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wfjm.w11/rtl/w11a/pdp11_lunit.vhd
Walter F.J. Mueller 3f455d5236 - interim release w11a_V0.532 (untagged) 
- re-organize modules 'human I/O' interface on Digilent boards
- add test designs for 'human I/O' interface for atlys,nexys2, and s3board
- small updates in crc8 and dcm areas
- with one exception all vhdl sources use now numeric_std
2011-11-20 12:31:43 +00:00

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6.6 KiB
VHDL
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-- $Id: pdp11_lunit.vhd 427 2011-11-19 21:04:11Z mueller $
--
-- Copyright 2006-2011 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: pdp11_lunit - syn
-- Description: pdp11: logic unit for data (lunit)
--
-- Dependencies: -
-- Test bench: tb/tb_pdp11_core (implicit)
-- Target Devices: generic
-- Tool versions: xst 8.2, 9.1, 9.2, 12.1, 13.1; ghdl 0.18-0.29
-- Revision History:
-- Date Rev Version Comment
-- 2011-11-18 427 1.1.1 now numeric_std clean
-- 2010-09-18 300 1.1 renamed from lbox
-- 2008-03-30 131 1.0.2 BUGFIX: SXT clears V condition code
-- 2007-06-14 56 1.0.1 Use slvtypes.all
-- 2007-05-12 26 1.0 Initial version
------------------------------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use work.slvtypes.all;
use work.pdp11.all;
-- ----------------------------------------------------------------------------
entity pdp11_lunit is -- logic unit for data (lunit)
port (
DSRC : in slv16; -- 'src' data in
DDST : in slv16; -- 'dst' data in
CCIN : in slv4; -- condition codes in
FUNC : in slv4; -- function
BYTOP : in slbit; -- byte operation
DOUT : out slv16; -- data output
CCOUT : out slv4 -- condition codes out
);
end pdp11_lunit;
architecture syn of pdp11_lunit is
-- --------------------------------------
begin
process (DSRC, DDST, CCIN, FUNC, BYTOP)
variable iout : slv16 := (others=>'0');
variable inzstd : slbit := '0';
variable ino : slbit := '0';
variable izo : slbit := '0';
variable ivo : slbit := '0';
variable ico : slbit := '0';
alias DSRC_L : slv8 is DSRC(7 downto 0);
alias DSRC_H : slv8 is DSRC(15 downto 8);
alias DDST_L : slv8 is DDST(7 downto 0);
alias DDST_H : slv8 is DDST(15 downto 8);
alias NI : slbit is CCIN(3);
alias ZI : slbit is CCIN(2);
alias VI : slbit is CCIN(1);
alias CI : slbit is CCIN(0);
alias iout_l : slv8 is iout(7 downto 0);
alias iout_h : slv8 is iout(15 downto 8);
begin
iout := (others=>'0');
inzstd := '1'; -- use standard logic by default
ino := '0';
izo := '0';
ivo := '0';
ico := '0';
--
-- the decoding of FUNC is done "manually" to get a structure based on
-- a 8->1 pattern. This matches the opcode structure and seems most
-- efficient.
--
if FUNC(3) = '0' then
if BYTOP = '0' then
case FUNC(2 downto 0) is
when "000" => -- ASR
iout := DDST(15) & DDST(15 downto 1);
ico := DDST(0);
ivo := iout(15) xor ico;
when "001" => -- ASL
iout := DDST(14 downto 0) & '0';
ico := DDST(15);
ivo := iout(15) xor ico;
when "010" => -- ROR
iout := CI & DDST(15 downto 1);
ico := DDST(0);
ivo := iout(15) xor ico;
when "011" => -- ROL
iout := DDST(14 downto 0) & CI;
ico := DDST(15);
ivo := iout(15) xor ico;
when "100" => -- BIS
iout := DDST or DSRC;
ico := CI;
when "101" => -- BIC
iout := DDST and not DSRC;
ico := CI;
when "110" => -- BIT
iout := DDST and DSRC;
ico := CI;
when "111" => -- MOV
iout := DSRC;
ico := CI;
when others => null;
end case;
else
case FUNC(2 downto 0) is
when "000" => -- ASRB
iout_l := DDST_L(7) & DDST_L(7 downto 1);
ico := DDST_L(0);
ivo := iout_l(7) xor ico;
when "001" => -- ASLB
iout_l := DDST(6 downto 0) & '0';
ico := DDST(7);
ivo := iout_l(7) xor ico;
when "010" => -- RORB
iout_l := CI & DDST_L(7 downto 1);
ico := DDST_L(0);
ivo := iout_l(7) xor ico;
when "011" => -- ROLB
iout_l := DDST_L(6 downto 0) & CI;
ico := DDST_L(7);
ivo := iout_l(7) xor ico;
when "100" => -- BISB
iout_l := DDST_L or DSRC_L;
ico := CI;
when "101" => -- BICB
iout_l := DDST_L and not DSRC_L;
ico := CI;
when "110" => -- BITB
iout_l := DDST_L and DSRC_L;
ico := CI;
when "111" => -- MOVB
iout_l := DSRC_L;
iout_h := (others=>DSRC_L(7));
ico := CI;
when others => null;
end case;
end if;
else
case FUNC(2 downto 0) is
when "000" => -- SXT
iout := (others=>NI);
inzstd := '0';
ino := NI;
izo := not NI;
ivo := '0';
ico := CI;
when "001" => -- SWAP
iout := DDST_L & DDST_H;
inzstd := '0';
ino := iout(7);
if unsigned(iout(7 downto 0)) = 0 then
izo := '1';
else
izo := '0';
end if;
when "010" => -- XOR
iout := DDST xor DSRC;
ico := CI;
when others => null;
end case;
end if;
DOUT <= iout;
if inzstd = '1' then
if BYTOP = '1' then
ino := iout(7);
if unsigned(iout(7 downto 0)) = 0 then
izo := '1';
else
izo := '0';
end if;
else
ino := iout(15);
if unsigned(iout) = 0 then
izo := '1';
else
izo := '0';
end if;
end if;
end if;
CCOUT(3) <= ino;
CCOUT(2) <= izo;
CCOUT(1) <= ivo;
CCOUT(0) <= ico;
end process;
end syn;
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