📄 trap.vhd
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--===========================================================================--
--
-- S Y N T H E Z I A B L E Timer C O R E
--
-- www.OpenCores.Org - May 2003
-- This core adheres to the GNU public license
--
-- File name : Trap.vhd
--
-- entity name : trap
--
-- Purpose : Implements a 8 bit address and data comparitor module
--
-- Dependencies : ieee.Std_Logic_1164
-- ieee.std_logic_unsigned
--
-- Author : John E. Kent
--
--===========================================================================----
--
-- Revision History:
--
-- Date: Revision Author
-- 5 May 2003 0.1 John Kent
--
--===========================================================================----
--
-- Register Memory Map
--
-- $00 - Address Comparitor High Byte
-- $01 - Address Comparitor Low byte
-- $02 - Data Comparitor
-- $03 - Control Comparitor
-- $04 - Address Qualifier High Byte
-- $05 - Address Qualifier Low byte
-- $06 - Data Qualifier
-- $07 - Control Qualifier
--
-- Address, Data and Control signals must match in the Comparitor registers
-- Matches are qualified by setting a bit in the Qualifier registers
--
-- Control Comparitor / Qualify (write)
-- b0 - r/w 1=read 0=write
-- b1 - vma 1=valid 0=invalid
-- b7 - irq output 1=match 0=mismatch
--
-- Control Qualifier Read
-- b7 - match flag
--
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity trap is
port (
clk : in std_logic;
rst : in std_logic;
cs : in std_logic;
rw : in std_logic;
vma : in std_logic;
addr : in std_logic_vector(15 downto 0);
data_in : in std_logic_vector(7 downto 0);
data_out : out std_logic_vector(7 downto 0);
irq : out std_logic
);
end;
architecture trap_arch of trap is
--
-- Trap registers
--
signal comp_addr_hi : std_logic_vector(7 downto 0);
signal comp_addr_lo : std_logic_vector(7 downto 0);
signal qual_addr_hi : std_logic_vector(7 downto 0);
signal qual_addr_lo : std_logic_vector(7 downto 0);
signal comp_data : std_logic_vector(7 downto 0);
signal qual_data : std_logic_vector(7 downto 0);
signal comp_ctrl : std_logic_vector(7 downto 0);
signal qual_ctrl : std_logic_vector(7 downto 0);
signal match_flag : std_logic;
begin
--------------------------------
--
-- write control registers
--
--------------------------------
trap_write : process( clk, rst, cs, rw, addr, data_in,
comp_addr_hi, comp_addr_lo, comp_data, comp_ctrl,
qual_addr_hi, qual_addr_lo, qual_data, qual_ctrl )
begin
if clk'event and clk = '0' then
if rst = '1' then
comp_addr_hi <= "00000000";
comp_addr_lo <= "00000000";
comp_data <= "00000000";
comp_ctrl <= "00000000";
qual_addr_hi <= "00000000";
qual_addr_lo <= "00000000";
qual_data <= "00000000";
qual_ctrl <= "00000000";
elsif cs = '1' and rw = '0' then
case addr(2 downto 0) is
when "000" =>
comp_addr_hi <= data_in;
comp_addr_lo <= comp_addr_lo;
comp_data <= comp_data;
comp_ctrl <= comp_ctrl;
qual_addr_hi <= qual_addr_hi;
qual_addr_lo <= qual_addr_lo;
qual_data <= qual_data;
qual_ctrl <= qual_ctrl;
when "001" =>
comp_addr_hi <= comp_addr_hi;
comp_addr_lo <= data_in;
comp_data <= comp_data;
comp_ctrl <= comp_ctrl;
qual_addr_hi <= qual_addr_hi;
qual_addr_lo <= qual_addr_lo;
qual_data <= qual_data;
qual_ctrl <= qual_ctrl;
when "010" =>
comp_addr_hi <= comp_addr_hi;
comp_addr_lo <= comp_addr_lo;
comp_data <= data_in;
comp_ctrl <= comp_ctrl;
qual_addr_hi <= qual_addr_hi;
qual_addr_lo <= qual_addr_lo;
qual_data <= qual_data;
qual_ctrl <= qual_ctrl;
when "011" =>
comp_addr_hi <= comp_addr_hi;
comp_addr_lo <= comp_addr_lo;
comp_data <= comp_data;
comp_ctrl <= data_in;
qual_addr_hi <= qual_addr_hi;
qual_addr_lo <= qual_addr_lo;
qual_data <= qual_data;
qual_ctrl <= qual_ctrl;
when "100" =>
comp_addr_hi <= comp_addr_hi;
comp_addr_lo <= comp_addr_lo;
comp_data <= comp_data;
comp_ctrl <= comp_ctrl;
qual_addr_hi <= data_in;
qual_addr_lo <= qual_addr_lo;
qual_data <= qual_data;
qual_ctrl <= qual_ctrl;
when "101" =>
comp_addr_hi <= comp_addr_hi;
comp_addr_lo <= comp_addr_lo;
comp_data <= comp_data;
comp_ctrl <= comp_ctrl;
qual_addr_hi <= qual_addr_hi;
qual_addr_lo <= data_in;
qual_data <= qual_data;
qual_ctrl <= qual_ctrl;
when "110" =>
comp_addr_hi <= comp_addr_hi;
comp_addr_lo <= comp_addr_lo;
comp_data <= comp_data;
comp_ctrl <= comp_ctrl;
qual_addr_hi <= qual_addr_hi;
qual_addr_lo <= qual_addr_lo;
qual_data <= data_in;
qual_ctrl <= qual_ctrl;
-- when "111" =>
when others =>
comp_addr_hi <= comp_addr_hi;
comp_addr_lo <= comp_addr_lo;
comp_data <= comp_data;
comp_ctrl <= comp_ctrl;
qual_addr_hi <= qual_addr_hi;
qual_addr_lo <= qual_addr_lo;
qual_data <= qual_data;
qual_ctrl <= data_in;
end case;
else
comp_addr_hi <= comp_addr_hi;
comp_addr_lo <= comp_addr_lo;
comp_data <= comp_data;
comp_ctrl <= comp_ctrl;
qual_addr_hi <= qual_addr_hi;
qual_addr_lo <= qual_addr_lo;
qual_data <= qual_data;
qual_ctrl <= qual_ctrl;
end if;
end if;
end process;
--
-- trap data output mux
--
trap_read : process( addr,
comp_addr_hi, comp_addr_lo, comp_data, comp_ctrl,
qual_addr_hi, qual_addr_lo, qual_data, qual_ctrl,
match_flag )
begin
case addr(2 downto 0) is
when "000" =>
data_out <= comp_addr_hi;
when "001" =>
data_out <= comp_addr_lo;
when "010" =>
data_out <= comp_data;
when "011" =>
data_out <= comp_ctrl;
when "100" =>
data_out <= qual_addr_hi;
when "101" =>
data_out <= qual_addr_lo;
when "110" =>
data_out <= qual_data;
-- when "111" =>
when others =>
data_out(6 downto 0) <= qual_ctrl(6 downto 0);
data_out(7) <= match_flag;
end case;
end process;
--
-- Trap hardware
--
trap_match : process( Clk, rst, cs, rw, addr, vma, match_flag, data_in,
comp_addr_hi, comp_addr_lo, comp_data, comp_ctrl,
qual_addr_hi, qual_addr_lo, qual_data, qual_ctrl)
variable match : std_logic;
variable match_addr_hi : std_logic;
variable match_addr_lo : std_logic;
variable match_data : std_logic;
variable match_ctrl : std_logic;
begin
match_addr_hi :=
((comp_addr_hi(7) xor addr(15) ) and qual_addr_hi(7) ) or
((comp_addr_hi(6) xor addr(14) ) and qual_addr_hi(6) ) or
((comp_addr_hi(5) xor addr(13) ) and qual_addr_hi(5) ) or
((comp_addr_hi(4) xor addr(12) ) and qual_addr_hi(4) ) or
((comp_addr_hi(3) xor addr(11) ) and qual_addr_hi(3) ) or
((comp_addr_hi(2) xor addr(10) ) and qual_addr_hi(2) ) or
((comp_addr_hi(1) xor addr( 9) ) and qual_addr_hi(1) ) or
((comp_addr_hi(0) xor addr( 8) ) and qual_addr_hi(0) );
match_addr_lo :=
((comp_addr_lo(7) xor addr( 7) ) and qual_addr_lo(7) ) or
((comp_addr_lo(6) xor addr( 6) ) and qual_addr_lo(6) ) or
((comp_addr_lo(5) xor addr( 5) ) and qual_addr_lo(5) ) or
((comp_addr_lo(4) xor addr( 4) ) and qual_addr_lo(4) ) or
((comp_addr_lo(3) xor addr( 3) ) and qual_addr_lo(3) ) or
((comp_addr_lo(2) xor addr( 2) ) and qual_addr_lo(2) ) or
((comp_addr_lo(1) xor addr( 1) ) and qual_addr_lo(1) ) or
((comp_addr_lo(0) xor addr( 0) ) and qual_addr_lo(0) );
match_data :=
((comp_data(7) xor data_in(7)) and qual_data(7) ) or
((comp_data(6) xor data_in(6)) and qual_data(6) ) or
((comp_data(5) xor data_in(5)) and qual_data(5) ) or
((comp_data(4) xor data_in(4)) and qual_data(4) ) or
((comp_data(3) xor data_in(3)) and qual_data(3) ) or
((comp_data(2) xor data_in(2)) and qual_data(2) ) or
((comp_data(1) xor data_in(1)) and qual_data(1) ) or
((comp_data(0) xor data_in(0)) and qual_data(0) );
match_ctrl :=
((comp_ctrl(0) xor rw ) and qual_ctrl(0) ) or
((comp_ctrl(1) xor vma ) and qual_ctrl(1) );
match := not ( match_addr_hi or match_addr_lo or match_data or match_ctrl);
if clk'event and clk = '0' then
if rst = '1' then
match_flag <= '0';
elsif cs = '1' and rw = '0' then
match_flag <= '0';
else
if match = comp_ctrl(7) then
match_flag <= '1';
else
match_flag <= match_flag;
end if;
end if;
end if;
irq <= match_flag and qual_ctrl(7);
end process;
end trap_arch;
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