--*****************************************************************************
-- FILE    : PCI_CMDADR.vhd
-- DATE    : 1.9.1999
-- REVISION: 1.1
-- DESIGNER: KA
-- Descr   : PCI Command Decoder and Address Counter
-- Entities: PCI_CMDADR
-- Changes :
-- ******************************************************
-- *                       Entities                     *
-- ******************************************************
library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.std_logic_unsigned.all; -- Arithmetic operators
library WORK;
use WORK.PCI_COMMANDS.all;
entity PCI_CMDADR is
   port(
      RESET       : in std_logic;
      CLK         : in std_logic;
      DIN         : in std_logic_vector(31 downto 0);
      CBEnid       : in std_logic_vector(3 downto 0);
      IDSELd      : in std_logic;
      FRAMEnd     : in std_logic;
      ACC_END     : in std_logic;
      CFG_IOEN    : in std_logic;   -- I/O Space Decoding Enabled
      CFG_MEMEN   : in std_logic;   -- Memory Space Decoding Enabled
      INC_ADR     : in std_logic;   -- Incement Address Counter
      -- System Control
      FIRST_CYC   : out std_logic;  -- First Cycle After FRAME# falling edge
      -- Captured Address
      ADR         : out std_logic_vector(31 downto 0);   -- Captured address
      BURST_MODE  : out std_logic_vector(1 downto 0);--
       -- Decoded Commands:
      COMMAND     : out std_logic_vector(3 downto 0);-- Binary encoded 
command
      CMD_CFGRD   : out std_logic;  -- Configuration Read
      CMD_CFGWR   : out std_logic;  -- Configuration Write
      CMD_IORD    : out std_logic;  -- I/O Read
      CMD_IOWR    : out std_logic;  -- I/O Write
      CMD_MRD     : out std_logic;  -- Memory Read
      CMD_MWR     : out std_logic;  -- Memory Write
      CMD_MRM     : out std_logic;  -- Memory Read Multiple
      CMD_MRL     : out std_logic;  -- Memory Read Line
      CMD_MWI     : out std_logic;  -- Memory Write and Invalidate
      --
      ACC_CFG     : out std_logic;  -- Configuration Space Access
      ACC_IO      : out std_logic;  -- I/O Space Access
      ACC_MEM     : out std_logic;  -- Memory Space Access
      ACC_WR      : out std_logic;  -- Card Write Access
      ACC_RD      : out std_logic   -- Card Read Access
   ); end PCI_CMDADR;

-- ******************************************************
-- *                     Architectures                  *
-- ******************************************************
architecture RTL of PCI_CMDADR is

  signal OldFrame, CycBegin : std_logic;
  signal COMMANDi : std_logic_vector(3 downto 0);
  signal ADRi,ADRi_New : std_logic_vector(31 downto 0);

begin
   COMMAND <= COMMANDi;
   ADR <= ADRi_New;
   -- Remeber Previous value of FRAMEnd
   OldFrm: process (CLK,RESET) is
   begin
      if (RESET = '1') then
         OldFrame <= '1';
      elsif (CLK'event and CLK='1') then
         OldFrame <= FRAMEnd;
      end if;
   end process OldFrm;
   -- Beginning od PCI access cycle detection
   CycBegin <= OldFrame and not(FRAMEnd);
   FIRST_CYC <= OldFrame and not(FRAMEnd);
   -- CFG Space Access Decode
   ACC_CFG <= '1' when (DIN(1 downto 0)="00") and (CBEnid(3 downto 1)="101")
                      and (IDSELd = '1') and (CycBegin ='1')
              else '0';
   -- I/O Space Access
   ACC_IO <= '1' when (CFG_IOEN='1') and (CBEnid(3 downto 1)= "001")
             else '0';
   -- Memory Space Access
   ACC_MEM <= '1' when (CFG_MEMEN='1') and (CBEnid(3 downto 1)= "011" or 
CBEnid(3 downto 1)= "111"
                        or CBEnid(3 downto 0)= "1100")
             else '0';
   --
   RW_DEC: process(CLK,RESET)
   begin
      if (RESET = '1') then
         ACC_RD <= '0';
         ACC_WR <= '0';
      elsif (CLK'event and CLK='1') then
         if (ACC_END = '1') then
            ACC_RD <= '0';
            ACC_WR <= '0';
         elsif (CycBegin = '1') then
            ACC_RD <= not CBEnid(0);
            ACC_WR <= CBEnid(0);
         end if;
      end if;
   end process;
  -- PCI Command Decoder
   pCMD_DEC: process(CLK,RESET)
   begin
      if (RESET = '1') then
         COMMANDi    <= "1000";
         CMD_CFGRD   <= '0';
         CMD_CFGWR   <= '0';
         CMD_IORD    <= '0';
         CMD_IOWR    <= '0';
         CMD_MRD     <= '0';
         CMD_MWR     <= '0';
         CMD_MRM     <= '0';
         CMD_MRL     <= '0';
         CMD_MWI     <= '0';
         BURST_MODE <= "00";
      elsif (CLK'event and CLK='1') then
         if (ACC_END = '1') then
            COMMANDi    <= "1000";
            BURST_MODE  <= "00";
            CMD_CFGRD   <= '0';
            CMD_CFGWR   <= '0';
            CMD_IORD    <= '0';
            CMD_IOWR    <= '0';
            CMD_MRD     <= '0';
            CMD_MWR     <= '0';
            CMD_MRM     <= '0';
            CMD_MRL     <= '0';
            CMD_MWI     <= '0';
         elsif (CycBegin = '1') then
            BURST_MODE <= DIN(1 downto 0);
            COMMANDi     <= CBEnid;
            if CBEnid = CFGRD_CODE then -- Configuration Read
               CMD_CFGRD   <= '1';
            else
               CMD_CFGRD   <= '0';
            end if;
            if CBEnid = CFGWR_CODE then -- Configuration Write
               CMD_CFGWR   <= '1';
            else
               CMD_CFGWR   <= '0';
            end if;
            if CBEnid = IORD_CODE then  -- I/O READ
               CMD_IORD    <= '1';
            else
               CMD_IORD    <= '0';
            end if;
            if CBEnid = IOWR_CODE then  -- I/O Write
               CMD_IOWR    <= '1';
            else
               CMD_IOWR    <= '0';
            end if;
            if CBEnid = MRD_CODE then   -- Memory Read
               CMD_MRD     <= '1';
            else
               CMD_MRD     <= '0';
            end if;
            if CBEnid = MWR_CODE then   -- Memory Write
               CMD_MWR     <= '1';
            else
               CMD_MWR     <= '0';
            end if;
            if CBEnid = MRM_CODE then   -- Memory Read Multiple
               CMD_MRM     <= '1';
            else
               CMD_MRM     <= '0';
            end if;
            if CBEnid = MRL_CODE then   -- Memory Read Line
               CMD_MRL     <= '1';
            else
               CMD_MRL     <= '0';
            end if;
            if CBEnid = MWI_CODE then   -- Memory Write and Invalidate
               CMD_MWI     <= '1';
            else
               CMD_MWI     <= '0';
            end if;
         end if;
      end if;
   end process pCMD_DEC;
    -- Address Counter
   pADRCNT: process(CLK,RESET)
   begin
      if RESET='1'  then
         ADRi <= "00000000000000000000000000000000";
      elsif CLK'event and CLK='1' then
         if CycBegin = '1' then
            ADRi(23 downto 2) <= DIN(23 downto 2);
         elsif INC_ADR = '1' then
            ADRi <= ADRi_New;
         end if;
      end if;
   end process;
   pADRINC: process(ADRi,INC_ADR)
   begin
      if INC_ADR ='1' then
         ADRi_New <= ADRi + 4;
      else
         ADRi_New <= ADRi;
      end if;
   end process;
end RTL;