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--
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-- Z80 compatible microprocessor core
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--
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-- Version : 0247
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--
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-- Copyright (c) 2001-2002 Daniel Wallner (jesus@opencores.org)
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--
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-- All rights reserved
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--
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-- Redistribution and use in source and synthezised forms, with or without
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-- modification, are permitted provided that the following conditions are met:
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--
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-- Redistributions of source code must retain the above copyright notice,
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-- this list of conditions and the following disclaimer.
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--
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-- Redistributions in synthesized form must reproduce the above copyright
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-- notice, this list of conditions and the following disclaimer in the
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-- documentation and/or other materials provided with the distribution.
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--
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-- Neither the name of the author nor the names of other contributors may
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-- be used to endorse or promote products derived from this software without
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-- specific prior written permission.
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--
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-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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-- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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-- THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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-- PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE
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-- LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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-- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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-- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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-- INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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-- CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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-- ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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-- POSSIBILITY OF SUCH DAMAGE.
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--
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-- Please report bugs to the author, but before you do so, please
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-- make sure that this is not a derivative work and that
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-- you have the latest version of this file.
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--
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-- The latest version of this file can be found at:
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-- http://www.opencores.org/cvsweb.shtml/t80/
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--
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-- Limitations :
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--
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-- File history :
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--
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-- 0208 : First complete release
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--
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-- 0210 : Fixed wait and halt
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--
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-- 0211 : Fixed Refresh addition and IM 1
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--
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-- 0214 : Fixed mostly flags, only the block instructions now fail the zex regression test
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--
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-- 0232 : Removed refresh address output for Mode > 1 and added DJNZ M1_n fix by Mike Johnson
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--
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-- 0235 : Added clock enable and IM 2 fix by Mike Johnson
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--
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-- 0237 : Changed 8080 I/O address output, added IntE output
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--
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-- 0238 : Fixed (IX/IY+d) timing and 16 bit ADC and SBC zero flag
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--
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-- 0240 : Added interrupt ack fix by Mike Johnson, changed (IX/IY+d) timing and changed flags in GB mode
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--
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-- 0242 : Added I/O wait, fixed refresh address, moved some registers to RAM
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--
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-- 0247 : Fixed bus req/ack cycle
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--
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library IEEE;
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use IEEE.std_logic_1164.all;
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use IEEE.numeric_std.all;
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use work.T80_Pack.all;
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entity T80 is
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generic(
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Mode : integer := 0; -- 0 => Z80, 1 => Fast Z80, 2 => 8080, 3 => GB
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IOWait : integer := 0; -- 1 => Single cycle I/O, 1 => Std I/O cycle
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Flag_C : integer := 0;
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Flag_N : integer := 1;
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Flag_P : integer := 2;
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Flag_X : integer := 3;
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Flag_H : integer := 4;
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Flag_Y : integer := 5;
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Flag_Z : integer := 6;
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Flag_S : integer := 7
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);
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port(
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RESET_n : in std_logic;
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CLK_n : in std_logic;
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CEN : in std_logic;
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WAIT_n : in std_logic;
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INT_n : in std_logic;
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NMI_n : in std_logic;
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BUSRQ_n : in std_logic;
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M1_n : out std_logic;
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IORQ : out std_logic;
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NoRead : out std_logic;
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Write : out std_logic;
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RFSH_n : out std_logic;
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HALT_n : out std_logic;
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BUSAK_n : out std_logic;
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A : out std_logic_vector(15 downto 0);
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DInst : in std_logic_vector(7 downto 0);
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DI : in std_logic_vector(7 downto 0);
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DO : out std_logic_vector(7 downto 0);
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MC : out std_logic_vector(2 downto 0);
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TS : out std_logic_vector(2 downto 0);
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IntCycle_n : out std_logic;
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IntE : out std_logic;
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Stop : out std_logic
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);
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end T80;
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architecture rtl of T80 is
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constant aNone : std_logic_vector(2 downto 0) := "111";
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constant aBC : std_logic_vector(2 downto 0) := "000";
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constant aDE : std_logic_vector(2 downto 0) := "001";
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constant aXY : std_logic_vector(2 downto 0) := "010";
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constant aIOA : std_logic_vector(2 downto 0) := "100";
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constant aSP : std_logic_vector(2 downto 0) := "101";
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constant aZI : std_logic_vector(2 downto 0) := "110";
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-- Registers
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signal ACC, F : std_logic_vector(7 downto 0);
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signal Ap, Fp : std_logic_vector(7 downto 0);
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signal I : std_logic_vector(7 downto 0);
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signal R : unsigned(7 downto 0);
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signal SP, PC : unsigned(15 downto 0);
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signal RegDIH : std_logic_vector(7 downto 0);
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signal RegDIL : std_logic_vector(7 downto 0);
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signal RegBusA : std_logic_vector(15 downto 0);
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signal RegBusB : std_logic_vector(15 downto 0);
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signal RegBusC : std_logic_vector(15 downto 0);
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signal RegAddrA_r : std_logic_vector(2 downto 0);
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signal RegAddrA : std_logic_vector(2 downto 0);
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signal RegAddrB_r : std_logic_vector(2 downto 0);
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signal RegAddrB : std_logic_vector(2 downto 0);
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signal RegAddrC : std_logic_vector(2 downto 0);
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signal RegWEH : std_logic;
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signal RegWEL : std_logic;
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signal Alternate : std_logic;
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-- Help Registers
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signal TmpAddr : std_logic_vector(15 downto 0); -- Temporary address register
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signal IR : std_logic_vector(7 downto 0); -- Instruction register
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signal ISet : std_logic_vector(1 downto 0); -- Instruction set selector
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signal RegBusA_r : std_logic_vector(15 downto 0);
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signal ID16 : signed(15 downto 0);
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signal Save_Mux : std_logic_vector(7 downto 0);
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signal TState : unsigned(2 downto 0);
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signal MCycle : std_logic_vector(2 downto 0);
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signal IntE_FF1 : std_logic;
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signal IntE_FF2 : std_logic;
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signal Halt_FF : std_logic;
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signal BusReq_s : std_logic;
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signal BusAck : std_logic;
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signal ClkEn : std_logic;
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signal NMI_s : std_logic;
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signal INT_s : std_logic;
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signal IStatus : std_logic_vector(1 downto 0);
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signal DI_Reg : std_logic_vector(7 downto 0);
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signal T_Res : std_logic;
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signal XY_State : std_logic_vector(1 downto 0);
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signal Pre_XY_F_M : std_logic_vector(2 downto 0);
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signal NextIs_XY_Fetch : std_logic;
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signal XY_Ind : std_logic;
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signal No_BTR : std_logic;
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signal BTR_r : std_logic;
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signal Auto_Wait : std_logic;
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signal Auto_Wait_t1 : std_logic;
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signal Auto_Wait_t2 : std_logic;
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signal IncDecZ : std_logic;
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-- ALU signals
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signal BusB : std_logic_vector(7 downto 0);
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signal BusA : std_logic_vector(7 downto 0);
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signal ALU_Q : std_logic_vector(7 downto 0);
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signal F_Out : std_logic_vector(7 downto 0);
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-- Registered micro code outputs
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signal Read_To_Reg_r : std_logic_vector(4 downto 0);
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signal Arith16_r : std_logic;
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signal Z16_r : std_logic;
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signal ALU_Op_r : std_logic_vector(3 downto 0);
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signal Save_ALU_r : std_logic;
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signal PreserveC_r : std_logic;
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signal MCycles : std_logic_vector(2 downto 0);
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-- Micro code outputs
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signal MCycles_d : std_logic_vector(2 downto 0);
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signal TStates : std_logic_vector(2 downto 0);
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signal IntCycle : std_logic;
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signal NMICycle : std_logic;
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signal Inc_PC : std_logic;
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signal Inc_WZ : std_logic;
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signal IncDec_16 : std_logic_vector(3 downto 0);
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signal Prefix : std_logic_vector(1 downto 0);
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signal Read_To_Acc : std_logic;
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signal Read_To_Reg : std_logic;
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signal Set_BusB_To : std_logic_vector(3 downto 0);
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signal Set_BusA_To : std_logic_vector(3 downto 0);
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signal ALU_Op : std_logic_vector(3 downto 0);
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signal Save_ALU : std_logic;
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signal PreserveC : std_logic;
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signal Arith16 : std_logic;
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signal Set_Addr_To : std_logic_vector(2 downto 0);
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signal Jump : std_logic;
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signal JumpE : std_logic;
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signal JumpXY : std_logic;
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signal Call : std_logic;
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signal RstP : std_logic;
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signal LDZ : std_logic;
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signal LDW : std_logic;
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signal LDSPHL : std_logic;
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signal IORQ_i : std_logic;
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signal Special_LD : std_logic_vector(2 downto 0);
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signal ExchangeDH : std_logic;
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signal ExchangeRp : std_logic;
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signal ExchangeAF : std_logic;
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signal ExchangeRS : std_logic;
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signal I_DJNZ : std_logic;
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signal I_CPL : std_logic;
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signal I_CCF : std_logic;
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signal I_SCF : std_logic;
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signal I_RETN : std_logic;
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signal I_BT : std_logic;
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signal I_BC : std_logic;
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signal I_BTR : std_logic;
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signal I_RLD : std_logic;
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signal I_RRD : std_logic;
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signal I_INRC : std_logic;
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signal SetDI : std_logic;
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signal SetEI : std_logic;
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signal IMode : std_logic_vector(1 downto 0);
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signal Halt : std_logic;
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begin
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mcode : T80_MCode
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generic map(
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Mode => Mode,
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Flag_C => Flag_C,
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Flag_N => Flag_N,
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Flag_P => Flag_P,
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Flag_X => Flag_X,
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Flag_H => Flag_H,
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Flag_Y => Flag_Y,
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Flag_Z => Flag_Z,
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Flag_S => Flag_S)
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port map(
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IR => IR,
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ISet => ISet,
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MCycle => MCycle,
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F => F,
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NMICycle => NMICycle,
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IntCycle => IntCycle,
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MCycles => MCycles_d,
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TStates => TStates,
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Prefix => Prefix,
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Inc_PC => Inc_PC,
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Inc_WZ => Inc_WZ,
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IncDec_16 => IncDec_16,
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Read_To_Acc => Read_To_Acc,
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Read_To_Reg => Read_To_Reg,
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Set_BusB_To => Set_BusB_To,
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Set_BusA_To => Set_BusA_To,
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ALU_Op => ALU_Op,
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Save_ALU => Save_ALU,
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PreserveC => PreserveC,
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Arith16 => Arith16,
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Set_Addr_To => Set_Addr_To,
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IORQ => IORQ_i,
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Jump => Jump,
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JumpE => JumpE,
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JumpXY => JumpXY,
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Call => Call,
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RstP => RstP,
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LDZ => LDZ,
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LDW => LDW,
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LDSPHL => LDSPHL,
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Special_LD => Special_LD,
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| 287 |
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ExchangeDH => ExchangeDH,
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| 288 |
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ExchangeRp => ExchangeRp,
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| 289 |
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ExchangeAF => ExchangeAF,
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ExchangeRS => ExchangeRS,
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I_DJNZ => I_DJNZ,
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| 292 |
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I_CPL => I_CPL,
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I_CCF => I_CCF,
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I_SCF => I_SCF,
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I_RETN => I_RETN,
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I_BT => I_BT,
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I_BC => I_BC,
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I_BTR => I_BTR,
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I_RLD => I_RLD,
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I_RRD => I_RRD,
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I_INRC => I_INRC,
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SetDI => SetDI,
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SetEI => SetEI,
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IMode => IMode,
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Halt => Halt,
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NoRead => NoRead,
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Write => Write);
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| 308 |
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| 309 |
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alu : T80_ALU
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| 310 |
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generic map(
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Mode => Mode,
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| 312 |
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Flag_C => Flag_C,
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| 313 |
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Flag_N => Flag_N,
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| 314 |
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Flag_P => Flag_P,
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| 315 |
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Flag_X => Flag_X,
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| 316 |
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Flag_H => Flag_H,
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| 317 |
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Flag_Y => Flag_Y,
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| 318 |
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Flag_Z => Flag_Z,
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| 319 |
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Flag_S => Flag_S)
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| 320 |
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port map(
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Arith16 => Arith16_r,
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| 322 |
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Z16 => Z16_r,
|
| 323 |
|
|
ALU_Op => ALU_Op_r,
|
| 324 |
|
|
IR => IR(5 downto 0),
|
| 325 |
|
|
ISet => ISet,
|
| 326 |
|
|
BusA => BusA,
|
| 327 |
|
|
BusB => BusB,
|
| 328 |
|
|
F_In => F,
|
| 329 |
|
|
Q => ALU_Q,
|
| 330 |
|
|
F_Out => F_Out);
|
| 331 |
|
|
|
| 332 |
|
|
ClkEn <= CEN and not BusAck;
|
| 333 |
|
|
|
| 334 |
|
|
T_Res <= '1' when TState = unsigned(TStates) else '0';
|
| 335 |
|
|
|
| 336 |
|
|
NextIs_XY_Fetch <= '1' when XY_State /= "00" and XY_Ind = '0' and
|
| 337 |
|
|
((Set_Addr_To = aXY) or
|
| 338 |
|
|
(MCycle = "001" and IR = "11001011") or
|
| 339 |
|
|
(MCycle = "001" and IR = "00110110")) else '0';
|
| 340 |
|
|
|
| 341 |
|
|
Save_Mux <= BusB when ExchangeRp = '1' else
|
| 342 |
|
|
DI_Reg when Save_ALU_r = '0' else
|
| 343 |
|
|
ALU_Q;
|
| 344 |
|
|
|
| 345 |
|
|
process (RESET_n, CLK_n)
|
| 346 |
|
|
begin
|
| 347 |
|
|
if RESET_n = '0' then
|
| 348 |
|
|
PC <= (others => '0'); -- Program Counter
|
| 349 |
|
|
A <= (others => '0');
|
| 350 |
|
|
TmpAddr <= (others => '0');
|
| 351 |
|
|
IR <= "00000000";
|
| 352 |
|
|
ISet <= "00";
|
| 353 |
|
|
XY_State <= "00";
|
| 354 |
|
|
IStatus <= "00";
|
| 355 |
|
|
MCycles <= "000";
|
| 356 |
|
|
DO <= "00000000";
|
| 357 |
|
|
|
| 358 |
|
|
ACC <= (others => '1');
|
| 359 |
|
|
F <= (others => '1');
|
| 360 |
|
|
Ap <= (others => '1');
|
| 361 |
|
|
Fp <= (others => '1');
|
| 362 |
|
|
I <= (others => '0');
|
| 363 |
|
|
R <= (others => '0');
|
| 364 |
|
|
SP <= (others => '1');
|
| 365 |
|
|
Alternate <= '0';
|
| 366 |
|
|
|
| 367 |
|
|
Read_To_Reg_r <= "00000";
|
| 368 |
|
|
F <= (others => '1');
|
| 369 |
|
|
Arith16_r <= '0';
|
| 370 |
|
|
BTR_r <= '0';
|
| 371 |
|
|
Z16_r <= '0';
|
| 372 |
|
|
ALU_Op_r <= "0000";
|
| 373 |
|
|
Save_ALU_r <= '0';
|
| 374 |
|
|
PreserveC_r <= '0';
|
| 375 |
|
|
XY_Ind <= '0';
|
| 376 |
|
|
|
| 377 |
|
|
elsif CLK_n'event and CLK_n = '1' then
|
| 378 |
|
|
|
| 379 |
|
|
if ClkEn = '1' then
|
| 380 |
|
|
|
| 381 |
|
|
ALU_Op_r <= "0000";
|
| 382 |
|
|
Save_ALU_r <= '0';
|
| 383 |
|
|
Read_To_Reg_r <= "00000";
|
| 384 |
|
|
|
| 385 |
|
|
MCycles <= MCycles_d;
|
| 386 |
|
|
|
| 387 |
|
|
if IMode /= "11" then
|
| 388 |
|
|
IStatus <= IMode;
|
| 389 |
|
|
end if;
|
| 390 |
|
|
|
| 391 |
|
|
Arith16_r <= Arith16;
|
| 392 |
|
|
PreserveC_r <= PreserveC;
|
| 393 |
|
|
if ISet = "10" and ALU_OP(2) = '0' and ALU_OP(0) = '1' and MCycle = "011" then
|
| 394 |
|
|
Z16_r <= '1';
|
| 395 |
|
|
else
|
| 396 |
|
|
Z16_r <= '0';
|
| 397 |
|
|
end if;
|
| 398 |
|
|
|
| 399 |
|
|
if MCycle = "001" and TState(2) = '0' then
|
| 400 |
|
|
-- MCycle = 1 and TState = 1, 2, or 3
|
| 401 |
|
|
|
| 402 |
|
|
if TState = 2 and Wait_n = '1' then
|
| 403 |
|
|
if Mode < 2 then
|
| 404 |
|
|
A(7 downto 0) <= std_logic_vector(R);
|
| 405 |
|
|
A(15 downto 8) <= I;
|
| 406 |
|
|
R(6 downto 0) <= R(6 downto 0) + 1;
|
| 407 |
|
|
end if;
|
| 408 |
|
|
|
| 409 |
|
|
if Jump = '0' and Call = '0' and NMICycle = '0' and IntCycle = '0' and not (Halt_FF = '1' or Halt = '1') then
|
| 410 |
|
|
PC <= PC + 1;
|
| 411 |
|
|
end if;
|
| 412 |
|
|
|
| 413 |
|
|
if IntCycle = '1' and IStatus = "01" then
|
| 414 |
|
|
IR <= "11111111";
|
| 415 |
|
|
elsif Halt_FF = '1' or (IntCycle = '1' and IStatus = "10") or NMICycle = '1' then
|
| 416 |
|
|
IR <= "00000000";
|
| 417 |
|
|
else
|
| 418 |
|
|
IR <= DInst;
|
| 419 |
|
|
end if;
|
| 420 |
|
|
|
| 421 |
|
|
ISet <= "00";
|
| 422 |
|
|
if Prefix /= "00" then
|
| 423 |
|
|
if Prefix = "11" then
|
| 424 |
|
|
if IR(5) = '1' then
|
| 425 |
|
|
XY_State <= "10";
|
| 426 |
|
|
else
|
| 427 |
|
|
XY_State <= "01";
|
| 428 |
|
|
end if;
|
| 429 |
|
|
else
|
| 430 |
|
|
if Prefix = "10" then
|
| 431 |
|
|
XY_State <= "00";
|
| 432 |
|
|
XY_Ind <= '0';
|
| 433 |
|
|
end if;
|
| 434 |
|
|
ISet <= Prefix;
|
| 435 |
|
|
end if;
|
| 436 |
|
|
else
|
| 437 |
|
|
XY_State <= "00";
|
| 438 |
|
|
XY_Ind <= '0';
|
| 439 |
|
|
end if;
|
| 440 |
|
|
end if;
|
| 441 |
|
|
|
| 442 |
|
|
else
|
| 443 |
|
|
-- either (MCycle > 1) OR (MCycle = 1 AND TState > 3)
|
| 444 |
|
|
|
| 445 |
|
|
if MCycle = "110" then
|
| 446 |
|
|
XY_Ind <= '1';
|
| 447 |
|
|
if Prefix = "01" then
|
| 448 |
|
|
ISet <= "01";
|
| 449 |
|
|
end if;
|
| 450 |
|
|
end if;
|
| 451 |
|
|
|
| 452 |
|
|
if T_Res = '1' then
|
| 453 |
|
|
BTR_r <= (I_BT or I_BC or I_BTR) and not No_BTR;
|
| 454 |
|
|
if Jump = '1' then
|
| 455 |
|
|
A(15 downto 8) <= DI_Reg;
|
| 456 |
|
|
A(7 downto 0) <= TmpAddr(7 downto 0);
|
| 457 |
|
|
PC(15 downto 8) <= unsigned(DI_Reg);
|
| 458 |
|
|
PC(7 downto 0) <= unsigned(TmpAddr(7 downto 0));
|
| 459 |
|
|
elsif JumpXY = '1' then
|
| 460 |
|
|
A <= RegBusC;
|
| 461 |
|
|
PC <= unsigned(RegBusC);
|
| 462 |
|
|
elsif Call = '1' or RstP = '1' then
|
| 463 |
|
|
A <= TmpAddr;
|
| 464 |
|
|
PC <= unsigned(TmpAddr);
|
| 465 |
|
|
elsif MCycle = MCycles and NMICycle = '1' then
|
| 466 |
|
|
A <= "0000000001100110";
|
| 467 |
|
|
PC <= "0000000001100110";
|
| 468 |
|
|
elsif MCycle = "011" and IntCycle = '1' and IStatus = "10" then
|
| 469 |
|
|
A(15 downto 8) <= I;
|
| 470 |
|
|
A(7 downto 0) <= TmpAddr(7 downto 0);
|
| 471 |
|
|
PC(15 downto 8) <= unsigned(I);
|
| 472 |
|
|
PC(7 downto 0) <= unsigned(TmpAddr(7 downto 0));
|
| 473 |
|
|
else
|
| 474 |
|
|
case Set_Addr_To is
|
| 475 |
|
|
when aXY =>
|
| 476 |
|
|
if XY_State = "00" then
|
| 477 |
|
|
A <= RegBusC;
|
| 478 |
|
|
else
|
| 479 |
|
|
if NextIs_XY_Fetch = '1' then
|
| 480 |
|
|
A <= std_logic_vector(PC);
|
| 481 |
|
|
else
|
| 482 |
|
|
A <= TmpAddr;
|
| 483 |
|
|
end if;
|
| 484 |
|
|
end if;
|
| 485 |
|
|
when aIOA =>
|
| 486 |
|
|
if Mode = 3 then
|
| 487 |
|
|
-- Memory map I/O on GBZ80
|
| 488 |
|
|
A(15 downto 8) <= (others => '1');
|
| 489 |
|
|
elsif Mode = 2 then
|
| 490 |
|
|
-- Duplicate I/O address on 8080
|
| 491 |
|
|
A(15 downto 8) <= DI_Reg;
|
| 492 |
|
|
else
|
| 493 |
|
|
A(15 downto 8) <= ACC;
|
| 494 |
|
|
end if;
|
| 495 |
|
|
A(7 downto 0) <= DI_Reg;
|
| 496 |
|
|
when aSP =>
|
| 497 |
|
|
A <= std_logic_vector(SP);
|
| 498 |
|
|
when aBC =>
|
| 499 |
|
|
if Mode = 3 and IORQ_i = '1' then
|
| 500 |
|
|
-- Memory map I/O on GBZ80
|
| 501 |
|
|
A(15 downto 8) <= (others => '1');
|
| 502 |
|
|
A(7 downto 0) <= RegBusC(7 downto 0);
|
| 503 |
|
|
else
|
| 504 |
|
|
A <= RegBusC;
|
| 505 |
|
|
end if;
|
| 506 |
|
|
when aDE =>
|
| 507 |
|
|
A <= RegBusC;
|
| 508 |
|
|
when aZI =>
|
| 509 |
|
|
if Inc_WZ = '1' then
|
| 510 |
|
|
A <= std_logic_vector(unsigned(TmpAddr) + 1);
|
| 511 |
|
|
else
|
| 512 |
|
|
A(15 downto 8) <= DI_Reg;
|
| 513 |
|
|
A(7 downto 0) <= TmpAddr(7 downto 0);
|
| 514 |
|
|
end if;
|
| 515 |
|
|
when others =>
|
| 516 |
|
|
A <= std_logic_vector(PC);
|
| 517 |
|
|
end case;
|
| 518 |
|
|
end if;
|
| 519 |
|
|
|
| 520 |
|
|
Save_ALU_r <= Save_ALU;
|
| 521 |
|
|
ALU_Op_r <= ALU_Op;
|
| 522 |
|
|
|
| 523 |
|
|
if I_CPL = '1' then
|
| 524 |
|
|
-- CPL
|
| 525 |
|
|
ACC <= not ACC;
|
| 526 |
|
|
F(Flag_Y) <= not ACC(5);
|
| 527 |
|
|
F(Flag_H) <= '1';
|
| 528 |
|
|
F(Flag_X) <= not ACC(3);
|
| 529 |
|
|
F(Flag_N) <= '1';
|
| 530 |
|
|
end if;
|
| 531 |
|
|
if I_CCF = '1' then
|
| 532 |
|
|
-- CCF
|
| 533 |
|
|
F(Flag_C) <= not F(Flag_C);
|
| 534 |
|
|
F(Flag_Y) <= ACC(5);
|
| 535 |
|
|
F(Flag_H) <= F(Flag_C);
|
| 536 |
|
|
F(Flag_X) <= ACC(3);
|
| 537 |
|
|
F(Flag_N) <= '0';
|
| 538 |
|
|
end if;
|
| 539 |
|
|
if I_SCF = '1' then
|
| 540 |
|
|
-- SCF
|
| 541 |
|
|
F(Flag_C) <= '1';
|
| 542 |
|
|
F(Flag_Y) <= ACC(5);
|
| 543 |
|
|
F(Flag_H) <= '0';
|
| 544 |
|
|
F(Flag_X) <= ACC(3);
|
| 545 |
|
|
F(Flag_N) <= '0';
|
| 546 |
|
|
end if;
|
| 547 |
|
|
end if;
|
| 548 |
|
|
|
| 549 |
|
|
if TState = 2 and Wait_n = '1' then
|
| 550 |
|
|
if ISet = "01" and MCycle = "111" then
|
| 551 |
|
|
IR <= DInst;
|
| 552 |
|
|
end if;
|
| 553 |
|
|
if JumpE = '1' then
|
| 554 |
|
|
PC <= unsigned(signed(PC) + signed(DI_Reg));
|
| 555 |
|
|
elsif Inc_PC = '1' then
|
| 556 |
|
|
PC <= PC + 1;
|
| 557 |
|
|
end if;
|
| 558 |
|
|
if BTR_r = '1' then
|
| 559 |
|
|
PC <= PC - 2;
|
| 560 |
|
|
end if;
|
| 561 |
|
|
if RstP = '1' then
|
| 562 |
|
|
TmpAddr <= (others =>'0');
|
| 563 |
|
|
TmpAddr(5 downto 3) <= IR(5 downto 3);
|
| 564 |
|
|
end if;
|
| 565 |
|
|
end if;
|
| 566 |
|
|
if TState = 3 and MCycle = "110" then
|
| 567 |
|
|
TmpAddr <= std_logic_vector(signed(RegBusC) + signed(DI_Reg));
|
| 568 |
|
|
end if;
|
| 569 |
|
|
|
| 570 |
|
|
if (TState = 2 and Wait_n = '1') or (TState = 4 and MCycle = "001") then
|
| 571 |
|
|
if IncDec_16(2 downto 0) = "111" then
|
| 572 |
|
|
if IncDec_16(3) = '1' then
|
| 573 |
|
|
SP <= SP - 1;
|
| 574 |
|
|
else
|
| 575 |
|
|
SP <= SP + 1;
|
| 576 |
|
|
end if;
|
| 577 |
|
|
end if;
|
| 578 |
|
|
end if;
|
| 579 |
|
|
|
| 580 |
|
|
if LDSPHL = '1' then
|
| 581 |
|
|
SP <= unsigned(RegBusC);
|
| 582 |
|
|
end if;
|
| 583 |
|
|
if ExchangeAF = '1' then
|
| 584 |
|
|
Ap <= ACC;
|
| 585 |
|
|
ACC <= Ap;
|
| 586 |
|
|
Fp <= F;
|
| 587 |
|
|
F <= Fp;
|
| 588 |
|
|
end if;
|
| 589 |
|
|
if ExchangeRS = '1' then
|
| 590 |
|
|
Alternate <= not Alternate;
|
| 591 |
|
|
end if;
|
| 592 |
|
|
end if;
|
| 593 |
|
|
|
| 594 |
|
|
if TState = 3 then
|
| 595 |
|
|
if LDZ = '1' then
|
| 596 |
|
|
TmpAddr(7 downto 0) <= DI_Reg;
|
| 597 |
|
|
end if;
|
| 598 |
|
|
if LDW = '1' then
|
| 599 |
|
|
TmpAddr(15 downto 8) <= DI_Reg;
|
| 600 |
|
|
end if;
|
| 601 |
|
|
|
| 602 |
|
|
if Special_LD(2) = '1' then
|
| 603 |
|
|
case Special_LD(1 downto 0) is
|
| 604 |
|
|
when "00" =>
|
| 605 |
|
|
ACC <= I;
|
| 606 |
|
|
F(Flag_P) <= IntE_FF2;
|
| 607 |
|
|
when "01" =>
|
| 608 |
|
|
ACC <= std_logic_vector(R);
|
| 609 |
|
|
F(Flag_P) <= IntE_FF2;
|
| 610 |
|
|
when "10" =>
|
| 611 |
|
|
I <= ACC;
|
| 612 |
|
|
when others =>
|
| 613 |
|
|
R <= unsigned(ACC);
|
| 614 |
|
|
end case;
|
| 615 |
|
|
end if;
|
| 616 |
|
|
end if;
|
| 617 |
|
|
|
| 618 |
|
|
if (I_DJNZ = '0' and Save_ALU_r = '1') or ALU_Op_r = "1001" then
|
| 619 |
|
|
if Mode = 3 then
|
| 620 |
|
|
F(6) <= F_Out(6);
|
| 621 |
|
|
F(5) <= F_Out(5);
|
| 622 |
|
|
F(7) <= F_Out(7);
|
| 623 |
|
|
if PreserveC_r = '0' then
|
| 624 |
|
|
F(4) <= F_Out(4);
|
| 625 |
|
|
end if;
|
| 626 |
|
|
else
|
| 627 |
|
|
F(7 downto 1) <= F_Out(7 downto 1);
|
| 628 |
|
|
if PreserveC_r = '0' then
|
| 629 |
|
|
F(Flag_C) <= F_Out(0);
|
| 630 |
|
|
end if;
|
| 631 |
|
|
end if;
|
| 632 |
|
|
end if;
|
| 633 |
|
|
if T_Res = '1' and I_INRC = '1' then
|
| 634 |
|
|
F(Flag_H) <= '0';
|
| 635 |
|
|
F(Flag_N) <= '0';
|
| 636 |
|
|
if DI_Reg(7 downto 0) = "00000000" then
|
| 637 |
|
|
F(Flag_Z) <= '1';
|
| 638 |
|
|
else
|
| 639 |
|
|
F(Flag_Z) <= '0';
|
| 640 |
|
|
end if;
|
| 641 |
|
|
F(Flag_S) <= DI_Reg(7);
|
| 642 |
|
|
F(Flag_P) <= not (DI_Reg(0) xor DI_Reg(1) xor DI_Reg(2) xor DI_Reg(3) xor
|
| 643 |
|
|
DI_Reg(4) xor DI_Reg(5) xor DI_Reg(6) xor DI_Reg(7));
|
| 644 |
|
|
end if;
|
| 645 |
|
|
|
| 646 |
|
|
if TState = 1 and Auto_Wait_t1 = '0' then
|
| 647 |
|
|
DO <= BusB;
|
| 648 |
|
|
if I_RLD = '1' then
|
| 649 |
|
|
DO(3 downto 0) <= BusA(3 downto 0);
|
| 650 |
|
|
DO(7 downto 4) <= BusB(3 downto 0);
|
| 651 |
|
|
end if;
|
| 652 |
|
|
if I_RRD = '1' then
|
| 653 |
|
|
DO(3 downto 0) <= BusB(7 downto 4);
|
| 654 |
|
|
DO(7 downto 4) <= BusA(3 downto 0);
|
| 655 |
|
|
end if;
|
| 656 |
|
|
end if;
|
| 657 |
|
|
|
| 658 |
|
|
if T_Res = '1' then
|
| 659 |
|
|
Read_To_Reg_r(3 downto 0) <= Set_BusA_To;
|
| 660 |
|
|
Read_To_Reg_r(4) <= Read_To_Reg;
|
| 661 |
|
|
if Read_To_Acc = '1' then
|
| 662 |
|
|
Read_To_Reg_r(3 downto 0) <= "0111";
|
| 663 |
|
|
Read_To_Reg_r(4) <= '1';
|
| 664 |
|
|
end if;
|
| 665 |
|
|
end if;
|
| 666 |
|
|
|
| 667 |
|
|
if TState = 1 and I_BT = '1' then
|
| 668 |
|
|
F(Flag_X) <= ALU_Q(3);
|
| 669 |
|
|
F(Flag_Y) <= ALU_Q(1);
|
| 670 |
|
|
F(Flag_H) <= '0';
|
| 671 |
|
|
F(Flag_N) <= '0';
|
| 672 |
|
|
end if;
|
| 673 |
|
|
if I_BC = '1' or I_BT = '1' then
|
| 674 |
|
|
F(Flag_P) <= IncDecZ;
|
| 675 |
|
|
end if;
|
| 676 |
|
|
|
| 677 |
|
|
if (TState = 1 and Save_ALU_r = '0' and Auto_Wait_t1 = '0') or
|
| 678 |
|
|
(Save_ALU_r = '1' and ALU_OP_r /= "0111") then
|
| 679 |
|
|
case Read_To_Reg_r is
|
| 680 |
|
|
when "10111" =>
|
| 681 |
|
|
ACC <= Save_Mux;
|
| 682 |
|
|
when "10110" =>
|
| 683 |
|
|
DO <= Save_Mux;
|
| 684 |
|
|
when "11000" =>
|
| 685 |
|
|
SP(7 downto 0) <= unsigned(Save_Mux);
|
| 686 |
|
|
when "11001" =>
|
| 687 |
|
|
SP(15 downto 8) <= unsigned(Save_Mux);
|
| 688 |
|
|
when "11011" =>
|
| 689 |
|
|
F <= Save_Mux;
|
| 690 |
|
|
when others =>
|
| 691 |
|
|
end case;
|
| 692 |
|
|
end if;
|
| 693 |
|
|
|
| 694 |
|
|
end if;
|
| 695 |
|
|
|
| 696 |
|
|
end if;
|
| 697 |
|
|
|
| 698 |
|
|
end process;
|
| 699 |
|
|
|
| 700 |
|
|
---------------------------------------------------------------------------
|
| 701 |
|
|
--
|
| 702 |
|
|
-- BC('), DE('), HL('), IX and IY
|
| 703 |
|
|
--
|
| 704 |
|
|
---------------------------------------------------------------------------
|
| 705 |
|
|
process (CLK_n)
|
| 706 |
|
|
begin
|
| 707 |
|
|
if CLK_n'event and CLK_n = '1' then
|
| 708 |
|
|
if ClkEn = '1' then
|
| 709 |
|
|
-- Bus A / Write
|
| 710 |
|
|
RegAddrA_r <= Alternate & Set_BusA_To(2 downto 1);
|
| 711 |
|
|
if XY_Ind = '0' and XY_State /= "00" and Set_BusA_To(2 downto 1) = "10" then
|
| 712 |
|
|
RegAddrA_r <= XY_State(1) & "11";
|
| 713 |
|
|
end if;
|
| 714 |
|
|
|
| 715 |
|
|
-- Bus B
|
| 716 |
|
|
RegAddrB_r <= Alternate & Set_BusB_To(2 downto 1);
|
| 717 |
|
|
if XY_Ind = '0' and XY_State /= "00" and Set_BusB_To(2 downto 1) = "10" then
|
| 718 |
|
|
RegAddrB_r <= XY_State(1) & "11";
|
| 719 |
|
|
end if;
|
| 720 |
|
|
|
| 721 |
|
|
-- Address from register
|
| 722 |
|
|
RegAddrC <= Alternate & Set_Addr_To(1 downto 0);
|
| 723 |
|
|
-- Jump (HL), LD SP,HL
|
| 724 |
|
|
if (JumpXY = '1' or LDSPHL = '1') then
|
| 725 |
|
|
RegAddrC <= Alternate & "10";
|
| 726 |
|
|
end if;
|
| 727 |
|
|
if ((JumpXY = '1' or LDSPHL = '1') and XY_State /= "00") or (MCycle = "110") then
|
| 728 |
|
|
RegAddrC <= XY_State(1) & "11";
|
| 729 |
|
|
end if;
|
| 730 |
|
|
|
| 731 |
|
|
if I_DJNZ = '1' and Save_ALU_r = '1' and Mode < 2 then
|
| 732 |
|
|
IncDecZ <= F_Out(Flag_Z);
|
| 733 |
|
|
end if;
|
| 734 |
|
|
if (TState = 2 or (TState = 3 and MCycle = "001")) and IncDec_16(2 downto 0) = "100" then
|
| 735 |
|
|
if ID16 = 0 then
|
| 736 |
|
|
IncDecZ <= '0';
|
| 737 |
|
|
else
|
| 738 |
|
|
IncDecZ <= '1';
|
| 739 |
|
|
end if;
|
| 740 |
|
|
end if;
|
| 741 |
|
|
|
| 742 |
|
|
RegBusA_r <= RegBusA;
|
| 743 |
|
|
end if;
|
| 744 |
|
|
end if;
|
| 745 |
|
|
end process;
|
| 746 |
|
|
|
| 747 |
|
|
RegAddrA <=
|
| 748 |
|
|
-- 16 bit increment/decrement
|
| 749 |
|
|
Alternate & IncDec_16(1 downto 0) when (TState = 2 or
|
| 750 |
|
|
(TState = 3 and MCycle = "001" and IncDec_16(2) = '1')) and XY_State = "00" else
|
| 751 |
|
|
XY_State(1) & "11" when (TState = 2 or
|
| 752 |
|
|
(TState = 3 and MCycle = "001" and IncDec_16(2) = '1')) and IncDec_16(1 downto 0) = "10" else
|
| 753 |
|
|
-- EX HL,DL
|
| 754 |
|
|
Alternate & "10" when ExchangeDH = '1' and TState = 3 else
|
| 755 |
|
|
Alternate & "01" when ExchangeDH = '1' and TState = 4 else
|
| 756 |
|
|
-- Bus A / Write
|
| 757 |
|
|
RegAddrA_r;
|
| 758 |
|
|
|
| 759 |
|
|
RegAddrB <=
|
| 760 |
|
|
-- EX HL,DL
|
| 761 |
|
|
Alternate & "01" when ExchangeDH = '1' and TState = 3 else
|
| 762 |
|
|
-- Bus B
|
| 763 |
|
|
RegAddrB_r;
|
| 764 |
|
|
|
| 765 |
|
|
ID16 <= signed(RegBusA) - 1 when IncDec_16(3) = '1' else
|
| 766 |
|
|
signed(RegBusA) + 1;
|
| 767 |
|
|
|
| 768 |
|
|
process (Save_ALU_r, Auto_Wait_t1, ALU_OP_r, Read_To_Reg_r,
|
| 769 |
|
|
ExchangeDH, IncDec_16, MCycle, TState, Wait_n)
|
| 770 |
|
|
begin
|
| 771 |
|
|
RegWEH <= '0';
|
| 772 |
|
|
RegWEL <= '0';
|
| 773 |
|
|
if (TState = 1 and Save_ALU_r = '0' and Auto_Wait_t1 = '0') or
|
| 774 |
|
|
(Save_ALU_r = '1' and ALU_OP_r /= "0111") then
|
| 775 |
|
|
case Read_To_Reg_r is
|
| 776 |
|
|
when "10000" | "10001" | "10010" | "10011" | "10100" | "10101" =>
|
| 777 |
|
|
RegWEH <= not Read_To_Reg_r(0);
|
| 778 |
|
|
RegWEL <= Read_To_Reg_r(0);
|
| 779 |
|
|
when others =>
|
| 780 |
|
|
end case;
|
| 781 |
|
|
end if;
|
| 782 |
|
|
|
| 783 |
|
|
if ExchangeDH = '1' and (TState = 3 or TState = 4) then
|
| 784 |
|
|
RegWEH <= '1';
|
| 785 |
|
|
RegWEL <= '1';
|
| 786 |
|
|
end if;
|
| 787 |
|
|
|
| 788 |
|
|
if IncDec_16(2) = '1' and ((TState = 2 and Wait_n = '1' and MCycle /= "001") or (TState = 3 and MCycle = "001")) then
|
| 789 |
|
|
case IncDec_16(1 downto 0) is
|
| 790 |
|
|
when "00" | "01" | "10" =>
|
| 791 |
|
|
RegWEH <= '1';
|
| 792 |
|
|
RegWEL <= '1';
|
| 793 |
|
|
when others =>
|
| 794 |
|
|
end case;
|
| 795 |
|
|
end if;
|
| 796 |
|
|
end process;
|
| 797 |
|
|
|
| 798 |
|
|
process (Save_Mux, RegBusB, RegBusA_r, ID16,
|
| 799 |
|
|
ExchangeDH, IncDec_16, MCycle, TState, Wait_n)
|
| 800 |
|
|
begin
|
| 801 |
|
|
RegDIH <= Save_Mux;
|
| 802 |
|
|
RegDIL <= Save_Mux;
|
| 803 |
|
|
|
| 804 |
|
|
if ExchangeDH = '1' and TState = 3 then
|
| 805 |
|
|
RegDIH <= RegBusB(15 downto 8);
|
| 806 |
|
|
RegDIL <= RegBusB(7 downto 0);
|
| 807 |
|
|
end if;
|
| 808 |
|
|
if ExchangeDH = '1' and TState = 4 then
|
| 809 |
|
|
RegDIH <= RegBusA_r(15 downto 8);
|
| 810 |
|
|
RegDIL <= RegBusA_r(7 downto 0);
|
| 811 |
|
|
end if;
|
| 812 |
|
|
|
| 813 |
|
|
if IncDec_16(2) = '1' and ((TState = 2 and MCycle /= "001") or (TState = 3 and MCycle = "001")) then
|
| 814 |
|
|
RegDIH <= std_logic_vector(ID16(15 downto 8));
|
| 815 |
|
|
RegDIL <= std_logic_vector(ID16(7 downto 0));
|
| 816 |
|
|
end if;
|
| 817 |
|
|
end process;
|
| 818 |
|
|
|
| 819 |
|
|
Regs : T80_Reg
|
| 820 |
|
|
port map(
|
| 821 |
|
|
Clk => CLK_n,
|
| 822 |
|
|
CEN => ClkEn,
|
| 823 |
|
|
WEH => RegWEH,
|
| 824 |
|
|
WEL => RegWEL,
|
| 825 |
|
|
AddrA => RegAddrA,
|
| 826 |
|
|
AddrB => RegAddrB,
|
| 827 |
|
|
AddrC => RegAddrC,
|
| 828 |
|
|
DIH => RegDIH,
|
| 829 |
|
|
DIL => RegDIL,
|
| 830 |
|
|
DOAH => RegBusA(15 downto 8),
|
| 831 |
|
|
DOAL => RegBusA(7 downto 0),
|
| 832 |
|
|
DOBH => RegBusB(15 downto 8),
|
| 833 |
|
|
DOBL => RegBusB(7 downto 0),
|
| 834 |
|
|
DOCH => RegBusC(15 downto 8),
|
| 835 |
|
|
DOCL => RegBusC(7 downto 0));
|
| 836 |
|
|
|
| 837 |
|
|
---------------------------------------------------------------------------
|
| 838 |
|
|
--
|
| 839 |
|
|
-- Buses
|
| 840 |
|
|
--
|
| 841 |
|
|
---------------------------------------------------------------------------
|
| 842 |
|
|
process (CLK_n)
|
| 843 |
|
|
begin
|
| 844 |
|
|
if CLK_n'event and CLK_n = '1' then
|
| 845 |
|
|
if ClkEn = '1' then
|
| 846 |
|
|
case Set_BusB_To is
|
| 847 |
|
|
when "0111" =>
|
| 848 |
|
|
BusB <= ACC;
|
| 849 |
|
|
when "0000" | "0001" | "0010" | "0011" | "0100" | "0101" =>
|
| 850 |
|
|
if Set_BusB_To(0) = '1' then
|
| 851 |
|
|
BusB <= RegBusB(7 downto 0);
|
| 852 |
|
|
else
|
| 853 |
|
|
BusB <= RegBusB(15 downto 8);
|
| 854 |
|
|
end if;
|
| 855 |
|
|
when "0110" =>
|
| 856 |
|
|
BusB <= DI_Reg;
|
| 857 |
|
|
when "1000" =>
|
| 858 |
|
|
BusB <= std_logic_vector(SP(7 downto 0));
|
| 859 |
|
|
when "1001" =>
|
| 860 |
|
|
BusB <= std_logic_vector(SP(15 downto 8));
|
| 861 |
|
|
when "1010" =>
|
| 862 |
|
|
BusB <= "00000001";
|
| 863 |
|
|
when "1011" =>
|
| 864 |
|
|
BusB <= F;
|
| 865 |
|
|
when "1100" =>
|
| 866 |
|
|
BusB <= std_logic_vector(PC(7 downto 0));
|
| 867 |
|
|
when "1101" =>
|
| 868 |
|
|
BusB <= std_logic_vector(PC(15 downto 8));
|
| 869 |
|
|
when "1110" =>
|
| 870 |
|
|
BusB <= "00000000";
|
| 871 |
|
|
when others =>
|
| 872 |
|
|
BusB <= "--------";
|
| 873 |
|
|
end case;
|
| 874 |
|
|
|
| 875 |
|
|
case Set_BusA_To is
|
| 876 |
|
|
when "0111" =>
|
| 877 |
|
|
BusA <= ACC;
|
| 878 |
|
|
when "0000" | "0001" | "0010" | "0011" | "0100" | "0101" =>
|
| 879 |
|
|
if Set_BusA_To(0) = '1' then
|
| 880 |
|
|
BusA <= RegBusA(7 downto 0);
|
| 881 |
|
|
else
|
| 882 |
|
|
BusA <= RegBusA(15 downto 8);
|
| 883 |
|
|
end if;
|
| 884 |
|
|
when "0110" =>
|
| 885 |
|
|
BusA <= DI_Reg;
|
| 886 |
|
|
when "1000" =>
|
| 887 |
|
|
BusA <= std_logic_vector(SP(7 downto 0));
|
| 888 |
|
|
when "1001" =>
|
| 889 |
|
|
BusA <= std_logic_vector(SP(15 downto 8));
|
| 890 |
|
|
when "1010" =>
|
| 891 |
|
|
BusA <= "00000000";
|
| 892 |
|
|
when others =>
|
| 893 |
|
|
BusB <= "--------";
|
| 894 |
|
|
end case;
|
| 895 |
|
|
end if;
|
| 896 |
|
|
end if;
|
| 897 |
|
|
end process;
|
| 898 |
|
|
|
| 899 |
|
|
---------------------------------------------------------------------------
|
| 900 |
|
|
--
|
| 901 |
|
|
-- Generate external control signals
|
| 902 |
|
|
--
|
| 903 |
|
|
---------------------------------------------------------------------------
|
| 904 |
|
|
process (RESET_n,CLK_n)
|
| 905 |
|
|
begin
|
| 906 |
|
|
if RESET_n = '0' then
|
| 907 |
|
|
RFSH_n <= '1';
|
| 908 |
|
|
elsif CLK_n'event and CLK_n = '1' then
|
| 909 |
|
|
if CEN = '1' then
|
| 910 |
|
|
if MCycle = "001" and ((TState = 2 and Wait_n = '1') or TState = 3) then
|
| 911 |
|
|
RFSH_n <= '0';
|
| 912 |
|
|
else
|
| 913 |
|
|
RFSH_n <= '1';
|
| 914 |
|
|
end if;
|
| 915 |
|
|
end if;
|
| 916 |
|
|
end if;
|
| 917 |
|
|
end process;
|
| 918 |
|
|
|
| 919 |
|
|
MC <= std_logic_vector(MCycle);
|
| 920 |
|
|
TS <= std_logic_vector(TState);
|
| 921 |
|
|
DI_Reg <= DI;
|
| 922 |
|
|
HALT_n <= not Halt_FF;
|
| 923 |
|
|
BUSAK_n <= not BusAck;
|
| 924 |
|
|
IntCycle_n <= not IntCycle;
|
| 925 |
|
|
IntE <= IntE_FF1;
|
| 926 |
|
|
IORQ <= IORQ_i;
|
| 927 |
|
|
Stop <= I_DJNZ;
|
| 928 |
|
|
|
| 929 |
|
|
-------------------------------------------------------------------------
|
| 930 |
|
|
--
|
| 931 |
|
|
-- Syncronise inputs
|
| 932 |
|
|
--
|
| 933 |
|
|
-------------------------------------------------------------------------
|
| 934 |
|
|
process (RESET_n, CLK_n)
|
| 935 |
|
|
variable OldNMI_n : std_logic;
|
| 936 |
|
|
begin
|
| 937 |
|
|
if RESET_n = '0' then
|
| 938 |
|
|
BusReq_s <= '0';
|
| 939 |
|
|
INT_s <= '0';
|
| 940 |
|
|
NMI_s <= '0';
|
| 941 |
|
|
OldNMI_n := '0';
|
| 942 |
|
|
elsif CLK_n'event and CLK_n = '1' then
|
| 943 |
|
|
if CEN = '1' then
|
| 944 |
|
|
BusReq_s <= not BUSRQ_n;
|
| 945 |
|
|
INT_s <= not INT_n;
|
| 946 |
|
|
if NMICycle = '1' then
|
| 947 |
|
|
NMI_s <= '0';
|
| 948 |
|
|
elsif NMI_n = '0' and OldNMI_n = '1' then
|
| 949 |
|
|
NMI_s <= '1';
|
| 950 |
|
|
end if;
|
| 951 |
|
|
OldNMI_n := NMI_n;
|
| 952 |
|
|
end if;
|
| 953 |
|
|
end if;
|
| 954 |
|
|
end process;
|
| 955 |
|
|
|
| 956 |
|
|
-------------------------------------------------------------------------
|
| 957 |
|
|
--
|
| 958 |
|
|
-- Main state machine
|
| 959 |
|
|
--
|
| 960 |
|
|
-------------------------------------------------------------------------
|
| 961 |
|
|
process (RESET_n, CLK_n)
|
| 962 |
|
|
begin
|
| 963 |
|
|
if RESET_n = '0' then
|
| 964 |
|
|
MCycle <= "001";
|
| 965 |
|
|
TState <= "000";
|
| 966 |
|
|
Pre_XY_F_M <= "000";
|
| 967 |
|
|
Halt_FF <= '0';
|
| 968 |
|
|
BusAck <= '0';
|
| 969 |
|
|
NMICycle <= '0';
|
| 970 |
|
|
IntCycle <= '0';
|
| 971 |
|
|
IntE_FF1 <= '0';
|
| 972 |
|
|
IntE_FF2 <= '0';
|
| 973 |
|
|
No_BTR <= '0';
|
| 974 |
|
|
Auto_Wait_t1 <= '0';
|
| 975 |
|
|
Auto_Wait_t2 <= '0';
|
| 976 |
|
|
M1_n <= '1';
|
| 977 |
|
|
elsif CLK_n'event and CLK_n = '1' then
|
| 978 |
|
|
if CEN = '1' then
|
| 979 |
|
|
if T_Res = '1' then
|
| 980 |
|
|
Auto_Wait_t1 <= '0';
|
| 981 |
|
|
else
|
| 982 |
|
|
Auto_Wait_t1 <= Auto_Wait or IORQ_i;
|
| 983 |
|
|
end if;
|
| 984 |
|
|
Auto_Wait_t2 <= Auto_Wait_t1;
|
| 985 |
|
|
No_BTR <= (I_BT and (not IR(4) or not F(Flag_P))) or
|
| 986 |
|
|
(I_BC and (not IR(4) or F(Flag_Z) or not F(Flag_P))) or
|
| 987 |
|
|
(I_BTR and (not IR(4) or F(Flag_Z)));
|
| 988 |
|
|
if TState = 2 then
|
| 989 |
|
|
if SetEI = '1' then
|
| 990 |
|
|
IntE_FF1 <= '1';
|
| 991 |
|
|
IntE_FF2 <= '1';
|
| 992 |
|
|
end if;
|
| 993 |
|
|
if I_RETN = '1' then
|
| 994 |
|
|
IntE_FF1 <= IntE_FF2;
|
| 995 |
|
|
end if;
|
| 996 |
|
|
end if;
|
| 997 |
|
|
if TState = 3 then
|
| 998 |
|
|
if SetDI = '1' then
|
| 999 |
|
|
IntE_FF1 <= '0';
|
| 1000 |
|
|
IntE_FF2 <= '0';
|
| 1001 |
|
|
end if;
|
| 1002 |
|
|
end if;
|
| 1003 |
|
|
if IntCycle = '1' or NMICycle = '1' then
|
| 1004 |
|
|
Halt_FF <= '0';
|
| 1005 |
|
|
end if;
|
| 1006 |
|
|
if MCycle = "001" and TState = 2 and Wait_n = '1' then
|
| 1007 |
|
|
M1_n <= '1';
|
| 1008 |
|
|
end if;
|
| 1009 |
|
|
if BusReq_s = '1' and BusAck = '1' then
|
| 1010 |
|
|
else
|
| 1011 |
|
|
BusAck <= '0';
|
| 1012 |
|
|
if TState = 2 and Wait_n = '0' then
|
| 1013 |
|
|
elsif T_Res = '1' then
|
| 1014 |
|
|
if Halt = '1' then
|
| 1015 |
|
|
Halt_FF <= '1';
|
| 1016 |
|
|
end if;
|
| 1017 |
|
|
if BusReq_s = '1' then
|
| 1018 |
|
|
BusAck <= '1';
|
| 1019 |
|
|
else
|
| 1020 |
|
|
TState <= "001";
|
| 1021 |
|
|
if NextIs_XY_Fetch = '1' then
|
| 1022 |
|
|
MCycle <= "110";
|
| 1023 |
|
|
Pre_XY_F_M <= MCycle;
|
| 1024 |
|
|
if IR = "00110110" and Mode = 0 then
|
| 1025 |
|
|
Pre_XY_F_M <= "010";
|
| 1026 |
|
|
end if;
|
| 1027 |
|
|
elsif (MCycle = "111") or
|
| 1028 |
|
|
(MCycle = "110" and Mode = 1 and ISet /= "01") then
|
| 1029 |
|
|
MCycle <= std_logic_vector(unsigned(Pre_XY_F_M) + 1);
|
| 1030 |
|
|
elsif (MCycle = MCycles) or
|
| 1031 |
|
|
No_BTR = '1' or
|
| 1032 |
|
|
(MCycle = "010" and I_DJNZ = '1' and IncDecZ = '1') then
|
| 1033 |
|
|
M1_n <= '0';
|
| 1034 |
|
|
MCycle <= "001";
|
| 1035 |
|
|
IntCycle <= '0';
|
| 1036 |
|
|
NMICycle <= '0';
|
| 1037 |
|
|
if NMI_s = '1' and Prefix = "00" then
|
| 1038 |
|
|
NMICycle <= '1';
|
| 1039 |
|
|
IntE_FF1 <= '0';
|
| 1040 |
|
|
elsif (IntE_FF1 = '1' and INT_s = '1') and Prefix = "00" and SetEI = '0' then
|
| 1041 |
|
|
IntCycle <= '1';
|
| 1042 |
|
|
IntE_FF1 <= '0';
|
| 1043 |
|
|
IntE_FF2 <= '0';
|
| 1044 |
|
|
end if;
|
| 1045 |
|
|
else
|
| 1046 |
|
|
MCycle <= std_logic_vector(unsigned(MCycle) + 1);
|
| 1047 |
|
|
end if;
|
| 1048 |
|
|
end if;
|
| 1049 |
|
|
else
|
| 1050 |
|
|
if (Auto_Wait = '1' and Auto_Wait_t2 = '0') nor
|
| 1051 |
|
|
(IOWait = 1 and IORQ_i = '1' and Auto_Wait_t1 = '0') then
|
| 1052 |
|
|
TState <= TState + 1;
|
| 1053 |
|
|
end if;
|
| 1054 |
|
|
end if;
|
| 1055 |
|
|
end if;
|
| 1056 |
|
|
if TState = 0 then
|
| 1057 |
|
|
M1_n <= '0';
|
| 1058 |
|
|
end if;
|
| 1059 |
|
|
end if;
|
| 1060 |
|
|
end if;
|
| 1061 |
|
|
end process;
|
| 1062 |
|
|
|
| 1063 |
|
|
process (IntCycle, NMICycle, MCycle)
|
| 1064 |
|
|
begin
|
| 1065 |
|
|
Auto_Wait <= '0';
|
| 1066 |
|
|
if IntCycle = '1' or NMICycle = '1' then
|
| 1067 |
|
|
if MCycle = "001" then
|
| 1068 |
|
|
Auto_Wait <= '1';
|
| 1069 |
|
|
end if;
|
| 1070 |
|
|
end if;
|
| 1071 |
|
|
end process;
|
| 1072 |
|
|
|
| 1073 |
|
|
end;
|
