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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 -- -- clk - System clock. -- areset_n - System reset. Asynchronous, active low. -- -- 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. -- outboundSymbol_o - The outbound symbol. The two MSB bits are the type of the -- symbol. -- bit 34-33 -- 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 symbol data. -- 10=ERROR, the rest of the bits are not used. -- 11=DATA, all the remaining bits contain the data-symbol payload. -- 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); 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(31 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(31 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(33 downto 0); inboundSymbolFull_o : out std_logic; inboundSymbolWrite_i : in std_logic; inboundSymbol_i : in std_logic_vector(33 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); 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; txControl_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; readContentData_i : in std_logic_vector(31 downto 0)); end component; component RioReceiver is 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; rxControl_i : in std_logic_vector(1 downto 0); rxData_i : in std_logic_vector(31 downto 0); txControlWrite_o : out std_logic; txControlSymbol_o : out std_logic_vector(12 downto 0); rxControlWrite_o : out std_logic; rxControlSymbol_o : out std_logic_vector(12 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; writeContentData_o : out std_logic_vector(31 downto 0)); end component; signal linkInitializedRx : std_logic; signal linkInitializedTx : std_logic; signal ackIdStatus : std_logic_vector(4 downto 0); signal txControlWrite : std_logic; signal txControlWriteSymbol : std_logic_vector(12 downto 0); signal txControlReadEmpty : std_logic; signal txControlRead : std_logic; signal txControlReadSymbol : std_logic_vector(12 downto 0); signal rxControlWrite : std_logic; signal rxControlWriteSymbol : std_logic_vector(12 downto 0); signal rxControlReadEmpty : std_logic; signal rxControlRead : std_logic; signal rxControlReadSymbol : std_logic_vector(12 downto 0); signal outboundFull : std_logic; signal outboundWrite : std_logic; signal outboundControl : std_logic_vector(1 downto 0); signal outboundData : std_logic_vector(31 downto 0); signal outboundSymbol : std_logic_vector(33 downto 0); signal inboundEmpty : std_logic; signal inboundRead : std_logic; signal inboundControl : std_logic_vector(1 downto 0); signal inboundData : std_logic_vector(31 downto 0); signal inboundSymbol : std_logic_vector(33 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) 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, txControl_o=>outboundControl, txData_o=>outboundData, txControlEmpty_i=>txControlReadEmpty, txControlSymbol_i=>txControlReadSymbol, txControlUpdate_o=>txControlRead, rxControlEmpty_i=>rxControlReadEmpty, rxControlSymbol_i=>rxControlReadSymbol, rxControlUpdate_o=>rxControlRead, 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, readContentData_i=>readContentData_i); TxSymbolFifo: RioFifo1 generic map(WIDTH=>13) port map( clk=>clk, areset_n=>areset_n, empty_o=>txControlReadEmpty, read_i=>txControlRead, data_o=>txControlReadSymbol, full_o=>open, write_i=>txControlWrite, data_i=>txControlWriteSymbol); RxSymbolFifo: RioFifo1 generic map(WIDTH=>13) port map( clk=>clk, areset_n=>areset_n, empty_o=>rxControlReadEmpty, read_i=>rxControlRead, data_o=>rxControlReadSymbol, full_o=>open, write_i=>rxControlWrite, data_i=>rxControlWriteSymbol); Receiver: RioReceiver 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, rxControl_i=>inboundControl, 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, writeContentData_o=>writeContentData_o); ----------------------------------------------------------------------------- -- PCS layer FIFO interface. ----------------------------------------------------------------------------- outboundSymbol <= outboundControl & outboundData; OutboundSymbolFifo: RioFifo1 generic map(WIDTH=>34) 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); inboundControl <= inboundSymbol(33 downto 32); inboundData <= inboundSymbol(31 downto 0); InboundSymbolFifo: RioFifo1 generic map(WIDTH=>34) 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); 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; txControl_o : out std_logic_vector(1 downto 0); txData_o : out std_logic_vector(31 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; readContentData_i : in std_logic_vector(31 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 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; component Crc5ITU is port( d_i : in std_logic_vector(18 downto 0); crc_o : out std_logic_vector(4 downto 0)); end component; type StateType is (STATE_UNINITIALIZED, STATE_PORT_INITIALIZED, STATE_NORMAL, STATE_OUTPUT_RETRY_STOPPED, STATE_SEND_LINK_REQUEST, STATE_OUTPUT_ERROR_STOPPED, STATE_RECOVER, STATE_FATAL_ERROR); signal stateCurrent, stateNext : StateType; signal statusReceivedCurrent, statusReceivedNext : std_logic; signal counterCurrent, counterNext : natural range 0 to 15; signal symbolsTransmittedCurrent, symbolsTransmittedNext : natural range 0 to 255; type FrameStateType is (FRAME_START, FRAME_CHECK, FRAME_ACKID, FRAME_BODY, FRAME_END); signal frameStateCurrent, frameStateNext : FrameStateType; signal ackIdCurrent, ackIdNext : unsigned(4 downto 0) := (others=>'0'); signal ackIdWindowCurrent, ackIdWindowNext : unsigned(4 downto 0) := (others=>'0'); signal bufferStatusCurrent, bufferStatusNext : std_logic_vector(4 downto 0); signal stype0 : std_logic_vector(2 downto 0); signal parameter0 : std_logic_vector(4 downto 0); signal parameter1 : std_logic_vector(4 downto 0); signal stype1 : std_logic_vector(2 downto 0); signal cmd : std_logic_vector(2 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); signal symbolWrite : std_logic; signal symbolType : std_logic_vector(1 downto 0); signal symbolControl : std_logic_vector(31 downto 0); signal symbolData : std_logic_vector(31 downto 0); signal crcCalculated : std_logic_vector(4 downto 0); signal timeoutWrite : std_logic; signal timeoutCounter : unsigned(TIMEOUT_WIDTH downto 0); signal timeoutFrame : unsigned(TIMEOUT_WIDTH downto 0); signal timeoutElapsed : unsigned(TIMEOUT_WIDTH downto 0); signal timeoutDelta : unsigned(TIMEOUT_WIDTH downto 0); signal timeoutExpired : std_logic; signal timeoutAddress : std_logic_vector(4 downto 0); signal timeoutMemoryOut : std_logic_vector(TIMEOUT_WIDTH downto 0); begin linkInitialized_o <= '0' when ((stateCurrent = STATE_UNINITIALIZED) or (stateCurrent = STATE_PORT_INITIALIZED)) else '1'; ----------------------------------------------------------------------------- -- 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); ----------------------------------------------------------------------------- -- Outbound symbol creation logic. ----------------------------------------------------------------------------- symbolControl(31 downto 29) <= stype0; symbolControl(28 downto 24) <= parameter0; symbolControl(23 downto 19) <= parameter1; symbolControl(18 downto 16) <= stype1; symbolControl(15 downto 13) <= cmd; symbolControl(12 downto 8) <= crcCalculated; symbolControl(7 downto 0) <= x"00"; Crc5Calculator: Crc5ITU port map( d_i=>symbolControl(31 downto 13), crc_o=>crcCalculated); txWrite_o <= symbolWrite; txControl_o <= symbolType; txData_o <= symbolControl when (symbolType = SYMBOL_CONTROL) else symbolData; ----------------------------------------------------------------------------- -- Packet timeout logic. ----------------------------------------------------------------------------- -- Note that the timer is one bit larger to be able to detect a timeout on a -- free-running counter. process(areset_n, clk) begin if (areset_n = '0') then timeoutCounter <= (others=>'0'); elsif (clk'event and clk = '1') then timeoutCounter <= timeoutCounter + 1; end if; end process; timeoutElapsed <= timeoutCounter - timeoutFrame; timeoutDelta <= unsigned('0' & portLinkTimeout_i) - timeoutElapsed; timeoutExpired <= timeoutDelta(TIMEOUT_WIDTH); timeoutFrame <= unsigned(timeoutMemoryOut); TimeoutMemory: MemorySimpleDualPortAsync generic map(ADDRESS_WIDTH=>5, DATA_WIDTH=>TIMEOUT_WIDTH+1, INIT_VALUE=>'0') port map( clkA_i=>clk, enableA_i=>timeoutWrite, addressA_i=>timeoutAddress, dataA_i=>std_logic_vector(timeoutCounter), addressB_i=>std_logic_vector(ackIdCurrent), dataB_o=>timeoutMemoryOut); ----------------------------------------------------------------------------- -- Main outbound symbol handler, synchronous part. ----------------------------------------------------------------------------- process(areset_n, clk) begin if (areset_n = '0') then stateCurrent <= STATE_UNINITIALIZED; statusReceivedCurrent <= '0'; counterCurrent <= 0; symbolsTransmittedCurrent <= 0; frameStateCurrent <= FRAME_START; ackIdCurrent <= (others => '0'); ackIdWindowCurrent <= (others => '0'); bufferStatusCurrent <= (others => '0'); elsif (clk'event and clk = '1') then stateCurrent <= stateNext; statusReceivedCurrent <= statusReceivedNext; counterCurrent <= counterNext; symbolsTransmittedCurrent <= symbolsTransmittedNext; frameStateCurrent <= frameStateNext; ackIdCurrent <= ackIdNext; ackIdWindowCurrent <= ackIdWindowNext; bufferStatusCurrent <= bufferStatusNext; end if; end process; ----------------------------------------------------------------------------- -- Main outbound symbol handler, combinatorial part. ----------------------------------------------------------------------------- process(stateCurrent, statusReceivedCurrent, counterCurrent, symbolsTransmittedCurrent, frameStateCurrent, ackIdCurrent, ackIdWindowCurrent, bufferStatusCurrent, txControlStype0, txControlParameter0, txControlParameter1, rxControlStype0, rxControlParameter0, rxControlParameter1, portEnable_i, localAckIdWrite_i, clrOutstandingAckId_i, outstandingAckId_i, outboundAckId_i, txFull_i, txControlEmpty_i, txControlSymbol_i, rxControlEmpty_i, rxControlSymbol_i, portInitialized_i, linkInitialized_i, ackIdStatus_i, readFrameEmpty_i, readFrameAborted_i, readWindowEmpty_i, readContentEmpty_i, readContentEnd_i, readContentData_i, timeoutExpired) begin stateNext <= stateCurrent; statusReceivedNext <= statusReceivedCurrent; counterNext <= counterCurrent; symbolsTransmittedNext <= symbolsTransmittedCurrent; frameStateNext <= frameStateCurrent; ackIdNext <= ackIdCurrent; ackIdWindowNext <= ackIdWindowCurrent; bufferStatusNext <= bufferStatusCurrent; txControlUpdate_o <= '0'; rxControlUpdate_o <= '0'; readFrame_o <= '0'; readFrameRestart_o <= '0'; readWindowReset_o <= '0'; readWindowNext_o <= '0'; readContent_o <= '0'; symbolWrite <= '0'; symbolType <= (others=>'U'); stype0 <= (others=>'U'); parameter0 <= (others=>'U'); parameter1 <= (others=>'U'); stype1 <= (others=>'U'); cmd <= (others=>'U'); symbolData <= (others=>'U'); timeoutWrite <= '0'; timeoutAddress <= (others=>'U'); outstandingAckId_o <= std_logic_vector(ackIdCurrent); outboundAckId_o <= std_logic_vector(ackIdWindowCurrent); -- Check if a localAckIdWrite is active. if (localAckIdWrite_i = '1') then -- A localAckIdWrite is active. -- Check if all outstanding packets should be discarded. if (clrOutstandingAckId_i = '1') then -- Delete all outbound packets. -- REMARK: Remove all packets in another way... what if uninitialized??? stateNext <= STATE_RECOVER; end if; -- Set ackIds. ackIdNext <= unsigned(outstandingAckId_i); ackIdWindowNext <= unsigned(outboundAckId_i); else -- A localAckIdWrite is not active. -- Act on the current state. case (stateCurrent) is when STATE_UNINITIALIZED => ----------------------------------------------------------------------- -- 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 = '0') then -- Port not initialized. -- Check if any new symbols from the link partner has been received. if (txControlEmpty_i = '0') then -- New symbols have been received. -- Discard all new symbols in this state. txControlUpdate_o <= '1'; else -- No new symbols from the link partner. -- Dont do anything. end if; -- Check if any new symbols should be transmitted to the link partner. if (rxControlEmpty_i = '0') then -- New symbols should be transmitted. -- Do not forward any symbols in this state. rxControlUpdate_o <= '1'; else -- No new symbols to transmit. -- Dont do anything. end if; -- Check if a new symbol should be transmitted. if (txFull_i = '0') then -- A new symbol should be transmitted. -- Send idle sequence. symbolWrite <= '1'; symbolType <= SYMBOL_IDLE; else -- The outbound fifo is full. -- Dont do anything. end if; -- Check if a new full packet is ready. if (readFrameEmpty_i = '0') then -- A new full packet is ready. -- It is not possible to send the packet now. If the packet is not -- discarded it might congest the full system if the link does not -- go initialized. To avoid a congested switch, the packet is -- discarded and will have to be resent by the source when the link -- is up and running. readFrame_o <= '1'; else -- No new full packets are ready. -- Dont do anything. end if; else -- Port is initialized. -- Go to the initialized state and reset the counters. statusReceivedNext <= '0'; counterNext <= NUMBER_STATUS_TRANSMIT; symbolsTransmittedNext <= 0; stateNext <= STATE_PORT_INITIALIZED; end if; when STATE_PORT_INITIALIZED => ----------------------------------------------------------------------- -- 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 the port is initialized. if (portInitialized_i = '1') then -- Port is initialized. -- Check if we are ready to change state to linkInitialized. if ((linkInitialized_i = '1') and (counterCurrent = 0)) then -- Receiver has received enough error free status symbols and we have -- transmitted enough. -- Initialize framing before entering the normal state. ackIdWindowNext <= ackIdCurrent; frameStateNext <= FRAME_START; readWindowReset_o <= '1'; -- Considder the link initialized. stateNext <= STATE_NORMAL; else -- Not ready to change state to linkInitialized. -- Dont do anything. end if; -- Check if any new symbols from the link partner has been received. if (txControlEmpty_i = '0') then -- New symbols have been received. -- Check if the new symbol is a status. if (txControlStype0 = STYPE0_STATUS) then -- A new status control symbol has been received. statusReceivedNext <= '1'; -- Set the ackId and the linkpartner buffer status to what is indicated -- in the received control symbol. ackIdNext <= unsigned(txControlParameter0); bufferStatusNext <= txControlParameter1; else -- Did not receive a status control symbol. -- Discard it. end if; -- Update to the next control symbol received by the receiver. txControlUpdate_o <= '1'; else -- No new symbols from the link partner. -- Dont do anything. end if; -- Check if any new symbols should be transmitted to the link partner. if (rxControlEmpty_i = '0') then -- New symbols should be transmitted. -- Do not forward any symbols in this state. rxControlUpdate_o <= '1'; else -- No new symbols to transmit. -- Dont do anything. end if; -- Check if a new symbol may be transmitted. if (txFull_i = '0') then -- A new symbol can be transmitted. -- Check if idle sequence or a status symbol should be transmitted. if (((statusReceivedCurrent = '0') and (symbolsTransmittedCurrent = 255)) or ((statusReceivedCurrent = '1') and (symbolsTransmittedCurrent > 15))) then -- A status symbol should be transmitted. -- Send a status control symbol to the link partner. symbolWrite <= '1'; symbolType <= SYMBOL_CONTROL; stype0 <= STYPE0_STATUS; parameter0 <= ackIdStatus_i; parameter1 <= "11111"; stype1 <= STYPE1_NOP; cmd <= "000"; -- Reset idle sequence transmission counter. symbolsTransmittedNext <= 0; -- Check if the number of transmitted statuses should be updated. if (statusReceivedCurrent = '1') and (counterCurrent /= 0) then counterNext <= counterCurrent - 1; end if; else -- A idle sequence should be transmitted. symbolWrite <= '1'; symbolType <= SYMBOL_IDLE; -- Increment the idle sequence transmission counter. symbolsTransmittedNext <= symbolsTransmittedCurrent + 1; end if; else -- Cannot send a new symbol. -- Dont do anything. end if; else -- Go back to the uninitialized state. stateNext <= STATE_UNINITIALIZED; end if; when STATE_NORMAL => ------------------------------------------------------------------- -- This state is the normal state. It relays frames and handle flow -- control. ------------------------------------------------------------------- -- Check that both the port and link is initialized. if (portInitialized_i = '1') and (linkInitialized_i = '1') then -- The port and link is initialized. -- 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 => -- Save the number of buffers in the link partner. bufferStatusNext <= txControlParameter1; when STYPE0_PACKET_ACCEPTED => -- The link partner is accepting a frame. -- Save the number of buffers in the link partner. bufferStatusNext <= txControlParameter1; -- Check if expecting this type of reply and that the ackId is -- expected. if ((ackIdCurrent /= ackIdWindowCurrent) and (ackIdCurrent = unsigned(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. readFrame_o <= '1'; ackIdNext <= ackIdCurrent + 1; else -- Unexpected packet-accepted or packet-accepted for -- unexpected ackId. counterNext <= NUMBER_LINK_RESPONSE_RETRIES; stateNext <= STATE_SEND_LINK_REQUEST; end if; when STYPE0_PACKET_RETRY => -- The link partner has asked for a frame retransmission. -- Save the number of buffers in the link partner. bufferStatusNext <= txControlParameter1; -- Check if the ackId is the one expected. if (ackIdCurrent = unsigned(txControlParameter0)) then -- The ackId to retry is expected. -- Go to the output-retry-stopped state. stateNext <= STATE_OUTPUT_RETRY_STOPPED; else -- Unexpected ackId to retry. counterNext <= NUMBER_LINK_RESPONSE_RETRIES; stateNext <= STATE_SEND_LINK_REQUEST; end if; when STYPE0_PACKET_NOT_ACCEPTED => -- Packet was rejected by the link-partner. -- REMARK: Indicate that this has happened to the outside... counterNext <= NUMBER_LINK_RESPONSE_RETRIES; stateNext <= STATE_SEND_LINK_REQUEST; when STYPE0_LINK_RESPONSE => -- Dont expect or need a link-response in this state. -- Discard it. 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. txControlUpdate_o <= '1'; else -- No control symbol has been received. -- Check if the oldest frame timeout has expired. if ((ackIdCurrent /= ackIdWindowCurrent) and (timeoutExpired = '1')) then -- There has been a timeout on a transmitted frame. -- Send link-request. counterNext <= NUMBER_LINK_RESPONSE_RETRIES; stateNext <= STATE_SEND_LINK_REQUEST; else -- There has been no timeout. -- Check if the outbound fifo needs new data. if (txFull_i = '0') then -- There is room available in the outbound FIFO. -- Check if there are any events from the receiver. if (rxControlEmpty_i = '0') then -- A symbol from the receiver should be transmitted. -- Send the receiver symbol and a NOP. -- REMARK: Combine this symbol with an STYPE1 to more effectivly -- utilize the link. symbolWrite <= '1'; symbolType <= SYMBOL_CONTROL; stype0 <= rxControlStype0; parameter0 <= rxControlParameter0; parameter1 <= rxControlParameter1; stype1 <= STYPE1_NOP; cmd <= "000"; -- Remove the symbol from the fifo. rxControlUpdate_o <= '1'; -- 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. symbolsTransmittedNext <= 0; else -- A symbol not containing the bufferStatus has been sent. -- REMARK: symbolsTransmitted might overflow... symbolsTransmittedNext <= symbolsTransmittedCurrent + 1; end if; else -- No events from the receiver. -- Check if a status symbol must be sent. if (symbolsTransmittedCurrent = 255) then -- A status symbol must be sent. -- Reset the number of transmitted symbols between statuses. symbolsTransmittedNext <= 0; -- Send status. symbolWrite <= '1'; symbolType <= SYMBOL_CONTROL; stype0 <= STYPE0_STATUS; parameter0 <= ackIdStatus_i; parameter1 <= "11111"; stype1 <= STYPE1_NOP; cmd <= "000"; else -- A status symbol does not have to be sent. -- Check if a frame transfer is in progress. case frameStateCurrent is when FRAME_START => --------------------------------------------------------------- -- No frame has been started. --------------------------------------------------------------- -- Wait for a new frame to arrive from the frame buffer, -- for new buffers to be available at the link-partner -- and also check that a maximum 31 frames are outstanding. if ((readWindowEmpty_i = '0') and (bufferStatusCurrent /= "00000") and ((ackIdWindowCurrent - ackIdCurrent) /= 31)) then -- New data is available for transmission and there -- is room to receive it at the other side. -- Indicate that a control symbol has been sent to start the -- transmission of the frame. frameStateNext <= FRAME_CHECK; -- Update the output from the frame buffer to contain the -- data when it is read later. readContent_o <= '1'; else -- There are no frame data to send or the link partner has -- no available buffers. -- Send idle-sequence. symbolWrite <= '1'; symbolType <= SYMBOL_IDLE; -- A symbol not containing the buffer status has been sent. symbolsTransmittedNext <= symbolsTransmittedCurrent + 1; end if; when FRAME_CHECK => ------------------------------------------------------- -- Check if we are allowed to transmit this packet. ------------------------------------------------------- -- Check if this packet is allowed to be transmitted. if ((portEnable_i = '1') or (readContentData_i(19 downto 16) = FTYPE_MAINTENANCE_CLASS)) then -- The packet may be transmitted. -- Indicate that a control symbol has been sent to start the -- transmission of the frame. frameStateNext <= FRAME_ACKID; -- Send a control symbol to start the packet and a status to complete -- the symbol. symbolWrite <= '1'; symbolType <= SYMBOL_CONTROL; stype0 <= STYPE0_STATUS; parameter0 <= ackIdStatus_i; parameter1 <= "11111"; stype1 <= STYPE1_START_OF_PACKET; cmd <= "000"; -- A symbol containing the bufferStatus has been sent. symbolsTransmittedNext <= 0; else -- The packet should be discarded. -- Check that there are no outstanding packets that -- has not been acknowledged. if(ackIdWindowCurrent /= ackIdCurrent) then -- There are packets that has not been acknowledged. -- Send idle-sequence. symbolWrite <= '1'; symbolType <= SYMBOL_IDLE; -- A symbol not containing the buffer status has been sent. symbolsTransmittedNext <= symbolsTransmittedCurrent + 1; else -- No unacknowledged packets. -- It is now safe to remove the unallowed frame. readFrame_o <= '1'; -- Go back and send a new frame. frameStateNext <= FRAME_START; end if; end if; when FRAME_ACKID => --------------------------------------------------------------- -- Send the first packet content containing our current -- ackId. --------------------------------------------------------------- -- Write a new data symbol and fill in our ackId on the -- packet. symbolWrite <= '1'; symbolType <= SYMBOL_DATA; symbolData <= std_logic_vector(ackIdWindowCurrent) & "0" & readContentData_i(25 downto 0); -- Continue to send the rest of the body of the packet. readContent_o <= '1'; frameStateNext <= FRAME_BODY; -- A symbol not containing the buffer status has been sent. symbolsTransmittedNext <= symbolsTransmittedCurrent + 1; when FRAME_BODY => --------------------------------------------------------------- -- The frame has not been fully sent. -- Send a data symbol. --------------------------------------------------------------- -- REMARK: Add support for partial frames... -- Check if the frame is ending. if (readContentEnd_i = '0') then -- The frame is not ending. -- Write a new data symbol. symbolWrite <= '1'; symbolType <= SYMBOL_DATA; symbolData <= readContentData_i; -- Continue to send the rest of the body of the packet. readContent_o <= '1'; -- A symbol not containing the buffer status has been sent. symbolsTransmittedNext <= symbolsTransmittedCurrent + 1; else -- 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. readWindowNext_o <= '1'; -- Proceed to check if there is another frame to start -- with directly. frameStateNext <= FRAME_END; end if; when FRAME_END => --------------------------------------------------------------- -- 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. --------------------------------------------------------------- -- Check if there is a new frame pending. if (readWindowEmpty_i = '1') then -- No new frame is pending. -- Send a control symbol to end the packet. symbolWrite <= '1'; symbolType <= SYMBOL_CONTROL; stype0 <= STYPE0_STATUS; parameter0 <= ackIdStatus_i; parameter1 <= "11111"; stype1 <= STYPE1_END_OF_PACKET; cmd <= "000"; -- A symbol containing the bufferStatus has been sent. symbolsTransmittedNext <= 0; end if; -- Update the window ackId. ackIdWindowNext <= ackIdWindowCurrent + 1; -- Start timeout supervision for transmitted frame. timeoutWrite <= '1'; timeoutAddress <= std_logic_vector(ackIdWindowCurrent); -- Start a new frame the next time. frameStateNext <= FRAME_START; when others => --------------------------------------------------------------- -- --------------------------------------------------------------- null; end case; end if; end if; else -- Wait for new storage in the transmission FIFO to become -- available. -- Dont do anything. end if; end if; end if; else -- The port or the link has become uninitialized. -- Go back to the uninitialized state. stateNext <= STATE_UNINITIALIZED; end if; when STATE_OUTPUT_RETRY_STOPPED => ----------------------------------------------------------------------- -- This is the output-retry-stopped state described in 5.9.1.5. ----------------------------------------------------------------------- -- Check if the outbound fifo needs new data. if (txFull_i = '0') then -- There is room available in the outbound FIFO. -- Send a restart-from-retry control symbol to acknowledge the restart -- of the frame. symbolWrite <= '1'; symbolType <= SYMBOL_CONTROL; stype0 <= STYPE0_STATUS; parameter0 <= ackIdStatus_i; parameter1 <= "11111"; stype1 <= STYPE1_RESTART_FROM_RETRY; cmd <= "000"; -- Make sure there wont be any timeout before the frame is -- starting to be retransmitted. timeoutWrite <= '1'; timeoutAddress <= std_logic_vector(ackIdCurrent); -- Restart the frame transmission. ackIdWindowNext <= ackIdCurrent; frameStateNext <= FRAME_START; readWindowReset_o <= '1'; -- Proceed back to the normal state. stateNext <= STATE_NORMAL; -- A symbol containing the bufferStatus has been sent. symbolsTransmittedNext <= 0; end if; when STATE_SEND_LINK_REQUEST => ----------------------------------------------------------------------- -- Send a link-request symbol when the transmission fifo is ready. Then -- always proceed to the output-error-state. ----------------------------------------------------------------------- -- Check if the outbound fifo needs new data. if (txFull_i = '0') then -- There is room available in the outbound FIFO. -- Send a link-request symbol. symbolWrite <= '1'; symbolType <= SYMBOL_CONTROL; stype0 <= STYPE0_STATUS; parameter0 <= ackIdStatus_i; parameter1 <= "11111"; stype1 <= STYPE1_LINK_REQUEST; cmd <= LINK_REQUEST_CMD_INPUT_STATUS; -- Write the current timer value. timeoutWrite <= '1'; timeoutAddress <= std_logic_vector(ackIdCurrent); -- Proceed to the output-error-stopped state. stateNext <= STATE_OUTPUT_ERROR_STOPPED; -- A symbol containing the bufferStatus has been sent. symbolsTransmittedNext <= 0; end if; when STATE_OUTPUT_ERROR_STOPPED => ------------------------------------------------------------------- -- This state is the error stopped state described in 5.13.2.7. ------------------------------------------------------------------- -- Check that both the port and link is initialized. if (portInitialized_i = '1') and (linkInitialized_i = '1') then -- The port and link is initialized. -- 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_PACKET_ACCEPTED => -- Wait for a link-response. -- Discard these. when STYPE0_PACKET_RETRY => -- Wait for a link-response. -- Discard these. when STYPE0_PACKET_NOT_ACCEPTED => -- Wait for a link-response. -- Discard these. when STYPE0_STATUS => -- Wait for a link-response. -- Discard these. when STYPE0_LINK_RESPONSE => -- Check if the link partner return value is acceptable. if ((unsigned(txControlParameter0) - ackIdCurrent) <= (ackIdWindowCurrent - ackIdCurrent)) then -- Recoverable error. -- Use the received ackId and recover by removing packets -- that were received by the link-partner. ackIdWindowNext <= unsigned(txControlParameter0); stateNext <= STATE_RECOVER; else -- Totally out of sync. stateNext <= STATE_FATAL_ERROR; end if; when STYPE0_VC_STATUS => -- Not supported. when STYPE0_RESERVED => -- Not supported. when STYPE0_IMPLEMENTATION_DEFINED => -- Not supported. when others => null; end case; -- Indicate the control symbol has been processed. txControlUpdate_o <= '1'; else -- No control symbol has been received. -- Check if the timeout for a link-response has expired. if (timeoutExpired = '1') then -- There was no reply on the link-request. -- Count the number of retransmissions and abort if -- no reply has been received for too many times. if (counterCurrent /= 0) then -- Not sent link-request too many times. -- Send another link-request. counterNext <= counterCurrent - 1; stateNext <= STATE_SEND_LINK_REQUEST; else -- No response for too many times. stateNext <= STATE_FATAL_ERROR; end if; else -- There has been no timeout. -- Check if the outbound fifo needs new data. if (txFull_i = '0') then -- There is room available in the outbound FIFO. -- Check if there are any events from the receiver. if (rxControlEmpty_i = '0') then -- A symbol from the receiver should be transmitted. -- Send the receiver symbol and a NOP. symbolWrite <= '1'; symbolType <= SYMBOL_CONTROL; stype0 <= rxControlStype0; parameter0 <= rxControlParameter0; parameter1 <= rxControlParameter1; stype1 <= STYPE1_NOP; cmd <= "000"; -- Remove the symbol from the fifo. rxControlUpdate_o <= '1'; -- Check if the transmitted symbol contains status about -- available buffers. -- The receiver never send any status so that does not have -- to be checked. if ((rxControlStype0 = STYPE0_PACKET_ACCEPTED) or (rxControlStype0 = STYPE0_PACKET_RETRY)) then -- A symbol containing the bufferStatus has been sent. symbolsTransmittedNext <= 0; else -- A symbol not containing the buffer status has been sent. symbolsTransmittedNext <= symbolsTransmittedCurrent + 1; end if; else -- No events from the receiver. -- There are no frame data to send or the link partner has -- no available buffers. -- Check if a status symbol must be sent. if (symbolsTransmittedCurrent = 255) then -- A status symbol must be sent. -- Reset the number of transmitted symbols between statuses. symbolsTransmittedNext <= 0; -- Send status. symbolWrite <= '1'; symbolType <= SYMBOL_CONTROL; stype0 <= STYPE0_STATUS; parameter0 <= ackIdStatus_i; parameter1 <= "11111"; stype1 <= STYPE1_NOP; cmd <= "000"; else -- A status symbol does not have to be sent. -- Send idle-sequence. symbolWrite <= '1'; symbolType <= SYMBOL_IDLE; -- A symbol not containing the buffer status has been sent. symbolsTransmittedNext <= symbolsTransmittedCurrent + 1; end if; end if; else -- Wait for new storage in the transmission FIFO to become -- available. -- Dont do anything. end if; end if; end if; else -- The port or the link has become uninitialized. -- Go back to the uninitialized state. stateNext <= STATE_UNINITIALIZED; end if; when STATE_RECOVER => ----------------------------------------------------------------------- -- A recoverable error condition has occurred. -- When this state is entered, ackIdWindow should contain the ackId to -- proceed with. ----------------------------------------------------------------------- -- Check if the expected ackId has incremented enough. if (ackIdCurrent /= ackIdWindowCurrent) then -- Remove this frame. It has been received by the link-partner. readFrame_o <= '1'; ackIdNext <= ackIdCurrent + 1; else -- Keep this frame. -- Restart the window and the frame transmission. frameStateNext <= FRAME_START; readWindowReset_o <= '1'; stateNext <= STATE_NORMAL; end if; when STATE_FATAL_ERROR => ----------------------------------------------------------------------- -- A fatal error condition has occurred. ----------------------------------------------------------------------- -- Reset the window and resynchronize the link. -- REMARK: Count these situations... -- REMARK: Do something else here??? readWindowReset_o <= '1'; stateNext <= STATE_UNINITIALIZED; when others => ------------------------------------------------------------------- -- ------------------------------------------------------------------- null; end case; 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 port( clk : in std_logic; areset_n : in std_logic; -- Status signals used for maintenance. portEnable_i : in std_logic; -- Support for localAckIdCSR. 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; rxControl_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; -- Frame buffering 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(31 downto 0)); end entity; ------------------------------------------------------------------------------- -- ------------------------------------------------------------------------------- architecture RioReceiverImpl of RioReceiver 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; type StateType is (STATE_UNINITIALIZED, STATE_PORT_INITIALIZED, STATE_NORMAL, STATE_INPUT_RETRY_STOPPED, STATE_INPUT_ERROR_STOPPED); signal state : StateType; signal statusCounter : natural range 0 to 8; signal ackId : unsigned(4 downto 0); signal frameIndex : natural range 0 to 70; signal stype0 : std_logic_vector(2 downto 0); signal parameter0 : std_logic_vector(4 downto 0); signal parameter1 : std_logic_vector(4 downto 0); signal stype1 : std_logic_vector(2 downto 0); signal cmd : std_logic_vector(2 downto 0); signal crc5 : std_logic_vector(4 downto 0); signal crc5Calculated : std_logic_vector(4 downto 0); signal crc16Valid : 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 rxRead : std_logic; begin linkInitialized_o <= '0' when ((state = STATE_UNINITIALIZED) or (state = STATE_PORT_INITIALIZED)) else '1'; ackIdStatus_o <= std_logic_vector(ackId); ----------------------------------------------------------------------------- -- Get the entries in a control symbol. ----------------------------------------------------------------------------- stype0 <= rxData_i(31 downto 29); parameter0 <= rxData_i(28 downto 24); parameter1 <= rxData_i(23 downto 19); stype1 <= rxData_i(18 downto 16); cmd <= rxData_i(15 downto 13); crc5 <= rxData_i(12 downto 8); ----------------------------------------------------------------------------- -- Entity for CRC-5 calculation on control symbols according to the standard. ----------------------------------------------------------------------------- Crc5Calculator: Crc5ITU port map( d_i=>rxData_i(31 downto 13), crc_o=>crc5Calculated); ----------------------------------------------------------------------------- -- Entities for CRC-16 calculation on 32-bit data in frames according to the -- standard. ----------------------------------------------------------------------------- -- If the CRC is correct, there is either zero in crc16Next if no pad exists -- or zero in crc16Temp and crc16Data(15 downto 0). This means that crc16Next -- will always be zero here if the CRC is correct. crc16Valid <= '1' when (crc16Next = x"0000") else '0'; Crc16High: Crc16CITT port map( d_i=>crc16Data(31 downto 16), crc_i=>crc16Current, crc_o=>crc16Temp); Crc16Low: Crc16CITT port map( d_i=>crc16Data(15 downto 0), crc_i=>crc16Temp, crc_o=>crc16Next); ----------------------------------------------------------------------------- -- Main inbound symbol handler. ----------------------------------------------------------------------------- rxRead_o <= rxRead; inboundAckId_o <= std_logic_vector(ackId); process(areset_n, clk) begin if (areset_n = '0') then state <= STATE_UNINITIALIZED; rxRead <= '0'; txControlWrite_o <= '0'; txControlSymbol_o <= (others => '0'); rxControlWrite_o <= '0'; rxControlSymbol_o <= (others => '0'); writeFrame_o <= '0'; writeFrameAbort_o <= '0'; writeContent_o <= '0'; writeContentData_o <= (others => '0'); -- REMARK: Use frameIndex instead of this... statusCounter <= 0; frameIndex <= 0; ackId <= (others => '0'); crc16Current <= (others => '0'); crc16Data <= (others => '0'); elsif (clk'event and clk = '1') then rxRead <= '0'; txControlWrite_o <= '0'; rxControlWrite_o <= '0'; writeFrame_o <= '0'; writeFrameAbort_o <= '0'; writeContent_o <= '0'; -- Check if a locakAckIdWrite is active. if (localAckIdWrite_i = '1') then -- A localAckIdWrite is active. -- Set ackId. ackId <= unsigned(inboundAckId_i); else -- A localAckIdWrite is not active. -- Act on the current state. case state is when STATE_UNINITIALIZED => ----------------------------------------------------------------------- -- This state is entered at startup. A port that is not initialized -- should discard all received symbols. ----------------------------------------------------------------------- -- Check if the port is initialized. if (portInitialized_i = '0') then -- Port not initialized. -- Check if a new symbol is ready to be read. if (rxRead = '0') and (rxEmpty_i = '0') then -- New symbol ready. -- Discard all received symbols in this state. rxRead <= '1'; else -- No new symbol ready to be read. -- Dont do anything. end if; else -- Port is initialized. -- Go to the initialized state and reset the counters. state <= STATE_PORT_INITIALIZED; statusCounter <= 0; end if; when STATE_PORT_INITIALIZED => --------------------------------------------------------------------- -- The port has been initialized and status control symbols are being -- received on the link to check if it is working. Count the number -- of error-free status symbols and considder the link initialized -- 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 a new symbol is ready to be read. if (rxRead = '0') and (rxEmpty_i = '0') then -- There is a new symbol to read. -- Check the type of symbol. if (rxControl_i = SYMBOL_CONTROL) then -- This is a control symbol that is not a packet delimiter. -- Check if the control symbol has a valid checksum. if (crc5Calculated = crc5) then -- The control symbol has a valid checksum. -- Forward the stype0 part of the symbol to the transmitter. txControlWrite_o <= '1'; txControlSymbol_o <= stype0 & parameter0 & parameter1; -- Check the stype0 part if we should count the number of -- error-free status symbols. if (stype0 = STYPE0_STATUS) then -- The symbol is a status. -- Check if enough status symbols have been received. if (statusCounter = 7) then -- Enough status symbols have been received. -- Reset all packets. frameIndex <= 0; writeFrameAbort_o <= '1'; -- Set the link as initialized. state <= STATE_NORMAL; else -- Increase the number of error-free status symbols that -- has been received. statusCounter <= statusCounter + 1; end if; else -- The symbol is not a status. -- Dont do anything. end if; else -- A control symbol with CRC5 error was recevied. statusCounter <= 0; end if; else -- Symbol that is not allowed in this state have been received. -- Discard it. end if; -- Update to the next symbol. rxRead <= '1'; else -- No new symbol ready to be read. -- Dont do anything. end if; else -- Go back to the uninitialized state. state <= STATE_UNINITIALIZED; end if; when STATE_NORMAL => --------------------------------------------------------------------- -- 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 a new symbol is ready to be read. if (rxRead = '0') and (rxEmpty_i = '0') then -- There is a new symbol to read. -- Check the type of symbol. if (rxControl_i = SYMBOL_CONTROL) then -- This is a control symbol with or without a packet delimiter. -- Check if the control symbol has a valid CRC-5. if (crc5Calculated = crc5) then -- The control symbol is correct. -- Forward the stype0 part of the symbol to the transmitter. txControlWrite_o <= '1'; txControlSymbol_o <= stype0 & parameter0 & parameter1; -- Check the stype1 part. case stype1 is when STYPE1_START_OF_PACKET => ------------------------------------------------------------- -- Start the reception of a new frame or end a currently -- ongoing frame. ------------------------------------------------------------- -- Check if a frame has already been started. if (frameIndex /= 0) then -- A frame is already started. -- Complete the last frame and start to ackumulate a new one -- and update the ackId. -- Check the CRC-16 and the length of the received frame. if (crc16Valid = '1') and (frameIndex > 3) then -- The CRC-16 is ok. -- Reset the frame index to indicate the frame is started. frameIndex <= 1; -- Update the frame buffer to indicate that the frame has -- been completly received. writeFrame_o <= '1'; -- Update ackId. ackId <= ackId + 1; -- Send packet-accepted. -- The buffer status is appended by the transmitter -- when sent to get the latest number. rxControlWrite_o <= '1'; rxControlSymbol_o <= STYPE0_PACKET_ACCEPTED & std_logic_vector(ackId) & "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_o <= '1'; rxControlSymbol_o <= STYPE0_PACKET_NOT_ACCEPTED & "00000" & PACKET_NOT_ACCEPTED_CAUSE_PACKET_CRC; state <= STATE_INPUT_ERROR_STOPPED; end if; else -- No frame has been started. -- Reset the frame index to indicate the frame is started. frameIndex <= 1; end if; when STYPE1_END_OF_PACKET => ------------------------------------------------------------- -- End the reception of an old frame. ------------------------------------------------------------- -- Check the CRC-16 and the length of the received frame. if (crc16Valid = '1') and (frameIndex > 3) then -- The CRC-16 is ok. -- Reset frame reception to indicate that no frame is ongoing. frameIndex <= 0; -- Update the frame buffer to indicate that the frame has -- been completly received. writeFrame_o <= '1'; -- Update ackId. ackId <= ackId + 1; -- Send packet-accepted. -- The buffer status is appended by the transmitter -- when sent to get the latest number. rxControlWrite_o <= '1'; rxControlSymbol_o <= STYPE0_PACKET_ACCEPTED & std_logic_vector(ackId) & "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_o <= '1'; rxControlSymbol_o <= STYPE0_PACKET_NOT_ACCEPTED & "00000" & PACKET_NOT_ACCEPTED_CAUSE_PACKET_CRC; state <= STATE_INPUT_ERROR_STOPPED; end if; when STYPE1_STOMP => ------------------------------------------------------------- -- 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_o <= '1'; rxControlSymbol_o <= STYPE0_PACKET_RETRY & std_logic_vector(ackId) & "11111"; -- Enter the input retry-stopped state. state <= STATE_INPUT_RETRY_STOPPED; when STYPE1_RESTART_FROM_RETRY => ------------------------------------------------------------- -- 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_o <= '1'; rxControlSymbol_o <= STYPE0_PACKET_NOT_ACCEPTED & "00000" & PACKET_NOT_ACCEPTED_CAUSE_GENERAL_ERROR; state <= STATE_INPUT_ERROR_STOPPED; when STYPE1_LINK_REQUEST => ------------------------------------------------------------- -- Reply to a LINK-REQUEST. ------------------------------------------------------------- -- Check the command part. if (cmd = "100") then -- Return input port status command. -- This functions as a link-request(restart-from-error) -- control symbol under error situations. -- Send a link response containing an ok reply. rxControlWrite_o <= '1'; rxControlSymbol_o <= STYPE0_LINK_RESPONSE & std_logic_vector(ackId) & "10000"; elsif (cmd = "011") then -- Reset device command. -- Discard this. else -- Unsupported command. -- Discard this. end if; -- Abort the frame and reset frame reception. frameIndex <= 0; writeFrameAbort_o <= '1'; when STYPE1_MULTICAST_EVENT => ------------------------------------------------------------- -- Multicast symbol. ------------------------------------------------------------- -- Discard the symbol. when STYPE1_RESERVED => ------------------------------------------------------------- -- Reserved. ------------------------------------------------------------- -- Not supported, dont do anything. when STYPE1_NOP => ------------------------------------------------------------- -- NOP, no operation. ------------------------------------------------------------- -- Dont do anything. when others => ------------------------------------------------------------- -- ------------------------------------------------------------- -- NOP, no operation, dont do anything. null; end case; else -- The 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_o <= '1'; rxControlSymbol_o <= STYPE0_PACKET_NOT_ACCEPTED & "00000" & PACKET_NOT_ACCEPTED_CAUSE_CONTROL_CRC; state <= STATE_INPUT_ERROR_STOPPED; end if; elsif (rxControl_i = SYMBOL_DATA) then -- This is a data symbol. -- REMARK: Add check for in-the-middle-crc here... -- Check if a frame has been started. -- Index=0 not started -- index=1 started and expecting to receive the first data. -- index=others, the index of the received data. if (frameIndex /= 0) and (frameIndex /= 70) then -- A frame has been started and is not too long. -- Check if the ackId is correct. if (((frameIndex = 1) and (unsigned(rxData_i(31 downto 27)) = ackId)) or (frameIndex /= 1)) then -- This is the first data symbol containing the ackId which -- is matching or receiving the rest of the frame. -- Check if the packet ftype is allowed. -- If the portEnable is deasserted only maintenance -- packets are allowed. if (((frameIndex = 1) and ((portEnable_i = '1') or (rxData_i(19 downto 16) = FTYPE_MAINTENANCE_CLASS))) or (frameIndex /= 1)) then -- The packet is allowed. -- Check if there is buffers available to store the new packet. if(writeFrameFull_i = '0') then -- There is buffering space available to store the new data. -- Write the data to the frame FIFO. writeContent_o <= '1'; writeContentData_o <= rxData_i; -- Increment the number of received data symbols. frameIndex <= frameIndex + 1; -- Update the saved crc result with the output from the CRC calculation. if (frameIndex = 1) then -- Note that the ackId should not be included when the CRC -- is calculated. crc16Data <= "000000" & rxData_i(25 downto 0); crc16Current <= (others => '1'); else crc16Data <= rxData_i; crc16Current <= crc16Next; end if; else -- The packet buffer is full. -- Let the link-partner resend the packet. rxControlWrite_o <= '1'; rxControlSymbol_o <= STYPE0_PACKET_RETRY & std_logic_vector(ackId) & "11111"; state <= STATE_INPUT_RETRY_STOPPED; end if; else -- The non-maintenance packets are not allowed. -- Send packet-not-accepted. rxControlWrite_o <= '1'; rxControlSymbol_o <= STYPE0_PACKET_NOT_ACCEPTED & "00000" & PACKET_NOT_ACCEPTED_CAUSE_NON_MAINTENANCE_STOPPED; state <= STATE_INPUT_ERROR_STOPPED; end if; else -- The ackId is unexpected. -- Send packet-not-accepted. rxControlWrite_o <= '1'; rxControlSymbol_o <= STYPE0_PACKET_NOT_ACCEPTED & "00000" & PACKET_NOT_ACCEPTED_CAUSE_UNEXPECTED_ACKID; state <= STATE_INPUT_ERROR_STOPPED; end if; else -- A frame has not been started or is too long. -- Send packet-not-accepted. rxControlWrite_o <= '1'; rxControlSymbol_o <= STYPE0_PACKET_NOT_ACCEPTED & "00000" & PACKET_NOT_ACCEPTED_CAUSE_GENERAL_ERROR; state <= STATE_INPUT_ERROR_STOPPED; end if; else -- Idle sequence received. -- Discard these. end if; -- Update to the next symbol. rxRead <= '1'; else -- No new symbol received. -- Dont do anything. end if; else -- The port has become uninitialized. -- Go back to the uninitialized state. state <= STATE_UNINITIALIZED; end if; when STATE_INPUT_RETRY_STOPPED => --------------------------------------------------------------------- -- This state is entered when a frame could not be accepted. All -- symbols except restart-from-retry and link-request are discarded. -- A restart-from-retry triggers a state change into the normal -- link-initialized state. --------------------------------------------------------------------- -- Check that the port is initialized. if (portInitialized_i = '1') then -- The port and link is initialized. -- Check if a new symbol is ready to be read. if (rxRead = '0') and (rxEmpty_i = '0') then -- There is a new symbol to read. -- Check the type of symbol. if (rxControl_i = SYMBOL_CONTROL) then -- This is a control symbol with or without a packet delimiter. -- Check if the control symbol has a valid CRC-5. if (crc5Calculated = crc5) then -- The control symbol is correct. -- Forward the stype0 part of the symbol to the transmitter. txControlWrite_o <= '1'; txControlSymbol_o <= stype0 & parameter0 & parameter1; -- Check the stype1 part. case stype1 is when STYPE1_RESTART_FROM_RETRY => ------------------------------------------------------------- -- The receiver indicates a restart from a retry sent -- from us. ------------------------------------------------------------- -- Abort the frame and reset frame reception. frameIndex <= 0; writeFrameAbort_o <= '1'; -- Go back to the normal operational state. state <= STATE_NORMAL; when STYPE1_LINK_REQUEST => ------------------------------------------------------------- -- Received a link-request. ------------------------------------------------------------- -- Check the command part. if (cmd = "100") then -- Return input port status command. -- This functions as a link-request(restart-from-error) -- control symbol under error situations. -- Send a link response containing an ok reply. rxControlWrite_o <= '1'; rxControlSymbol_o <= STYPE0_LINK_RESPONSE & std_logic_vector(ackId) & "00100"; elsif (cmd = "011") then -- Reset device command. -- Discard this. else -- Unsupported command. -- Discard this. end if; -- Abort the frame and reset frame reception. frameIndex <= 0; writeFrameAbort_o <= '1'; -- Go back to the normal operational state. state <= STATE_NORMAL; when others => ------------------------------------------------------------- -- ------------------------------------------------------------- -- Discard other control symbols. null; end case; else -- The 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_o <= '1'; rxControlSymbol_o <= STYPE0_PACKET_NOT_ACCEPTED & "00000" & PACKET_NOT_ACCEPTED_CAUSE_CONTROL_CRC; state <= STATE_INPUT_ERROR_STOPPED; end if; elsif (rxControl_i = SYMBOL_DATA) then -- This is a data symbol. -- Discard all data symbols in this state. else -- Idle sequence received. -- Discard other symbols. end if; -- Update to the next symbol. rxRead <= '1'; else -- No new symbol received. -- Dont do anything. end if; else -- The port has become uninitialized. -- Go back to the uninitialized state. state <= STATE_UNINITIALIZED; end if; when STATE_INPUT_ERROR_STOPPED => --------------------------------------------------------------------- -- This state is entered when an error situation has occurred. When in this -- state, all symbols should be discarded until a link-request-symbols has -- been received. See section 5.13.2.6 in part 6 of the standard. -- Note that it is only the input side of the port that are affected, not the -- output side. Packets may still be transmitted and acknowledges should be -- accepted. --------------------------------------------------------------------- -- Check that the port is initialized. if (portInitialized_i = '1') then -- The port and link is initialized. -- Check if a new symbol is ready to be read. if (rxRead = '0') and (rxEmpty_i = '0') then -- There is a new symbol to read. -- Check the type of symbol. if (rxControl_i = SYMBOL_CONTROL) then -- This is a control symbol with or without a packet delimiter. -- Check if the control symbol has a valid CRC-5. if (crc5Calculated = crc5) then -- The control symbol is correct. -- Forward the stype0 part of the symbol to the transmitter. txControlWrite_o <= '1'; txControlSymbol_o <= stype0 & parameter0 & parameter1; -- Check the stype1 part. case stype1 is when STYPE1_LINK_REQUEST => ------------------------------------------------------------- -- Received a link-request. ------------------------------------------------------------- -- Check the command part. -- REMARK: Should also send a status-control-symbol -- directly following this symbol... if (cmd = "100") then -- Return input port status command. -- This functions as a link-request(restart-from-error) -- control symbol under error situations. -- Send a link response containing an ok reply. rxControlWrite_o <= '1'; rxControlSymbol_o <= STYPE0_LINK_RESPONSE & std_logic_vector(ackId) & "00101"; elsif (cmd = "011") then -- Reset device command. -- Discard this. else -- Unsupported command. -- Discard this. end if; -- Abort the frame and reset frame reception. frameIndex <= 0; writeFrameAbort_o <= '1'; -- Go back to the normal operational state. state <= STATE_NORMAL; when others => ------------------------------------------------------------- -- ------------------------------------------------------------- -- Discard other control symbols. null; end case; else -- The control symbol contains a crc error. -- Error is ignored in this state. end if; else -- Other symbol received. -- All other symbols are discarded in this state. end if; -- Update to the next symbol. rxRead <= '1'; else -- No new symbol received. -- Dont do anything. end if; else -- The port has become uninitialized. -- Go back to the uninitialized state. state <= STATE_UNINITIALIZED; end if; when others => --------------------------------------------------------------------- -- --------------------------------------------------------------------- null; end case; 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;