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ndumitrach |
//////////////////////////////////////////////////////////////////////////////////
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//
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// This file is part of the NextZ80 project
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// http://www.opencores.org/cores/nextz80/
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//
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// Filename: NextZ80CPU.v
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// Description: Implementation of Z80 compatible CPU
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// Version 1.0
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// Creation date: 28Jan2011 - 18Mar2011
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//
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// Author: Nicolae Dumitrache
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// e-mail: ndumitrache@opencores.org
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//
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/////////////////////////////////////////////////////////////////////////////////
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//
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// Copyright (C) 2011 Nicolae Dumitrache
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//
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// This source file may be used and distributed without
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// restriction provided that this copyright statement is not
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// removed from the file and that any derivative work contains
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// the original copyright notice and the associated disclaimer.
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//
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// This source file is free software; you can redistribute it
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// and/or modify it under the terms of the GNU Lesser General
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// Public License as published by the Free Software Foundation;
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// either version 2.1 of the License, or (at your option) any
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// later version.
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//
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// This source is distributed in the hope that it will be
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// useful, but WITHOUT ANY WARRANTY; without even the implied
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// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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// PURPOSE. See the GNU Lesser General Public License for more
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// details.
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//
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// You should have received a copy of the GNU Lesser General
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// Public License along with this source; if not, download it
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// from http://www.opencores.org/lgpl.shtml
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//
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///////////////////////////////////////////////////////////////////////////////////
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//
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// Comments:
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// This project was developed and tested on a XILINX Spartan3AN board.
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//
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// NextZ80 processor features:
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// All documented/undocumented intstructions are implemented
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// All documented/undocumented flags are implemented
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// All (doc/undoc)flags are changed accordingly by all (doc/undoc)instructions.
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// The block instructions (LDx, CPx, INx, OUTx) have only the documented effects on flags.
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// The Bit n,(IX/IY+d) and BIT n,(HL) undocumented flags XF and YF are implemented like the BIT n,r and not actually like on the real Z80 CPU.
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// All interrupt modes implemented: NMI, IM0, IM1, IM2
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// R register available
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// Fast conditional jump/call/ret takes only 1 T state if not executed
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// Fast block instructions: LDxR - 3 T states/byte, INxR/OTxR - 2 T states/byte, CPxR - 4 T states / byte
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// Each CPU machine cycle takes (mainly) one clock T state. This makes this processor over 4 times faster than a Z80 at the same
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// clock frequency (some instructions are up to 10 times faster).
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// Works at ~40MHZ on Spartan XC3S700AN speed grade -4)
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// Small size ( ~12% ~700 slices - on Spartan XC3S700AN )
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// Tested with ZEXDOC (fully compliant).
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// Tested with ZEXALL (all OK except CPx(R), LDx(R), BIT n, (IX/IY+d), BIT n, (HL) - fail because of the un-documented XF and YF flags).
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//
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///////////////////////////////////////////////////////////////////////////////////
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`timescale 1ns / 1ps
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module NextZ80
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(
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input wire[7:0] DI,
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output wire[7:0] DO,
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output wire[15:0] ADDR,
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output reg WR,
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output reg MREQ,
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output reg IORQ,
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output reg HALT,
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output reg M1,
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input wire CLK,
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input wire RESET,
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input wire INT,
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input wire NMI,
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input wire WAIT
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);
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// connections and registers
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reg [9:0] CPUStatus = 0; // 0=AF-AF', 1=HL-HL', 2=DE-HL, 3=DE'-HL', 4=HL-X, 5=IX-IY, 6=IFF1,7=IFF2, 9:8=IMODE
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wire [7:0] ALU8FLAGS;
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wire [7:0] FLAGS;
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wire [7:0] ALU80;
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wire [7:0] ALU81;
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wire [15:0]ALU160;
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wire [7:0] ALU161;
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wire [15:0]ALU8OUT;
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reg [9:0] FETCH = 0;
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reg [2:0] STAGE = 0;
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wire [5:0] opd;
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wire [2:0] op16;
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wire op0mem = FETCH[2:0] == 6;
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wire op1mem = FETCH[5:3] == 6;
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reg [1:0]fetch98;
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// stage status
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reg [1:0]DO_SEL; // ALU80 - th - flags - ALU8OUT[7:0]
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reg ALU160_SEL; // regs - pc
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reg DINW_SEL; // ALU8OUT - DI
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reg [5:0]WE; // 5 = flags, 4 = PC, 3 = SP, 2 = tmpHI, 1 = hi, 0 = lo
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reg [4:0] ALU8OP;
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reg [2:0] ALU16OP;
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reg next_stage;
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reg [3:0]REG_WSEL;
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reg [3:0]REG_RSEL;
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reg [11:0]status; // 0=AF-AF', 1=HL-HL', 2=DE-HL, 3=DE'-HL', 4=HL-X, 5=IX-IY, 7:6=IFFVAL, 9:8=imode, 10=setIMODE, 11=set IFFVAL
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// FETCH[5:3]: 000 NZ, 001 Z, 010 NC, 011 C, 100 PO, 101 PE, 110 P, 111 M
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wire [7:0]FlagMux = {FLAGS[7], !FLAGS[7], FLAGS[2], !FLAGS[2], FLAGS[0], !FLAGS[0], FLAGS[6], !FLAGS[6]};
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reg tzf;
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reg FNMI = 0, SNMI = 0;
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reg SRESET = 0;
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reg SINT = 0;
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wire [2:0]intop = FETCH[1] ? 4 : (FETCH[0] ? 5 : 6);
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reg xmask;
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Z80Reg CPU_REGS (
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.rstatus(CPUStatus[7:0]),
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.M1(M1),
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.WE(WE),
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.CLK(CLK),
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.ALU8OUT(ALU8OUT),
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.DI(DI),
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.DO(DO),
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.ADDR(ADDR),
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.CONST(FETCH[7] ? {2'b00, FETCH[5:3], 3'b000} : 8'h66), // RST/NMI address
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.ALU80(ALU80),
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.ALU81(ALU81),
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.ALU160(ALU160),
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.ALU161(ALU161),
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.ALU8FLAGS(ALU8FLAGS),
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.FLAGS(FLAGS),
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.DO_SEL(DO_SEL),
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.ALU160_sel(ALU160_SEL),
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.REG_WSEL(REG_WSEL),
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.REG_RSEL(REG_RSEL),
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.DINW_SEL(DINW_SEL),
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.XMASK(xmask),
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.ALU16OP(ALU16OP), // used for post increment for ADDR, SP mux re-direct
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.WAIT(WAIT)
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);
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ALU8 CPU_ALU8 (
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.D0(ALU80),
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.D1(ALU81),
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.FIN(FLAGS),
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.FOUT(ALU8FLAGS),
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.ALU8DOUT(ALU8OUT),
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.OP(ALU8OP),
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.EXOP(FETCH[8:3]),
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.LDIFLAGS(REG_WSEL[2]), // inc16 HL
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.DSTHI(!REG_WSEL[0])
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);
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ALU16 CPU_ALU16 (
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.D0(ALU160),
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.D1(ALU161),
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.DOUT(ADDR),
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.OP(ALU16OP)
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);
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always @(posedge CLK)
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if(!WAIT) begin
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SRESET <= RESET;
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SNMI <= NMI;
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SINT <= INT;
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if(!SNMI) FNMI <= 0;
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if(SRESET) FETCH <= 10'b1110000000;
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else
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if(FETCH[9:6] == 4'b1110) {FETCH[9:7]} <= 3'b000; // exit RESET state
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else begin
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ndumitrach |
if(M1 || (fetch98 == 2'b10)) // [DD/FD CB disp op] - M1 is inactive during <op> byte read, but FETCH is performed
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ndumitrach |
case({MREQ, CPUStatus[9:8]})
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3'b000, 3'b001, 3'b100, 3'b101, 3'b110, 3'b111: FETCH <= {fetch98, DI};
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3'b010: FETCH <= {fetch98, 8'hff}; // IM1 - RST38
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3'b011: ; // IM2 - get addrLO
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endcase
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if(~|{next_stage, fetch98[1:0], status[4]}) // INT or NMI sample
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if(SNMI & !FNMI) begin // NMI posedge
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{FETCH[9:6], FETCH[1:0]} <= {4'b1101, HALT, M1};
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FNMI <= 1; // NMI acknowledged
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end else if(SINT & CPUStatus[6] & !status[11]) {FETCH[9:6], FETCH[1:0]} <= {4'b1100, HALT, M1}; // INT request
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end
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if(next_stage) STAGE <= STAGE + 3'b001;
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else STAGE <= 0;
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if(status[4]) CPUStatus[5:4] <= status[5:4];
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else if(~|{next_stage, fetch98[1]} | fetch98[0]) CPUStatus[4] <= 1'b0; // clear X
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CPUStatus[3:0] <= CPUStatus[3:0] ^ status[3:0];
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if(status[11]) CPUStatus[7:6] <= status[7:6]; // IFF2:1
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if(status[10]) CPUStatus[9:8] <= status[9:8]; // IMM
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tzf <= ALU8FLAGS[6];
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end
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assign opd[0] = FETCH[0] ^ &FETCH[2:1];
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assign opd[2:1] = FETCH[2:1];
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assign opd[3] = FETCH[3] ^ &FETCH[5:4];
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assign opd[5:4] = FETCH[5:4];
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assign op16[2:0] = &FETCH[5:4] ? 3'b101 : {1'b0, FETCH[5:4]};
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always @* begin
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DO_SEL = 2'bxx; // ALU80 - th - flags - ALU8OUT[7:0]
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ALU160_SEL = 1'bx; // regs - pc
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DINW_SEL = 1'bx; // ALU8OUT - DI
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WE = 6'bxxxxxx; // 5 = flags, 4 = PC, 3 = SP, 2 = tmpHI, 1 = hi, 0 = lo
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ALU8OP = 5'bxxxxx;
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ALU16OP = 3'b000; // NOP, post inc
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next_stage = 0;
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REG_WSEL = 4'bxxxx;
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ndumitrach |
REG_RSEL = 4'bx0xx; // prevents default 4'b0100 which leads to incorrect P flag value in some cases (like RLA)
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ndumitrach |
M1 = 1;
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MREQ = 1;
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WR = 0;
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HALT = 0;
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IORQ = 0;
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status = 12'b00xxxxx00000;
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fetch98 = 2'b00;
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case({FETCH[7:6], op1mem, op0mem})
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4'b0000, 4'b0001, 4'b0010, 4'b0011, 4'b0100, 4'b1000, 4'b1100: xmask = 1;
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default: xmask = 0;
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endcase
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case(FETCH[9:6])
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//------------------------------------------- block 00 ----------------------------------------------------
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4'b0000:
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case(FETCH[3:0])
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// ----------------------- NOP, EX AF, AF', DJNZ, JR, JR c --------------------
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4'b0000, 4'b1000:
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case(FETCH[5:4])
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2'b00: begin // NOP, EX AF, AF'
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DO_SEL = 2'bxx;
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ALU160_SEL = 1; // PC
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WE = 6'b010x00; // PC
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status[0] = FETCH[3];
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end
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2'b01:
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if(!STAGE[0]) begin // DJNZ, JR - stage1
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ALU160_SEL = 1; // pc
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WE = 6'b010100; // PC, tmpHI
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if(!FETCH[3]) begin
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ALU8OP = 5'b01010; // DEC, for tzf only
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REG_WSEL = 4'b0000; // B
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end
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next_stage = 1;
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M1 = 0;
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end else if(FETCH[3]) begin // JR - stage2
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ALU160_SEL = 1; // pc
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WE = 6'b010x00; // PC
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ALU16OP = 3; // ADD
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end else begin // DJNZ - stage2
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ALU160_SEL = 1; // pc
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DINW_SEL = 0; // ALU8OUT
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WE = 6'b010x10; // PC, hi
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ALU8OP = 5'b01010; // DEC
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ALU16OP = tzf ? 3'd0 : 3'd3; // NOP/ADD
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REG_WSEL = 4'b0000; // B
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end
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2'b10, 2'b11: // JR cc, stage1, stage2
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case({STAGE[0], FlagMux[{1'b0, FETCH[4:3]}]})
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2'b00, 2'b11: begin
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ALU160_SEL = 1; // pc
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WE = 6'b010x00; // PC
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ALU16OP = STAGE[0] ? 3'd3 : 3'd1; // ADD/ INC, post inc
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end
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2'b01: begin
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ALU160_SEL = 1; // pc
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WE = 6'b010100; // PC, tmpHI
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next_stage = 1;
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M1 = 0;
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end
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endcase
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endcase
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// ----------------------- LD rr,nn --------------------
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4'b0001: // LD rr,nn, stage1
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case({STAGE[1:0], op16[2]})
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3'b00_0, 3'b00_1, 3'b01_0, 3'b01_1: begin // LD rr,nn, stage1,2
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ALU160_SEL = 1; // pc
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DINW_SEL = 1; // DI
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WE = {4'b010x, STAGE[0] ? 1'b1 : 1'bx, !STAGE[0]}; // PC, lo/HI
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next_stage = 1;
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REG_WSEL = {op16, 1'bx};
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M1 = 0;
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end
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3'b10_0, 3'b11_1: begin // BC, DE, HL, stage3, SP stage4
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ALU160_SEL = 1; // pc
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WE = 6'b010x00; // PC
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end
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3'b10_1: begin // SP stage3
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ALU160_SEL = 0; // regs
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WE = 6'b001x00; // SP
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ALU16OP = 4; // NOP
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next_stage = 1;
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REG_RSEL = 4'b101x; // tmpSP
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|
|
M1 = 0;
|
| 298 |
|
|
MREQ = 0;
|
| 299 |
|
|
end
|
| 300 |
|
|
endcase
|
| 301 |
|
|
// ----------------------- LD (BC) A - LD (DE) A - LD (nn) HL, LD (nn),A --------------------
|
| 302 |
|
|
// ----------------------- LD A (BC) - LD A (DE) - LD HL (nn), LD A (nn) --------------------
|
| 303 |
|
|
4'b0010, 4'b1010:
|
| 304 |
|
|
case(STAGE[2:0])
|
| 305 |
|
|
3'b000:
|
| 306 |
|
|
if(FETCH[5] == 0) begin // LD (BC) A, LD (DE) A - stage1
|
| 307 |
|
|
if(FETCH[3]) DINW_SEL = 1; // DI
|
| 308 |
|
|
else DO_SEL = 2'b00; // ALU80
|
| 309 |
|
|
ALU160_SEL = 0; // regs
|
| 310 |
|
|
WE = {4'b000x, FETCH[3], 1'bx}; // hi
|
| 311 |
|
|
next_stage = 1;
|
| 312 |
|
|
REG_WSEL = FETCH[3] ? 4'b011x : 4'b0110; // A
|
| 313 |
|
|
REG_RSEL = {op16, 1'bx};
|
| 314 |
|
|
M1 = 0;
|
| 315 |
|
|
WR = !FETCH[3];
|
| 316 |
|
|
end else begin // LD (nn) A - LD (nn) HL - stage 1
|
| 317 |
|
|
ALU160_SEL = 1; // PC
|
| 318 |
|
|
DINW_SEL = 1; // DI
|
| 319 |
|
|
WE = 6'b010xx1; // PC, lo
|
| 320 |
|
|
next_stage = 1;
|
| 321 |
|
|
REG_WSEL = 4'b111x;
|
| 322 |
|
|
M1 = 0;
|
| 323 |
|
|
end
|
| 324 |
|
|
3'b001:
|
| 325 |
|
|
if(FETCH[5] == 0) begin // LD (BC), A, LD (DE), A - stage2
|
| 326 |
|
|
ALU160_SEL = 1; // pc
|
| 327 |
|
|
WE = 6'b010x00; // PC
|
| 328 |
|
|
end else begin // LD (nn),A - LH (nn),HL - stage 2
|
| 329 |
|
|
ALU160_SEL = 1; // pc
|
| 330 |
|
|
DINW_SEL = 1; // DI
|
| 331 |
|
|
WE = 6'b010x10; // PC, hi
|
| 332 |
|
|
next_stage = 1;
|
| 333 |
|
|
REG_WSEL = 4'b111x;
|
| 334 |
|
|
M1 = 0;
|
| 335 |
|
|
end
|
| 336 |
|
|
3'b010: begin
|
| 337 |
|
|
ALU160_SEL = 1'b0; // regs
|
| 338 |
|
|
REG_RSEL = 4'b111x;
|
| 339 |
|
|
M1 = 0;
|
| 340 |
|
|
WR = !FETCH[3];
|
| 341 |
|
|
next_stage = 1;
|
| 342 |
|
|
if(FETCH[3]) begin // LD A (nn) - LD HL (nn) - stage 3
|
| 343 |
|
|
DINW_SEL = 1; // DI
|
| 344 |
|
|
WE = {4'b000x, FETCH[4] ? 1'b1 : 1'bx, FETCH[4] ? 1'bx : 1'b1}; // lo/hi
|
| 345 |
|
|
REG_WSEL = FETCH[4] ? 4'b011x : 4'b010x; // A or L
|
| 346 |
|
|
end else begin // LD (nn),A - LD (nn),HL - stage 3
|
| 347 |
|
|
DO_SEL = 2'b00; // ALU80
|
| 348 |
|
|
WE = 6'b000x00; // nothing
|
| 349 |
|
|
REG_WSEL = FETCH[4] ? 4'b0110 : 4'b0101; // A or L
|
| 350 |
|
|
end
|
| 351 |
|
|
end
|
| 352 |
|
|
3'b011:
|
| 353 |
|
|
if(FETCH[4]) begin // LD (nn),A - stage 4
|
| 354 |
|
|
ALU160_SEL = 1; // pc
|
| 355 |
|
|
WE = 6'b010x00; // PC
|
| 356 |
|
|
end else begin
|
| 357 |
|
|
REG_RSEL = 4'b111x;
|
| 358 |
|
|
M1 = 0;
|
| 359 |
|
|
WR = !FETCH[3];
|
| 360 |
|
|
ALU160_SEL = 1'b0; // regs
|
| 361 |
|
|
ALU16OP = 1; // INC
|
| 362 |
|
|
next_stage = 1;
|
| 363 |
|
|
if(FETCH[3]) begin // LD HL (nn) - stage 4
|
| 364 |
|
|
DINW_SEL = 1; // DI
|
| 365 |
|
|
WE = 6'b000x10; // hi
|
| 366 |
|
|
REG_WSEL = 4'b010x; // H
|
| 367 |
|
|
end else begin // LD (nn),HL - stage 4
|
| 368 |
|
|
DO_SEL = 2'b00; // ALU80
|
| 369 |
|
|
WE = 6'b000x00; // nothing
|
| 370 |
|
|
REG_WSEL = 4'b0100; // H
|
| 371 |
|
|
end
|
| 372 |
|
|
end
|
| 373 |
|
|
3'b100: begin // LD (nn),HL - stage 5
|
| 374 |
|
|
ALU160_SEL = 1; // pc
|
| 375 |
|
|
WE = 6'b010x00; // PC
|
| 376 |
|
|
end
|
| 377 |
|
|
endcase
|
| 378 |
|
|
// ----------------------- inc/dec rr --------------------
|
| 379 |
|
|
4'b0011, 4'b1011:
|
| 380 |
|
|
if(!STAGE[0])
|
| 381 |
|
|
if(op16[2]) begin // SP - stage1
|
| 382 |
|
|
ALU160_SEL = 0; // regs
|
| 383 |
|
|
WE = 6'b001x00; // SP
|
| 384 |
|
|
ALU16OP = {FETCH[3], 1'b0, FETCH[3]}; // post inc, dec
|
| 385 |
|
|
next_stage = 1;
|
| 386 |
|
|
REG_RSEL = 4'b101x; // sp
|
| 387 |
|
|
M1 = 0;
|
| 388 |
|
|
MREQ = 0;
|
| 389 |
|
|
end else begin // BC, DE, HL - stage 1
|
| 390 |
|
|
ALU160_SEL = 1; // pc
|
| 391 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 392 |
|
|
WE = 6'b010x11; // PC, hi, lo
|
| 393 |
|
|
ALU8OP = {4'b0111, FETCH[3]}; // INC16 / DEC16
|
| 394 |
|
|
REG_WSEL = {op16, 1'b0}; // hi
|
| 395 |
|
|
REG_RSEL = {op16, 1'b1}; // lo
|
| 396 |
|
|
end
|
| 397 |
|
|
else begin // SP, stage2
|
| 398 |
|
|
ALU160_SEL = 1; // pc
|
| 399 |
|
|
WE = 6'b010x00; // PC
|
| 400 |
|
|
end
|
| 401 |
|
|
// ----------------------- inc/dec 8 --------------------
|
| 402 |
|
|
4'b0100, 4'b0101, 4'b1100, 4'b1101:
|
| 403 |
|
|
if(!op1mem) begin //regs
|
| 404 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 405 |
|
|
ALU160_SEL = 1; // pc
|
| 406 |
|
|
WE = opd[3] ? 6'b110x01 : 6'b110x10; // flags, PC, hi/lo
|
| 407 |
|
|
ALU8OP = {3'b010, FETCH[0], 1'b0}; // inc / dec
|
| 408 |
|
|
REG_WSEL = {1'b0, opd[5:3]};
|
| 409 |
|
|
end else case({STAGE[1:0], CPUStatus[4]})
|
| 410 |
|
|
3'b00_0, 3'b01_1: begin // (HL) - stage1, (X) - stage2
|
| 411 |
|
|
ALU160_SEL = 0; // regs
|
| 412 |
|
|
DINW_SEL = 1; // DI
|
| 413 |
|
|
WE = 6'b000001; // lo
|
| 414 |
|
|
ALU16OP = CPUStatus[4] ? 3'd3 : 3'd0;
|
| 415 |
|
|
next_stage = 1;
|
| 416 |
|
|
REG_WSEL = 4'b011x; // tmpLO
|
| 417 |
|
|
REG_RSEL = 4'b010x; // HL
|
| 418 |
|
|
M1 = 0;
|
| 419 |
|
|
end
|
| 420 |
|
|
3'b00_1: begin // (X) - stage1
|
| 421 |
|
|
ALU160_SEL = 1; // pc
|
| 422 |
|
|
WE = 6'b010100; // PC, tmpHI
|
| 423 |
|
|
next_stage = 1;
|
| 424 |
|
|
M1 = 0;
|
| 425 |
|
|
end
|
| 426 |
|
|
3'b01_0, 3'b10_1: begin // (HL) stage2, (X) - stage3
|
| 427 |
|
|
DO_SEL = 2'b11; // ALU80OUT
|
| 428 |
|
|
ALU160_SEL = 0; // regs
|
| 429 |
|
|
WE = 6'b100x0x; // flags
|
| 430 |
|
|
ALU8OP = {3'b010, FETCH[0], 1'b0}; // inc / dec
|
| 431 |
|
|
ALU16OP = CPUStatus[4] ? 3'd3 : 3'd0;
|
| 432 |
|
|
next_stage = 1;
|
| 433 |
|
|
REG_WSEL = 4'b0111; // tmpLO
|
| 434 |
|
|
REG_RSEL = 4'b010x; // HL
|
| 435 |
|
|
M1 = 0;
|
| 436 |
|
|
WR = 1;
|
| 437 |
|
|
end
|
| 438 |
|
|
3'b10_0, 3'b11_1: begin // (HL) - stage3, (X) - stage 4
|
| 439 |
|
|
ALU160_SEL = 1; // pc
|
| 440 |
|
|
WE = 6'b010x00; // PC
|
| 441 |
|
|
end
|
| 442 |
|
|
endcase
|
| 443 |
|
|
// ----------------------- ld r/(HL-X), n --------------------
|
| 444 |
|
|
4'b0110, 4'b1110:
|
| 445 |
|
|
case({STAGE[1:0], CPUStatus[4], op1mem})
|
| 446 |
|
|
4'b00_0_0, 4'b00_0_1, 4'b00_1_0, 4'b01_1_1: begin // r, (HL) - stage1, (X) - stage2 (read n)
|
| 447 |
|
|
ALU160_SEL = 1; // pc
|
| 448 |
|
|
DINW_SEL = 1; // DI
|
| 449 |
|
|
WE = opd[3] ? 6'b010001 : 6'b010010; // PC, hi/lo
|
| 450 |
|
|
next_stage = 1;
|
| 451 |
|
|
REG_WSEL = {1'b0, opd[5:4], 1'bx};
|
| 452 |
|
|
M1 = 0;
|
| 453 |
|
|
end
|
| 454 |
|
|
4'b01_0_0, 4'b01_1_0, 4'b10_0_1, 4'b11_1_1: begin // r - stage2, (HL) - stage3, (X) - stage4
|
| 455 |
|
|
ALU160_SEL = 1; // pc
|
| 456 |
|
|
WE = 6'b010x00; // PC
|
| 457 |
|
|
end
|
| 458 |
|
|
4'b01_0_1, 4'b10_1_1: begin // (HL) - stage2, (X) - stage3
|
| 459 |
|
|
DO_SEL = 2'b00; // ALU80
|
| 460 |
|
|
ALU160_SEL = 0; // regs
|
| 461 |
|
|
WE = 6'b000x0x; // nothing
|
| 462 |
|
|
ALU16OP = CPUStatus[4] ? 3'd3 : 3'd0;
|
| 463 |
|
|
next_stage = 1;
|
| 464 |
|
|
REG_WSEL = 4'b0111; // tmpLO
|
| 465 |
|
|
REG_RSEL = 4'b010x; // HL
|
| 466 |
|
|
M1 = 0;
|
| 467 |
|
|
WR = 1;
|
| 468 |
|
|
end
|
| 469 |
|
|
4'b00_1_1: begin // (X) - stage1
|
| 470 |
|
|
ALU160_SEL = 1; // pc
|
| 471 |
|
|
WE = 6'b010100; // PC, tmpHI
|
| 472 |
|
|
next_stage = 1;
|
| 473 |
|
|
M1 = 0;
|
| 474 |
|
|
end
|
| 475 |
|
|
endcase
|
| 476 |
|
|
// ----------------------- rlca, rrca, rla, rra, daa, cpl, scf, ccf --------------------
|
| 477 |
|
|
4'b0111, 4'b1111:
|
| 478 |
|
|
case(FETCH[5:3])
|
| 479 |
|
|
3'b000, 3'b001, 3'b010, 3'b011, 3'b100, 3'b101: begin // rlca, rrca, rla, rra, daa, cpl
|
| 480 |
|
|
ALU160_SEL = 1; // pc
|
| 481 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 482 |
|
|
WE = 6'b110x1x; // flags, PC, hi
|
| 483 |
|
|
ALU8OP = FETCH[5] ? {2'b01, !FETCH[3], 2'b01} : {3'b110, FETCH[4:3]};
|
| 484 |
|
|
REG_WSEL = 4'b0110; // A
|
| 485 |
|
|
end
|
| 486 |
|
|
3'b110, 3'b111: begin // scf, ccf
|
| 487 |
|
|
ALU160_SEL = 1; // pc
|
| 488 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 489 |
|
|
WE = 6'b110x0x; // flags, PC
|
| 490 |
|
|
ALU8OP = {4'b1010, !FETCH[3]};
|
| 491 |
|
|
end
|
| 492 |
|
|
endcase
|
| 493 |
|
|
// ----------------------- add 16 --------------------
|
| 494 |
|
|
4'b1001:
|
| 495 |
|
|
if(!STAGE[0]) begin
|
| 496 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 497 |
|
|
WE = 6'b100x01; // flags, lo
|
| 498 |
|
|
ALU8OP = 5'b10000; // ADD16LO
|
| 499 |
|
|
next_stage = 1;
|
| 500 |
|
|
REG_WSEL = 4'b0101; // L
|
| 501 |
|
|
REG_RSEL = {op16, 1'b1};
|
| 502 |
|
|
M1 = 0;
|
| 503 |
|
|
MREQ = 0;
|
| 504 |
|
|
end else begin
|
| 505 |
|
|
ALU160_SEL = 1; // pc
|
| 506 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 507 |
|
|
WE = 6'b110x10; // flags, PC, hi
|
| 508 |
|
|
ALU8OP = 5'b10001; // ADD16HI
|
| 509 |
|
|
REG_WSEL = 4'b0100; // H
|
| 510 |
|
|
REG_RSEL = {op16, 1'b0};
|
| 511 |
|
|
end
|
| 512 |
|
|
endcase
|
| 513 |
|
|
|
| 514 |
|
|
// ---------------------------------------------- block 01 LD8 ---------------------------------------------------
|
| 515 |
|
|
4'b0001:
|
| 516 |
|
|
case({STAGE[1:0], CPUStatus[4], op1mem, op0mem})
|
| 517 |
|
|
5'b00_0_00, 5'b00_1_00, // LD r, r 1st stage
|
| 518 |
|
|
5'b01_0_01, // LD r, (HL) 2nd stage
|
| 519 |
|
|
5'b10_1_01: // LD r, (X) 3rd stage
|
| 520 |
|
|
begin
|
| 521 |
|
|
ALU160_SEL = 1; // PC
|
| 522 |
|
|
DINW_SEL = 0; // ALU8
|
| 523 |
|
|
WE = opd[3] ? 6'b010x01 : 6'b010x10; // PC and LO or HI
|
| 524 |
|
|
ALU8OP = 29; // PASS D1
|
| 525 |
|
|
REG_WSEL = {1'b0, opd[5:4], 1'bx};
|
| 526 |
|
|
REG_RSEL = {1'b0, opd[2:0]};
|
| 527 |
|
|
end
|
| 528 |
|
|
5'b00_0_01, // LD r, (HL) 1st stage
|
| 529 |
|
|
5'b01_1_01: // LD r, (X) 2nd stage
|
| 530 |
|
|
begin
|
| 531 |
|
|
ALU160_SEL = 0; // regs
|
| 532 |
|
|
DINW_SEL = 1; // DI
|
| 533 |
|
|
WE = 6'b000x01; // LO
|
| 534 |
|
|
ALU16OP = CPUStatus[4] ? 3'd3 : 3'd0; // ADD - NOP
|
| 535 |
|
|
next_stage = 1;
|
| 536 |
|
|
REG_WSEL = 4'b011x; // A - tmpLO
|
| 537 |
|
|
REG_RSEL = 4'b010x; // HL
|
| 538 |
|
|
M1 = 0;
|
| 539 |
|
|
end
|
| 540 |
|
|
5'b00_1_01, // LD r, (X) 1st stage
|
| 541 |
|
|
5'b00_1_10: // LD (X), r 1st stage
|
| 542 |
|
|
begin
|
| 543 |
|
|
ALU160_SEL = 1; // pc
|
| 544 |
|
|
WE = 6'b010100; // PC, tmpHI
|
| 545 |
|
|
next_stage = 1;
|
| 546 |
|
|
M1 = 0;
|
| 547 |
|
|
end
|
| 548 |
|
|
5'b00_0_10, // LD (HL), r 1st stage
|
| 549 |
|
|
5'b01_1_10: // LD (X), r 2nd stage
|
| 550 |
|
|
begin
|
| 551 |
|
|
DO_SEL = 0; // ALU80
|
| 552 |
|
|
ALU160_SEL = 0; // regs
|
| 553 |
|
|
WE = 6'b000x00; // no write
|
| 554 |
|
|
ALU16OP = CPUStatus[4] ? 3'd3 : 3'd0; // ADD - NOP
|
| 555 |
|
|
next_stage = 1;
|
| 556 |
|
|
REG_WSEL = {1'b0, opd[2:0]};
|
| 557 |
|
|
REG_RSEL = 4'b010x; // HL
|
| 558 |
|
|
M1 = 0;
|
| 559 |
|
|
WR = 1;
|
| 560 |
|
|
end
|
| 561 |
|
|
5'b01_0_10, // LD (HL), r 2nd stage
|
| 562 |
|
|
5'b10_1_10: // LD (X), r 3rd stage
|
| 563 |
|
|
begin
|
| 564 |
|
|
ALU160_SEL = 1; // pc
|
| 565 |
|
|
WE = 6'b010x00; // PC
|
| 566 |
|
|
end
|
| 567 |
|
|
5'b00_0_11, 5'b00_1_11: begin // HALT
|
| 568 |
|
|
WE = 6'b000x00; // no write
|
| 569 |
|
|
M1 = 0;
|
| 570 |
|
|
MREQ = 0;
|
| 571 |
|
|
HALT = 1;
|
| 572 |
|
|
end
|
| 573 |
|
|
endcase
|
| 574 |
|
|
// ---------------------------------------------- block 10 arith8 ---------------------------------------------------
|
| 575 |
|
|
4'b0010:
|
| 576 |
|
|
case({STAGE[1:0], CPUStatus[4], op0mem})
|
| 577 |
|
|
4'b00_0_0, 4'b00_1_0, // OP r,r 1st stage
|
| 578 |
|
|
4'b01_0_1, // OP r, (HL) 2nd stage
|
| 579 |
|
|
4'b10_1_1: // OP r, (X) 3rd stage
|
| 580 |
|
|
begin
|
| 581 |
|
|
ALU160_SEL = 1; // pc
|
| 582 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 583 |
|
|
WE = {4'b110x, ~&FETCH[5:3], 1'bx}; // flags, PC, hi
|
| 584 |
|
|
ALU8OP = {2'b00, FETCH[5:3]};
|
| 585 |
|
|
REG_WSEL = 4'b0110; // A
|
| 586 |
|
|
REG_RSEL = {1'b0, opd[2:0]};
|
| 587 |
|
|
end
|
| 588 |
|
|
4'b00_0_1, // OP r, (HL) 1st stage
|
| 589 |
|
|
4'b01_1_1: // OP r, (X) 2nd stage
|
| 590 |
|
|
begin
|
| 591 |
|
|
ALU160_SEL = 0; // HL
|
| 592 |
|
|
DINW_SEL = 1; // DI
|
| 593 |
|
|
WE = 6'b000x01; // lo
|
| 594 |
|
|
ALU16OP = CPUStatus[4] ? 3'd3 : 3'd0; // ADD - NOP
|
| 595 |
|
|
next_stage = 1;
|
| 596 |
|
|
REG_WSEL = 4'b011x; // A-tmpLO
|
| 597 |
|
|
REG_RSEL = 4'b010x; // HL
|
| 598 |
|
|
M1 = 0;
|
| 599 |
|
|
end
|
| 600 |
|
|
4'b00_1_1: // OP r, (X) 1st stage
|
| 601 |
|
|
begin
|
| 602 |
|
|
ALU160_SEL = 1; // pc
|
| 603 |
|
|
WE = 6'b010100; // PC, tmpHI
|
| 604 |
|
|
next_stage = 1;
|
| 605 |
|
|
M1 = 0;
|
| 606 |
|
|
end
|
| 607 |
|
|
endcase
|
| 608 |
|
|
//------------------------------------------- block 11 ----------------------------------------------------
|
| 609 |
|
|
4'b0011:
|
| 610 |
|
|
case(FETCH[3:0])
|
| 611 |
|
|
// ----------------------- RET cc --------------------
|
| 612 |
|
|
4'b0000, 4'b1000:
|
| 613 |
|
|
case(STAGE[1:0])
|
| 614 |
|
|
2'b00, 2'b01: // stage1, stage2
|
| 615 |
|
|
if(FlagMux[FETCH[5:3]]) begin // POP addr
|
| 616 |
|
|
ALU160_SEL = 0; // regs
|
| 617 |
|
|
DINW_SEL = 1; // DI
|
| 618 |
|
|
WE = {4'b001x, STAGE[0] ? 1'b1 : 1'bx, !STAGE[0]}; // SP, lo/hi
|
| 619 |
|
|
next_stage = 1;
|
| 620 |
|
|
REG_WSEL = 4'b111x; // tmp16
|
| 621 |
|
|
REG_RSEL = 4'b101x; // SP
|
| 622 |
|
|
M1 = 0;
|
| 623 |
|
|
end else begin
|
| 624 |
|
|
ALU160_SEL = 1; // pc
|
| 625 |
|
|
WE = 6'b010x00; // PC
|
| 626 |
|
|
end
|
| 627 |
|
|
2'b10: begin // stage3
|
| 628 |
|
|
ALU160_SEL = 0; // regs
|
| 629 |
|
|
WE = 6'b010x00; // PC
|
| 630 |
|
|
REG_RSEL = 4'b111x; // tmp16
|
| 631 |
|
|
end
|
| 632 |
|
|
endcase
|
| 633 |
|
|
// ----------------------- POP --------------------
|
| 634 |
|
|
4'b0001:
|
| 635 |
|
|
case(STAGE[1:0])
|
| 636 |
|
|
2'b00, 2'b01: begin
|
| 637 |
|
|
if(op16[2]) begin // AF
|
| 638 |
|
|
WE = STAGE[0] ? 6'b101x1x : 6'b001xx1; // flags, SP, lo/hi
|
| 639 |
|
|
REG_WSEL = {3'b011, STAGE[0] ? 1'b1 : 1'bx};
|
| 640 |
|
|
if(STAGE[0]) ALU8OP = 30; // FLAGS <- D0
|
| 641 |
|
|
end else begin // r16
|
| 642 |
|
|
WE = STAGE[0] ? 6'b001x10 : 6'b001xx1; // SP, lo/hi
|
| 643 |
|
|
REG_WSEL = {1'b0, FETCH[5:4], 1'bx};
|
| 644 |
|
|
end
|
| 645 |
|
|
ALU160_SEL = 0; // regs
|
| 646 |
|
|
DINW_SEL = 1; // DI
|
| 647 |
|
|
next_stage = 1;
|
| 648 |
|
|
REG_RSEL = 4'b101x; // SP
|
| 649 |
|
|
M1 = 0;
|
| 650 |
|
|
end
|
| 651 |
|
|
2'b10: begin // stage3
|
| 652 |
|
|
ALU160_SEL = 1; // PC
|
| 653 |
|
|
WE = 6'b010x00; // PC
|
| 654 |
|
|
end
|
| 655 |
|
|
endcase
|
| 656 |
|
|
// ----------------------- JP cc --------------------
|
| 657 |
|
|
4'b0010, 4'b1010:
|
| 658 |
|
|
case(STAGE[1:0])
|
| 659 |
|
|
2'b00, 2'b01: begin // stage1,2
|
| 660 |
|
|
if(FlagMux[FETCH[5:3]]) begin
|
| 661 |
|
|
ALU160_SEL = 1; // pc
|
| 662 |
|
|
DINW_SEL = 1; // DI
|
| 663 |
|
|
WE = {4'b010x, STAGE[0] ? 1'b1 : 1'bx, !STAGE[0]}; // PC, hi/lo
|
| 664 |
|
|
next_stage = 1;
|
| 665 |
|
|
REG_WSEL = 4'b111x; // tmp7
|
| 666 |
|
|
M1 = 0;
|
| 667 |
|
|
end else begin
|
| 668 |
|
|
ALU160_SEL = 1; // pc
|
| 669 |
|
|
WE = 6'b010x00; // PC
|
| 670 |
|
|
ALU16OP = 2; // add2
|
| 671 |
|
|
end
|
| 672 |
|
|
end
|
| 673 |
|
|
2'b10: begin // stage3
|
| 674 |
|
|
ALU160_SEL = 0; // regs
|
| 675 |
|
|
WE = 6'b010x00; // PC
|
| 676 |
|
|
REG_RSEL = 4'b111x; // tmp7
|
| 677 |
|
|
end
|
| 678 |
|
|
endcase
|
| 679 |
|
|
// ----------------------- JP, OUT (n) A, EX (SP) HL, DI --------------------
|
| 680 |
|
|
4'b0011:
|
| 681 |
|
|
case(FETCH[5:4])
|
| 682 |
|
|
2'b00: // JP
|
| 683 |
|
|
case(STAGE[1:0])
|
| 684 |
|
|
2'b00, 2'b01: begin // stage1,2 - read addr
|
| 685 |
|
|
ALU160_SEL = 1; // pc
|
| 686 |
|
|
DINW_SEL = 1; // DI
|
| 687 |
|
|
WE = {4'b010x, STAGE[0] ? 1'b1 : 1'bx, !STAGE[0]}; // PC, hi/lo
|
| 688 |
|
|
next_stage = 1;
|
| 689 |
|
|
REG_WSEL = 4'b111x; // tmp7
|
| 690 |
|
|
M1 = 0;
|
| 691 |
|
|
end
|
| 692 |
|
|
2'b10: begin // stage3
|
| 693 |
|
|
ALU160_SEL = 0; // regs
|
| 694 |
|
|
WE = 6'b010x00; // PC
|
| 695 |
|
|
REG_RSEL = 4'b111x; // tmp7
|
| 696 |
|
|
end
|
| 697 |
|
|
endcase
|
| 698 |
|
|
2'b01: // OUT (n), a - stage1 - read n
|
| 699 |
|
|
case(STAGE[1:0])
|
| 700 |
|
|
2'b00: begin
|
| 701 |
|
|
ALU160_SEL = 1; // pc
|
| 702 |
|
|
DINW_SEL = 1; // DI
|
| 703 |
|
|
WE = 6'b010x01; // PC, lo
|
| 704 |
|
|
next_stage = 1;
|
| 705 |
|
|
REG_WSEL = 4'b011x; // tmpLO
|
| 706 |
|
|
M1 = 0;
|
| 707 |
|
|
end
|
| 708 |
|
|
2'b01: begin // stage2 - OUT
|
| 709 |
|
|
DO_SEL = 2'b00; // ALU80
|
| 710 |
|
|
ALU160_SEL = 0; // regs
|
| 711 |
|
|
WE = 6'b000x00; // nothing
|
| 712 |
|
|
next_stage = 1;
|
| 713 |
|
|
REG_WSEL = 4'b0110; // A
|
| 714 |
|
|
REG_RSEL = 4'b011x; // A-tmpLO
|
| 715 |
|
|
M1 = 0;
|
| 716 |
|
|
MREQ = 0;
|
| 717 |
|
|
WR = 1;
|
| 718 |
|
|
IORQ = 1;
|
| 719 |
|
|
end
|
| 720 |
|
|
2'b10: begin // stage3 - fetch
|
| 721 |
|
|
ALU160_SEL = 1; // PC
|
| 722 |
|
|
WE = 6'b010x00; // PC
|
| 723 |
|
|
end
|
| 724 |
|
|
endcase
|
| 725 |
|
|
2'b10: // EX (SP), HL
|
| 726 |
|
|
case(STAGE[2:0])
|
| 727 |
|
|
3'b000, 3'b001: begin // stage1,2 - pop tmp16
|
| 728 |
|
|
ALU160_SEL = 0; // regs
|
| 729 |
|
|
DINW_SEL = 1; // DI
|
| 730 |
|
|
WE = {4'b001x, STAGE[0] ? 1'b1 : 1'bx, !STAGE[0]}; // SP, lo/hi
|
| 731 |
|
|
next_stage = 1;
|
| 732 |
|
|
REG_WSEL = 4'b111x; // tmp16
|
| 733 |
|
|
REG_RSEL = 4'b101x; // SP
|
| 734 |
|
|
M1 = 0;
|
| 735 |
|
|
end
|
| 736 |
|
|
3'b010, 3'b011: begin // stage3,4 - push hl
|
| 737 |
|
|
DO_SEL = 2'b00; // ALU80
|
| 738 |
|
|
ALU160_SEL = 0; // regs
|
| 739 |
|
|
WE = 6'b001x00; // SP
|
| 740 |
|
|
ALU16OP = 5; // dec
|
| 741 |
|
|
next_stage = 1;
|
| 742 |
|
|
REG_WSEL = {3'b010, STAGE[0]};// H/L
|
| 743 |
|
|
REG_RSEL = 4'b101x; // SP
|
| 744 |
|
|
M1 = 0;
|
| 745 |
|
|
WR = 1;
|
| 746 |
|
|
end
|
| 747 |
|
|
3'b100, 3'b101: begin // stage5,6
|
| 748 |
|
|
ALU160_SEL = 1; // pc
|
| 749 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 750 |
|
|
WE = {1'b0, STAGE[0], 2'b0x, STAGE[0] ? 1'b1 : 1'bx, !STAGE[0]}; // PC, lo/hi
|
| 751 |
|
|
ALU8OP = 29; // pass D1
|
| 752 |
|
|
next_stage = !STAGE[0];
|
| 753 |
|
|
REG_WSEL = 4'b010x; // HL
|
| 754 |
|
|
REG_RSEL = {3'b111, !STAGE[0]}; // tmp16
|
| 755 |
|
|
M1 = STAGE[0];
|
| 756 |
|
|
MREQ = STAGE[0];
|
| 757 |
|
|
end
|
| 758 |
|
|
endcase
|
| 759 |
|
|
2'b11: begin // DI
|
| 760 |
|
|
ALU160_SEL = 1; // PC
|
| 761 |
|
|
WE = 6'b010x00; // PC
|
| 762 |
|
|
status[11] = 1'b1; // set IFF flags
|
| 763 |
|
|
status[7:6] = 2'b00;
|
| 764 |
|
|
end
|
| 765 |
|
|
endcase
|
| 766 |
|
|
// ----------------------- CALL cc --------------------
|
| 767 |
|
|
4'b0100, 4'b1100:
|
| 768 |
|
|
case(STAGE[2:0])
|
| 769 |
|
|
3'b000, 3'b001: // stage 1,2 - load addr
|
| 770 |
|
|
if(FlagMux[FETCH[5:3]]) begin
|
| 771 |
|
|
ALU160_SEL = 1; // pc
|
| 772 |
|
|
DINW_SEL = 1; // DI
|
| 773 |
|
|
WE = {4'b010x, STAGE[0] ? 1'b1 : 1'bx, !STAGE[0]}; // PC, hi/lo
|
| 774 |
|
|
next_stage = 1;
|
| 775 |
|
|
REG_WSEL = 4'b111x; // tmp7
|
| 776 |
|
|
M1 = 0;
|
| 777 |
|
|
end else begin
|
| 778 |
|
|
ALU160_SEL = 1; // pc
|
| 779 |
|
|
WE = 6'b010x00; // PC
|
| 780 |
|
|
ALU16OP = 2; // add2
|
| 781 |
|
|
end
|
| 782 |
|
|
3'b010, 3'b011: begin // stage 3,4 - push pc
|
| 783 |
|
|
DO_SEL = {1'b0, STAGE[0]}; // pc hi/lo
|
| 784 |
|
|
ALU160_SEL = 0; // regs
|
| 785 |
|
|
WE = 6'b001x00; // SP
|
| 786 |
|
|
ALU16OP = 5; // DEC
|
| 787 |
|
|
next_stage = 1;
|
| 788 |
|
|
REG_WSEL = 4'b1xxx; // pc
|
| 789 |
|
|
REG_RSEL = 4'b101x; // sp
|
| 790 |
|
|
M1 = 0;
|
| 791 |
|
|
WR = 1;
|
| 792 |
|
|
end
|
| 793 |
|
|
3'b100: begin // stage5
|
| 794 |
|
|
ALU160_SEL = 0; // regs
|
| 795 |
|
|
WE = 6'b010x00; // PC
|
| 796 |
|
|
REG_RSEL = 4'b111x; // tmp7
|
| 797 |
|
|
end
|
| 798 |
|
|
endcase
|
| 799 |
|
|
// ----------------------- PUSH --------------------
|
| 800 |
|
|
4'b0101:
|
| 801 |
|
|
case(STAGE[1:0])
|
| 802 |
|
|
2'b00, 2'b01: begin // stage1,2
|
| 803 |
|
|
DO_SEL = {STAGE[0] & op16[2], 1'b0}; // FLAGS/ALU80
|
| 804 |
|
|
ALU160_SEL = 0; // regs
|
| 805 |
|
|
WE = 6'b001x00; // SP
|
| 806 |
|
|
ALU16OP = 5; // dec
|
| 807 |
|
|
next_stage = 1;
|
| 808 |
|
|
REG_WSEL = {1'b0, FETCH[5:4], STAGE[0]};
|
| 809 |
|
|
REG_RSEL = 4'b101x; // SP
|
| 810 |
|
|
M1 = 0;
|
| 811 |
|
|
WR = 1;
|
| 812 |
|
|
end
|
| 813 |
|
|
2'b10: begin //stage3
|
| 814 |
|
|
ALU160_SEL = 1; // PC
|
| 815 |
|
|
WE = 6'b010x00; // PC
|
| 816 |
|
|
end
|
| 817 |
|
|
endcase
|
| 818 |
|
|
// ----------------------- op A, n --------------------
|
| 819 |
|
|
4'b0110, 4'b1110:
|
| 820 |
|
|
if(!STAGE[0]) begin // stage1, read n
|
| 821 |
|
|
ALU160_SEL = 1; // pc
|
| 822 |
|
|
DINW_SEL = 1; // DI
|
| 823 |
|
|
WE = 6'b010x01; // PC, lo
|
| 824 |
|
|
next_stage = 1;
|
| 825 |
|
|
REG_WSEL = 4'b011x; // tmpLO
|
| 826 |
|
|
M1 = 0;
|
| 827 |
|
|
end else begin // stage 2
|
| 828 |
|
|
DINW_SEL = 0; // ALU8OUT[7:0]
|
| 829 |
|
|
ALU160_SEL = 1; // pc
|
| 830 |
|
|
WE = {4'b110x, ~&FETCH[5:3], 1'bx}; // flags, PC, hi
|
| 831 |
|
|
ALU8OP = {2'b00, FETCH[5:3]};
|
| 832 |
|
|
REG_WSEL = 4'b0110; // A
|
| 833 |
|
|
REG_RSEL = 4'b0111; // tmpLO
|
| 834 |
|
|
end
|
| 835 |
|
|
// ----------------------- RST --------------------
|
| 836 |
|
|
4'b0111, 4'b1111:
|
| 837 |
|
|
case(STAGE[1:0])
|
| 838 |
|
|
2'b00, 2'b01: begin // stage 1,2 - push pc
|
| 839 |
|
|
DO_SEL = {1'b0, STAGE[0]}; // pc hi/lo
|
| 840 |
|
|
ALU160_SEL = 0; // regs
|
| 841 |
|
|
WE = 6'b001x00; // SP
|
| 842 |
|
|
ALU16OP = 5; // DEC
|
| 843 |
|
|
next_stage = 1;
|
| 844 |
|
|
REG_WSEL = 4'b1xxx; // pc
|
| 845 |
|
|
REG_RSEL = 4'b101x; // sp
|
| 846 |
|
|
M1 = 0;
|
| 847 |
|
|
WR = 1;
|
| 848 |
|
|
end
|
| 849 |
|
|
2'b10: begin // stage3
|
| 850 |
|
|
ALU160_SEL = 0; // regs
|
| 851 |
|
|
WE = 6'b010x00; // PC
|
| 852 |
|
|
REG_RSEL = 4'b110x; // const
|
| 853 |
|
|
end
|
| 854 |
|
|
endcase
|
| 855 |
|
|
// ----------------------- RET, EXX, JP (HL), LD SP HL --------------------
|
| 856 |
|
|
4'b1001:
|
| 857 |
|
|
case(FETCH[5:4])
|
| 858 |
|
|
2'b00: // RET
|
| 859 |
|
|
case(STAGE[1:0])
|
| 860 |
|
|
2'b00, 2'b01: begin // stage1, stage2 - pop addr
|
| 861 |
|
|
ALU160_SEL = 0; // regs
|
| 862 |
|
|
DINW_SEL = 1; // DI
|
| 863 |
|
|
WE = {4'b001x, STAGE[0] ? 1'b1 : 1'bx, !STAGE[0]}; // SP, lo/hi
|
| 864 |
|
|
next_stage = 1;
|
| 865 |
|
|
REG_WSEL = 4'b111x; // tmp16
|
| 866 |
|
|
REG_RSEL = 4'b101x; // SP
|
| 867 |
|
|
M1 = 0;
|
| 868 |
|
|
end
|
| 869 |
|
|
2'b10: begin // stage3 - jump
|
| 870 |
|
|
ALU160_SEL = 0; // regs
|
| 871 |
|
|
WE = 6'b010x00; // PC
|
| 872 |
|
|
REG_RSEL = 4'b111x; // tmp16
|
| 873 |
|
|
end
|
| 874 |
|
|
endcase
|
| 875 |
|
|
2'b01: begin // EXX
|
| 876 |
|
|
ALU160_SEL = 1; // PC
|
| 877 |
|
|
WE = 6'b010x00; // PC
|
| 878 |
|
|
status[1] = 1;
|
| 879 |
|
|
end
|
| 880 |
|
|
2'b10: begin // JP (HL)
|
| 881 |
|
|
ALU160_SEL = 0; // regs
|
| 882 |
|
|
WE = 6'b010x00; // PC
|
| 883 |
|
|
REG_RSEL = 4'b010x; // HL
|
| 884 |
|
|
end
|
| 885 |
|
|
2'b11: begin // LD SP,HL
|
| 886 |
|
|
if(!STAGE[0]) begin // stage1
|
| 887 |
|
|
ALU160_SEL = 0; // regs
|
| 888 |
|
|
WE = 6'b001x00; // SP
|
| 889 |
|
|
ALU16OP = 4; // NOP, no post inc
|
| 890 |
|
|
next_stage = 1;
|
| 891 |
|
|
REG_RSEL = 4'b010x; // HL
|
| 892 |
|
|
M1 = 0;
|
| 893 |
|
|
MREQ = 0;
|
| 894 |
|
|
end else begin // stage2
|
| 895 |
|
|
ALU160_SEL = 1; // pc
|
| 896 |
|
|
WE = 6'b010x00; // PC
|
| 897 |
|
|
end
|
| 898 |
|
|
end
|
| 899 |
|
|
endcase
|
| 900 |
|
|
// ----------------------- CB, IN A (n), EX DE HL, EI --------------------
|
| 901 |
|
|
4'b1011:
|
| 902 |
|
|
case(FETCH[5:4])
|
| 903 |
|
|
2'b00: // CB prefix
|
| 904 |
|
|
case({STAGE[0], CPUStatus[4]})
|
| 905 |
|
|
2'b00, 2'b11: begin
|
| 906 |
|
|
ALU160_SEL = 1; // PC
|
| 907 |
|
|
WE = 6'b010000; // PC
|
| 908 |
|
|
fetch98 = 2'b10;
|
| 909 |
13 |
ndumitrach |
M1 = !CPUStatus[4]; // [DD/FD CB disp op] - M1 is inactive during <op> byte read
|
| 910 |
2 |
ndumitrach |
end
|
| 911 |
|
|
2'b01: begin
|
| 912 |
|
|
ALU160_SEL = 1; // PC
|
| 913 |
|
|
WE = 6'b010100; // PC, tmpHI
|
| 914 |
|
|
next_stage = 1;
|
| 915 |
|
|
M1 = 0;
|
| 916 |
|
|
end
|
| 917 |
|
|
endcase
|
| 918 |
|
|
2'b01: // IN A, (n)
|
| 919 |
|
|
case(STAGE[1:0])
|
| 920 |
|
|
2'b00: begin //stage1 - read n
|
| 921 |
|
|
ALU160_SEL = 1; // pc
|
| 922 |
|
|
DINW_SEL = 1; // DI
|
| 923 |
|
|
WE = 6'b010x01; // PC, lo
|
| 924 |
|
|
next_stage = 1;
|
| 925 |
|
|
REG_WSEL = 4'b011x; // tmpLO
|
| 926 |
|
|
M1 = 0;
|
| 927 |
|
|
end
|
| 928 |
|
|
2'b01: begin // stage2 - IN
|
| 929 |
|
|
ALU160_SEL = 0; // regs
|
| 930 |
|
|
DINW_SEL = 1; // DI
|
| 931 |
|
|
WE = 6'b000x1x; // hi
|
| 932 |
|
|
next_stage = 1;
|
| 933 |
|
|
REG_WSEL = 4'b011x; // A
|
| 934 |
|
|
REG_RSEL = 4'b011x; // A - tmpLO
|
| 935 |
|
|
M1 = 0;
|
| 936 |
|
|
MREQ = 0;
|
| 937 |
|
|
IORQ = 1;
|
| 938 |
|
|
end
|
| 939 |
|
|
2'b10: begin // stage3 - fetch
|
| 940 |
|
|
ALU160_SEL = 1; // PC
|
| 941 |
|
|
WE = 6'b010x00; // PC
|
| 942 |
|
|
end
|
| 943 |
|
|
endcase
|
| 944 |
|
|
2'b10: begin // EX DE, HL
|
| 945 |
|
|
ALU160_SEL = 1; // PC
|
| 946 |
|
|
WE = 6'b010x00; // PC
|
| 947 |
|
|
if(CPUStatus[1]) status[3] = 1;
|
| 948 |
|
|
else status[2] = 1;
|
| 949 |
|
|
end
|
| 950 |
|
|
2'b11: begin // EI
|
| 951 |
|
|
ALU160_SEL = 1; // PC
|
| 952 |
|
|
WE = 6'b010x00; // PC
|
| 953 |
|
|
status[11] = 1'b1;
|
| 954 |
|
|
status[7:6] = 2'b11;
|
| 955 |
|
|
end
|
| 956 |
|
|
endcase
|
| 957 |
|
|
// ----------------------- CALL , IX, ED, IY --------------------
|
| 958 |
|
|
4'b1101:
|
| 959 |
|
|
case(FETCH[5:4])
|
| 960 |
|
|
2'b00: // CALL
|
| 961 |
|
|
case(STAGE[2:0])
|
| 962 |
|
|
3'b000, 3'b001: begin // stage 1,2 - load addr
|
| 963 |
|
|
ALU160_SEL = 1; // pc
|
| 964 |
|
|
DINW_SEL = 1; // DI
|
| 965 |
|
|
WE = {4'b010x, STAGE[0] ? 1'b1 : 1'bx, !STAGE[0]}; // PC, hi/lo
|
| 966 |
|
|
next_stage = 1;
|
| 967 |
|
|
REG_WSEL = 4'b111x; // tmp7
|
| 968 |
|
|
M1 = 0;
|
| 969 |
|
|
end
|
| 970 |
|
|
3'b010, 3'b011: begin // stage 3,4 - push pc
|
| 971 |
|
|
DO_SEL = {1'b0, STAGE[0]}; // pc hi/lo
|
| 972 |
|
|
ALU160_SEL = 0; // regs
|
| 973 |
|
|
WE = 6'b001x00; // SP
|
| 974 |
|
|
ALU16OP = 5; // DEC
|
| 975 |
|
|
next_stage = 1;
|
| 976 |
|
|
REG_WSEL = 4'b1xxx; // pc
|
| 977 |
|
|
REG_RSEL = 4'b101x; // sp
|
| 978 |
|
|
M1 = 0;
|
| 979 |
|
|
WR = 1;
|
| 980 |
|
|
end
|
| 981 |
|
|
3'b100: begin // stage5 - jump
|
| 982 |
|
|
ALU160_SEL = 0; // regs
|
| 983 |
|
|
WE = 6'b010x00; // PC
|
| 984 |
|
|
REG_RSEL = 4'b111x; // tmp7
|
| 985 |
|
|
end
|
| 986 |
|
|
endcase
|
| 987 |
|
|
2'b01: begin // DD - IX
|
| 988 |
|
|
ALU160_SEL = 1; // PC
|
| 989 |
|
|
WE = 6'b010x00; // PC
|
| 990 |
|
|
status[5:4] = 2'b01;
|
| 991 |
|
|
end
|
| 992 |
|
|
2'b10: begin // ED prefix
|
| 993 |
|
|
ALU160_SEL = 1; // PC
|
| 994 |
|
|
WE = 6'b010x00; // PC
|
| 995 |
|
|
fetch98 = 2'b01;
|
| 996 |
|
|
end
|
| 997 |
|
|
2'b11: begin // FD - IY
|
| 998 |
|
|
ALU160_SEL = 1; // PC
|
| 999 |
|
|
WE = 6'b010x00; // PC
|
| 1000 |
|
|
status[5:4] = 2'b11;
|
| 1001 |
|
|
end
|
| 1002 |
|
|
endcase
|
| 1003 |
|
|
endcase
|
| 1004 |
|
|
|
| 1005 |
|
|
// ------------------------------------------- ED + opcode ----------------------------------------------------
|
| 1006 |
|
|
4'b0100, 4'b0111: begin // ED + 2'b00, ED + 2'b11 = NOP
|
| 1007 |
|
|
ALU160_SEL = 1; // PC
|
| 1008 |
|
|
WE = 6'b010x00; // PC
|
| 1009 |
|
|
end
|
| 1010 |
|
|
4'b0101:
|
| 1011 |
|
|
case(FETCH[2:0])
|
| 1012 |
|
|
// ----------------------- in r (C) --------------------
|
| 1013 |
|
|
3'b000:
|
| 1014 |
|
|
if(!STAGE[0]) begin
|
| 1015 |
|
|
ALU160_SEL = 0; // regs
|
| 1016 |
|
|
DINW_SEL = 1; // DI
|
| 1017 |
|
|
WE = {4'b000x, !opd[3], opd[3]} ; // hi/lo
|
| 1018 |
|
|
next_stage = 1;
|
| 1019 |
|
|
REG_WSEL = {1'b0, opd[5:4], 1'bx};
|
| 1020 |
|
|
REG_RSEL = 4'b000x; // BC
|
| 1021 |
|
|
M1 = 0;
|
| 1022 |
|
|
MREQ = 0;
|
| 1023 |
|
|
IORQ = 1;
|
| 1024 |
|
|
end else begin
|
| 1025 |
|
|
ALU160_SEL = 1; // pc
|
| 1026 |
|
|
WE = 6'b110x00; // flags, PC
|
| 1027 |
|
|
ALU8OP = 29; // IN
|
| 1028 |
|
|
REG_RSEL = {1'b0, opd[5:3]}; // reg
|
| 1029 |
|
|
end
|
| 1030 |
|
|
// ----------------------- out (C) r --------------------
|
| 1031 |
|
|
3'b001:
|
| 1032 |
|
|
if(!STAGE[0]) begin
|
| 1033 |
|
|
DO_SEL = 2'b00; // ALU80
|
| 1034 |
|
|
ALU160_SEL = 0; // regs
|
| 1035 |
|
|
WE = 6'b000x00; // nothing
|
| 1036 |
|
|
next_stage = 1;
|
| 1037 |
|
|
REG_WSEL = &opd[5:3] ? 4'b110x : {1'b0, opd[5:3]}; // zero/reg
|
| 1038 |
|
|
REG_RSEL = 4'b000x; // BC
|
| 1039 |
|
|
M1 = 0;
|
| 1040 |
|
|
MREQ = 0;
|
| 1041 |
|
|
WR = 1;
|
| 1042 |
|
|
IORQ = 1;
|
| 1043 |
|
|
end else begin
|
| 1044 |
|
|
ALU160_SEL = 1; // pc
|
| 1045 |
|
|
WE = 6'b010x00; // PC
|
| 1046 |
|
|
end
|
| 1047 |
|
|
// ----------------------- SBC16, ADC16 --------------------
|
| 1048 |
|
|
3'b010:
|
| 1049 |
|
|
if(!STAGE[0]) begin // stage1
|
| 1050 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 1051 |
|
|
WE = 6'b100x01; // flags, lo
|
| 1052 |
|
|
ALU8OP = {3'b000, !FETCH[3], 1'b1}; // SBC/ADC
|
| 1053 |
|
|
next_stage = 1;
|
| 1054 |
|
|
REG_WSEL = 4'b0101; // L
|
| 1055 |
|
|
REG_RSEL = {op16, 1'b1};
|
| 1056 |
|
|
M1 = 0;
|
| 1057 |
|
|
MREQ = 0;
|
| 1058 |
|
|
end else begin
|
| 1059 |
|
|
ALU160_SEL = 1; // pc
|
| 1060 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 1061 |
|
|
WE = 6'b110x10; // flags, PC, hi
|
| 1062 |
|
|
ALU8OP = {3'b000, !FETCH[3], 1'b1};
|
| 1063 |
|
|
REG_WSEL = 4'b0100; // H
|
| 1064 |
|
|
REG_RSEL = {op16, 1'b0};
|
| 1065 |
|
|
end
|
| 1066 |
|
|
// ----------------------- LD (nn) r16, ld r16 (nn) --------------------
|
| 1067 |
|
|
3'b011:
|
| 1068 |
|
|
case(STAGE[2:1])
|
| 1069 |
|
|
2'b00: begin // stage 1,2 - read address
|
| 1070 |
|
|
ALU160_SEL = 1; // pc
|
| 1071 |
|
|
DINW_SEL = 1; // DI
|
| 1072 |
|
|
WE = {4'b010x, STAGE[0] ? 1'b1 : 1'bx, !STAGE[0]}; // PC, hi/lo
|
| 1073 |
|
|
next_stage = 1;
|
| 1074 |
|
|
REG_WSEL = 4'b111x; // tmp16
|
| 1075 |
|
|
M1 = 0;
|
| 1076 |
|
|
end
|
| 1077 |
|
|
2'b01: begin
|
| 1078 |
|
|
ALU160_SEL = 0; // regs
|
| 1079 |
|
|
next_stage = 1;
|
| 1080 |
|
|
ALU16OP = {2'b00, STAGE[0]};
|
| 1081 |
|
|
REG_RSEL = 4'b111x; // tmp16
|
| 1082 |
|
|
REG_WSEL = {op16, !STAGE[0]};
|
| 1083 |
|
|
M1 = 0;
|
| 1084 |
|
|
if(FETCH[3]) begin // LD rr, (nn) - stage3,4
|
| 1085 |
|
|
DINW_SEL = 1; // DI
|
| 1086 |
|
|
WE = {4'b000x, STAGE[0] ? 1'b1 : 1'bx, !STAGE[0]}; // lo
|
| 1087 |
|
|
end else begin // LD (nn), rr - stage3,4
|
| 1088 |
|
|
DO_SEL = op16[2] ? {1'b1, !STAGE[0]} : 2'b00; // ALU80/sp
|
| 1089 |
|
|
WE = 6'b000x00; // nothing
|
| 1090 |
|
|
WR = 1;
|
| 1091 |
|
|
end
|
| 1092 |
|
|
end
|
| 1093 |
|
|
2'b10: // stage5
|
| 1094 |
|
|
if(FETCH[3] & op16[2] & !STAGE[0]) begin // LD sp, (nn) - stage5
|
| 1095 |
|
|
ALU160_SEL = 0; // regs
|
| 1096 |
|
|
WE = 6'b001x00; // SP
|
| 1097 |
|
|
ALU16OP = 4; // NOP
|
| 1098 |
|
|
next_stage = 1;
|
| 1099 |
|
|
REG_RSEL = 4'b101x; // tmp SP
|
| 1100 |
|
|
M1 = 0;
|
| 1101 |
|
|
MREQ = 0;
|
| 1102 |
|
|
end else begin
|
| 1103 |
|
|
ALU160_SEL = 1; // pc
|
| 1104 |
|
|
WE = 6'b010x00; // PC
|
| 1105 |
|
|
end
|
| 1106 |
|
|
endcase
|
| 1107 |
|
|
// ----------------------- NEG --------------------
|
| 1108 |
|
|
3'b100: begin
|
| 1109 |
|
|
ALU160_SEL = 1; // pc
|
| 1110 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 1111 |
|
|
WE = 6'b110x10; // flags, PC, hi
|
| 1112 |
|
|
ALU8OP = 5'b11111; // NEG
|
| 1113 |
|
|
REG_WSEL = 4'b011x; // A
|
| 1114 |
|
|
REG_RSEL = 4'b0110; // A
|
| 1115 |
|
|
end
|
| 1116 |
|
|
// ----------------------- RETN, RETI --------------------
|
| 1117 |
|
|
3'b101:
|
| 1118 |
|
|
case(STAGE[1:0])
|
| 1119 |
|
|
2'b00, 2'b01: begin // stage1, stage2 - pop addr
|
| 1120 |
|
|
ALU160_SEL = 0; // regs
|
| 1121 |
|
|
DINW_SEL = 1; // DI
|
| 1122 |
|
|
WE = {4'b001x, STAGE[0] ? 1'b1 : 1'bx, !STAGE[0]}; // SP, lo/hi
|
| 1123 |
|
|
next_stage = 1;
|
| 1124 |
|
|
REG_WSEL = 4'b111x; // tmp16
|
| 1125 |
|
|
REG_RSEL = 4'b101x; // SP
|
| 1126 |
|
|
M1 = 0;
|
| 1127 |
|
|
end
|
| 1128 |
|
|
2'b10: begin // stage3 - jump
|
| 1129 |
|
|
ALU160_SEL = 0; // regs
|
| 1130 |
|
|
WE = 6'b010x00; // PC
|
| 1131 |
|
|
REG_RSEL = 4'b111x; // tmp16
|
| 1132 |
|
|
status[11] = 1'b1;
|
| 1133 |
|
|
status[7:6] = {CPUStatus[7], CPUStatus[7]};
|
| 1134 |
|
|
end
|
| 1135 |
|
|
endcase
|
| 1136 |
|
|
// ----------------------- IM --------------------
|
| 1137 |
|
|
3'b110: begin
|
| 1138 |
|
|
ALU160_SEL = 1; // PC
|
| 1139 |
|
|
WE = 6'b010x00; // PC
|
| 1140 |
|
|
status[10:8] = {1'b1, FETCH[4:3]};
|
| 1141 |
|
|
end
|
| 1142 |
|
|
// ----------------------- LD I A, LD R A, LD A I, LD A R, RRD, RLD --------------------
|
| 1143 |
|
|
3'b111:
|
| 1144 |
|
|
case(FETCH[5:4])
|
| 1145 |
|
|
2'b00: begin // LD I/R A
|
| 1146 |
|
|
ALU160_SEL = 1; // pc
|
| 1147 |
|
|
DINW_SEL = 1'b0; // ALU8OUT
|
| 1148 |
|
|
WE = {4'b010x, !FETCH[3], FETCH[3]}; // PC, hi/lo
|
| 1149 |
|
|
ALU8OP = 29; // pass D1
|
| 1150 |
11 |
ndumitrach |
REG_WSEL = 4'b1001; // IR, write r
|
| 1151 |
2 |
ndumitrach |
REG_RSEL = 4'b0110; // A
|
| 1152 |
|
|
end
|
| 1153 |
|
|
2'b01: begin // LD A I/R
|
| 1154 |
|
|
ALU160_SEL = 1; // pc
|
| 1155 |
|
|
DINW_SEL = 1'b0; // ALU8OUT
|
| 1156 |
|
|
WE = 6'b110x1x; // flags, PC, hi
|
| 1157 |
|
|
ALU8OP = 29; // PASS D1
|
| 1158 |
|
|
REG_WSEL = 4'b011x; // A
|
| 1159 |
|
|
REG_RSEL = {3'b100, FETCH[3]};// I/R
|
| 1160 |
|
|
end
|
| 1161 |
|
|
2'b10: // RRD, RLD
|
| 1162 |
|
|
case(STAGE[1:0])
|
| 1163 |
|
|
2'b00:begin // stage1, read data
|
| 1164 |
|
|
ALU160_SEL = 0; // regs
|
| 1165 |
|
|
DINW_SEL = 1; // DI
|
| 1166 |
|
|
WE = 6'b000x01; // lo
|
| 1167 |
|
|
next_stage = 1;
|
| 1168 |
|
|
REG_WSEL = 4'b011x; // tmpLO
|
| 1169 |
|
|
REG_RSEL = 4'b010x; // HL
|
| 1170 |
|
|
M1 = 0;
|
| 1171 |
|
|
end
|
| 1172 |
|
|
2'b01: begin // stage2, shift data
|
| 1173 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 1174 |
|
|
WE = 6'b100x11; // flags, hi, lo
|
| 1175 |
|
|
ALU8OP = FETCH[3] ? 5'b01100 : 5'b01011; // RRD/RLD
|
| 1176 |
|
|
next_stage = 1;
|
| 1177 |
|
|
REG_WSEL = 4'b0110; // A
|
| 1178 |
|
|
REG_RSEL = 4'b0111; // tmpLO
|
| 1179 |
|
|
M1 = 0;
|
| 1180 |
|
|
MREQ = 0;
|
| 1181 |
|
|
end
|
| 1182 |
|
|
2'b10: begin // stage3 - write
|
| 1183 |
|
|
DO_SEL = 2'b00; // ALU80
|
| 1184 |
|
|
ALU160_SEL = 0; // regs
|
| 1185 |
|
|
WE = 6'b000x0x; // nothing
|
| 1186 |
|
|
next_stage = 1;
|
| 1187 |
|
|
REG_WSEL = 4'b0111; // tmpLO
|
| 1188 |
|
|
REG_RSEL = 4'b010x; // HL
|
| 1189 |
|
|
M1 = 0;
|
| 1190 |
|
|
WR = 1;
|
| 1191 |
|
|
end
|
| 1192 |
|
|
2'b11: begin
|
| 1193 |
|
|
ALU160_SEL = 1; // PC
|
| 1194 |
|
|
WE = 6'b010x00; // PC
|
| 1195 |
|
|
end
|
| 1196 |
|
|
endcase
|
| 1197 |
|
|
2'b11: begin // NOP
|
| 1198 |
|
|
ALU160_SEL = 1; // PC
|
| 1199 |
|
|
WE = 6'b010x00; // PC
|
| 1200 |
|
|
end
|
| 1201 |
|
|
endcase
|
| 1202 |
|
|
endcase
|
| 1203 |
|
|
// ----------------------- block instructions --------------------
|
| 1204 |
|
|
4'b0110:
|
| 1205 |
|
|
if({FETCH[5], FETCH[2]} == 4'b10)
|
| 1206 |
|
|
case(FETCH[1:0])
|
| 1207 |
|
|
2'b00: // LDI, LDD, LDIR, LDDR
|
| 1208 |
|
|
case(STAGE[1:0])
|
| 1209 |
|
|
2'b00: begin // stage1, read data, inc/dec HL
|
| 1210 |
|
|
ALU160_SEL = 0; // regs
|
| 1211 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 1212 |
|
|
WE = 6'b100111; // flags, tmpHI, hi, lo
|
| 1213 |
|
|
ALU8OP = {4'b0111, FETCH[3]}; // INC/DEC16
|
| 1214 |
|
|
next_stage = 1;
|
| 1215 |
|
|
REG_WSEL = 4'b0100; // H
|
| 1216 |
|
|
REG_RSEL = 4'b0101; // L
|
| 1217 |
|
|
M1 = 0;
|
| 1218 |
|
|
end
|
| 1219 |
|
|
2'b01: begin // stage2, dec BC
|
| 1220 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 1221 |
|
|
WE = 6'b100011; // flags, hi, lo (affects PF only)
|
| 1222 |
|
|
ALU8OP = 5'b01111; // DEC
|
| 1223 |
|
|
next_stage = 1;
|
| 1224 |
|
|
REG_WSEL = 4'b0000; // B
|
| 1225 |
|
|
REG_RSEL = 4'b0001; // C
|
| 1226 |
|
|
M1 = 0;
|
| 1227 |
|
|
MREQ = 0;
|
| 1228 |
|
|
end
|
| 1229 |
|
|
2'b10: begin // stage2, write data, inc/dec DE
|
| 1230 |
|
|
DO_SEL = 2'b01; // th
|
| 1231 |
|
|
ALU160_SEL = 0; // regs
|
| 1232 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 1233 |
|
|
WE = 6'b000x11; // hi, lo
|
| 1234 |
|
|
ALU8OP = {4'b0111, FETCH[3]}; // INC / DEC
|
| 1235 |
|
|
next_stage = FETCH[4] ? !FLAGS[2] : 1'b1;
|
| 1236 |
|
|
REG_WSEL = 4'b0010; // D
|
| 1237 |
|
|
REG_RSEL = 4'b0011; // E
|
| 1238 |
|
|
M1 = 0;
|
| 1239 |
|
|
WR = 1;
|
| 1240 |
|
|
end
|
| 1241 |
|
|
2'b11: begin
|
| 1242 |
|
|
ALU160_SEL = 1; // PC
|
| 1243 |
|
|
WE = 6'b010x00; // PC
|
| 1244 |
|
|
end
|
| 1245 |
|
|
endcase
|
| 1246 |
|
|
2'b01: // CPI, CPD, CPIR, CPDR
|
| 1247 |
|
|
case(STAGE[1:0])
|
| 1248 |
|
|
2'b00: begin // stage1, load data
|
| 1249 |
|
|
ALU160_SEL = 0; // regs
|
| 1250 |
|
|
DINW_SEL = 1; // DI
|
| 1251 |
|
|
WE = 6'b000x01; // lo
|
| 1252 |
|
|
next_stage = 1;
|
| 1253 |
|
|
REG_WSEL = 4'b011x; // tmpLO
|
| 1254 |
|
|
REG_RSEL = 4'b010x; // HL
|
| 1255 |
|
|
M1 = 0;
|
| 1256 |
|
|
end
|
| 1257 |
|
|
2'b01: begin // stage2, CP
|
| 1258 |
|
|
WE = 6'b100x0x; // flags
|
| 1259 |
|
|
ALU8OP = 7; // CP
|
| 1260 |
|
|
next_stage = 1;
|
| 1261 |
|
|
REG_WSEL = 4'b0110; // A
|
| 1262 |
|
|
REG_RSEL = 4'b0111; // tmpLO
|
| 1263 |
|
|
M1 = 0;
|
| 1264 |
|
|
MREQ = 0;
|
| 1265 |
|
|
end
|
| 1266 |
|
|
2'b10: begin // stage3, dec BC
|
| 1267 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 1268 |
|
|
WE = 6'b100x11; // flags, hi, lo
|
| 1269 |
|
|
ALU8OP = 5'b01111; // DEC16
|
| 1270 |
|
|
next_stage = 1;
|
| 1271 |
|
|
REG_WSEL = 4'b0000; // B
|
| 1272 |
|
|
REG_RSEL = 4'b0001; // C
|
| 1273 |
|
|
M1 = 0;
|
| 1274 |
|
|
MREQ = 0;
|
| 1275 |
|
|
end
|
| 1276 |
|
|
2'b11: begin // stage4, inc/dec HL
|
| 1277 |
|
|
ALU160_SEL = 1; // pc
|
| 1278 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 1279 |
|
|
M1 = FETCH[4] ? (!FLAGS[2] || FLAGS[6]) : 1'b1;
|
| 1280 |
|
|
WE = {1'b0, M1, 4'b0x11}; // PC, hi, lo
|
| 1281 |
|
|
ALU8OP = {4'b0111, FETCH[3]}; // INC / DEC
|
| 1282 |
|
|
REG_WSEL = 4'b0100; // H
|
| 1283 |
|
|
REG_RSEL = 4'b0101; // L
|
| 1284 |
|
|
MREQ = M1;
|
| 1285 |
|
|
end
|
| 1286 |
|
|
endcase
|
| 1287 |
|
|
2'b10: // INI, IND, INIR, INDR
|
| 1288 |
|
|
case(STAGE[1:0])
|
| 1289 |
|
|
2'b00: begin // stage1, in data, dec B
|
| 1290 |
|
|
ALU160_SEL = 0; // regs
|
| 1291 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 1292 |
|
|
WE = 6'b100110; // flags, tmpHI, hi
|
| 1293 |
|
|
ALU8OP = 10; // DEC
|
| 1294 |
|
|
next_stage = 1;
|
| 1295 |
|
|
REG_WSEL = 4'b0000; // B
|
| 1296 |
|
|
REG_RSEL = 4'b000x; // BC
|
| 1297 |
|
|
M1 = 0;
|
| 1298 |
|
|
MREQ = 0;
|
| 1299 |
|
|
IORQ = 1;
|
| 1300 |
|
|
end
|
| 1301 |
|
|
2'b01: begin // stage2, write data, inc/dec HL
|
| 1302 |
|
|
DO_SEL = 2'b01; // th
|
| 1303 |
|
|
ALU160_SEL = 0; // regs
|
| 1304 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 1305 |
|
|
WE = 6'b000x11; // hi, lo
|
| 1306 |
|
|
ALU8OP = {4'b0111, FETCH[3]}; // INC / DEC
|
| 1307 |
|
|
next_stage = FETCH[4] ? FLAGS[6] : 1'b1;
|
| 1308 |
|
|
REG_WSEL = 4'b0100; // H
|
| 1309 |
|
|
REG_RSEL = 4'b0101; // L
|
| 1310 |
|
|
M1 = 0;
|
| 1311 |
|
|
WR = 1;
|
| 1312 |
|
|
end
|
| 1313 |
|
|
2'b10: begin // stage3
|
| 1314 |
|
|
ALU160_SEL = 1; // pc
|
| 1315 |
|
|
WE = 6'b010x00; // PC
|
| 1316 |
|
|
end
|
| 1317 |
|
|
endcase
|
| 1318 |
|
|
2'b11: // OUTI/OUTD/OTIR/OTDR
|
| 1319 |
|
|
case(STAGE[1:0])
|
| 1320 |
|
|
2'b00: begin // stage1, load data, inc/dec HL
|
| 1321 |
|
|
ALU160_SEL = 0; // regs
|
| 1322 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 1323 |
|
|
WE = 6'b000111; // tmpHI, hi, lo
|
| 1324 |
|
|
ALU8OP = {4'b0111, FETCH[3]}; // INC / DEC
|
| 1325 |
|
|
next_stage = 1;
|
| 1326 |
|
|
REG_WSEL = 4'b0100; // H
|
| 1327 |
|
|
REG_RSEL = 4'b0101; // L
|
| 1328 |
|
|
M1 = 0;
|
| 1329 |
|
|
end
|
| 1330 |
|
|
2'b01: begin // stage2, out data, dec B
|
| 1331 |
|
|
DO_SEL = 2'b01; // th
|
| 1332 |
|
|
ALU160_SEL = 0; // regs
|
| 1333 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 1334 |
|
|
WE = 6'b100x10; // flags, hi
|
| 1335 |
|
|
ALU8OP = 10; // DEC
|
| 1336 |
|
|
next_stage = FETCH[4] ? (ALU80 == 8'b00000001) : 1'b1;
|
| 1337 |
|
|
REG_WSEL = 4'b0000; // B
|
| 1338 |
|
|
REG_RSEL = 4'b000x; // BC
|
| 1339 |
|
|
M1 = 0;
|
| 1340 |
|
|
MREQ = 0;
|
| 1341 |
|
|
IORQ = 1;
|
| 1342 |
|
|
WR = 1;
|
| 1343 |
|
|
end
|
| 1344 |
|
|
2'b10: begin // stage3
|
| 1345 |
|
|
ALU160_SEL = 1; // pc
|
| 1346 |
|
|
WE = 6'b010x00; // PC
|
| 1347 |
|
|
end
|
| 1348 |
|
|
endcase
|
| 1349 |
|
|
endcase
|
| 1350 |
|
|
else begin // NOP
|
| 1351 |
|
|
ALU160_SEL = 1; // PC
|
| 1352 |
|
|
WE = 6'b010x00; // PC
|
| 1353 |
|
|
end
|
| 1354 |
|
|
//------------------------------------------- CB + opcode ----------------------------------------------------
|
| 1355 |
|
|
4'b1000, 4'b1001, 4'b1010, 4'b1011: // CB class (rot/shift, bit/res/set)
|
| 1356 |
|
|
case({STAGE[1:0], CPUStatus[4], op0mem})
|
| 1357 |
|
|
4'b00_0_0: begin // execute reg-reg
|
| 1358 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 1359 |
|
|
ALU160_SEL = 1; // pc
|
| 1360 |
|
|
WE = {!FETCH[7], 3'b10x, FETCH[7:6] == 2'b01 ? 2'b00 : {!opd[0], opd[0]}}; // flags, hi/lo
|
| 1361 |
|
|
ALU8OP = 28; // BIT
|
| 1362 |
|
|
REG_WSEL = {1'b0, opd[2:0]};
|
| 1363 |
|
|
end
|
| 1364 |
|
|
4'b00_0_1, 4'b00_1_0, 4'b00_1_1: begin // stage1, (HL-X) - read data
|
| 1365 |
|
|
ALU160_SEL = 0; // regs
|
| 1366 |
|
|
DINW_SEL = 1; // DI
|
| 1367 |
|
|
WE = opd[0] ? 6'b000001 : 6'b000010; // lo/hi
|
| 1368 |
|
|
ALU16OP = CPUStatus[4] ? 3'd3 : 3'd0; // ADD - NOP
|
| 1369 |
|
|
next_stage = 1;
|
| 1370 |
|
|
REG_WSEL = FETCH[7:6] == 2'b01 ? 4'b111x : {1'b0, opd[2:0]}; // dest, tmp16 for BIT
|
| 1371 |
|
|
REG_RSEL = 4'b010x; // HL
|
| 1372 |
|
|
M1 = 0;
|
| 1373 |
|
|
end
|
| 1374 |
|
|
4'b01_0_1, 4'b01_1_0, 4'b01_1_1: // stage2 (HL-X) - execute, write
|
| 1375 |
|
|
case(FETCH[7:6])
|
| 1376 |
|
|
2'b00, 2'b10, 2'b11: begin // exec + write
|
| 1377 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 1378 |
|
|
DO_SEL = 2'b11; // ALU8OUT[7:0]
|
| 1379 |
|
|
ALU160_SEL = 0; // regs
|
| 1380 |
|
|
WE = {!FETCH[7], 3'b00x, !opd[0], opd[0]}; // flags, hi/lo
|
| 1381 |
|
|
ALU8OP = 28;
|
| 1382 |
|
|
ALU16OP = CPUStatus[4] ? 3'd3 : 3'd0;
|
| 1383 |
|
|
next_stage = 1;
|
| 1384 |
|
|
REG_WSEL = {1'b0, opd[2:0]};
|
| 1385 |
|
|
REG_RSEL = 4'b010x; // HL
|
| 1386 |
|
|
M1 = 0;
|
| 1387 |
|
|
WR = 1;
|
| 1388 |
|
|
end
|
| 1389 |
|
|
2'b01: begin // BIT, no write
|
| 1390 |
|
|
ALU160_SEL = 1; // pc
|
| 1391 |
|
|
WE = 6'b110xxx; // flags, PC
|
| 1392 |
|
|
ALU8OP = 28; // BIT
|
| 1393 |
|
|
REG_WSEL = {3'b111, opd[0]}; // tmp
|
| 1394 |
|
|
end
|
| 1395 |
|
|
endcase
|
| 1396 |
|
|
4'b10_0_1, 4'b10_1_0, 4'b10_1_1: begin // (HL-X) - load next op
|
| 1397 |
|
|
ALU160_SEL = 1; // pc
|
| 1398 |
|
|
WE = 6'b010x00; // PC
|
| 1399 |
|
|
end
|
| 1400 |
|
|
endcase
|
| 1401 |
|
|
//------------------------------------------- // RST, NMI, INT ----------------------------------------------------
|
| 1402 |
|
|
4'b1110: begin // RESET: IR <- 0, IM <- 0, IFF1,IFF2 <- 0, pC <- 0
|
| 1403 |
|
|
ALU160_SEL = 0; // regs
|
| 1404 |
|
|
DINW_SEL = 0; // ALU8OUT
|
| 1405 |
|
|
WE = 6'bx1xx11; // PC, hi, lo
|
| 1406 |
|
|
ALU8OP = 29; // pass D1
|
| 1407 |
|
|
ALU16OP = 4; // NOP
|
| 1408 |
11 |
ndumitrach |
REG_WSEL = 4'b1001; // IR, write r
|
| 1409 |
2 |
ndumitrach |
REG_RSEL = 4'b110x; // const
|
| 1410 |
|
|
M1 = 0;
|
| 1411 |
|
|
MREQ = 0;
|
| 1412 |
|
|
status[11:6] = 6'b110000; // IM0, DI
|
| 1413 |
|
|
end
|
| 1414 |
|
|
4'b1101: // NMI
|
| 1415 |
|
|
case(STAGE[1:0])
|
| 1416 |
|
|
2'b00: begin
|
| 1417 |
|
|
ALU160_SEL = 1; // pc
|
| 1418 |
|
|
WE = 6'b010x00; // PC
|
| 1419 |
|
|
ALU16OP = intop; // DEC/DEC2 (if block instruction interrupted)
|
| 1420 |
|
|
next_stage = 1;
|
| 1421 |
|
|
M1 = 0;
|
| 1422 |
|
|
MREQ = 0;
|
| 1423 |
|
|
end
|
| 1424 |
|
|
2'b01, 2'b10: begin
|
| 1425 |
|
|
DO_SEL = {1'b0, !STAGE[0]}; // pc hi/lo
|
| 1426 |
|
|
ALU160_SEL = 0; // regs
|
| 1427 |
|
|
WE = 6'b001x00; // SP
|
| 1428 |
|
|
ALU16OP = 5; // DEC
|
| 1429 |
|
|
next_stage = 1;
|
| 1430 |
|
|
REG_WSEL = 4'b1xxx; // pc
|
| 1431 |
|
|
REG_RSEL = 4'b101x; // sp
|
| 1432 |
|
|
M1 = 0;
|
| 1433 |
|
|
WR = 1;
|
| 1434 |
|
|
status[11] = 1'b1;
|
| 1435 |
|
|
status[7:6] = {CPUStatus[7], 1'b0}; // reset IFF1
|
| 1436 |
|
|
end
|
| 1437 |
|
|
2'b11: begin
|
| 1438 |
|
|
ALU160_SEL = 0; // regs
|
| 1439 |
|
|
WE = 6'b010x00; // PC
|
| 1440 |
|
|
REG_RSEL = 4'b110x; // const
|
| 1441 |
|
|
end
|
| 1442 |
|
|
endcase
|
| 1443 |
|
|
4'b1100: // INT
|
| 1444 |
|
|
case(CPUStatus[9:8])
|
| 1445 |
|
|
2'b00, 2'b01, 2'b10: begin // IM0, IM1
|
| 1446 |
|
|
ALU160_SEL = 1; // pc
|
| 1447 |
|
|
WE = 6'b010x00; // PC
|
| 1448 |
|
|
ALU16OP = intop; // DEC/DEC2 (if block instruction interrupted)
|
| 1449 |
|
|
MREQ = 0;
|
| 1450 |
|
|
IORQ = 1;
|
| 1451 |
|
|
status[11] = 1'b1;
|
| 1452 |
|
|
status[7:6] = 2'b0; // reset IFF1, IFF2
|
| 1453 |
|
|
end
|
| 1454 |
|
|
2'b11: // IM2
|
| 1455 |
|
|
case(STAGE[2:0])
|
| 1456 |
|
|
3'b000: begin
|
| 1457 |
|
|
ALU160_SEL = 1; // pc
|
| 1458 |
|
|
DINW_SEL = 1; // DI
|
| 1459 |
|
|
WE = 6'b010x01; // PC, lo
|
| 1460 |
|
|
ALU16OP = intop; // DEC/DEC2 (if block instruction interrupted)
|
| 1461 |
|
|
next_stage = 1;
|
| 1462 |
11 |
ndumitrach |
REG_WSEL = 4'b1000; // Itmp, no write r
|
| 1463 |
2 |
ndumitrach |
MREQ = 0;
|
| 1464 |
|
|
IORQ = 1;
|
| 1465 |
|
|
status[11] = 1'b1;
|
| 1466 |
|
|
status[7:6] = 2'b0; // reset IFF1, IFF2
|
| 1467 |
|
|
end
|
| 1468 |
|
|
3'b001, 3'b010: begin // push pc
|
| 1469 |
|
|
DO_SEL = {1'b0, !STAGE[0]}; // pc hi/lo
|
| 1470 |
|
|
ALU160_SEL = 0; // regs
|
| 1471 |
|
|
WE = 6'b001x00; // SP
|
| 1472 |
|
|
ALU16OP = 5; // DEC
|
| 1473 |
|
|
next_stage = 1;
|
| 1474 |
|
|
REG_WSEL = 4'b1xxx; // pc
|
| 1475 |
|
|
REG_RSEL = 4'b101x; // sp
|
| 1476 |
|
|
M1 = 0;
|
| 1477 |
|
|
WR = 1;
|
| 1478 |
|
|
end
|
| 1479 |
|
|
3'b011, 3'b100: begin // read address
|
| 1480 |
|
|
ALU160_SEL = 0; // regs
|
| 1481 |
|
|
DINW_SEL = 1; // DI
|
| 1482 |
|
|
WE = {4'b0x0x, STAGE[0] ? 1'bx : 1'b1, STAGE[0]}; // hi/lo
|
| 1483 |
|
|
ALU16OP = {2'b00, !STAGE[0]};// NOP/INC
|
| 1484 |
|
|
next_stage = 1;
|
| 1485 |
|
|
REG_WSEL = 4'b111x; // tmp16
|
| 1486 |
|
|
REG_RSEL = 4'b1000; // I-Itmp
|
| 1487 |
|
|
M1 = 0;
|
| 1488 |
|
|
end
|
| 1489 |
|
|
3'b101: begin // jump
|
| 1490 |
|
|
ALU160_SEL = 0; // regs
|
| 1491 |
|
|
WE = 6'b010x00; // PC
|
| 1492 |
|
|
REG_RSEL = 4'b111x; // tmp16
|
| 1493 |
|
|
end
|
| 1494 |
|
|
endcase
|
| 1495 |
|
|
endcase
|
| 1496 |
|
|
endcase
|
| 1497 |
|
|
end
|
| 1498 |
|
|
|
| 1499 |
|
|
endmodule
|
