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-- $Id: rbd_rbmon.vhd 427 2011-11-19 21:04:11Z mueller $

--

-- Copyright 2010-2011 by Walter F.J. Mueller <W.F.J.Mueller@gsi.de>

--

-- This program is free software; you may redistribute and/or modify it under

-- the terms of the GNU General Public License as published by the Free

-- Software Foundation, either version 2, or at your option any later version.

--

-- This program 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 General Public License

-- for complete details.

--

------------------------------------------------------------------------------

-- Module Name:    rbd_rbmon - syn

-- Description:    rbus dev: rbus monitor

--

-- Dependencies:   memlib/ram_1swsr_wfirst_gen

--

-- Test bench:     rlink/tb/tb_rlink_tba_ttcombo

--

-- Target Devices: generic

-- Tool versions:  xst 12.1, 13.1; ghdl 0.29

--

-- Synthesized (xst):

-- Date         Rev  ise         Target      flop lutl lutm slic t peri

-- 2010-12-27   349 12.1    M53d xc3s1000-4    95  228    -  154 s 10.4

--

-- Revision History: 

-- Date         Rev Version  Comment

-- 2011-11-19   427   1.0.3  now numeric_std clean

-- 2011-03-27   374   1.0.2  rename ncyc -> nbusy because it counts busy cycles

-- 2010-12-31   352   1.0.1  simplify irb_ack logic

-- 2010-12-27   349   1.0    Initial version 

------------------------------------------------------------------------------

--

-- Address   Bits Name        r/w/f  Function

-- bbbbbb00       cntl        r/w/f  Control register

--             00   go        r/w/f    writing 1 clears add

-- bbbbbb01       alim        r/w/-  Address limit register

--          15:08   hilim     r/w/-    upper address limit (def: ff)

--          07:00   lolim     r/w/-    lower address limit (def: 00)

-- bbbbbb10       addr        r/w/-  Address register

--             15   wrap      r/0/-    line address wrapped (cleared on write)

--           *:02   laddr     r/w/-    line address

--          01:00   waddr     r/w/-    word address

-- bbbbbb11       data        r/w/-  Data register

--

--     data format:

--     word 3     15 : ack

--                14 : busy

--                13 : err

--                12 : nak

--                11 : tout

--                09 : init

--                08 : we

--             07:00 : addr

--     word 2          data

--     word 1  15:00 : delay to prev (lsb's)

--     word 0  15:12 : delay to prev (msb's)

--             11:00 : number of busy cycles

-- 

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

use work.slvtypes.all;

use work.memlib.all;

use work.rblib.all;

entity rbd_rbmon is                     -- rbus dev: rbus monitor

  generic (

    RB_ADDR : slv8 := slv(to_unsigned(2#11111100#,8));

    AWIDTH : positive := 9);

  port (

    CLK  : in slbit;                    -- clock

    RESET : in slbit;                   -- reset

    RB_MREQ : in rb_mreq_type;          -- rbus: request

    RB_SRES : out rb_sres_type;         -- rbus: response

    RB_SRES_SUM : in rb_sres_type       -- rbus: response (sum for monitor)

  );

end entity rbd_rbmon;

architecture syn of rbd_rbmon is

  constant rbaddr_cntl : slv2 := "00";   -- cntl address offset

  constant rbaddr_alim : slv2 := "01";   -- alim address offset

  constant rbaddr_addr : slv2 := "10";   -- addr address offset

  constant rbaddr_data : slv2 := "11";   -- data address offset

  constant cntl_rbf_go       : integer :=     0;

  subtype  alim_rbf_hilim   is integer range 15 downto  8;

  subtype  alim_rbf_lolim   is integer range  7 downto  0;

  constant addr_rbf_wrap     : integer :=    15;

  subtype  addr_rbf_laddr   is integer range 2+AWIDTH-1 downto  2;

  subtype  addr_rbf_waddr   is integer range  1 downto  0;

  constant dat3_rbf_ack      : integer :=    15;

  constant dat3_rbf_busy     : integer :=    14;

  constant dat3_rbf_err      : integer :=    13;

  constant dat3_rbf_nak      : integer :=    12;

  constant dat3_rbf_tout     : integer :=    11;

  constant dat3_rbf_init     : integer :=     9;

  constant dat3_rbf_we       : integer :=     8;

  subtype  dat3_rbf_addr    is integer range  7 downto  0;

  subtype  dat0_rbf_ndlymsb is integer range 15 downto 12;

  subtype  dat0_rbf_nbusy   is integer range 11 downto  0;

  type regs_type is record              -- state registers

    rbsel : slbit;                      -- rbus select

    go : slbit;                         -- go flag

    hilim : slv8;                       -- upper address limit

    lolim : slv8;                       -- lower address limit

    wrap : slbit;                       -- laddr wrap flag

    laddr : slv(AWIDTH-1 downto 0);     -- line address

    waddr : slv2;                       -- word address

    rbtake_1 : slbit;                   -- rb capture active in last cycle

    rbaddr  : slv8;                     -- rbus trace: addr

    rbinit  : slbit;                    -- rbus trace: init

    rbwe    : slbit;                    -- rbus trace: we

    rback   : slbit;                    -- rbus trace: ack  seen

    rbbusy  : slbit;                    -- rbus trace: busy seen

    rberr   : slbit;                    -- rbus trace: err  seen

    rbnak   : slbit;                    -- rbus trace: nak  detected

    rbtout  : slbit;                    -- rbus trace: tout detected

    rbdata  : slv16;                    -- rbus trace: data

    rbnbusy : slv12;                    -- rbus number of busy cycles

    rbndly  : slv20;                    -- rbus delay to prev. access

  end record regs_type;

  constant laddrzero : slv(AWIDTH-1 downto 0) := (others=>'0');

  constant laddrlast : slv(AWIDTH-1 downto 0) := (others=>'1');

  constant regs_init : regs_type := (

    '0',                                -- rbsel

    '0',                                -- go    (default is off)

    (others=>'1'),                      -- hilim (def: ff)

    (others=>'0'),                      -- lolim (def: 00)

    '0',                                -- wrap

    laddrzero,                          -- laddr

    "00",                               -- waddr

    '0',                                -- rbtake_1

    (others=>'0'),                      -- rbaddr

    '0','0','0','0','0',                -- rbinit,rbwe,rback,rbbusy,rberr

    '0','0',                            -- rbnak,rbtout

    (others=>'0'),                      -- rbdata

    (others=>'0'),                      -- rbnbusy

    (others=>'0')                       -- rbndly

  );

  constant rbnbusylast : slv12 := (others=>'1');

  constant rbndlylast  : slv20 := (others=>'1');

  signal R_REGS : regs_type := regs_init;

  signal N_REGS : regs_type := regs_init;

  signal BRAM_EN : slbit := '0';

  signal BRAM_WE : slbit := '0';

  signal BRAM0_DI : slv32 := (others=>'0');

  signal BRAM1_DI : slv32 := (others=>'0');

  signal BRAM0_DO : slv32 := (others=>'0');

  signal BRAM1_DO : slv32 := (others=>'0');

begin

  assert AWIDTH<=13

    report "assert(AWIDTH<=13): max address width supported"

    severity failure;

  BRAM1 : ram_1swsr_wfirst_gen

    generic map (

      AWIDTH => AWIDTH,

      DWIDTH => 32)

    port map (

      CLK   => CLK,

      EN    => BRAM_EN,

      WE    => BRAM_WE,

      ADDR  => R_REGS.laddr,

      DI    => BRAM1_DI,

      DO    => BRAM1_DO

    );

  BRAM0 : ram_1swsr_wfirst_gen

    generic map (

      AWIDTH => AWIDTH,

      DWIDTH => 32)

    port map (

      CLK   => CLK,

      EN    => BRAM_EN,

      WE    => BRAM_WE,

      ADDR  => R_REGS.laddr,

      DI    => BRAM0_DI,

      DO    => BRAM0_DO

    );

  proc_regs: process (CLK)

  begin

    if rising_edge(CLK) then

      if RESET = '1' then

        R_REGS <= regs_init;

      else

        R_REGS <= N_REGS;

      end if;

    end if;

  end process proc_regs;

  proc_next : process (R_REGS, RB_MREQ, RB_SRES_SUM, BRAM0_DO, BRAM1_DO)

    variable r : regs_type := regs_init;

    variable n : regs_type := regs_init;

    variable irb_ack  : slbit := '0';

    variable irb_busy : slbit := '0';

    variable irb_err  : slbit := '0';

    variable irb_dout  : slv16 := (others=>'0');

    variable irbena  : slbit := '0';

    variable ibramen : slbit := '0';

    variable ibramwe : slbit := '0';

    variable rbtake : slbit := '0';

    variable laddr_inc : slbit := '0';

    variable idat0 : slv16 := (others=>'0');

    variable idat1 : slv16 := (others=>'0');

    variable idat2 : slv16 := (others=>'0');

    variable idat3 : slv16 := (others=>'0');

  begin

    r := R_REGS;

    n := R_REGS;

    irb_ack  := '0';

    irb_busy := '0';

    irb_err  := '0';

    irb_dout := (others=>'0');

    irbena  := RB_MREQ.re or RB_MREQ.we;

    ibramen := '0';

    ibramwe := '0';

    laddr_inc := '0';

    -- rbus address decoder

    n.rbsel := '0';

    if RB_MREQ.aval='1' and RB_MREQ.addr(7 downto 2)=RB_ADDR(7 downto 2) then

      n.rbsel := '1';

      ibramen := '1';

    end if;

    -- rbus transactions

    if r.rbsel = '1' then

      irb_ack := irbena;                  -- ack all accesses

      case RB_MREQ.addr(1 downto 0) is

        when rbaddr_cntl =>

          if RB_MREQ.we = '1' then

            n.go  := RB_MREQ.din(cntl_rbf_go);

            if RB_MREQ.din(cntl_rbf_go)='1' then

              n.wrap  := '0';

              n.laddr := laddrzero;

              n.waddr := "00";

            end if;

          end if;

        when rbaddr_alim =>

          if RB_MREQ.we = '1' then

            n.hilim := RB_MREQ.din(alim_rbf_hilim);

            n.lolim := RB_MREQ.din(alim_rbf_lolim);

          end if;

        when rbaddr_addr =>

          if RB_MREQ.we = '1' then

            n.go    := '0';

            n.wrap  := '0';

            n.laddr := RB_MREQ.din(addr_rbf_laddr);

            n.waddr := RB_MREQ.din(addr_rbf_waddr);

          end if;

        when rbaddr_data =>

          if r.go='1' or RB_MREQ.we='1' then

            irb_err := '1';

          end if;

          if RB_MREQ.re = '1' then

            n.waddr := slv(unsigned(r.waddr) + 1);

            if r.waddr = "11" then

              laddr_inc := '1';

            end if;

          end if;

        when others => null;

      end case;

    end if;

    -- rbus output driver

    if r.rbsel = '1' then

      case RB_MREQ.addr(1 downto 0) is

        when rbaddr_cntl =>

          irb_dout(cntl_rbf_go)    := r.go;

        when rbaddr_alim =>

          irb_dout(alim_rbf_hilim) := r.hilim;

          irb_dout(alim_rbf_lolim) := r.lolim;

        when rbaddr_addr =>

          irb_dout(addr_rbf_wrap)  := r.wrap;

          irb_dout(addr_rbf_laddr) := r.laddr;

          irb_dout(addr_rbf_waddr) := r.waddr;

        when rbaddr_data =>

          case r.waddr is

            when "11" => irb_dout := BRAM1_DO(31 downto 16);

            when "10" => irb_dout := BRAM1_DO(15 downto  0);

            when "01" => irb_dout := BRAM0_DO(31 downto 16);

            when "00" => irb_dout := BRAM0_DO(15 downto  0);

            when others => null;

          end case;

        when others => null;

      end case;

    end if;

    -- rbus monitor 

    --   a rbus transaction are captured if the address is in alim window

    --   and the access is not refering to rbd_rbmon itself

    rbtake := '0';

    if RB_MREQ.aval='1' and irbena='1' then              -- aval and (re or we)

      if unsigned(RB_MREQ.addr)>=unsigned(r.lolim) and   -- and in addr window

         unsigned(RB_MREQ.addr)<=unsigned(r.hilim) and

         r.rbsel='0' then                                -- and not self

        rbtake := '1';

      end if;

    end if;

    if RB_MREQ.init = '1' then                           -- also take init's

      rbtake := '1';

    end if;

    if rbtake = '1' then                -- if capture active

      n.rbaddr := RB_MREQ.addr;           -- keep track of some state

      n.rbinit := RB_MREQ.init;

      n.rbwe   := RB_MREQ.we;

      if RB_MREQ.init='1' or RB_MREQ.we='1' then  -- for write/init of din

        n.rbdata := RB_MREQ.din;

      else                                        -- for read of dout

        n.rbdata := RB_SRES_SUM.dout;

      end if;

      if r.rbtake_1 = '0' then            -- if initial cycle of a transaction

        n.rback  := RB_SRES_SUM.ack;

        n.rbbusy := RB_SRES_SUM.busy;

        n.rberr  := RB_SRES_SUM.err;

        n.rbnbusy := (others=>'0');

      else                                -- if non-initial cycles

        if RB_SRES_SUM.err = '1' then       -- keep track of err flags

          n.rberr := '1';

        end if;

        if r.rbnbusy /= rbnbusylast then      -- and count  

          n.rbnbusy := slv(unsigned(r.rbnbusy) + 1);

        end if;

      end if;

      n.rbnak  := not RB_SRES_SUM.ack;

      n.rbtout := RB_SRES_SUM.busy;

    else                                -- if capture not active

      if r.go='1' and r.rbtake_1='1' then -- active and transaction just ended

        ibramen := '1';

        ibramwe := '1';

        laddr_inc := '1';

      end if;

      if r.rbtake_1 = '1' then            -- rbus transaction just ended

        n.rbndly := (others=>'0');          -- clear delay counter

      else                                -- just idle

        if r.rbndly /= rbndlylast then      -- count cycles

          n.rbndly := slv(unsigned(r.rbndly) + 1);

        end if;

      end if;

    end if;

    if laddr_inc = '1' then

      n.laddr := slv(unsigned(r.laddr) + 1);

      if r.go='1' and r.laddr=laddrlast then

        n.wrap := '1';

      end if;

    end if;

    idat3 := (others=>'0');

    idat3(dat3_rbf_ack)  := r.rback;

    idat3(dat3_rbf_busy) := r.rbbusy;

    idat3(dat3_rbf_err)  := r.rberr;

    idat3(dat3_rbf_nak)  := r.rbnak;

    idat3(dat3_rbf_tout) := r.rbtout;

    idat3(dat3_rbf_init) := r.rbinit;

    idat3(dat3_rbf_we)   := r.rbwe;

    idat3(dat3_rbf_addr) := r.rbaddr;

    idat2 := r.rbdata;

    idat1 := r.rbndly(15 downto 0);

    idat0(dat0_rbf_ndlymsb) := r.rbndly(19 downto 16);

    idat0(dat0_rbf_nbusy)   := r.rbnbusy;

    n.rbtake_1 := rbtake;

    N_REGS <= n;

    BRAM_EN <= ibramen;

    BRAM_WE <= ibramwe;

    BRAM1_DI <= idat3 & idat2;

    BRAM0_DI <= idat1 & idat0;

    RB_SRES.dout <= irb_dout;

    RB_SRES.ack  <= irb_ack;

    RB_SRES.err  <= irb_err;

    RB_SRES.busy <= irb_busy;

  end process proc_next;

end syn;