
      clkA_i : in std_logic;
      enableA_i : in std_logic;
      addressA_i : in std_logic_vector(ADDRESS_WIDTH-1 downto 0);
      dataA_i : in std_logic_vector(DATA_WIDTH-1 downto 0);
 
      addressB_i : in std_logic_vector(ADDRESS_WIDTH-1 downto 0);
      dataB_o : out std_logic_vector(DATA_WIDTH-1 downto 0));
  end component;
 
  signal timeCurrent : std_logic_vector(TIMEOUT_WIDTH downto 0);
  signal timeSentElapsed : unsigned(TIMEOUT_WIDTH downto 0);
  signal timeSentDelta : unsigned(TIMEOUT_WIDTH downto 0);
  signal timeSentExpired : std_logic;
  signal timeSentSet : std_logic;
  signal timeSentReset : std_logic;
 
  signal timeSentEnable : std_logic;
  signal timeSentWriteAddress : std_logic_vector(4 downto 0);
  signal timeSentReadAddress : std_logic_vector(4 downto 0);
  signal timeSentReadData : std_logic_vector(TIMEOUT_WIDTH downto 0);
 
  signal operationalCurrent, operationalNext : std_logic;
  signal ackIdCurrent, ackIdNext : std_logic_vector(4 downto 0);
  signal bufferStatusCurrent, bufferStatusNext : std_logic_vector(4 downto 0);
  signal statusReceivedCurrent, statusReceivedNext : std_logic;
  signal numberSentLinkRequestsCurrent, numberSentLinkRequestsNext : std_logic_vector(1 downto 0);
  signal outputErrorStoppedCurrent, outputErrorStoppedNext : std_logic;
  signal fatalErrorCurrent, fatalErrorNext : std_logic;
  signal recoverActiveCurrent, recoverActiveNext : std_logic;
  signal recoverCounterCurrent, recoverCounterNext : std_logic_vector(4 downto 0);
  signal ackIdWindowCurrent, ackIdWindowNext : std_logic_vector(4 downto 0);
  signal frameStateCurrent, frameStateNext : std_logic_vector(6 downto 0);
  signal frameWordCounterCurrent, frameWordCounterNext : std_logic_vector(1 downto 0);
  signal frameContentCurrent, frameContentNext : std_logic_vector(32*NUMBER_WORDS-1 downto 0);
  signal counterCurrent, counterNext : std_logic_vector(3 downto 0);
  signal symbolsTransmittedCurrent, symbolsTransmittedNext : std_logic_vector(7 downto 0);
 
begin
 
  process(areset_n, clk)
  begin
    if (areset_n = '0') then
      timeCurrent <= (others=>'0');
    elsif (clk'event and clk = '1') then
      timeCurrent <= std_logic_vector(unsigned(timeCurrent) + 1);
    end if;
  end process;
 
  timeSentElapsed <= unsigned(timeCurrent) - unsigned(timeSentReadData);
  timeSentDelta <= unsigned('0' & portLinkTimeout_i) - timeSentElapsed;
  timeSentExpired <= timeSentDelta(TIMEOUT_WIDTH);
 
  timeSentEnable <= (not txFull_i) and (timeSentSet or timeSentReset);
  timeSentWriteAddress <= ackIdWindowCurrent when timeSentSet = '1' else
                          ackIdCurrent;
  timeSentReadAddress <= ackIdCurrent;
 
  TimeoutMemory: MemorySimpleDualPortAsync
    generic map(ADDRESS_WIDTH=>5, DATA_WIDTH=>TIMEOUT_WIDTH+1, INIT_VALUE=>'0')
    port map(
      clkA_i=>clk, enableA_i=>timeSentEnable,
      addressA_i=>timeSentWriteAddress, dataA_i=>timeCurrent,
      addressB_i=>timeSentReadAddress, dataB_o=>timeSentReadData);
 
  process(areset_n, clk)
  begin
    if (areset_n = '0') then
      operationalCurrent <= '0';
      ackIdCurrent <= (others=>'0');
      bufferStatusCurrent <= (others=>'0');
      statusReceivedCurrent <= '0';
      numberSentLinkRequestsCurrent <= (others=>'0');
      outputErrorStoppedCurrent <= '0';
      fatalErrorCurrent <= '0';
      recoverActiveCurrent <= '0';
      recoverCounterCurrent <= (others=>'0');
      ackIdWindowCurrent <= (others=>'0');
      frameStateCurrent <= (others=>'0');
      frameWordCounterCurrent <= (others=>'0');
      frameContentCurrent <= (others=>'0');
      counterCurrent <= (others=>'0');
      symbolsTransmittedCurrent <= (others=>'0');
    elsif (clk'event and clk = '1') then
      if (txFull_i = '0') then
        operationalCurrent <= operationalNext;
        ackIdCurrent <= ackIdNext;
        bufferStatusCurrent <= bufferStatusNext;
        statusReceivedCurrent <= statusReceivedNext;
        numberSentLinkRequestsCurrent <= numberSentLinkRequestsNext;
        outputErrorStoppedCurrent <= outputErrorStoppedNext;
        fatalErrorCurrent <= fatalErrorNext;
        recoverActiveCurrent <= recoverActiveNext;
        recoverCounterCurrent <= recoverCounterNext;
        ackIdWindowCurrent <= ackIdWindowNext;
        frameStateCurrent <= frameStateNext;
        frameWordCounterCurrent <= frameWordCounterNext;
        frameContentCurrent <= frameContentNext;
        counterCurrent <= counterNext;
        symbolsTransmittedCurrent <= symbolsTransmittedNext;
      end if;
    end if;
  end process;
 
  TxCore: RioTransmitterCore
    generic map(NUMBER_WORDS=>NUMBER_WORDS)
    port map(
      clk=>clk, areset_n=>areset_n,
      portEnable_i=>portEnable_i,
      portInitialized_i=>portInitialized_i,
      txFull_i=>txFull_i, txWrite_o=>txWrite_o, txType_o=>txType_o, txData_o=>txData_o,
      txControlEmpty_i=>txControlEmpty_i,
      txControlSymbol_i=>txControlSymbol_i,
      txControlUpdate_o=>txControlUpdate_o,
      rxControlEmpty_i=>rxControlEmpty_i,
      rxControlSymbol_i=>rxControlSymbol_i,
      rxControlUpdate_o=>rxControlUpdate_o,
      linkInitialized_o=>linkInitialized_o,
      linkInitialized_i=>linkInitialized_i,
      ackIdStatus_i=>ackIdStatus_i,
 
      timeSentSet_o=>timeSentSet,
      timeSentReset_o=>timeSentReset,
      timeSentExpired_i=>timeSentExpired,
 
      operational_i=>operationalCurrent, operational_o=>operationalNext,
      ackId_i=>ackIdCurrent, ackId_o=>ackIdNext,
      bufferStatus_i=>bufferStatusCurrent, bufferStatus_o=>bufferStatusNext,
      statusReceived_i=>statusReceivedCurrent, statusReceived_o=>statusReceivedNext,
      numberSentLinkRequests_i=>numberSentLinkRequestsCurrent, numberSentLinkRequests_o=>numberSentLinkRequestsNext,
      outputErrorStopped_i=>outputErrorStoppedCurrent, outputErrorStopped_o=>outputErrorStoppedNext,
      fatalError_i=>fatalErrorCurrent, fatalError_o=>fatalErrorNext,
      recoverActive_i=>recoverActiveCurrent, recoverActive_o=>recoverActiveNext,
      recoverCounter_i=>recoverCounterCurrent, recoverCounter_o=>recoverCounterNext,
      ackIdWindow_i=>ackIdWindowCurrent, ackIdWindow_o=>ackIdWindowNext,
      frameState_i=>frameStateCurrent, frameState_o=>frameStateNext,
      frameWordCounter_i=>frameWordCounterCurrent, frameWordCounter_o=>frameWordCounterNext,
      frameContent_i=>frameContentCurrent, frameContent_o=>frameContentNext,
      counter_i=>counterCurrent, counter_o=>counterNext,
      symbolsTransmitted_i=>symbolsTransmittedCurrent, symbolsTransmitted_o=>symbolsTransmittedNext,
 
      readFrameEmpty_i=>readFrameEmpty_i,
      readFrame_o=>readFrame_o,
      readFrameRestart_o=>readFrameRestart_o,
      readFrameAborted_i=>readFrameAborted_i,
      readWindowEmpty_i=>readWindowEmpty_i,
      readWindowReset_o=>readWindowReset_o,
      readWindowNext_o=>readWindowNext_o,
      readContentEmpty_i=>readContentEmpty_i,
      readContent_o=>readContent_o,
      readContentEnd_i=>readContentEnd_i,
      readContentWords_i=>readContentWords_i,
      readContentData_i=>readContentData_i);
 
end architecture;
 
 
 
-------------------------------------------------------------------------------
-- RioTransmitterCore
-------------------------------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use work.rio_common.all;
 
-------------------------------------------------------------------------------
-- Entity for RioTransmitterCore.
-------------------------------------------------------------------------------
entity RioTransmitterCore is
  generic(
    NUMBER_WORDS : natural range 1 to 4 := 1);
  port(
    -- System signals.
    clk : in std_logic;
    areset_n : in std_logic;
 
    -- Status signals used for maintenance.
    portEnable_i : in std_logic;
 
    -- Port output interface.
    portInitialized_i : in std_logic;
    txFull_i : in std_logic;
    txWrite_o : out std_logic;
    txType_o : out std_logic_vector(2*NUMBER_WORDS-1 downto 0);
    txData_o : out std_logic_vector(32*NUMBER_WORDS-1 downto 0);
 
    -- Control symbols aimed to the transmitter.
    txControlEmpty_i : in std_logic;
    txControlSymbol_i : in std_logic_vector(13*NUMBER_WORDS-1 downto 0);
    txControlUpdate_o : out std_logic;
 
    -- Control symbols from the receiver to send.
    rxControlEmpty_i : in std_logic;
    rxControlSymbol_i : in std_logic_vector(13*NUMBER_WORDS-1 downto 0);
    rxControlUpdate_o : out std_logic;
 
    -- Internal signalling from the receiver part.
    linkInitialized_o : out std_logic;
    linkInitialized_i : in std_logic;
    ackIdStatus_i : in std_logic_vector(4 downto 0);
 
    -- Internal core variables for cascading.
    timeSentSet_o : out std_logic;
    timeSentReset_o : out std_logic;
    timeSentExpired_i : in std_logic;
 
    operational_i : in std_logic;
    operational_o : out std_logic;
    ackId_i : in std_logic_vector(4 downto 0);
    ackId_o : out std_logic_vector(4 downto 0);
    bufferStatus_i : in std_logic_vector(4 downto 0);
    bufferStatus_o : out std_logic_vector(4 downto 0);
    statusReceived_i : in std_logic;
    statusReceived_o : out std_logic;
    numberSentLinkRequests_i : in std_logic_vector(1 downto 0);
    numberSentLinkRequests_o : out std_logic_vector(1 downto 0);
    outputErrorStopped_i : in std_logic;
    outputErrorStopped_o : out std_logic;
    fatalError_i : in std_logic;
    fatalError_o : out std_logic;
    recoverActive_i : in std_logic;
    recoverActive_o : out std_logic;
    recoverCounter_i : in std_logic_vector(4 downto 0);
    recoverCounter_o : out std_logic_vector(4 downto 0);
    ackIdWindow_i : in std_logic_vector(4 downto 0);
    ackIdWindow_o : out std_logic_vector(4 downto 0);
    frameState_i : in std_logic_vector(6 downto 0);
    frameState_o : out std_logic_vector(6 downto 0);
    frameWordCounter_i : in std_logic_vector(1 downto 0);
    frameWordCounter_o : out std_logic_vector(1 downto 0);
    frameContent_i : in std_logic_vector(32*NUMBER_WORDS-1 downto 0);
    frameContent_o : out std_logic_vector(32*NUMBER_WORDS-1 downto 0);
    counter_i : in std_logic_vector(3 downto 0);
    counter_o : out std_logic_vector(3 downto 0);
    symbolsTransmitted_i : in std_logic_vector(7 downto 0);
    symbolsTransmitted_o : out std_logic_vector(7 downto 0);
 
    -- Frame buffer interface.
    readFrameEmpty_i : in std_logic;
    readFrame_o : out std_logic;
    readFrameRestart_o : out std_logic;
    readFrameAborted_i : in std_logic;
    readWindowEmpty_i : in std_logic;
    readWindowReset_o : out std_logic;
    readWindowNext_o : out std_logic;
    readContentEmpty_i : in std_logic;
    readContent_o : out std_logic;
    readContentEnd_i : in std_logic;
    readContentWords_i : in std_logic_vector(1 downto 0);
    readContentData_i : in std_logic_vector(32*NUMBER_WORDS-1 downto 0));
end entity;
 
 
-------------------------------------------------------------------------------
-- Architecture for RioTransmitterCore.
-------------------------------------------------------------------------------
-- REMARK: Check that all _o except channel variables are registered...
architecture RioTransmitterCoreImpl of RioTransmitterCore is
 
  constant NUMBER_STATUS_TRANSMIT : std_logic_vector := "1111";
  constant NUMBER_LINK_RESPONSE_RETRIES : std_logic_vector := "10";
 
  -- REMARK: Binary coding???
  constant FRAME_IDLE : std_logic_vector(6 downto 0) := "0000001";
  constant FRAME_START : std_logic_vector(6 downto 0) := "0000010";
  constant FRAME_FIRST : std_logic_vector(6 downto 0) := "0000100";
  constant FRAME_MIDDLE : std_logic_vector(6 downto 0) := "0001000";
  constant FRAME_LAST : std_logic_vector(6 downto 0) := "0010000";
  constant FRAME_END : std_logic_vector(6 downto 0) := "0100000";
  constant FRAME_DISCARD : std_logic_vector(6 downto 0) := "1000000";
 
  component Crc5ITU is
    port(
      d_i : in  std_logic_vector(18 downto 0);
      crc_o : out std_logic_vector(4 downto 0));
  end component;
 
  signal txControlUpdateOut : std_logic;
  signal sendRestartFromRetry, sendRestartFromRetryOut : std_logic;
  signal sendLinkRequest, sendLinkRequestOut : std_logic;
 
  signal readFrameOut : std_logic;
  signal readFrameRestartOut : std_logic;
  signal readWindowResetOut : std_logic;
  signal readWindowNextOut : std_logic;
  signal readContentOut : std_logic;
  signal symbolControlRestartOut, symbolControlRestart : std_logic;
  signal symbolControlLinkRequestOut, symbolControlLinkRequest : std_logic;
  signal symbolControlStartOut, symbolControlStart : std_logic;
  signal symbolControlEndOut, symbolControlEnd : std_logic;
  signal symbolDataOut, symbolData : std_logic;
  signal symbolDataContentOut, symbolDataContent : std_logic_vector(31 downto 0);
 
  signal rxControlUpdateOut : std_logic;
  signal symbolControlStype1 : std_logic;
  signal controlValidOut, controlValid : std_logic;
  signal stype0Out, stype0 : std_logic_vector(2 downto 0);
  signal parameter0Out, parameter0 : std_logic_vector(4 downto 0);
  signal parameter1Out, parameter1 : std_logic_vector(4 downto 0);
  signal stype1 : std_logic_vector(2 downto 0);
  signal cmd : std_logic_vector(2 downto 0);
  signal dataValid : std_logic;
  signal dataContent : std_logic_vector(31 downto 0);
 
  signal controlContent : std_logic_vector(31 downto 0);
  signal crc5 : std_logic_vector(4 downto 0);
 
  signal txControlStype0 : std_logic_vector(2 downto 0);
  signal txControlParameter0 : std_logic_vector(4 downto 0);
  signal txControlParameter1 : std_logic_vector(4 downto 0);
 
  signal rxControlStype0 : std_logic_vector(2 downto 0);
  signal rxControlParameter0 : std_logic_vector(4 downto 0);
  signal rxControlParameter1 : std_logic_vector(4 downto 0);
 
begin
 
  linkInitialized_o <= operational_i;
 
  -----------------------------------------------------------------------------
  -- Assign control symbol from fifo signals.
  -----------------------------------------------------------------------------
 
  txControlStype0 <= txControlSymbol_i(12 downto 10);
  txControlParameter0 <= txControlSymbol_i(9 downto 5);
  txControlParameter1 <= txControlSymbol_i(4 downto 0);
 
  rxControlStype0 <= rxControlSymbol_i(12 downto 10);
  rxControlParameter0 <= rxControlSymbol_i(9 downto 5);
  rxControlParameter1 <= rxControlSymbol_i(4 downto 0);
 
  -----------------------------------------------------------------------------
  -- N-3
  -- Receive stuff from link-partner and timeout supervision.
  -- Input: ackId, ackIdWindow, timeoutExpired
  -- Output: sendLinkRequest, sendRestartFromRetry, ackId,
  -----------------------------------------------------------------------------
 
  process(clk, areset_n)
  begin
    if (areset_n = '0') then
      txControlUpdate_o <= '0';
      readFrame_o <= '0';
 
      sendRestartFromRetry <= '0';
      sendLinkRequest <= '0';
    elsif (clk'event and clk = '1') then
      txControlUpdate_o <= '0';
      readFrame_o <= '0';
 
      if (txFull_i = '0') then
        txControlUpdate_o <= txControlUpdateOut;
        readFrame_o <= readFrameOut;
 
        sendRestartFromRetry <= sendRestartFromRetryOut;
        sendLinkRequest <= sendLinkRequestOut;
      end if;
    end if;
  end process;
 
  process(outputErrorStopped_i, recoverActive_i, recoverCounter_i,
          ackId_i, ackIdWindow_i, bufferStatus_i, statusReceived_i,
          numberSentLinkRequests_i,
          operational_i,
          txControlEmpty_i, txControlStype0,
          txControlParameter0, txControlParameter1,
          timeSentExpired_i,
          fatalError_i)
  begin
    outputErrorStopped_o <= outputErrorStopped_i;
    fatalError_o <= fatalError_i;
    recoverActive_o <= recoverActive_i;
    recoverCounter_o <= recoverCounter_i;
    ackId_o <= ackId_i;
    bufferStatus_o <= bufferStatus_i;
    statusReceived_o <= statusReceived_i;
    numberSentLinkRequests_o <= numberSentLinkRequests_i;
 
    timeSentReset_o <= '0';
    txControlUpdateOut <= '0';
    readFrameOut <= '0';
 
    sendRestartFromRetryOut <= '0';
    sendLinkRequestOut <= '0';
 
    if (fatalError_i = '1') then
      outputErrorStopped_o <= '0';
      fatalError_o <= '0';
    elsif (recoverActive_i = '1') then
      if (ackId_i = recoverCounter_i) then
        recoverActive_o <= '0';
        outputErrorStopped_o <= '0';
      else
        ackId_o <= std_logic_vector(unsigned(ackId_i) + 1);
        readFrameOut <= '1';
      end if;
    else
      if (operational_i = '0') then
        if (txControlEmpty_i = '0') then
          if (txControlStype0 = STYPE0_STATUS) then
            -- A status-control symbol has been received.
            ackId_o <= txControlParameter0;
            bufferStatus_o <= txControlParameter1;
            statusReceived_o <= '1';
          else
            -- Discard all other received symbols in this state.
          end if;
          txControlUpdateOut <= '1';
        end if;
      else
        -- Operational mode.
 
        -- Make sure to reset the status received flag.
        statusReceived_o <= '0';
 
        -- Check if the oldest frame timeout has expired.
        -- REMARK: Two link-requests are transmitted when a timeout occurrs...
        if ((ackId_i /= ackIdWindow_i) and
            (timeSentExpired_i = '1')) then
          -- There has been a timeout on a transmitted frame.
 
          -- Reset the timeout to expire when the transmitted link-request has
          -- timed out instead.
          timeSentReset_o <= '1';
 
          if (outputErrorStopped_i = '1') then
            -- Count the number of retransmissions and abort if
            -- no reply has been received for too many times.
            if (unsigned(numberSentLinkRequests_i) /= 0) then
              -- Not sent link-request too many times.
 
              -- Send another link-request.
              sendLinkRequestOut <= '1';
              numberSentLinkRequests_o <= std_logic_vector(unsigned(numberSentLinkRequests_i) - 1);
            else
              -- No response for too many times.
 
              -- Indicate that a fatal error has occurred.
              fatalError_o <= '1';
            end if;
          else
            sendLinkRequestOut <= '1';
            numberSentLinkRequests_o <= NUMBER_LINK_RESPONSE_RETRIES;
            outputErrorStopped_o <= '1';
          end if;
        else
          -- There has been no timeout.
 
          -- Check if any control symbol has been received from the link
          -- partner.
          if (txControlEmpty_i = '0') then
            -- A control symbol has been received.
 
            -- Check the received control symbol.
            case txControlStype0 is
 
              when STYPE0_STATUS =>
                if (outputErrorStopped_i = '0') then
                  -- Save the number of buffers in the link partner.
                  bufferStatus_o <= txControlParameter1;
                end if;
 
              when STYPE0_PACKET_ACCEPTED =>
                -- The link partner is accepting a frame.
 
                if (outputErrorStopped_i = '0') then
                  -- Save the number of buffers in the link partner.
                  bufferStatus_o <= txControlParameter1;
 
                  -- Check if expecting this type of reply and that the ackId is
                  -- expected.
                  if ((ackId_i /= ackIdWindow_i) and
                      (ackId_i = txControlParameter0)) then
                    -- The packet-accepted is expected and the ackId is the expected.
                    -- The frame has been accepted by the link partner.
 
                    -- Update to a new buffer and increment the ackId.
                    readFrameOut <= '1';
                    ackId_o <= std_logic_vector(unsigned(ackId_i) + 1);
                  else
                    -- Unexpected packet-accepted or packet-accepted for
                    -- unexpected ackId.
                    sendLinkRequestOut <= '1';
                    numberSentLinkRequests_o <= NUMBER_LINK_RESPONSE_RETRIES;
                    outputErrorStopped_o <= '1';
                  end if;
                end if;
 
              when STYPE0_PACKET_RETRY =>
                -- The link partner has asked for a frame retransmission.
 
                if (outputErrorStopped_i = '0') then
                  -- Save the number of buffers in the link partner.
                  bufferStatus_o <= txControlParameter1;
 
                  -- Check if the ackId is the one expected.
                  if (ackId_i = txControlParameter0) then
                    -- The ackId to retry is expected.
                    -- Go to the output-retry-stopped state.
                    -- REMARK: The output-retry-stopped state is equivalent
                    -- to sending a restart-from-retry.
                    sendRestartFromRetryOut <= '1';
                  else
                    -- Unexpected ackId to retry.
                    sendLinkRequestOut <= '1';
                    numberSentLinkRequests_o <= NUMBER_LINK_RESPONSE_RETRIES;
                    outputErrorStopped_o <= '1';
                  end if;
                end if;
 
              when STYPE0_PACKET_NOT_ACCEPTED =>
                if (outputErrorStopped_i = '0') then
                  -- Packet was rejected by the link-partner.
                  sendLinkRequestOut <= '1';
                  numberSentLinkRequests_o <= NUMBER_LINK_RESPONSE_RETRIES;
                  outputErrorStopped_o <= '1';
                end if;
 
              when STYPE0_LINK_RESPONSE =>
                if (outputErrorStopped_i = '1') then
                  -- Check if the link partner return value is acceptable.
                  if ((unsigned(txControlParameter0) - unsigned(ackId_i)) <=
                      (unsigned(ackIdWindow_i) - unsigned(ackId_i))) then
                    -- Recoverable error.
                    -- Use the received ackId and recover by removing packets
                    -- that has been received by the link-partner.
                    recoverCounter_o <= txControlParameter0;
                    recoverActive_o <= '1';
                  else
                    -- Totally out of sync.
 
                    -- Indicate that a fatal error has occurred.
                    fatalError_o <= '1';
 
                    -- REMARK: What to do here???
                    --readWindowReset_o <= '1';
                    --stateNext <= STATE_UNINITIALIZED;
                  end if;
                else
                  -- Dont expect or need a link-response in this state.
                  -- Discard it.
                end if;
 
              when STYPE0_VC_STATUS =>
                -- Not supported.
                -- Discard it.
 
              when STYPE0_RESERVED =>
                -- Not supported.
                -- Discard it.
 
              when STYPE0_IMPLEMENTATION_DEFINED =>
                -- Not supported.
                -- Discard it.
 
              when others =>
                null;
            end case;
 
            -- Indicate the control symbol has been processed.
            txControlUpdateOut <= '1';
          end if;
        end if;
      end if;
    end if;
  end process;
 
  -----------------------------------------------------------------------------
  -- N-2 pipeline stage.
  -- Create stype1-part of symbols and data symbols. Save the time when a
  -- packet was fully sent.
  -- Input:  sendRestartFromRetry, sendLinkRequest
  -- Output: ackIdWindow, frameState, timeout(0 to 31), 
  --         symbolControlStart, symbolControlEnd, symbolControlRestart,
  --         symbolControlLinkRequest, symbolData2, symbolData2Content.
  -----------------------------------------------------------------------------
 
  process(clk, areset_n)
  begin
    if (areset_n = '0') then
      readFrameRestart_o <= '0';
      readWindowReset_o <= '0';
      readWindowNext_o <= '0';
      readContent_o <= '0';
 
      symbolControlRestart <= '0';
      symbolControlLinkRequest <= '0';
      symbolControlStart <= '0';
      symbolControlEnd <= '0';
      symbolData <= '0';
      symbolDataContent <= (others => '0');
    elsif (clk'event and clk = '1') then
      readFrameRestart_o <= '0';
      readWindowReset_o <= '0';
      readWindowNext_o <= '0';
      readContent_o <= '0';
 
      if (txFull_i = '0') then
        readFrameRestart_o <= readFrameRestartOut;
        readWindowReset_o <= readWindowResetOut;
        readWindowNext_o <= readWindowNextOut;
        readContent_o <= readContentOut;
 
        symbolControlRestart <= symbolControlRestartOut;
        symbolControlLinkRequest <= symbolControlLinkRequestOut;
        symbolControlStart <= symbolControlStartOut;
        symbolControlEnd <= symbolControlEndOut;
        symbolData <= symbolDataOut;
        symbolDataContent <= symbolDataContentOut;
      end if;
    end if;
  end process;
 
  -- This process decide which stype1-part of a control symbols to send as well
  -- as all data symbols.
  process(readWindowEmpty_i, bufferStatus_i,
          recoverActive_i, recoverCounter_i, ackId_i, operational_i, outputErrorStopped_i, portEnable_i, readContentData_i, readContentWords_i, readContentEnd_i,
          frameState_i, frameWordCounter_i, frameContent_i,
          ackIdWindow_i,
          sendRestartFromRetry, sendLinkRequest,
          fatalError_i)
  begin
    readFrameRestartOut <= '0';
    readWindowResetOut <= '0';
    readWindowNextOut <= '0';
    readContentOut <= '0';
 
    frameState_o <= frameState_i;
    frameWordCounter_o <= frameWordCounter_i;
    frameContent_o <= frameContent_i;
    ackIdWindow_o <= ackIdWindow_i;
 
    timeSentSet_o <= '0';
 
    symbolControlRestartOut <= '0';
    symbolControlLinkRequestOut <= '0';
    symbolControlStartOut <= '0';
    symbolControlEndOut <= '0';
    symbolDataOut <= '0';
    symbolDataContentOut <= (others => '0');
 
    if (fatalError_i = '1') then
      readWindowResetOut <= '1';
    elsif (recoverActive_i = '1') then
      -- REMARK: Make sure idle is generated when this state is active...
      ackIdWindow_o <= ackId_i;
      frameState_o <= FRAME_IDLE;
      readWindowResetOut <= '1';
    else
      if (operational_i = '0') then
        -----------------------------------------------------------------------
        -- This state is entered at startup. A port that is not initialized
        -- should only transmit idle sequences.
        -----------------------------------------------------------------------
 
        -- Initialize framing before entering the operational state.
        -- REMARK: Only do this when the portInitialized becomes asserted???
        frameState_o <= FRAME_IDLE;
        ackIdWindow_o <= ackId_i;
        readWindowResetOut <= '1';
      else
        -------------------------------------------------------------------
        -- This state is the operational state. It relays frames and handle
        -- flow control.
        -------------------------------------------------------------------
 
        if (sendRestartFromRetry = '1') then
          -- Send a restart-from-retry control symbol to acknowledge the restart
          -- of the frame.
          symbolControlRestartOut <= '1';
 
          -- Make sure there wont be any timeout before the frame is
          -- starting to be retransmitted.
          timeSentSet_o <= '1';
 
          -- Restart the frame transmission.
          ackIdWindow_o <= ackId_i;
          frameState_o <= FRAME_IDLE;
          readWindowResetOut <= '1';
        end if;
 
        if (sendLinkRequest = '1') then
          -- Dont restart the packet transmission since we do not yet know which
          -- packets that was successfully received by our link partner.
 
          -- Send a link-request symbol.
          symbolControlLinkRequestOut <= '1';
 
          -- Write the current timer value.
          timeSentSet_o <= '1';
        end if;
 
        if ((sendRestartFromRetry = '0') and (sendLinkRequest = '0')  and
            (outputErrorStopped_i = '0')) then
          -- Check if a frame transfer is in progress.
          -- REMARK: Hold any data symbol if there is a pending symbol from the
          -- receiver side...
 
          case frameState_i is
 
            when FRAME_IDLE =>
              ---------------------------------------------------------------
              -- No frame has been started.
              ---------------------------------------------------------------
 
              -- Wait for a new frame to arrive from the frame buffer.
              if (readWindowEmpty_i = '0') then
                -- Update the output from the frame buffer to contain the
                -- data when it is read later.
                readContentOut <= '1';
 
                -- Indicate that a control symbol has been sent to start the
                -- transmission of the frame.
                frameState_o <= FRAME_START;
              end if;
 
            when FRAME_START =>
              -------------------------------------------------------
              -- Check if we are allowed to transmit this packet.
              -------------------------------------------------------
              -- The packet may be either not allowed, i.e. a non-maintenance
              -- sent when only maintenance is allowed. The link-partner can be
              -- busy, i.e. no having enough buffers to receive the new packet
              -- in or the number of outstanding packets may be too large.
              -- REMARK: Only update readContent_o in the last instance
              -- if cascaded...
 
              -- Check if the packet is allowed.
              if ((portEnable_i = '1') or
                  (readContentData_i(19 downto 16) = FTYPE_MAINTENANCE_CLASS)) then
                -- Packet is allowed.
 
                -- Check if the link is able to accept the new frame.
                if ((bufferStatus_i /= "00000") and
                    ((unsigned(ackIdWindow_i) - unsigned(ackId_i)) /= 31)) then
                  -- New data is available for transmission and there
                  -- is room to receive it at the other side.
                  -- The packet may be transmitted.
 
                  -- Indicate that a control symbol has been sent to start the
                  -- transmission of the frame.
                  frameWordCounter_o <= readContentWords_i;
                  frameContent_o <= readContentData_i;
                  readContentOut <= '1';
 
                  -- Send a control symbol to start the packet and a status to
                  -- complete the symbol.
                  symbolControlStartOut <= '1';
 
                  -- Proceed to send the first packet data symbol containing
                  -- the ackId.
                  frameState_o <= FRAME_FIRST;
                else
                  -- The link cannot accept the packet.
                  -- Wait in this state and dont do anything.
                end if;
              else
                -- The packet is not allowed.
                -- Discard it.
                frameState_o <= FRAME_DISCARD;
              end if;
 
            when FRAME_FIRST =>
              ---------------------------------------------------------------
              -- Send the first packet content containing our current
              -- ackId.
              ---------------------------------------------------------------
 
              -- Write a new data symbol and fill in our ackId on the
              -- packet.
              symbolDataOut <= '1';
              symbolDataContentOut <=
                std_logic_vector(ackIdWindow_i) & "0" &
                frameContent_i((32*NUMBER_WORDS)-7 downto (32*(NUMBER_WORDS-1)));
 
              -- REMARK: Code frameWordCounter as 0=1 or 1=1???
              if (unsigned(frameWordCounter_i) /= 0) then
                frameWordCounter_o <=
                  std_logic_vector(unsigned(frameWordCounter_i) - 1);
                frameContent_o <=
                  frameContent_i((32*(NUMBER_WORDS-1))-1 downto 0) & x"00000000";
              else
                frameWordCounter_o <= readContentWords_i;
                frameContent_o <= readContentData_i;
                readContentOut <= '1';
              end if;
 
              -- Continue to send the rest of the body of the packet.
              frameState_o <= FRAME_MIDDLE;
 
            when FRAME_MIDDLE =>
              ---------------------------------------------------------------
              -- The frame has not been fully sent.
              -- Send a data symbol until the last part of the packet is
              -- detected.
              ---------------------------------------------------------------
              -- REMARK: Dont send anything if there is a pending symbol in the
              -- rx-control fifo to let it be transmitted in the middle of the
              -- packet...
 
              -- Write a new data symbol.
              symbolDataOut <= '1';
              symbolDataContentOut <=
                frameContent_i((32*NUMBER_WORDS)-1 downto (32*(NUMBER_WORDS-1)));
 
              if (unsigned(frameWordCounter_i) /= 0) then
                frameWordCounter_o <=
                  std_logic_vector(unsigned(frameWordCounter_i) - 1);
                frameContent_o <=
                  frameContent_i((32*(NUMBER_WORDS-1))-1 downto 0) & x"00000000";
              else
                frameWordCounter_o <= readContentWords_i;
                frameContent_o <= readContentData_i;
 
                -- Check if the frame is ending.
                -- REMARK: Dont forget to update RioPacketBuffer to support this...
                if (readContentEnd_i = '1') then
                  -- The frame is ending.
 
                  -- Update the window to the next frame.
                  -- It takes one tick for the output from the frame
                  -- buffer to get updated.
                  readWindowNextOut <= '1';
 
                  -- Proceed to check if there is another frame to start
                  -- with directly.
                  frameState_o <= FRAME_LAST;
                else
                  readContentOut <= '1';
                end if;
              end if;
 
            when FRAME_LAST =>
              ---------------------------------------------------------------
              -- A frame has ended and the window has been updated.
              -- Check if the next symbol should end the frame or if a
              -- new one should be started.
              ---------------------------------------------------------------
 
              -- Write a new data symbol.
              symbolDataOut <= '1';
              symbolDataContentOut <=
                frameContent_i((32*NUMBER_WORDS)-1 downto (32*(NUMBER_WORDS-1)));
 
              if (unsigned(frameWordCounter_i) /= 0) then
                frameWordCounter_o <=
                  std_logic_vector(unsigned(frameWordCounter_i) - 1);
                frameContent_o <=
                  frameContent_i((32*(NUMBER_WORDS-1))-1 downto 0) & x"00000000";
              else
                -- Update the window ackId.
                ackIdWindow_o <= std_logic_vector(unsigned(ackIdWindow_i) + 1);
 
                -- Start timeout supervision for transmitted frame.
                timeSentSet_o <= '1';
 
                -- Note that the packet must be ended if the link-partner
                -- cannot receive it.
                if ((readWindowEmpty_i = '0') and
                    (bufferStatus_i /= "00000") and
                    ((unsigned(ackIdWindow_i) - unsigned(ackId_i)) /= 31)) then
                  readContentOut <= '1';
                  frameState_o <= FRAME_START;
                else
                  frameState_o <= FRAME_END;
                end if;
              end if;
 
            when FRAME_END =>
              -----------------------------------------------------------------
              -- 
              -----------------------------------------------------------------
 
              -- Start a new frame the next time.
              frameState_o <= FRAME_IDLE;
 
              -- Send a control symbol to end the packet.
              symbolControlEndOut <= '1';
 
            when FRAME_DISCARD =>
              ---------------------------------------------------------------
              -- 
              ---------------------------------------------------------------
              -- The packet should be discarded.
              -- Send idle-sequence.
 
              -- Check that there are no outstanding packets that
              -- has not been acknowledged.
              if(unsigned(ackIdWindow_i) = unsigned(ackId_i)) then
                -- No unacknowledged packets.
                -- It is now safe to remove the unallowed frame.
                -- REMARK: Discard packet; readFrameOut <= '1';
 
                -- Go back and send a new frame.
                frameState_o <= FRAME_IDLE;
              end if;
 
            when others =>
              ---------------------------------------------------------------
              -- 
              ---------------------------------------------------------------
              null;
 
          end case;
        end if;
      end if;
    end if;
  end process;
 
  -----------------------------------------------------------------------------
  -- N-1
  -- Create the stype0 and stype1 part of a control symbol.
  -- This process makes sure that the buffer status are transmitted at least
  -- every 255 symbol.
  -- At startup it makes sure that at least 16 status symbols are transmitted
  -- before the operational-state is entered.
  -- Input:  symbolControlStart, symbolControlEnd, symbolControlRestart,
  --         symbolControlLinkRequest, symbolData, symbolDataContent
  -- Output: symbolsTransmitted_o, operational_o, 
  --         symbolControl, stype0, parameter0, parameter1, stype1, cmd,
  --         symbolData1, symbolData1Content
  -----------------------------------------------------------------------------
 
  process(clk, areset_n)
  begin
    if (areset_n = '0') then
      rxControlUpdate_o <= '0';
 
      controlValid <= '0';
      stype0 <= (others=>'0');
      parameter0 <= (others=>'0');
      parameter1 <= (others=>'0');
      stype1 <= STYPE1_NOP;
      cmd <= (others=>'0');
      dataValid <= '0';
      dataContent <= (others=>'0');
    elsif (clk'event and clk = '1') then
      if (txFull_i = '0') then
        rxControlUpdate_o <= rxControlUpdateOut;
 
        controlValid <= controlValidOut;
        stype0 <= stype0Out;
        parameter0 <= parameter0Out;
        parameter1 <= parameter1Out;
        stype1 <= STYPE1_NOP;
        cmd <= "000";
        dataValid <= symbolData;
        dataContent <= symbolDataContent;
 
        if (symbolControlStart = '1') then
          stype1 <= STYPE1_START_OF_PACKET;
        end if;
        if (symbolControlEnd = '1') then
          stype1 <= STYPE1_END_OF_PACKET;
        end if;
        if (symbolControlRestart = '1') then
          stype1 <= STYPE1_RESTART_FROM_RETRY;
        end if;
        if (symbolControlLinkRequest = '1') then
          stype1 <= STYPE1_LINK_REQUEST;
          cmd <= LINK_REQUEST_CMD_INPUT_STATUS;
        end if;
      end if;
    end if;
  end process;
 
  symbolControlStype1 <=
    symbolControlRestart or symbolControlLinkRequest or
    symbolControlStart or symbolControlEnd;
 
  process(linkInitialized_i, ackIdStatus_i, portInitialized_i,
          operational_i, counter_i, statusReceived_i, symbolsTransmitted_i,
          rxControlEmpty_i,
          symbolControlStype1, symbolData,
          rxControlStype0, rxControlParameter0, rxControlParameter1,
          fatalError_i)
  begin
    operational_o <= operational_i;
    counter_o <= counter_i;
    symbolsTransmitted_o <= symbolsTransmitted_i;
    rxControlUpdateOut <= '0';
 
    controlValidOut <= '0';
    stype0Out <= STYPE0_STATUS;
    parameter0Out <= ackIdStatus_i;
    parameter1Out <= "11111";
 
    if (fatalError_i = '1') then
      operational_o <= '0';
      counter_o <= NUMBER_STATUS_TRANSMIT;
      symbolsTransmitted_o <= (others=>'0');
    else
      -- Check the operational state.
      if (operational_i = '0') then
        -----------------------------------------------------------------------
        -- This state is entered at startup. A port that is not initialized
        -- should only transmit idle sequences.
        -----------------------------------------------------------------------
 
        -- Check if the port is initialized.
        if (portInitialized_i = '1') then
          ---------------------------------------------------------------------
          -- The specification requires a status control symbol being sent at
          -- least every 1024 code word until an error-free status has been
          -- received. This implies that at most 256 idle sequences should be
          -- sent in between status control symbols. Once an error-free status 
          -- has been received, status symbols may be sent more rapidly. At
          -- least 15 statuses has to be transmitted once an error-free status
          -- has been received.
          ---------------------------------------------------------------------
 
          -- Check if we are ready to change state to operational.
          if ((linkInitialized_i = '1') and
              (unsigned(counter_i) = 0)) then
            -- Receiver has received enough error free status symbols and we
            -- have transmitted enough.
 
            -- Considder ourselfs operational.
            operational_o <= '1';
          else
            -- Not ready to change state to operational.
            -- Dont do anything.
          end if;
 
          -- Check if idle sequence or a status symbol should be transmitted.
          if (((statusReceived_i = '0') and (symbolsTransmitted_i = x"ff")) or
              ((statusReceived_i = '1') and (symbolsTransmitted_i > x"0f"))) then
            -- A status symbol should be transmitted.
 
            -- Send a status control symbol to the link partner.
            controlValidOut <= '1';
 
            -- Reset idle sequence transmission counter.
            symbolsTransmitted_o <= (others=>'0');
 
            -- Check if the number of transmitted statuses should be updated.
            if (statusReceived_i = '1') and (unsigned(counter_i) /= 0) then
              counter_o <= std_logic_vector(unsigned(counter_i) - 1);
            end if;
          else
            -- Increment the idle sequence transmission counter.
            symbolsTransmitted_o <= std_logic_vector(unsigned(symbolsTransmitted_i) + 1);
          end if;
        else
          -- The port is not initialized.
          -- Reset initialization variables.
          counter_o <= NUMBER_STATUS_TRANSMIT;
        end if;
      else
        ---------------------------------------------------------------------
        -- This is the operational state.
        -- It is entered once the link has been considdered up and running.
        ---------------------------------------------------------------------
 
        -- Check if the port is still initialized.
        if (portInitialized_i = '1') then
          -- The port is still initialized.
 
          -- Check if a status must be sent.
          -- A status must be sent when there are not other stype0 value to
          -- send or if too many symbols without buffer-status has been sent.
          -- REMARK: Is there a risk of a race when a generated status-symbol
          -- is sent before another symbol stored in the rx-control fifo???
          if (((symbolControlStype1 = '1') and (rxControlEmpty_i = '1')) or
              ((symbolControlStype1 = '0') and (symbolData = '0') and
               (symbolsTransmitted_i = x"ff"))) then
            -- A control symbol is about to be sent without pending symbol from
            -- receiver or too many idle symbols has been sent.
 
            -- Force the sending of a status containing the bufferStatus.
            controlValidOut <= '1';
            symbolsTransmitted_o <= (others=>'0');
          elsif ((symbolData = '0') and (rxControlEmpty_i = '0')) then
            -- A control symbol is about to be sent and there is a pending
            -- symbol from the receiver.
 
            -- Remove the symbol from the fifo.
            rxControlUpdateOut <= '1';
 
            -- Send the receiver symbol.
            controlValidOut <= '1';
            stype0Out <= rxControlStype0;
            parameter0Out <= rxControlParameter0;
            parameter1Out <= rxControlParameter1;
 
            -- Check if the transmitted symbol contains status about
            -- available buffers.
            if ((rxControlStype0 = STYPE0_PACKET_ACCEPTED) or
                (rxControlStype0 = STYPE0_PACKET_RETRY)) then
              -- A symbol containing the bufferStatus has been sent.
              symbolsTransmitted_o <= (others=>'0');
            else
              -- A symbol not containing the bufferStatus has been sent.
              symbolsTransmitted_o <= std_logic_vector(unsigned(symbolsTransmitted_i) + 1);
            end if;
          else
            -- A symbol not containing the bufferStatus has been sent.
            controlValidOut <= '0';
            symbolsTransmitted_o <= std_logic_vector(unsigned(symbolsTransmitted_i) + 1);
          end if;
        else
          -- The port is not initialized anymore.
          -- Change the operational state.
          operational_o <= '0';
        end if;
      end if;
    end if;
  end process;
 
  -----------------------------------------------------------------------------
  -- N pipeline stage.
  -- Make all symbols ready for transmission, i.e. calculate the CRC5 on
  -- control symbols.
  -- Inputs: controlValid, stype0, parameter0, parameter1, stype1, cmd,
  --         symbolData1, symbolData1Content 
  -----------------------------------------------------------------------------
 
  controlContent(31 downto 29) <= stype0;
  controlContent(28 downto 24) <= parameter0;
  controlContent(23 downto 19) <= parameter1;
  controlContent(18 downto 16) <= stype1;
  controlContent(15 downto 13) <= cmd;
  controlContent(12 downto 8) <= crc5;
  controlContent(7 downto 0) <= x"00";
 
  Crc5Calculator: Crc5ITU
    port map(
      d_i=>controlContent(31 downto 13), crc_o=>crc5);
 
  txWrite_o <= not txFull_i;
  process(clk, areset_n)
  begin
    if (areset_n = '0') then
      txType_o <= SYMBOL_IDLE;
      txData_o <= (others=>'0');
    elsif (clk'event and clk = '1') then
      if (txFull_i = '0') then
        txType_o <= SYMBOL_IDLE;
        if (controlValid = '1') then
          txType_o <= SYMBOL_CONTROL;
          txData_o <= controlContent;
        end if;
        if (dataValid = '1') then
          txType_o <= SYMBOL_DATA;
          txData_o <= dataContent;
        end if;
      end if;
    end if;
  end process;
 
end architecture;
 
 
 
-------------------------------------------------------------------------------
-- 
-------------------------------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use work.rio_common.all;
 
 
entity RioReceiver is
  generic(
    NUMBER_WORDS : natural range 1 to 4 := 1);
  port(
    clk : in std_logic;
    areset_n : in std_logic;
 
    portEnable_i : in std_logic;
 
    localAckIdWrite_i : in std_logic;
    inboundAckId_i : in std_logic_vector(4 downto 0);
    inboundAckId_o : out std_logic_vector(4 downto 0);
 
    portInitialized_i : in std_logic;
    rxEmpty_i : in std_logic;
    rxRead_o : out std_logic;
    rxType_i : in std_logic_vector(2*NUMBER_WORDS-1 downto 0);
    rxData_i : in std_logic_vector(32*NUMBER_WORDS-1 downto 0);
 
    txControlWrite_o : out std_logic_vector(NUMBER_WORDS-1 downto 0);
    txControlSymbol_o : out std_logic_vector(12*NUMBER_WORDS downto 0);
    rxControlWrite_o : out std_logic_vector(NUMBER_WORDS-1 downto 0);
    rxControlSymbol_o : out std_logic_vector(12*NUMBER_WORDS downto 0);
 
    ackIdStatus_o : out std_logic_vector(4 downto 0);
    linkInitialized_o : out std_logic;
 
    writeFrameFull_i : in std_logic;
    writeFrame_o : out std_logic;
    writeFrameAbort_o : out std_logic;
    writeContent_o : out std_logic;
    writeContentWords_o : out std_logic_vector(1 downto 0);
    writeContentData_o : out std_logic_vector(32*NUMBER_WORDS-1 downto 0));
end entity;
 
-------------------------------------------------------------------------------
-- 
-------------------------------------------------------------------------------
architecture RioReceiverImpl of RioReceiver is
 
  component RioReceiverCore is
    generic(
      NUMBER_WORDS : natural range 1 to 4 := 1);
    port(
      clk : in std_logic;
      areset_n : in std_logic;
 
      -- Status signals used for maintenance.
      portEnable_i : in std_logic;
 
      -- Support for localAckIdCSR.
      -- REMARK: Add support for this???
      localAckIdWrite_i : in std_logic;
      inboundAckId_i : in std_logic_vector(4 downto 0);
      inboundAckId_o : out std_logic_vector(4 downto 0);
 
      -- Port input interface.
      portInitialized_i : in std_logic;
      rxEmpty_i : in std_logic;
      rxRead_o : out std_logic;
      rxType_i : in std_logic_vector(1 downto 0);
      rxData_i : in std_logic_vector(31 downto 0);
 
      -- Receiver has received a control symbol containing:
      -- packet-accepted, packet-retry, packet-not-accepted, 
      -- status, VC_status, link-response
      txControlWrite_o : out std_logic;
      txControlSymbol_o : out std_logic_vector(12 downto 0);
 
      -- Reciever wants to signal the link partner:
      -- a new frame has been accepted => packet-accepted(rxAckId, bufferStatus)
      -- a frame needs to be retransmitted due to buffering =>
      -- packet-retry(rxAckId, bufferStatus)
      -- a frame is rejected due to errors => packet-not-accepted
      -- a link-request should be answered => link-response
      rxControlWrite_o : out std_logic;
      rxControlSymbol_o : out std_logic_vector(12 downto 0);
 
      -- Status signals used internally.
      ackIdStatus_o : out std_logic_vector(4 downto 0);
      linkInitialized_o : out std_logic;
 
      -- Core->Core cascading signals.
      enable_o : out std_logic;
      operational_i : in std_logic;
      operational_o : out std_logic;
      inputRetryStopped_i : in std_logic;
      inputRetryStopped_o : out std_logic;
      inputErrorStopped_i : in std_logic;
      inputErrorStopped_o : out std_logic;
      ackId_i : in unsigned(4 downto 0);
      ackId_o : out unsigned(4 downto 0);
      frameIndex_i : in std_logic_vector(6 downto 0);
      frameIndex_o : out std_logic_vector(6 downto 0);
      frameWordCounter_i : in std_logic_vector(1 downto 0);
      frameWordCounter_o : out std_logic_vector(1 downto 0);
      frameContent_i : in std_logic_vector(32*NUMBER_WORDS-1 downto 0);
      frameContent_o : out std_logic_vector(32*NUMBER_WORDS-1 downto 0);
      crc_i : in std_logic_vector(15 downto 0);
      crc_o : out std_logic_vector(15 downto 0);
 
      -- Frame buffering interface.
      writeFrameFull_i : in std_logic;
      writeFrame_o : out std_logic;
      writeFrameAbort_o : out std_logic;
      writeContent_o : out std_logic;
      writeContentWords_o : out std_logic_vector(1 downto 0);
      writeContentData_o : out std_logic_vector(32*NUMBER_WORDS-1 downto 0));
  end component;
 
  signal enable : std_logic_vector(NUMBER_WORDS-1 downto 0);
  signal operationalCurrent, operationalNext : std_logic_vector(NUMBER_WORDS-1 downto 0);
  signal inputRetryStoppedCurrent, inputRetryStoppedNext : std_logic_vector(NUMBER_WORDS-1 downto 0);
  signal inputErrorStoppedCurrent, inputErrorStoppedNext : std_logic_vector(NUMBER_WORDS-1 downto 0);
  signal ackIdCurrent, ackIdNext : unsigned(5*NUMBER_WORDS-1 downto 0);
  signal frameIndexCurrent, frameIndexNext : std_logic_vector(7*NUMBER_WORDS-1 downto 0);
  signal frameWordCounterCurrent, frameWordCounterNext : std_logic_vector(2*NUMBER_WORDS-1 downto 0);
  signal frameContentCurrent, frameContentNext : std_logic_vector(32*NUMBER_WORDS-1 downto 0);
  signal crcCurrent, crcNext : std_logic_vector(16*NUMBER_WORDS-1 downto 0);
 
  signal txControlWrite : std_logic_vector(NUMBER_WORDS-1 downto 0);
  signal rxControlWrite : std_logic_vector(NUMBER_WORDS-1 downto 0);
 
  signal writeFrame : std_logic_vector(NUMBER_WORDS-1 downto 0);
  signal writeFrameAbort : std_logic_vector(NUMBER_WORDS-1 downto 0);
  signal writeContent : std_logic_vector(NUMBER_WORDS-1 downto 0);
  signal writeContentWords : std_logic_vector(2*NUMBER_WORDS-1 downto 0);
  signal writeContentData : std_logic_vector(32*NUMBER_WORDS-1 downto 0);
 
begin
 
  -----------------------------------------------------------------------------
  -- Output generation to packet buffer.
  -----------------------------------------------------------------------------
  process(enable, writeFrame, writeFrameAbort,
          writeContent, writeContentWords, writeContentData)
  begin
    writeFrame_o <= '0';
    writeFrameAbort_o <= '0';
    writeContent_o <= '0';
    writeContentWords_o <= (others=>'0');
    writeContentData_o <= (others=>'0');
    for i in 0 to NUMBER_WORDS-1 loop
      if ((writeFrame(i) = '1') and (enable(i) = '1')) then
        writeFrame_o <= '1';
      end if;
 
      if ((writeFrameAbort(i) = '1') and (enable(i) = '1')) then
        writeFrameAbort_o <= '1';
      end if;
 
      if ((writeContent(i) = '1') and (enable(i) = '1')) then
        writeContent_o <= '1';
        writeContentWords_o <= writeContentWords(2*(i+1)-1 downto 2*i);
        writeContentData_o <= writeContentData(32*(i+1)-1 downto 32*i);
      end if;
    end loop;
  end process;
 
  -----------------------------------------------------------------------------
  -- Protocol core and synchronization.
  -----------------------------------------------------------------------------
  process(clk, areset_n)
  begin
    if (areset_n = '0') then
      operationalCurrent <= (others=>'0');
      inputRetryStoppedCurrent <= (others=>'0');
      inputErrorStoppedCurrent <= (others=>'0');
      ackIdCurrent <= (others=>'0');
      frameIndexCurrent <= (others => '0');
      frameWordCounterCurrent <= (others=>'0');
      frameContentCurrent <= (others=>'0');
      crcCurrent <= (others=>'0');
    elsif (clk'event and clk = '1') then
      if (enable(0) = '1') then
        operationalCurrent <= operationalNext;
        inputRetryStoppedCurrent <= inputRetryStoppedNext;
        inputErrorStoppedCurrent <= inputErrorStoppedNext;
        ackIdCurrent <= ackIdNext;
        frameIndexCurrent <= frameIndexNext;
        frameWordCounterCurrent <= frameWordCounterNext;
        frameContentCurrent <= frameContentNext;
        crcCurrent <= crcNext;
      end if;
    end if;
  end process;
 
  CoreGeneration: for i in 0 to NUMBER_WORDS-1 generate
    txControlWrite_o(i) <= txControlWrite(i) and enable(i);
    rxControlWrite_o(i) <= rxControlWrite(i);
 
    ReceiverCore: RioReceiverCore
      generic map(NUMBER_WORDS=>NUMBER_WORDS)
      port map(
        clk=>clk,
        areset_n=>areset_n,
        portEnable_i=>portEnable_i,
        localAckIdWrite_i=>localAckIdWrite_i,
        inboundAckId_i=>inboundAckId_i,
        inboundAckId_o=>inboundAckId_o,
        portInitialized_i=>portInitialized_i,
        rxEmpty_i=>rxEmpty_i,
        rxRead_o=>rxRead_o,
        rxType_i=>rxType_i,
        rxData_i=>rxData_i,
        txControlWrite_o=>txControlWrite(i),
        txControlSymbol_o=>txControlSymbol_o(13*(i+1)-1 downto 13*i),
        rxControlWrite_o=>rxControlWrite(i),
        rxControlSymbol_o=>rxControlSymbol_o(13*(i+1)-1 downto 13*i),
        ackIdStatus_o=>ackIdStatus_o,
        linkInitialized_o=>linkInitialized_o,
        enable_o=>enable(i),
        operational_i=>operationalCurrent(i),
        operational_o=>operationalNext(i),
        inputRetryStopped_i=>inputRetryStoppedCurrent(i),
        inputRetryStopped_o=>inputRetryStoppedNext(i),
        inputErrorStopped_i=>inputErrorStoppedCurrent(i),
        inputErrorStopped_o=>inputErrorStoppedNext(i),
        ackId_i=>ackIdCurrent(5*(i+1)-1 downto 5*i),
        ackId_o=>ackIdNext(5*(i+1)-1 downto 5*i),
        frameIndex_i=>frameIndexCurrent(7*(i+1)-1 downto 7*i),
        frameIndex_o=>frameIndexNext(7*(i+1)-1 downto 7*i),
        frameWordCounter_i=>frameWordCounterCurrent(2*(i+1)-1 downto 2*i),
        frameWordCounter_o=>frameWordCounterNext(2*(i+1)-1 downto 2*i),
        frameContent_i=>frameContentCurrent(32*(i+1)-1 downto 32*i),
        frameContent_o=>frameContentNext(32*(i+1)-1 downto 32*i),
        crc_i=>crcCurrent(16*(i+1)-1 downto 16*i),
        crc_o=>crcNext(16*(i+1)-1 downto 16*i),
        writeFrameFull_i=>writeFrameFull_i,
        writeFrame_o=>writeFrame(i),
        writeFrameAbort_o=>writeFrameAbort(i),
        writeContent_o=>writeContent(i),
        writeContentWords_o=>writeContentWords(2*(i+1)-1 downto 2*i),
        writeContentData_o=>writeContentData(32*(i+1)-1 downto 32*i));
  end generate;
 
end architecture;
 
-------------------------------------------------------------------------------
-- RioReceiverCore
-------------------------------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use work.rio_common.all;
 
 
-------------------------------------------------------------------------------
-- 
-------------------------------------------------------------------------------
entity RioReceiverCore is
  generic(
    NUMBER_WORDS : natural range 1 to 4 := 1);
  port(
    clk : in std_logic;
    areset_n : in std_logic;
 
    -- Status signals used for maintenance.
    portEnable_i : in std_logic;
 
    -- Support for localAckIdCSR.
    -- REMARK: Add support for this???
    localAckIdWrite_i : in std_logic;
    inboundAckId_i : in std_logic_vector(4 downto 0);
    inboundAckId_o : out std_logic_vector(4 downto 0);
 
    -- Port input interface.
    portInitialized_i : in std_logic;
    rxEmpty_i : in std_logic;
    rxRead_o : out std_logic;
    rxType_i : in std_logic_vector(1 downto 0);
    rxData_i : in std_logic_vector(31 downto 0);
 
    -- Receiver has received a control symbol containing:
    -- packet-accepted, packet-retry, packet-not-accepted, 
    -- status, VC_status, link-response
    txControlWrite_o : out std_logic;
    txControlSymbol_o : out std_logic_vector(12 downto 0);
 
    -- Reciever wants to signal the link partner:
    -- a new frame has been accepted => packet-accepted(rxAckId, bufferStatus)
    -- a frame needs to be retransmitted due to buffering =>
    -- packet-retry(rxAckId, bufferStatus)
    -- a frame is rejected due to errors => packet-not-accepted
    -- a link-request should be answered => link-response
    rxControlWrite_o : out std_logic;
    rxControlSymbol_o : out std_logic_vector(12 downto 0);
 
    -- Status signals used internally.
    ackIdStatus_o : out std_logic_vector(4 downto 0);
    linkInitialized_o : out std_logic;
 
    -- Core->Core cascading signals.
    enable_o : out std_logic;
    operational_i : in std_logic;
    operational_o : out std_logic;
    inputRetryStopped_i : in std_logic;
    inputRetryStopped_o : out std_logic;
    inputErrorStopped_i : in std_logic;
    inputErrorStopped_o : out std_logic;
    ackId_i : in unsigned(4 downto 0);
    ackId_o : out unsigned(4 downto 0);
    frameIndex_i : in std_logic_vector(6 downto 0);
    frameIndex_o : out std_logic_vector(6 downto 0);
    frameWordCounter_i : in std_logic_vector(1 downto 0);
    frameWordCounter_o : out std_logic_vector(1 downto 0);
    frameContent_i : in std_logic_vector(32*NUMBER_WORDS-1 downto 0);
    frameContent_o : out std_logic_vector(32*NUMBER_WORDS-1 downto 0);
    crc_i : in std_logic_vector(15 downto 0);
    crc_o : out std_logic_vector(15 downto 0);
 
    -- Frame buffering interface.
    writeFrameFull_i : in std_logic;
    writeFrame_o : out std_logic;
    writeFrameAbort_o : out std_logic;
    writeContent_o : out std_logic;
    writeContentWords_o : out std_logic_vector(1 downto 0);
    writeContentData_o : out std_logic_vector(32*NUMBER_WORDS-1 downto 0));
end entity;
 
 
-------------------------------------------------------------------------------
-- 
-------------------------------------------------------------------------------
architecture RioReceiverCoreImpl of RioReceiverCore is
 
  component Crc5ITU is
    port(
      d_i : in  std_logic_vector(18 downto 0);
      crc_o : out std_logic_vector(4 downto 0));
  end component;
 
  component Crc16CITT is
    port(
      d_i : in  std_logic_vector(15 downto 0);
      crc_i : in  std_logic_vector(15 downto 0);
      crc_o : out std_logic_vector(15 downto 0));
  end component;
 
  signal symbolEnable0, symbolEnable1 : std_logic;
  signal symbolType0 : std_logic_vector(1 downto 0);
  signal symbolContent0, symbolContent1 : std_logic_vector(31 downto 0);
  signal crc5Valid : std_logic;
  signal crc5 : std_logic_vector(4 downto 0);
 
  signal symbolValid : std_logic;
  signal stype0Status : std_logic;
  signal stype1Start : std_logic;
  signal stype1End : std_logic;
  signal stype1Stomp : std_logic;
  signal stype1Restart : std_logic;
  signal stype1LinkRequest : std_logic;
  signal symbolData : std_logic;
 
  signal crc16Data : std_logic_vector(31 downto 0);
  signal crc16Current : std_logic_vector(15 downto 0);
  signal crc16Temp : std_logic_vector(15 downto 0);
  signal crc16Next : std_logic_vector(15 downto 0);
  signal crc16Valid : std_logic;
 
  signal frameContent : std_logic_vector(32*NUMBER_WORDS-1 downto 0);
 
  signal rxControlWrite : std_logic;
  signal rxControlSymbol : std_logic_vector(12 downto 0);
 
begin
 
  linkInitialized_o <= operational_i;
  ackIdStatus_o <= std_logic_vector(ackId_i);
  inboundAckId_o <= std_logic_vector(ackId_i);
 
  -----------------------------------------------------------------------------
  -- First pipeline stage.
  -- Check the validity of the symbol, CRC5 on control symbols, and save the
  -- symbol content for the next stage.
  -----------------------------------------------------------------------------
 
  -- Read the fifo immediatly.
  rxRead_o <= not rxEmpty_i;
 
  Crc5Calculator: Crc5ITU
    port map(
      d_i=>rxData_i(31 downto 13), crc_o=>crc5);
 
  process(clk, areset_n)
  begin
    if (areset_n = '0') then
      crc5Valid <= '0';
      symbolType0 <= (others => '0');
      symbolContent0 <= (others => '0');
    elsif (clk'event and clk = '1') then
      if (rxEmpty_i = '0') then
        if (crc5 = rxData_i(12 downto 8)) then
          crc5Valid <= '1';
        else
          crc5Valid <= '0';
        end if;
        symbolEnable0 <= '1';
        symbolType0 <= rxType_i;
        symbolContent0 <= rxData_i;
      else
        symbolEnable0 <= '0';
      end if;
    end if;
  end process;
 
  -----------------------------------------------------------------------------
  -- Second pipeline stage.
  -- Separate the part of the control symbol that are going to the transmitter
  -- side and check the type of symbol for this side. 
  -----------------------------------------------------------------------------
 
  process(clk, areset_n)
  begin
    if (areset_n = '0') then
      txControlWrite_o <= '0';
      txControlSymbol_o <= (others => '0');
 
      symbolValid <= '0';
      stype0Status <= '0';
      stype1Start <= '0';
      stype1End <= '0';
      stype1Stomp <= '0';
      stype1Restart <= '0';
      stype1LinkRequest <= '0';
      symbolData <= '0';
 
      symbolContent1 <= (others => '0');
    elsif (clk'event and clk = '1') then
      if (symbolEnable0 = '1') then
        symbolEnable1 <= '1';
        symbolContent1 <= symbolContent0;
 
        if (symbolType0 = SYMBOL_CONTROL) then
          if (crc5Valid = '1') then
            -- REMARK: Check if stype0 is nop and dont forward it???
            symbolValid <= '1';
            txControlWrite_o <= '1';
            txControlSymbol_o <= symbolContent0(31 downto 19);
          else
            symbolValid <= '0';
            txControlWrite_o <= '0';
            txControlSymbol_o <= (others => '0');
          end if;
        else
          symbolValid <= '1';
        end if;
 
        if ((symbolType0 = SYMBOL_CONTROL) and
            (symbolContent0(31 downto 29) = STYPE0_STATUS)) then
          stype0Status <= '1';
        else
          stype0Status <= '0';
        end if;
        if ((symbolType0 = SYMBOL_CONTROL) and
            (symbolContent0(18 downto 16) = STYPE1_START_OF_PACKET)) then
          stype1Start <= '1';
        else
          stype1Start <= '0';
        end if;
        if ((symbolType0 = SYMBOL_CONTROL) and
            (symbolContent0(18 downto 16) = STYPE1_END_OF_PACKET)) then
          stype1End <= '1';
        else
          stype1End <= '0';
        end if;
        if ((symbolType0 = SYMBOL_CONTROL) and
            (symbolContent0(18 downto 16) = STYPE1_STOMP)) then
          stype1Stomp <= '1';
        else
          stype1Stomp <= '0';
        end if;
        if ((symbolType0 = SYMBOL_CONTROL) and
            (symbolContent0(18 downto 16) = STYPE1_RESTART_FROM_RETRY)) then
          stype1Restart <= '1';
        else
          stype1Restart <= '0';
        end if;
        if ((symbolType0 = SYMBOL_CONTROL) and
            (symbolContent0(18 downto 16) = STYPE1_LINK_REQUEST)) then
          stype1LinkRequest <= '1';
        else
          stype1LinkRequest <= '0';
        end if;
        if (symbolType0 = SYMBOL_DATA) then
          symbolData <= '1';
        else
          symbolData <= '0';
        end if;
      else
        symbolEnable1 <= '0';
      end if;
    end if;
  end process;
 
  -----------------------------------------------------------------------------
  -- Third pipeline stage.
  -- Update the CRC16 for the packet.
  -- Update the buffered data and write it to the packet buffer if needed.
  -- Update the main receiver state machine.
  -- Generate reply symbols to the link-partner.
  -- Note that this stage cannot contain any registers as it could be cascaded
  -- to other cores.
  -----------------------------------------------------------------------------
 
  -----------------------------------------------------------------------------
  -- CRC-calculation.
  -- Add a data symbol to the calculated CRC for the packet.
  -- controlSymbol->just forward old crc16.
  -- first data-symbol in packet->crc_o is product of 11111 and the
  -- symbolContent1 without ackid.
  -- not first data-symbol->crc_o is product of crc_i and symbolContent1.
  -----------------------------------------------------------------------------
 
  crc16Data(31 downto 26) <= "000000" when (unsigned(frameIndex_i) = 1) else
                             symbolContent1(31 downto 26);
  crc16Data(25 downto 0) <= symbolContent1(25 downto 0);
 
  crc16Current <= crc_i when (unsigned(frameIndex_i) /= 1) else
                  (others => '1');
 
  Crc16Msb: Crc16CITT
    port map(
      d_i=>crc16Data(31 downto 16), crc_i=>crc16Current, crc_o=>crc16Temp);
  Crc16Lsb: Crc16CITT
    port map(
      d_i=>crc16Data(15 downto 0), crc_i=>crc16Temp, crc_o=>crc16Next);
 
  crc_o <= crc_i when (symbolData = '0') else
           crc16Next;
 
  crc16Valid <= '1' when (crc_i = x"0000") else '0';
 
  -----------------------------------------------------------------------------
  -- Update buffered data.
  -----------------------------------------------------------------------------
 
  -- Append the new symbol content to the end of the
  -- current frame content if the symbol is a data symbol.
  frameContentSingle:
  if (NUMBER_WORDS = 1) generate
    frameContent <= symbolContent1;
  end generate;
  frameContentMulti:
  if (NUMBER_WORDS > 1) generate
    frameContent <=
      (frameContent_i((32*(NUMBER_WORDS-1))-1 downto 0) & symbolContent1) when (symbolData = '1') else
      frameContent_i;
  end generate;
 
  -- Update outputs.
  enable_o <= symbolEnable1;
  frameContent_o <= frameContent;
  writeContentData_o <= frameContent;
 
  -----------------------------------------------------------------------------
  -- Main inbound symbol handler.
  -----------------------------------------------------------------------------
  process(portInitialized_i, portEnable_i, writeFrameFull_i,
          operational_i, ackId_i, frameIndex_i, frameWordCounter_i,
          inputRetryStopped_i, inputErrorStopped_i,
          symbolValid,
          stype0Status,
          stype1Start, stype1End, stype1Stomp, stype1Restart, stype1LinkRequest,
          symbolData,
          symbolContent1,
          frameContent,
          crc16Valid)
  begin
    operational_o <= operational_i;
    ackId_o <= ackId_i;
    frameIndex_o <= frameIndex_i;
    frameWordCounter_o <= frameWordCounter_i;
    inputRetryStopped_o <= inputRetryStopped_i;
    inputErrorStopped_o <= inputErrorStopped_i;
 
    rxControlWrite <= '0';
    rxControlSymbol <= (others => '0');
 
    writeFrame_o <= '0';
    writeFrameAbort_o <= '0';
    writeContent_o <= '0';
    writeContentWords_o <= (others => '0');
 
    -- Act on the current state.
    if (operational_i = '0') then
      ---------------------------------------------------------------------
      -- The port is not operational and is waiting for status control
      -- symbols to be received on the link. Count the number
      -- of error-free status symbols and considder the link operational
      -- when enough of them has been received. Frames are not allowed
      -- here.
      ---------------------------------------------------------------------
 
      -- Check if the port is initialized.
      if (portInitialized_i = '1') then
        -- Port is initialized.
 
        -- Check if the control symbol has a valid checksum.
        if (symbolValid = '1') then
          -- The control symbol has a valid checksum.
 
          -- Check the stype0 part if we should count the number of
          -- error-free status symbols.
          if (stype0Status = '1') then
            -- The symbol is a status.
 
            -- Check if enough status symbols have been received.
            if (unsigned(frameIndex_i) = 7) then
              -- Enough status symbols have been received.
 
              -- Reset all packets.
              frameIndex_o <= (others => '0');
              writeFrameAbort_o <= '1';
 
              -- Set the link as initialized.
              operational_o <= '1';
            else
              -- Increase the number of error-free status symbols that
              -- has been received.
              frameIndex_o <= std_logic_vector(unsigned(frameIndex_i) + 1);
            end if;
          else
            -- The symbol is not a status.
            -- Dont do anything.
          end if;
        else
          -- A control symbol with CRC5 error was recevied.
          frameIndex_o <= (others => '0');
        end if;
      else
        -- The port has become uninitialized.
        frameIndex_o <= (others => '0');
      end if;
    else
      ---------------------------------------------------------------------
      -- The port has been initialized and enough error free status symbols
      -- have been received. Forward data frames to the frame buffer
      -- interface. This is the normal operational state.
      ---------------------------------------------------------------------
 
      -- Check that the port is initialized.
      if (portInitialized_i = '1') then
        -- The port and link is initialized.
 
        -- Check if the control symbol has a valid CRC-5.
        if (symbolValid = '1') then
          -- The symbol is correct.
 
          if ((stype1Start = '1') and
              (inputRetryStopped_i = '0') and (inputErrorStopped_i = '0')) then
            -------------------------------------------------------------
            -- Start the reception of a new frame or end a currently
            -- ongoing frame and start a new one.
            -------------------------------------------------------------
 
            -- Check if a frame has already been started.
            if (unsigned(frameIndex_i) /= 0) then
              -- A frame is already started.
              -- Complete the last frame and start to ackumulate a new one
              -- and update the ackId.
 
              if (unsigned(frameIndex_i) > 3) then
 
                -- Reset the frame index to indicate the frame is started.
                frameIndex_o <= "0000001";
                frameWordCounter_o <= (others=>'0');
 
                -- Check the CRC-16 and the length of the received frame.
                if (crc16Valid = '1') then
                  -- The CRC-16 is ok.
 
                  -- Check if there are any unwritten buffered packet content
                  -- and write it if there is.
                  -- REMARK: Multi-symbol support...
                  if (unsigned(frameWordCounter_i) /= 0) then
                    writeContent_o <= '1';
                  end if;
 
                  -- Update the frame buffer to indicate that the frame has
                  -- been completly received.
                  writeFrame_o <= '1';
 
                  -- Update ackId.
                  ackId_o <= ackId_i + 1;
 
                  -- Send packet-accepted.
                  -- The buffer status is appended by the transmitter
                  -- when sent to get the latest number.
                  rxControlWrite <= '1';
                  rxControlSymbol <= STYPE0_PACKET_ACCEPTED &
                                     std_logic_vector(ackId_i) &
                                     "11111";
                else
                  -- The CRC-16 is not ok.
 
                  -- Make the transmitter send a packet-not-accepted to indicate
                  -- that the received packet contained a CRC error.
                  rxControlWrite <= '1';
                  rxControlSymbol <= STYPE0_PACKET_NOT_ACCEPTED &
                                     "00000" &
                                     PACKET_NOT_ACCEPTED_CAUSE_PACKET_CRC;
                  inputErrorStopped_o <= '1';
                end if;
              else
                -- This packet is too small.
                -- Make the transmitter send a packet-not-accepted to indicated
                -- that the received packet was too small.
                rxControlWrite <= '1';
                rxControlSymbol <= STYPE0_PACKET_NOT_ACCEPTED &
                                   "00000" &
                                   PACKET_NOT_ACCEPTED_CAUSE_GENERAL_ERROR;
                inputErrorStopped_o <= '1';
              end if;
            else
              -- No frame has been started.
 
              -- Reset the frame index to indicate the frame is started.
              frameIndex_o <= "0000001";
              frameWordCounter_o <= (others=>'0');
            end if;
          end if;
 
          if ((stype1End = '1') and
              (inputRetryStopped_i = '0') and (inputErrorStopped_i = '0')) then
            -------------------------------------------------------------
            -- End the reception of an old frame.
            -------------------------------------------------------------
 
            -- Check if a frame has already been started.
            if (unsigned(frameIndex_i) > 3) then
              -- A frame has been started and it is large enough.
 
              -- Reset frame reception to indicate that no frame is ongoing.
              frameIndex_o <= (others => '0');
 
              -- Check the CRC-16 and the length of the received frame.
              if (crc16Valid = '1') then
                -- The CRC-16 is ok.
 
                -- Check if there are any unwritten buffered packet content
                -- and write it if there is.
                -- REMARK: Multi-symbol support...
                if (unsigned(frameWordCounter_i) /= 0) then
                  writeContent_o <= '1';
                end if;
 
                -- Update the frame buffer to indicate that the frame has
                -- been completly received.
                writeFrame_o <= '1';
 
                -- Update ackId.
                ackId_o <= ackId_i + 1;
 
                -- Send packet-accepted.
                -- The buffer status is appended by the transmitter
                -- when sent to get the latest number.
                rxControlWrite <= '1';
                rxControlSymbol <= STYPE0_PACKET_ACCEPTED &
                                   std_logic_vector(ackId_i) &
                                   "11111";
              else
                -- The CRC-16 is not ok.
 
                -- Make the transmitter send a packet-not-accepted to indicate
                -- that the received packet contained a CRC error.
                rxControlWrite <= '1';
                rxControlSymbol <= STYPE0_PACKET_NOT_ACCEPTED &
                                   "00000" &
                                   PACKET_NOT_ACCEPTED_CAUSE_PACKET_CRC;
                inputErrorStopped_o <= '1';
              end if;
            else
              -- This packet is too small.
              -- Make the transmitter send a packet-not-accepted to indicate
              -- that the received packet was too small.
              rxControlWrite <= '1';
              rxControlSymbol <= STYPE0_PACKET_NOT_ACCEPTED &
                                 "00000" &
                                 PACKET_NOT_ACCEPTED_CAUSE_GENERAL_ERROR;
              inputErrorStopped_o <= '1';
            end if;
          end if;
 
          if ((stype1Stomp = '1') and
              (inputRetryStopped_i = '0') and (inputErrorStopped_i = '0')) then
            -------------------------------------------------------------
            -- Restart the reception of an old frame.
            -------------------------------------------------------------
            -- See 5.10 in the standard.
 
            -- Make the transmitter send a packet-retry to indicate
            -- that the packet cannot be accepted.
            rxControlWrite <= '1';
            rxControlSymbol <= STYPE0_PACKET_RETRY &
                               std_logic_vector(ackId_i) &
                               "11111";
 
            -- Enter the input retry-stopped state.
            inputRetryStopped_o <= '1';
          end if;
 
          if (stype1Restart = '1') then
            if (inputRetryStopped_i = '1') then
              -------------------------------------------------------------
              -- The receiver indicates a restart from a retry sent
              -- from us.
              -------------------------------------------------------------
 
              -- Abort the frame and reset frame reception.
              frameIndex_o <= (others => '0');
              writeFrameAbort_o <= '1';
 
              -- Go back to the normal operational state.
              inputRetryStopped_o <= '0';
            else
              -------------------------------------------------------------
              -- The receiver indicates a restart from a retry sent
              -- from us.
              -------------------------------------------------------------
              -- See 5.10 in the standard.
              -- Protocol error, this symbol should not be received here since
              -- we should have been in input-retry-stopped. 
 
              -- Send a packet-not-accepted to indicate that a protocol
              -- error has occurred.
              rxControlWrite <= '1';
              rxControlSymbol <= STYPE0_PACKET_NOT_ACCEPTED &
                                 "00000" &
                                 PACKET_NOT_ACCEPTED_CAUSE_GENERAL_ERROR;
              inputErrorStopped_o <= '1';
            end if;
          end if;
 
          if (stype1LinkRequest = '1') then
            -------------------------------------------------------------
            -- Reply to a LINK-REQUEST.
            -------------------------------------------------------------
 
            -- Check the command part.
            if (symbolContent1(15 downto 13) = "100") then
              -- Return input port status command.
              -- This functions as a link-request(restart-from-error)
              -- control symbol under error situations.
 
              if (inputErrorStopped_i = '1') then
                rxControlWrite <= '1';
                rxControlSymbol <= STYPE0_LINK_RESPONSE &
                                   std_logic_vector(ackId_i) &
                                   "00101";
              elsif (inputRetryStopped_i = '1') then
                rxControlWrite <= '1';
                rxControlSymbol <= STYPE0_LINK_RESPONSE &
                                   std_logic_vector(ackId_i) &
                                   "00100";
              else
                -- Send a link response containing an ok reply.
                rxControlWrite <= '1';
                rxControlSymbol <= STYPE0_LINK_RESPONSE &
                                   std_logic_vector(ackId_i) &
                                   "10000";
              end if;
            else
              -- Reset device command or other unsupported command.
              -- Discard this.
            end if;
 
            -- Abort the frame and reset frame reception.
            inputRetryStopped_o <= '0';
            inputErrorStopped_o <= '0';
            frameIndex_o <= (others=>'0');
            writeFrameAbort_o <= '1';
          end if;
 
          if ((symbolData = '1')  and
              (inputRetryStopped_i = '0') and (inputErrorStopped_i = '0')) then
            -------------------------------------------------------------
            -- This is a data symbol.
            -------------------------------------------------------------
            -- REMARK: Add check for in-the-middle-crc here...
 
            case frameIndex_i is
              when "0000000" | "1000110" =>
                -- A frame has not been started or is too long.
                -- Send packet-not-accepted.
                rxControlWrite <= '1';
                rxControlSymbol <= STYPE0_PACKET_NOT_ACCEPTED &
                                   "00000" &
                                   PACKET_NOT_ACCEPTED_CAUSE_GENERAL_ERROR;
                inputErrorStopped_o <= '1';
              when "0000001" =>
                if (unsigned(symbolContent1(31 downto 27)) = ackId_i) then
                  if ((portEnable_i = '1') or
                      (symbolContent1(19 downto 16) = FTYPE_MAINTENANCE_CLASS)) then
 
                    -- Check if there are buffers available to store the new
                    -- packet.
                    if (writeFrameFull_i = '0') then
                      -- There are buffering space available to store the new
                      -- data.
 
                      -- Check if the buffer entry is ready to be written
                      -- into the packet buffer.
                      -- REMARK: Multi-symbol support...
                      if (unsigned(frameWordCounter_i) = (NUMBER_WORDS-1)) then
                        -- Write the data to the frame FIFO.
                        frameWordCounter_o <= (others=>'0');
                        writeContent_o <= '1';
                        writeContentWords_o <= frameWordCounter_i;
                      else
                        frameWordCounter_o <= std_logic_vector(unsigned(frameWordCounter_i) + 1);
                      end if;
 
                      -- Increment the number of received data symbols.
                      frameIndex_o <= std_logic_vector(unsigned(frameIndex_i) + 1);
                    else
                      -- The packet buffer is full.
                      -- Let the link-partner resend the packet.
                      rxControlWrite <= '1';
                      rxControlSymbol <= STYPE0_PACKET_RETRY &
                                         std_logic_vector(ackId_i) &
                                         "11111";
                      inputRetryStopped_o <= '1';
                    end if;
                  else
                    -- A non-maintenance packets are not allowed.
                    -- Send packet-not-accepted.
                    rxControlWrite <= '1';
                    rxControlSymbol <= STYPE0_PACKET_NOT_ACCEPTED &
                                       "00000" &
                                       PACKET_NOT_ACCEPTED_CAUSE_NON_MAINTENANCE_STOPPED;
                    inputErrorStopped_o <= '1';
                  end if;
                else
                  -- The ackId is unexpected.
                  -- Send packet-not-accepted.
                  rxControlWrite <= '1';
                  rxControlSymbol <= STYPE0_PACKET_NOT_ACCEPTED &
                                     "00000" &
                                     PACKET_NOT_ACCEPTED_CAUSE_UNEXPECTED_ACKID;
                  inputErrorStopped_o <= '1';
                end if;
              when others =>
                -- A frame has been started and is not too long.
                -- Check if the buffer entry is ready to be written
                -- into the packet buffer.
                -- REMARK: Multi-symbol support...
                if (unsigned(frameWordCounter_i) = (NUMBER_WORDS-1)) then
                  -- Write the data to the frame FIFO.
                  frameWordCounter_o <= (others=>'0');
                  writeContent_o <= '1';
                  writeContentWords_o <= frameWordCounter_i;
                else
                  frameWordCounter_o <= std_logic_vector(unsigned(frameWordCounter_i) + 1);
                end if;
 
                -- Increment the number of received data symbols.
                frameIndex_o <= std_logic_vector(unsigned(frameIndex_i) + 1);
            end case;
          end if;
        else
          -- A control symbol contains a crc error.
 
          -- Send a packet-not-accepted to indicate that a corrupted
          -- control-symbol has been received and change state.
          rxControlWrite <= '1';
          rxControlSymbol <= STYPE0_PACKET_NOT_ACCEPTED &
                             "00000" &
                             PACKET_NOT_ACCEPTED_CAUSE_CONTROL_CRC;
          inputErrorStopped_o <= '1';
        end if;
      else
        -- The port has become uninitialized.
        -- Go back to the uninitialized state.
        operational_o <= '0';
      end if;
    end if;
  end process;
 
  -----------------------------------------------------------------------------
  -- Fourth pipeline stage.
  -----------------------------------------------------------------------------
  -- REMARK: Do more stuff in this stage, convert a one-hot to the symbol to
  -- send...
  -- REMARK: Register other outputs here like writeContent_o...
 
  process(clk, areset_n)
  begin
    if (areset_n = '0') then
      rxControlWrite_o <= '0';
      rxControlSymbol_o <= (others=>'0');
    elsif (clk'event and clk = '1') then
      rxControlWrite_o <= rxControlWrite and symbolEnable1;
      rxControlSymbol_o <= rxControlSymbol;
    end if;
  end process;
 
end architecture;
 
 
 
-------------------------------------------------------------------------------
--
---------------------------------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
 
 
-------------------------------------------------------------------------------
-- 
-------------------------------------------------------------------------------
entity RioFifo1 is
  generic(
    WIDTH : natural);
  port(
    clk : in std_logic;
    areset_n : in std_logic;
 
    empty_o : out std_logic;
    read_i : in std_logic;
    data_o : out std_logic_vector(WIDTH-1 downto 0);
 
    full_o : out std_logic;
    write_i : in std_logic;
    data_i : in std_logic_vector(WIDTH-1 downto 0));
end entity;
 
 
-------------------------------------------------------------------------------
-- 
-------------------------------------------------------------------------------
architecture RioFifo1Impl of RioFifo1 is
  signal empty : std_logic;
  signal full : std_logic;
begin
 
  empty_o <= empty;
  full_o <= full;
 
  process(areset_n, clk)
  begin
    if (areset_n = '0') then
      empty <= '1';
      full <= '0';
      data_o <= (others => '0');
    elsif (clk'event and clk = '1') then
      if (empty = '1') then
        if (write_i = '1') then
          empty <= '0';
          full <= '1';
          data_o <= data_i;
        end if;
      else
        if (read_i = '1') then
          empty <= '1';
          full <= '0';
        end if;
      end if;
    end if;
  end process;
 
end architecture;
 
 
 
-------------------------------------------------------------------------------
-- A CRC-5 calculator following the implementation proposed in the 2.2
-- standard.
-------------------------------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
 
 
-------------------------------------------------------------------------------
-- 
-------------------------------------------------------------------------------
entity Crc5ITU is
  port(
    d_i : in  std_logic_vector(18 downto 0);
    crc_o : out std_logic_vector(4 downto 0));
end entity;
 
 
-------------------------------------------------------------------------------
-- 
-------------------------------------------------------------------------------
architecture Crc5Impl of Crc5ITU is
  signal d : std_logic_vector(0 to 18);
  signal c : std_logic_vector(0 to 4);
 
begin
  -- Reverse the bit vector indexes to make them the same as in the standard.
  d(18) <= d_i(0); d(17) <= d_i(1); d(16) <= d_i(2); d(15) <= d_i(3);
  d(14) <= d_i(4); d(13) <= d_i(5); d(12) <= d_i(6); d(11) <= d_i(7);
  d(10) <= d_i(8); d(9) <= d_i(9); d(8) <= d_i(10); d(7) <= d_i(11);
  d(6) <= d_i(12); d(5) <= d_i(13); d(4) <= d_i(14); d(3) <= d_i(15);
  d(2) <= d_i(16); d(1) <= d_i(17); d(0) <= d_i(18);
 
  -- Calculate the resulting crc.
  c(0) <= d(18) xor d(16) xor d(15) xor d(12) xor
          d(10) xor d(5) xor d(4) xor d(3) xor
          d(1) xor d(0);
  c(1) <= (not d(18)) xor d(17) xor d(15) xor d(13) xor
          d(12) xor d(11) xor d(10) xor d(6) xor
          d(3) xor d(2) xor d(0);
  c(2) <= (not d(18)) xor d(16) xor d(14) xor d(13) xor
          d(12) xor d(11) xor d(7) xor d(4) xor
          d(3) xor d(1);
  c(3) <= (not d(18)) xor d(17) xor d(16) xor d(14) xor
          d(13) xor d(10) xor d(8) xor d(3) xor
          d(2) xor d(1);
  c(4) <= d(18) xor d(17) xor d(15) xor d(14) xor
          d(11) xor d(9) xor d(4) xor d(3) xor
          d(2) xor d(0);
 
  -- Reverse the bit vector indexes to make them the same as in the standard.
  crc_o(4) <= c(0); crc_o(3) <= c(1); crc_o(2) <= c(2); crc_o(1) <= c(3);
  crc_o(0) <= c(4);
end architecture;
 
 
-------------------------------------------------------------------------------
-- 
-------------------------------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use work.rio_common.all;
 
-------------------------------------------------------------------------------
-- 
-------------------------------------------------------------------------------
entity Crc16Calculator is
 
  generic (
    NUMBER_WORDS : natural range 1 to 8 := 1);
 
  port (
    clk : in std_logic;
    areset_n : in std_logic;
 
    write_i : in std_logic;
    crc_i : in std_logic_vector(15 downto 0);
    data_i : in std_logic_vector((32*NUMBER_WORDS)-1 downto 0);
 
    crc_o : out std_logic_vector(15 downto 0);
    done_o : out std_logic);
 
end Crc16Calculator;
 
-------------------------------------------------------------------------------
-- 
-------------------------------------------------------------------------------
architecture Crc16CalculatorImpl of Crc16Calculator is
 
  component Crc16CITT is
    port(
      d_i : in  std_logic_vector(15 downto 0);
      crc_i : in  std_logic_vector(15 downto 0);
      crc_o : out std_logic_vector(15 downto 0));
  end component;
 
  signal iterator : natural range 0 to 2*NUMBER_WORDS;
  signal crcData : std_logic_vector((32*NUMBER_WORDS)-1 downto 0);
  signal crcCurrent : std_logic_vector(15 downto 0);
  signal crcNext : std_logic_vector(15 downto 0);
 
begin
 
  process(areset_n, clk)
  begin
    if (areset_n = '0') then
      iterator <= 0;
      done_o <= '0';
      crc_o <= (others => '0');
    elsif (clk'event and clk = '1') then
      if (write_i = '1') then
        iterator <= 2*NUMBER_WORDS-1;
        crcData <= data_i;
        crcCurrent <= crc_i;
        done_o <= '0';
      else
        if (iterator /= 0) then
          iterator <= iterator - 1;
          crcData <= crcData(((32*NUMBER_WORDS)-1)-16 downto 0) & x"0000";
          crcCurrent <= crcNext;
        else
          crc_o <= crcNext;
          done_o <= '1';
        end if;
      end if;
    end if;
  end process;
 
  Crc16Inst: Crc16CITT
    port map(
      d_i=>crcData((32*NUMBER_WORDS)-1 downto (32*NUMBER_WORDS)-16),
      crc_i=>crcCurrent, crc_o=>crcNext);
 
end architecture;
 

Line No.	Rev	Author	Line
1	4	magro732	`-------------------------------------------------------------------------------`
2			`--`
3			`-- RapidIO IP Library Core`
4			`--`
5			`-- This file is part of the RapidIO IP library project`
6			`-- http://www.opencores.org/cores/rio/`
7			`--`
8			`-- Description`
9			`-- Containing the transmission channel independent parts of the LP-Serial`
10			`-- Physical Layer Specification (RapidIO 2.2, part 6).`
11			`--`
12			`-- To Do:`
13			`-- -`
14			`--`
15			`-- Author(s):`
16			`-- - Magnus Rosenius, magro732@opencores.org`
17			`--`
18			`-------------------------------------------------------------------------------`
19			`--`
20			`-- Copyright (C) 2013 Authors and OPENCORES.ORG`
21			`--`
22			`-- This source file may be used and distributed without`
23			`-- restriction provided that this copyright statement is not`
24			`-- removed from the file and that any derivative work contains`
25			`-- the original copyright notice and the associated disclaimer.`
26			`--`
27			`-- This source file is free software; you can redistribute it`
28			`-- and/or modify it under the terms of the GNU Lesser General`
29			`-- Public License as published by the Free Software Foundation;`
30			`-- either version 2.1 of the License, or (at your option) any`
31			`-- later version.`
32			`--`
33			`-- This source is distributed in the hope that it will be`
34			`-- useful, but WITHOUT ANY WARRANTY; without even the implied`
35			`-- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR`
36			`-- PURPOSE. See the GNU Lesser General Public License for more`
37			`-- details.`
38			`--`
39			`-- You should have received a copy of the GNU Lesser General`
40			`-- Public License along with this source; if not, download it`
41			`-- from http://www.opencores.org/lgpl.shtml`
42			`--`
43			`-------------------------------------------------------------------------------`
44
45
46			`-------------------------------------------------------------------------------`
47			`-- RioSerial`
48	8	magro732	`--`
49	11	magro732	`-- Generics`
50			`-- --------`
51			`-- TIMEOUT_WIDTH - The number of bits to be used in the portLinkTimeout signal.`
52			`-- NUMBER_WORDS - The number of parallell words that the data symbols can`
53			`-- contain. This sizes the data buses. It can be used to increase the bandwidth`
54			`-- of the core. Note that it cannot be larger than 4. This is since two`
55			`-- packets may be completed at the same tick and the interface to the`
56			`-- packetBuffer cannot handle more than one packets in one tick.`
57			`--`
58			`-- Signals`
59			`-- -------`
60			`-- System signals.`
61	8	magro732	`-- clk - System clock.`
62			`-- areset_n - System reset. Asynchronous, active low.`
63			`--`
64	11	magro732	`-- Configuration signals. These are used to change the runtime behaviour.`
65	8	magro732	`-- portLinkTimeout_i - The number of ticks to wait for a packet-accepted before`
66			`-- a timeout occurrs.`
67			`-- linkInitialized_o - Indicates if a link partner is answering with valid`
68			`-- status-control-symbols.`
69			`-- inputPortEnable_i - Activate the input port for non-maintenance packets. If`
70			`-- deasserted, only non-maintenance packets are allowed.`
71			`-- outputPortEnable_i - Activate the output port for non-maintenance packets.`
72			`-- If deasserted, only non-maintenance packets are allowed.`
73			`--`
74			`-- This interface makes it possible to read and write ackId in both outbound`
75			`-- and inbound directions. All input signals are validated by localAckIdWrite.`
76			`-- localAckIdWrite_i - Indicate if a localAckId write operation is ongoing.`
77			`-- Usually this signal is high one tick.`
78			`-- clrOutstandingAckId_i - Clear outstanding ackId, i.e. reset the transmission`
79			`-- window. The signal is only read if localAckIdWrite_i is high.`
80			`-- inboundAckId_i - The value to set the inbound ackId (the ackId that the`
81			`-- next inbound packet should have) to. This signal is only read if localAckIdWrite`
82			`-- is high.`
83			`-- outstandingAckId_i - The value to set the outstanding ackId (the ackId`
84			`-- transmitted but not acknowledged) to. This signal is only read if localAckIdWrite`
85			`-- is high.`
86			`-- outboundAckId_i - The value to set the outbound ackId (the ackId that the`
87			`-- next outbound packet will have) to. This signal is only read if localAckIdWrite`
88			`-- is high.`
89			`-- inboundAckId_o - The current inbound ackId.`
90			`-- outstandingAckId_o - The current outstanding ackId.`
91			`-- outboundAckId_o - The current outbound ackId.`
92			`--`
93			`-- This is the interface to the packet buffering sublayer.`
94			`-- The window signals are used to send packets without removing them from the`
95			`-- memory storage. This way, many packet can be sent without awaiting`
96			`-- packet-accepted symbols and if a packet-accepted gets lost, it is possible`
97			`-- to revert and resend a packet. This is achived by reading readWindowEmpty`
98			`-- for new packet and asserting readWindowNext when a packet has been sent.`
99			`-- When the packet-accepted is received, readFrame should be asserted to remove the`
100			`-- packet from the storage. If a packet-accepted is missing, readWindowReset is`
101			`-- asserted to set the current packet to read to the one that has not received`
102			`-- a packet-accepted.`
103			`-- readFrameEmpty_i - Indicate if a packet is ready in the outbound direction.`
104			`-- Once deasserted, it is possible to read the packet content using`
105			`-- readContent_o to update readContentData and readContentEnd.`
106			`-- readFrame_o - Assert this signal for one tick to discard the oldest packet.`
107			`-- It should be used when a packet has been fully read, a linkpartner has`
108			`-- accepted it and the resources occupied by it should be returned to be`
109			`-- used for new packets.`
110			`-- readFrameRestart_o - Assert this signal to restart the reading of the`
111			`-- current packet. readContentData and readContentEnd will be reset to the`
112			`-- first content of the packet.`
113			`-- readFrameAborted_i - This signal is asserted if the current packet was`
114			`-- aborted while it was written. It is used when a transmitter starts to send a`
115			`-- packet before it has been fully received and it is cancelled before it is`
116			`-- completed. A one tick asserted readFrameRestart signal resets this signal.`
117			`-- readWindowEmpty_i - Indicate if there are more packets to send.`
118			`-- readWindowReset_o - Reset the current packet to the oldest stored in the memory.`
119			`-- readWindowNext_o - Indicate that a new packet should be read. Must only be`
120			`-- asserted if readWindowEmpty is deasserted. It should be high for one tick.`
121			`-- readContentEmpty_i - Indicate if there are any packet content to be read.`
122			`-- This signal is updated directly when packet content is written making it`
123			`-- possible to read packet content before the full packet has been written to`
124			`-- the memory storage.`
125			`-- readContent_o - Update readContentData and readContentEnd.`
126			`-- readContentEnd_i - Indicate if the end of the current packet has been`
127			`-- reached. When asserted, readContentData is not valid.`
128			`-- readContentData_i - The content of the current packet.`
129			`-- writeFrameFull_i - Indicate if the inbound packet storage is ready to accept`
130			`-- a new packet.`
131			`-- writeFrame_o - Indicate that a new complete inbound packet has been written.`
132			`-- writeFrameAbort_o - Indicate that the current packet is aborted and that all`
133			`-- data written for this packet should be discarded.`
134			`-- writeContent_o - Indicate that writeContentData is valid and should be`
135			`-- written into the packet content storage.`
136			`-- writeContentData_o - The content to write to the packet content storage.`
137			`--`
138			`-- This is the interface to the PCS (Physical Control Sublayer). Four types of`
139			`-- symbols exist, idle, control, data and error.`
140			`-- Idle symbols are transmitted when nothing else can be transmitted. They are`
141			`-- mainly intended to enforce a timing on the transmitted symbols. This is`
142			`-- needed to be able to guarantee that a status-control-symbol is transmitted`
143			`-- at least once every 256 symbol.`
144			`-- Control symbols contain control-symbols as described by the standard.`
145			`-- Data symbols contains a 32-bit fragment of a RapidIO packet.`
146			`-- Error symbols indicate that a corrupted symbol was received. This could be`
147			`-- used by a PCS layer to indicate that a transmission error was detected and`
148			`-- that the above layers should send link-requests to ensure the synchronism`
149			`-- between the link-partners.`
150			`-- The signals in this interface are:`
151			`-- portInitialized_i - An asserted signal on this pin indicates that the PCS`
152			`-- layer has established synchronization with the link and is ready to accept`
153			`-- symbols.`
154			`-- outboundSymbolEmpty_o - An asserted signal indicates that there are no`
155			`-- outbound symbols to read. Once deasserted, outboundSymbol_o will be`
156			`-- already be valid. This signal will be updated one tick after`
157			`-- outboundSymbolRead_i has been asserted.`
158			`-- outboundSymbolRead_i - Indicate that outboundSymbol_o has been read and a`
159			`-- new value could be accepted. It should be active for one tick.`
160	11	magro732	`-- REMARK: Update this comment...`
161			`-- outboundSymbol_o - The outbound symbol. It is divided into two parts,`
162			`-- symbolType and symbolContent.`
163			`-- symbolType - The two MSB bits are the type of the symbol according to`
164			`-- table below:`
165			`-- 00=IDLE, the rest of the bits are not used.`
166			`-- 01=CONTROL, the control symbols payload (24 bits) are placed in the MSB`
167			`-- part of the symbolContent.`
168			`-- 10=ERROR, the rest of the bits are not used.`
169			`-- 11=DATA, all the remaining bits contain the number of valid words and`
170			`-- the payload of the symbol.`
171			`-- symbolContent - The rest of the bits are symbol content. If there are`
172			`-- multiple words in the symbols they must be set to zero. The first`
173			`-- received word is placed in the MSB part of this field.`
174	8	magro732	`-- inboundSymbolFull_o - An asserted signal indicates that no more inbound`
175			`-- symbols can be accepted.`
176			`-- inboundSymbolWrite_i - Indicate that inboundSymbol_i contains valid`
177	11	magro732	`-- information that should be forwarded. Should be active for one tick.`
178	8	magro732	`-- inboundSymbol_i - The inbound symbol. See outboundSymbol_o for formating.`
179	4	magro732	`-------------------------------------------------------------------------------`
180			`library ieee;`
181			`use ieee.std_logic_1164.all;`
182			`use ieee.numeric_std.all;`
183			`use work.rio_common.all;`
184
185
186			`-------------------------------------------------------------------------------`
187			`-- Entity for RioSerial.`
188			`-------------------------------------------------------------------------------`
189			`entity RioSerial is`
190			`generic(`
191	13	magro732	`TIMEOUT_WIDTH : natural := 20;`
192	11	magro732	`NUMBER_WORDS : natural range 1 to 4 := 1);`
193	4	magro732	`port(`
194			`-- System signals.`
195			`clk : in std_logic;`
196			`areset_n : in std_logic;`
197
198			`-- Status signals for maintenance operations.`
199			`portLinkTimeout_i : in std_logic_vector(TIMEOUT_WIDTH-1 downto 0);`
200			`linkInitialized_o : out std_logic;`
201			`inputPortEnable_i : in std_logic;`
202			`outputPortEnable_i : in std_logic;`
203
204			`-- Support for portLocalAckIdCSR.`
205			`localAckIdWrite_i : in std_logic;`
206			`clrOutstandingAckId_i : in std_logic;`
207			`inboundAckId_i : in std_logic_vector(4 downto 0);`
208			`outstandingAckId_i : in std_logic_vector(4 downto 0);`
209			`outboundAckId_i : in std_logic_vector(4 downto 0);`
210			`inboundAckId_o : out std_logic_vector(4 downto 0);`
211			`outstandingAckId_o : out std_logic_vector(4 downto 0);`
212			`outboundAckId_o : out std_logic_vector(4 downto 0);`
213
214			`-- Outbound frame interface.`
215			`readFrameEmpty_i : in std_logic;`
216			`readFrame_o : out std_logic;`
217			`readFrameRestart_o : out std_logic;`
218			`readFrameAborted_i : in std_logic;`
219			`readWindowEmpty_i : in std_logic;`
220			`readWindowReset_o : out std_logic;`
221			`readWindowNext_o : out std_logic;`
222			`readContentEmpty_i : in std_logic;`
223			`readContent_o : out std_logic;`
224			`readContentEnd_i : in std_logic;`
225	11	magro732	`readContentData_i : in std_logic_vector(2+(32*NUMBER_WORDS-1) downto 0);`
226	4	magro732
227			`-- Inbound frame interface.`
228			`writeFrameFull_i : in std_logic;`
229			`writeFrame_o : out std_logic;`
230			`writeFrameAbort_o : out std_logic;`
231			`writeContent_o : out std_logic;`
232	11	magro732	`writeContentData_o : out std_logic_vector(2+(32*NUMBER_WORDS-1) downto 0);`
233	4	magro732
234			`-- PCS layer signals.`
235			`portInitialized_i : in std_logic;`
236			`outboundSymbolEmpty_o : out std_logic;`
237			`outboundSymbolRead_i : in std_logic;`
238	11	magro732	`outboundSymbol_o : out std_logic_vector(((2+32)*NUMBER_WORDS-1) downto 0);`
239	4	magro732	`inboundSymbolFull_o : out std_logic;`
240			`inboundSymbolWrite_i : in std_logic;`
241	11	magro732	`inboundSymbol_i : in std_logic_vector(((2+32)*NUMBER_WORDS-1) downto 0));`
242	4	magro732	`end entity;`
243
244
245			`-------------------------------------------------------------------------------`
246			`-- Architecture for RioSerial.`
247			`-------------------------------------------------------------------------------`
248			`architecture RioSerialImpl of RioSerial is`
249
250			`component RioFifo1 is`
251			`generic(`
252			`WIDTH : natural);`
253			`port(`
254			`clk : in std_logic;`
255			`areset_n : in std_logic;`
256
257			`empty_o : out std_logic;`
258			`read_i : in std_logic;`
259			`data_o : out std_logic_vector(WIDTH-1 downto 0);`
260
261			`full_o : out std_logic;`
262			`write_i : in std_logic;`
263			`data_i : in std_logic_vector(WIDTH-1 downto 0));`
264			`end component;`
265
266			`component RioTransmitter is`
267			`generic(`
268	11	magro732	`TIMEOUT_WIDTH : natural;`
269			`NUMBER_WORDS : natural range 1 to 4 := 1);`
270	4	magro732	`port(`
271			`clk : in std_logic;`
272			`areset_n : in std_logic;`
273
274			`portLinkTimeout_i : in std_logic_vector(TIMEOUT_WIDTH-1 downto 0);`
275			`portEnable_i : in std_logic;`
276
277			`localAckIdWrite_i : in std_logic;`
278			`clrOutstandingAckId_i : in std_logic;`
279			`outstandingAckId_i : in std_logic_vector(4 downto 0);`
280			`outboundAckId_i : in std_logic_vector(4 downto 0);`
281			`outstandingAckId_o : out std_logic_vector(4 downto 0);`
282			`outboundAckId_o : out std_logic_vector(4 downto 0);`
283
284			`portInitialized_i : in std_logic;`
285			`txFull_i : in std_logic;`
286			`txWrite_o : out std_logic;`
287	11	magro732	`txType_o : out std_logic_vector(1 downto 0);`
288	4	magro732	`txData_o : out std_logic_vector(31 downto 0);`
289
290			`txControlEmpty_i : in std_logic;`
291			`txControlSymbol_i : in std_logic_vector(12 downto 0);`
292			`txControlUpdate_o : out std_logic;`
293			`rxControlEmpty_i : in std_logic;`
294			`rxControlSymbol_i : in std_logic_vector(12 downto 0);`
295			`rxControlUpdate_o : out std_logic;`
296
297			`linkInitialized_i : in std_logic;`
298			`linkInitialized_o : out std_logic;`
299			`ackIdStatus_i : in std_logic_vector(4 downto 0);`
300
301			`readFrameEmpty_i : in std_logic;`
302			`readFrame_o : out std_logic;`
303			`readFrameRestart_o : out std_logic;`
304			`readFrameAborted_i : in std_logic;`
305			`readWindowEmpty_i : in std_logic;`
306			`readWindowReset_o : out std_logic;`
307			`readWindowNext_o : out std_logic;`
308			`readContentEmpty_i : in std_logic;`
309			`readContent_o : out std_logic;`
310			`readContentEnd_i : in std_logic;`
311	11	magro732	`readContentWords_i : in std_logic_vector(1 downto 0);`
312			`readContentData_i : in std_logic_vector(32*NUMBER_WORDS-1 downto 0));`
313	4	magro732	`end component;`
314
315			`component RioReceiver is`
316	11	magro732	`generic(`
317			`NUMBER_WORDS : natural range 1 to 4 := 1);`
318	4	magro732	`port(`
319			`clk : in std_logic;`
320			`areset_n : in std_logic;`
321
322			`portEnable_i : in std_logic;`
323
324			`localAckIdWrite_i : in std_logic;`
325			`inboundAckId_i : in std_logic_vector(4 downto 0);`
326			`inboundAckId_o : out std_logic_vector(4 downto 0);`
327
328			`portInitialized_i : in std_logic;`
329			`rxEmpty_i : in std_logic;`
330			`rxRead_o : out std_logic;`
331	11	magro732	`rxType_i : in std_logic_vector(2*NUMBER_WORDS-1 downto 0);`
332			`rxData_i : in std_logic_vector(32*NUMBER_WORDS-1 downto 0);`
333	4	magro732
334	11	magro732	`txControlWrite_o : out std_logic_vector(NUMBER_WORDS-1 downto 0);`
335			`txControlSymbol_o : out std_logic_vector(12*NUMBER_WORDS downto 0);`
336			`rxControlWrite_o : out std_logic_vector(NUMBER_WORDS-1 downto 0);`
337			`rxControlSymbol_o : out std_logic_vector(12*NUMBER_WORDS downto 0);`
338	4	magro732
339			`ackIdStatus_o : out std_logic_vector(4 downto 0);`
340			`linkInitialized_o : out std_logic;`
341
342			`writeFrameFull_i : in std_logic;`
343			`writeFrame_o : out std_logic;`
344			`writeFrameAbort_o : out std_logic;`
345			`writeContent_o : out std_logic;`
346	11	magro732	`writeContentWords_o : out std_logic_vector(1 downto 0);`
347			`writeContentData_o : out std_logic_vector(32*NUMBER_WORDS-1 downto 0));`
348	4	magro732	`end component;`
349
350			`signal linkInitializedRx : std_logic;`
351			`signal linkInitializedTx : std_logic;`
352			`signal ackIdStatus : std_logic_vector(4 downto 0);`
353
354	11	magro732	`signal txControlWrite : std_logic_vector(NUMBER_WORDS-1 downto 0);`
355			`signal txControlWriteSymbol : std_logic_vector(12*NUMBER_WORDS downto 0);`
356			`signal txControlReadEmpty : std_logic_vector(NUMBER_WORDS-1 downto 0);`
357			`signal txControlRead : std_logic_vector(NUMBER_WORDS-1 downto 0);`
358			`signal txControlReadSymbol : std_logic_vector(12*NUMBER_WORDS downto 0);`
359	4	magro732
360	11	magro732	`signal rxControlWrite : std_logic_vector(NUMBER_WORDS-1 downto 0);`
361			`signal rxControlWriteSymbol : std_logic_vector(12*NUMBER_WORDS downto 0);`
362			`signal rxControlReadEmpty : std_logic_vector(NUMBER_WORDS-1 downto 0);`
363			`signal rxControlRead : std_logic_vector(NUMBER_WORDS-1 downto 0);`
364			`signal rxControlReadSymbol : std_logic_vector(12*NUMBER_WORDS downto 0);`
365	4	magro732
366			`signal outboundFull : std_logic;`
367			`signal outboundWrite : std_logic;`
368	11	magro732	`signal outboundType : std_logic_vector(1 downto 0);`
369			`signal outboundData : std_logic_vector(32*NUMBER_WORDS-1 downto 0);`
370			`signal outboundSymbol : std_logic_vector(2+(32*NUMBER_WORDS-1) downto 0);`
371	4	magro732
372			`signal inboundEmpty : std_logic;`
373			`signal inboundRead : std_logic;`
374	11	magro732	`signal inboundType : std_logic_vector(1 downto 0);`
375			`signal inboundData : std_logic_vector(32*NUMBER_WORDS-1 downto 0);`
376			`signal inboundSymbol : std_logic_vector(((2+32)*NUMBER_WORDS-1) downto 0);`
377	4	magro732
378			`begin`
379
380			`linkInitialized_o <=`
381			`'1' when ((linkInitializedRx = '1') and (linkInitializedTx = '1')) else '0';`
382
383			`-----------------------------------------------------------------------------`
384			`-- Serial layer modules.`
385			`-----------------------------------------------------------------------------`
386
387			`Transmitter: RioTransmitter`
388			`generic map(`
389	11	magro732	`TIMEOUT_WIDTH=>TIMEOUT_WIDTH,`
390			`NUMBER_WORDS=>NUMBER_WORDS)`
391	4	magro732	`port map(`
392			`clk=>clk, areset_n=>areset_n,`
393			`portLinkTimeout_i=>portLinkTimeout_i,`
394			`portEnable_i=>outputPortEnable_i,`
395			`localAckIdWrite_i=>localAckIdWrite_i,`
396			`clrOutstandingAckId_i=>clrOutstandingAckId_i,`
397			`outstandingAckId_i=>outstandingAckId_i,`
398			`outboundAckId_i=>outboundAckId_i,`
399			`outstandingAckId_o=>outstandingAckId_o,`
400			`outboundAckId_o=>outboundAckId_o,`
401			`portInitialized_i=>portInitialized_i,`
402			`txFull_i=>outboundFull, txWrite_o=>outboundWrite,`
403	11	magro732	`txType_o=>outboundType, txData_o=>outboundData,`
404			`txControlEmpty_i=>txControlReadEmpty(0), txControlSymbol_i=>txControlReadSymbol,`
405			`txControlUpdate_o=>txControlRead(0),`
406			`rxControlEmpty_i=>rxControlReadEmpty(0), rxControlSymbol_i=>rxControlReadSymbol,`
407			`rxControlUpdate_o=>rxControlRead(0),`
408	4	magro732	`linkInitialized_o=>linkInitializedTx,`
409			`linkInitialized_i=>linkInitializedRx, ackIdStatus_i=>ackIdStatus,`
410			`readFrameEmpty_i=>readFrameEmpty_i, readFrame_o=>readFrame_o,`
411			`readFrameRestart_o=>readFrameRestart_o, readFrameAborted_i=>readFrameAborted_i,`
412			`readWindowEmpty_i=>readWindowEmpty_i,`
413			`readWindowReset_o=>readWindowReset_o, readWindowNext_o=>readWindowNext_o,`
414			`readContentEmpty_i=>readContentEmpty_i, readContent_o=>readContent_o,`
415	11	magro732	`readContentEnd_i=>readContentEnd_i,`
416			`readContentWords_i=>readContentData_i(2+(32NUMBER_WORDS-1) downto 1+(32NUMBER_WORDS-1)),`
417			`readContentData_i=>readContentData_i(32*NUMBER_WORDS-1 downto 0));`
418	4	magro732
419	11	magro732	`SymbolFifo: for i in 0 to NUMBER_WORDS-1 generate`
420			`TxSymbolFifo: RioFifo1`
421			`generic map(WIDTH=>13)`
422			`port map(`
423			`clk=>clk, areset_n=>areset_n,`
424			`empty_o=>txControlReadEmpty(i),`
425			`read_i=>txControlRead(i),`
426			`data_o=>txControlReadSymbol(12(i+1) downto 12i),`
427			`full_o=>open,`
428			`write_i=>txControlWrite(i),`
429			`data_i=>txControlWriteSymbol(12(i+1) downto 12i));`
430	4	magro732
431	11	magro732	`RxSymbolFifo: RioFifo1`
432			`generic map(WIDTH=>13)`
433			`port map(`
434			`clk=>clk, areset_n=>areset_n,`
435			`empty_o=>rxControlReadEmpty(i),`
436			`read_i=>rxControlRead(i),`
437			`data_o=>rxControlReadSymbol(12(i+1) downto 12i),`
438			`full_o=>open,`
439			`write_i=>rxControlWrite(i),`
440			`data_i=>rxControlWriteSymbol(12(i+1) downto 12i));`
441			`end generate;`
442
443	4	magro732	`Receiver: RioReceiver`
444	11	magro732	`generic map(NUMBER_WORDS=>NUMBER_WORDS)`
445	4	magro732	`port map(`
446			`clk=>clk, areset_n=>areset_n,`
447			`portEnable_i=>inputPortEnable_i,`
448			`localAckIdWrite_i=>localAckIdWrite_i,`
449			`inboundAckId_i=>inboundAckId_i,`
450			`inboundAckId_o=>inboundAckId_o,`
451			`portInitialized_i=>portInitialized_i,`
452			`rxEmpty_i=>inboundEmpty, rxRead_o=>inboundRead,`
453	11	magro732	`rxType_i=>inboundType, rxData_i=>inboundData,`
454	4	magro732	`txControlWrite_o=>txControlWrite, txControlSymbol_o=>txControlWriteSymbol,`
455			`rxControlWrite_o=>rxControlWrite, rxControlSymbol_o=>rxControlWriteSymbol,`
456			`ackIdStatus_o=>ackIdStatus,`
457			`linkInitialized_o=>linkInitializedRx,`
458			`writeFrameFull_i=>writeFrameFull_i,`
459			`writeFrame_o=>writeFrame_o, writeFrameAbort_o=>writeFrameAbort_o,`
460	11	magro732	`writeContent_o=>writeContent_o,`
461			`writeContentWords_o=>writeContentData_o(2+(32NUMBER_WORDS-1) downto 1+(32NUMBER_WORDS-1)),`
462			`writeContentData_o=>writeContentData_o(32*NUMBER_WORDS-1 downto 0));`
463	4	magro732
464			`-----------------------------------------------------------------------------`
465			`-- PCS layer FIFO interface.`
466			`-----------------------------------------------------------------------------`
467
468	11	magro732	`outboundSymbol <= outboundType & outboundData;`
469	4	magro732	`OutboundSymbolFifo: RioFifo1`
470	11	magro732	`generic map(WIDTH=>2+32*NUMBER_WORDS)`
471	4	magro732	`port map(`
472			`clk=>clk, areset_n=>areset_n,`
473			`empty_o=>outboundSymbolEmpty_o, read_i=>outboundSymbolRead_i, data_o=>outboundSymbol_o,`
474			`full_o=>outboundFull, write_i=>outboundWrite, data_i=>outboundSymbol);`
475
476	11	magro732	`inboundType <= inboundSymbol(2+(32NUMBER_WORDS-1) downto 1+(32NUMBER_WORDS-1));`
477			`inboundData <= inboundSymbol(32*NUMBER_WORDS-1 downto 0);`
478	4	magro732	`InboundSymbolFifo: RioFifo1`
479	11	magro732	`generic map(WIDTH=>2+32*NUMBER_WORDS)`
480	4	magro732	`port map(`
481			`clk=>clk, areset_n=>areset_n,`
482			`empty_o=>inboundEmpty, read_i=>inboundRead, data_o=>inboundSymbol,`
483			`full_o=>inboundSymbolFull_o, write_i=>inboundSymbolWrite_i, data_i=>inboundSymbol_i);`
484
485			`end architecture;`
486
487
488
489			`-------------------------------------------------------------------------------`
490			`-- RioTransmitter`
491			`-------------------------------------------------------------------------------`
492			`library ieee;`
493			`use ieee.std_logic_1164.all;`
494			`use ieee.numeric_std.all;`
495			`use work.rio_common.all;`
496
497
498			`-------------------------------------------------------------------------------`
499			`-- Entity for RioTransmitter.`
500			`-------------------------------------------------------------------------------`

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