//
// TV80 8-Bit Microprocessor Core
// Based on the VHDL T80 core by Daniel Wallner (jesus@opencores.org)
//
// Copyright (c) 2004,2007 Guy Hutchison (ghutchis@opencores.org)
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
module tv80_mcode
(/*AUTOARG*/
// Outputs
MCycles, TStates, Prefix, Inc_PC, Inc_WZ, IncDec_16, Read_To_Reg,
Read_To_Acc, Set_BusA_To, Set_BusB_To, ALU_Op, Save_ALU, PreserveC,
Arith16, Set_Addr_To, IORQ, Jump, JumpE, JumpXY, Call, RstP, LDZ,
LDW, LDSPHL, Special_LD, ExchangeDH, ExchangeRp, ExchangeAF,
ExchangeRS, I_DJNZ, I_CPL, I_CCF, I_SCF, I_RETN, I_BT, I_BC, I_BTR,
I_RLD, I_RRD, I_INRC, SetDI, SetEI, IMode, Halt, NoRead, Write,
// Inputs
IR, ISet, MCycle, F, NMICycle, IntCycle
);
parameter Mode = 0;
parameter Flag_C = 0;
parameter Flag_N = 1;
parameter Flag_P = 2;
parameter Flag_X = 3;
parameter Flag_H = 4;
parameter Flag_Y = 5;
parameter Flag_Z = 6;
parameter Flag_S = 7;
input [7:0] IR;
input [1:0] ISet ;
input [6:0] MCycle ;
input [7:0] F ;
input NMICycle ;
input IntCycle ;
output [2:0] MCycles ;
output [2:0] TStates ;
output [1:0] Prefix ; // None,BC,ED,DD/FD
output Inc_PC ;
output Inc_WZ ;
output [3:0] IncDec_16 ; // BC,DE,HL,SP 0 is inc
output Read_To_Reg ;
output Read_To_Acc ;
output [3:0] Set_BusA_To ; // B,C,D,E,H,L,DI/DB,A,SP(L),SP(M),0,F
output [3:0] Set_BusB_To ; // B,C,D,E,H,L,DI,A,SP(L),SP(M),1,F,PC(L),PC(M),0
output [3:0] ALU_Op ;
output Save_ALU ;
output PreserveC ;
output Arith16 ;
output [2:0] Set_Addr_To ; // aNone,aXY,aIOA,aSP,aBC,aDE,aZI
output IORQ ;
output Jump ;
output JumpE ;
output JumpXY ;
output Call ;
output RstP ;
output LDZ ;
output LDW ;
output LDSPHL ;
output [2:0] Special_LD ; // A,I;A,R;I,A;R,A;None
output ExchangeDH ;
output ExchangeRp ;
output ExchangeAF ;
output ExchangeRS ;
output I_DJNZ ;
output I_CPL ;
output I_CCF ;
output I_SCF ;
output I_RETN ;
output I_BT ;
output I_BC ;
output I_BTR ;
output I_RLD ;
output I_RRD ;
output I_INRC ;
output SetDI ;
output SetEI ;
output [1:0] IMode ;
output Halt ;
output NoRead ;
output Write ;
// regs
reg [2:0] MCycles ;
reg [2:0] TStates ;
reg [1:0] Prefix ; // None,BC,ED,DD/FD
reg Inc_PC ;
reg Inc_WZ ;
reg [3:0] IncDec_16 ; // BC,DE,HL,SP 0 is inc
reg Read_To_Reg ;
reg Read_To_Acc ;
reg [3:0] Set_BusA_To ; // B,C,D,E,H,L,DI/DB,A,SP(L),SP(M),0,F
reg [3:0] Set_BusB_To ; // B,C,D,E,H,L,DI,A,SP(L),SP(M),1,F,PC(L),PC(M),0
reg [3:0] ALU_Op ;
reg Save_ALU ;
reg PreserveC ;
reg Arith16 ;
reg [2:0] Set_Addr_To ; // aNone,aXY,aIOA,aSP,aBC,aDE,aZI
reg IORQ ;
reg Jump ;
reg JumpE ;
reg JumpXY ;
reg Call ;
reg RstP ;
reg LDZ ;
reg LDW ;
reg LDSPHL ;
reg [2:0] Special_LD ; // A,I;A,R;I,A;R,A;None
reg ExchangeDH ;
reg ExchangeRp ;
reg ExchangeAF ;
reg ExchangeRS ;
reg I_DJNZ ;
reg I_CPL ;
reg I_CCF ;
reg I_SCF ;
reg I_RETN ;
reg I_BT ;
reg I_BC ;
reg I_BTR ;
reg I_RLD ;
reg I_RRD ;
reg I_INRC ;
reg SetDI ;
reg SetEI ;
reg [1:0] IMode ;
reg Halt ;
reg NoRead ;
reg Write ;
parameter aNone = 3'b111;
parameter aBC = 3'b000;
parameter aDE = 3'b001;
parameter aXY = 3'b010;
parameter aIOA = 3'b100;
parameter aSP = 3'b101;
parameter aZI = 3'b110;
// constant aNone : std_logic_vector[2:0] = 3'b000;
// constant aXY : std_logic_vector[2:0] = 3'b001;
// constant aIOA : std_logic_vector[2:0] = 3'b010;
// constant aSP : std_logic_vector[2:0] = 3'b011;
// constant aBC : std_logic_vector[2:0] = 3'b100;
// constant aDE : std_logic_vector[2:0] = 3'b101;
// constant aZI : std_logic_vector[2:0] = 3'b110;
function is_cc_true;
input [7:0] FF;
input [2:0] cc;
begin
if (Mode == 3 )
begin
case (cc)
3'b000 : is_cc_true = FF[7] == 1'b0; // NZ
3'b001 : is_cc_true = FF[7] == 1'b1; // Z
3'b010 : is_cc_true = FF[4] == 1'b0; // NC
3'b011 : is_cc_true = FF[4] == 1'b1; // C
3'b100 : is_cc_true = 0;
3'b101 : is_cc_true = 0;
3'b110 : is_cc_true = 0;
3'b111 : is_cc_true = 0;
endcase
end
else
begin
case (cc)
3'b000 : is_cc_true = FF[6] == 1'b0; // NZ
3'b001 : is_cc_true = FF[6] == 1'b1; // Z
3'b010 : is_cc_true = FF[0] == 1'b0; // NC
3'b011 : is_cc_true = FF[0] == 1'b1; // C
3'b100 : is_cc_true = FF[2] == 1'b0; // PO
3'b101 : is_cc_true = FF[2] == 1'b1; // PE
3'b110 : is_cc_true = FF[7] == 1'b0; // P
3'b111 : is_cc_true = FF[7] == 1'b1; // M
endcase
end
end
endfunction // is_cc_true
reg [2:0] DDD;
reg [2:0] SSS;
reg [1:0] DPAIR;
always @ (/*AUTOSENSE*/F or IR or ISet or IntCycle or MCycle
or NMICycle)
begin
DDD = IR[5:3];
SSS = IR[2:0];
DPAIR = IR[5:4];
MCycles = 3'b001;
if (MCycle[0] )
begin
TStates = 3'b100;
end
else
begin
TStates = 3'b011;
end
Prefix = 2'b00;
Inc_PC = 1'b0;
Inc_WZ = 1'b0;
IncDec_16 = 4'b0000;
Read_To_Acc = 1'b0;
Read_To_Reg = 1'b0;
Set_BusB_To = 4'b0000;
Set_BusA_To = 4'b0000;
ALU_Op = { 1'b0, IR[5:3] };
Save_ALU = 1'b0;
PreserveC = 1'b0;
Arith16 = 1'b0;
IORQ = 1'b0;
Set_Addr_To = aNone;
Jump = 1'b0;
JumpE = 1'b0;
JumpXY = 1'b0;
Call = 1'b0;
RstP = 1'b0;
LDZ = 1'b0;
LDW = 1'b0;
LDSPHL = 1'b0;
Special_LD = 3'b000;
ExchangeDH = 1'b0;
ExchangeRp = 1'b0;
ExchangeAF = 1'b0;
ExchangeRS = 1'b0;
I_DJNZ = 1'b0;
I_CPL = 1'b0;
I_CCF = 1'b0;
I_SCF = 1'b0;
I_RETN = 1'b0;
I_BT = 1'b0;
I_BC = 1'b0;
I_BTR = 1'b0;
I_RLD = 1'b0;
I_RRD = 1'b0;
I_INRC = 1'b0;
SetDI = 1'b0;
SetEI = 1'b0;
IMode = 2'b11;
Halt = 1'b0;
NoRead = 1'b0;
Write = 1'b0;
case (ISet)
2'b00 :
begin
//----------------------------------------------------------------------------
//
// Unprefixed instructions
//
//----------------------------------------------------------------------------
casez (IR)
// 8 BIT LOAD GROUP
8'b01zzzzzz :
begin
if (IR[5:0] == 6'b110110)
Halt = 1'b1;
else if (IR[2:0] == 3'b110)
begin
// LD r,(HL)
MCycles = 3'b010;
if (MCycle[0])
Set_Addr_To = aXY;
if (MCycle[1])
begin
Set_BusA_To[2:0] = DDD;
Read_To_Reg = 1'b1;
end
end // if (IR[2:0] == 3'b110)
else if (IR[5:3] == 3'b110)
begin
// LD (HL),r
MCycles = 3'b010;
if (MCycle[0])
begin
Set_Addr_To = aXY;
Set_BusB_To[2:0] = SSS;
Set_BusB_To[3] = 1'b0;
end
if (MCycle[1])
Write = 1'b1;
end // if (IR[5:3] == 3'b110)
else
begin
Set_BusB_To[2:0] = SSS;
ExchangeRp = 1'b1;
Set_BusA_To[2:0] = DDD;
Read_To_Reg = 1'b1;
end // else: !if(IR[5:3] == 3'b110)
end // case: 8'b01zzzzzz
8'b00zzz110 :
begin
if (IR[5:3] == 3'b110)
begin
// LD (HL),n
MCycles = 3'b011;
if (MCycle[1])
begin
Inc_PC = 1'b1;
Set_Addr_To = aXY;
Set_BusB_To[2:0] = SSS;
Set_BusB_To[3] = 1'b0;
end
if (MCycle[2])
Write = 1'b1;
end // if (IR[5:3] == 3'b110)
else
begin
// LD r,n
MCycles = 3'b010;
if (MCycle[1])
begin
Inc_PC = 1'b1;
Set_BusA_To[2:0] = DDD;
Read_To_Reg = 1'b1;
end
end
end
8'b00001010 :
begin
// LD A,(BC)
MCycles = 3'b010;
if (MCycle[0])
Set_Addr_To = aBC;
if (MCycle[1])
Read_To_Acc = 1'b1;
end // case: 8'b00001010
8'b00011010 :
begin
// LD A,(DE)
MCycles = 3'b010;
if (MCycle[0])
Set_Addr_To = aDE;
if (MCycle[1])
Read_To_Acc = 1'b1;
end // case: 8'b00011010
8'b00111010 :
begin
if (Mode == 3 )
begin
// LDD A,(HL)
MCycles = 3'b010;
if (MCycle[0])
Set_Addr_To = aXY;
if (MCycle[1])
begin
Read_To_Acc = 1'b1;
IncDec_16 = 4'b1110;
end
end
else
begin
// LD A,(nn)
MCycles = 3'b100;
if (MCycle[1])
begin
Inc_PC = 1'b1;
LDZ = 1'b1;
end
if (MCycle[2])
begin
Set_Addr_To = aZI;
Inc_PC = 1'b1;
end
if (MCycle[3])
begin
Read_To_Acc = 1'b1;
end
end // else: !if(Mode == 3 )
end // case: 8'b00111010
8'b00000010 :
begin
// LD (BC),A
MCycles = 3'b010;
if (MCycle[0])
begin
Set_Addr_To = aBC;
Set_BusB_To = 4'b0111;
end
if (MCycle[1])
begin
Write = 1'b1;
end
end // case: 8'b00000010
8'b00010010 :
begin
// LD (DE),A
MCycles = 3'b010;
case (1'b1) // MCycle
MCycle[0] :
begin
Set_Addr_To = aDE;
Set_BusB_To = 4'b0111;
end
MCycle[1] :
Write = 1'b1;
default :;
endcase // case(MCycle)
end // case: 8'b00010010
8'b00110010 :
begin
if (Mode == 3 )
begin
// LDD (HL),A
MCycles = 3'b010;
case (1'b1) // MCycle
MCycle[0] :
begin
Set_Addr_To = aXY;
Set_BusB_To = 4'b0111;
end
MCycle[1] :
begin
Write = 1'b1;
IncDec_16 = 4'b1110;
end
default :;
endcase // case(MCycle)
end
else
begin
// LD (nn),A
MCycles = 3'b100;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
LDZ = 1'b1;
end
MCycle[2] :
begin
Set_Addr_To = aZI;
Inc_PC = 1'b1;
Set_BusB_To = 4'b0111;
end
MCycle[3] :
begin
Write = 1'b1;
end
default :;
endcase
end // else: !if(Mode == 3 )
end // case: 8'b00110010
// 16 BIT LOAD GROUP
8'b00000001,8'b00010001,8'b00100001,8'b00110001 :
begin
// LD dd,nn
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
Read_To_Reg = 1'b1;
if (DPAIR == 2'b11 )
begin
Set_BusA_To[3:0] = 4'b1000;
end
else
begin
Set_BusA_To[2:1] = DPAIR;
Set_BusA_To[0] = 1'b1;
end
end // case: 2
MCycle[2] :
begin
Inc_PC = 1'b1;
Read_To_Reg = 1'b1;
if (DPAIR == 2'b11 )
begin
Set_BusA_To[3:0] = 4'b1001;
end
else
begin
Set_BusA_To[2:1] = DPAIR;
Set_BusA_To[0] = 1'b0;
end
end // case: 3
default :;
endcase // case(MCycle)
end // case: 8'b00000001,8'b00010001,8'b00100001,8'b00110001
8'b00101010 :
begin
if (Mode == 3 )
begin
// LDI A,(HL)
MCycles = 3'b010;
case (1'b1) // MCycle
MCycle[0] :
Set_Addr_To = aXY;
MCycle[1] :
begin
Read_To_Acc = 1'b1;
IncDec_16 = 4'b0110;
end
default :;
endcase
end
else
begin
// LD HL,(nn)
MCycles = 3'b101;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
LDZ = 1'b1;
end
MCycle[2] :
begin
Set_Addr_To = aZI;
Inc_PC = 1'b1;
LDW = 1'b1;
end
MCycle[3] :
begin
Set_BusA_To[2:0] = 3'b101; // L
Read_To_Reg = 1'b1;
Inc_WZ = 1'b1;
Set_Addr_To = aZI;
end
MCycle[4] :
begin
Set_BusA_To[2:0] = 3'b100; // H
Read_To_Reg = 1'b1;
end
default :;
endcase
end // else: !if(Mode == 3 )
end // case: 8'b00101010
8'b00100010 :
begin
if (Mode == 3 )
begin
// LDI (HL),A
MCycles = 3'b010;
case (1'b1) // MCycle
MCycle[0] :
begin
Set_Addr_To = aXY;
Set_BusB_To = 4'b0111;
end
MCycle[1] :
begin
Write = 1'b1;
IncDec_16 = 4'b0110;
end
default :;
endcase
end
else
begin
// LD (nn),HL
MCycles = 3'b101;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
LDZ = 1'b1;
end
MCycle[2] :
begin
Set_Addr_To = aZI;
Inc_PC = 1'b1;
LDW = 1'b1;
Set_BusB_To = 4'b0101; // L
end
MCycle[3] :
begin
Inc_WZ = 1'b1;
Set_Addr_To = aZI;
Write = 1'b1;
Set_BusB_To = 4'b0100; // H
end
MCycle[4] :
Write = 1'b1;
default :;
endcase
end // else: !if(Mode == 3 )
end // case: 8'b00100010
8'b11111001 :
begin
// LD SP,HL
TStates = 3'b110;
LDSPHL = 1'b1;
end
8'b11zz0101 :
begin
// PUSH qq
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[0] :
begin
TStates = 3'b101;
IncDec_16 = 4'b1111;
Set_Addr_To = aSP;
if (DPAIR == 2'b11 )
begin
Set_BusB_To = 4'b0111;
end
else
begin
Set_BusB_To[2:1] = DPAIR;
Set_BusB_To[0] = 1'b0;
Set_BusB_To[3] = 1'b0;
end
end // case: 1
MCycle[1] :
begin
IncDec_16 = 4'b1111;
Set_Addr_To = aSP;
if (DPAIR == 2'b11 )
begin
Set_BusB_To = 4'b1011;
end
else
begin
Set_BusB_To[2:1] = DPAIR;
Set_BusB_To[0] = 1'b1;
Set_BusB_To[3] = 1'b0;
end
Write = 1'b1;
end // case: 2
MCycle[2] :
Write = 1'b1;
default :;
endcase // case(MCycle)
end // case: 8'b11000101,8'b11010101,8'b11100101,8'b11110101
8'b11zz0001 :
begin
// POP qq
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[0] :
Set_Addr_To = aSP;
MCycle[1] :
begin
IncDec_16 = 4'b0111;
Set_Addr_To = aSP;
Read_To_Reg = 1'b1;
if (DPAIR == 2'b11 )
begin
Set_BusA_To[3:0] = 4'b1011;
end
else
begin
Set_BusA_To[2:1] = DPAIR;
Set_BusA_To[0] = 1'b1;
end
end // case: 2
MCycle[2] :
begin
IncDec_16 = 4'b0111;
Read_To_Reg = 1'b1;
if (DPAIR == 2'b11 )
begin
Set_BusA_To[3:0] = 4'b0111;
end
else
begin
Set_BusA_To[2:1] = DPAIR;
Set_BusA_To[0] = 1'b0;
end
end // case: 3
default :;
endcase // case(MCycle)
end // case: 8'b11000001,8'b11010001,8'b11100001,8'b11110001
// EXCHANGE, BLOCK TRANSFER AND SEARCH GROUP
8'b11101011 :
begin
if (Mode != 3 )
begin
// EX DE,HL
ExchangeDH = 1'b1;
end
end
8'b00001000 :
begin
if (Mode == 3 )
begin
// LD (nn),SP
MCycles = 3'b101;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
LDZ = 1'b1;
end
MCycle[2] :
begin
Set_Addr_To = aZI;
Inc_PC = 1'b1;
LDW = 1'b1;
Set_BusB_To = 4'b1000;
end
MCycle[3] :
begin
Inc_WZ = 1'b1;
Set_Addr_To = aZI;
Write = 1'b1;
Set_BusB_To = 4'b1001;
end
MCycle[4] :
Write = 1'b1;
default :;
endcase
end
else if (Mode < 2 )
begin
// EX AF,AF'
ExchangeAF = 1'b1;
end
end // case: 8'b00001000
8'b11011001 :
begin
if (Mode == 3 )
begin
// RETI
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[0] :
Set_Addr_To = aSP;
MCycle[1] :
begin
IncDec_16 = 4'b0111;
Set_Addr_To = aSP;
LDZ = 1'b1;
end
MCycle[2] :
begin
Jump = 1'b1;
IncDec_16 = 4'b0111;
I_RETN = 1'b1;
SetEI = 1'b1;
end
default :;
endcase
end
else if (Mode < 2 )
begin
// EXX
ExchangeRS = 1'b1;
end
end // case: 8'b11011001
8'b11100011 :
begin
if (Mode != 3 )
begin
// EX (SP),HL
MCycles = 3'b101;
case (1'b1) // MCycle
MCycle[0] :
Set_Addr_To = aSP;
MCycle[1] :
begin
Read_To_Reg = 1'b1;
Set_BusA_To = 4'b0101;
Set_BusB_To = 4'b0101;
Set_Addr_To = aSP;
end
MCycle[2] :
begin
IncDec_16 = 4'b0111;
Set_Addr_To = aSP;
TStates = 3'b100;
Write = 1'b1;
end
MCycle[3] :
begin
Read_To_Reg = 1'b1;
Set_BusA_To = 4'b0100;
Set_BusB_To = 4'b0100;
Set_Addr_To = aSP;
end
MCycle[4] :
begin
IncDec_16 = 4'b1111;
TStates = 3'b101;
Write = 1'b1;
end
default :;
endcase
end // if (Mode != 3 )
end // case: 8'b11100011
// 8 BIT ARITHMETIC AND LOGICAL GROUP
8'b10zzzzzz :
begin
if (IR[2:0] == 3'b110)
begin
// ADD A,(HL)
// ADC A,(HL)
// SUB A,(HL)
// SBC A,(HL)
// AND A,(HL)
// OR A,(HL)
// XOR A,(HL)
// CP A,(HL)
MCycles = 3'b010;
case (1'b1) // MCycle
MCycle[0] :
Set_Addr_To = aXY;
MCycle[1] :
begin
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
Set_BusB_To[2:0] = SSS;
Set_BusA_To[2:0] = 3'b111;
end
default :;
endcase // case(MCycle)
end // if (IR[2:0] == 3'b110)
else
begin
// ADD A,r
// ADC A,r
// SUB A,r
// SBC A,r
// AND A,r
// OR A,r
// XOR A,r
// CP A,r
Set_BusB_To[2:0] = SSS;
Set_BusA_To[2:0] = 3'b111;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
end // else: !if(IR[2:0] == 3'b110)
end // case: 8'b10000000,8'b10000001,8'b10000010,8'b10000011,8'b10000100,8'b10000101,8'b10000111,...
8'b11zzz110 :
begin
// ADD A,n
// ADC A,n
// SUB A,n
// SBC A,n
// AND A,n
// OR A,n
// XOR A,n
// CP A,n
MCycles = 3'b010;
if (MCycle[1] )
begin
Inc_PC = 1'b1;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
Set_BusB_To[2:0] = SSS;
Set_BusA_To[2:0] = 3'b111;
end
end
8'b00zzz100 :
begin
if (IR[5:3] == 3'b110)
begin
// INC (HL)
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[0] :
Set_Addr_To = aXY;
MCycle[1] :
begin
TStates = 3'b100;
Set_Addr_To = aXY;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
PreserveC = 1'b1;
ALU_Op = 4'b0000;
Set_BusB_To = 4'b1010;
Set_BusA_To[2:0] = DDD;
end // case: 2
MCycle[2] :
Write = 1'b1;
default :;
endcase // case(MCycle)
end // case: 8'b00110100
else
begin
// INC r
Set_BusB_To = 4'b1010;
Set_BusA_To[2:0] = DDD;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
PreserveC = 1'b1;
ALU_Op = 4'b0000;
end
end
8'b00zzz101 :
begin
if (IR[5:3] == 3'b110)
begin
// DEC (HL)
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[0] :
Set_Addr_To = aXY;
MCycle[1] :
begin
TStates = 3'b100;
Set_Addr_To = aXY;
ALU_Op = 4'b0010;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
PreserveC = 1'b1;
Set_BusB_To = 4'b1010;
Set_BusA_To[2:0] = DDD;
end // case: 2
MCycle[2] :
Write = 1'b1;
default :;
endcase // case(MCycle)
end
else
begin
// DEC r
Set_BusB_To = 4'b1010;
Set_BusA_To[2:0] = DDD;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
PreserveC = 1'b1;
ALU_Op = 4'b0010;
end
end
// GENERAL PURPOSE ARITHMETIC AND CPU CONTROL GROUPS
8'b00100111 :
begin
// DAA
Set_BusA_To[2:0] = 3'b111;
Read_To_Reg = 1'b1;
ALU_Op = 4'b1100;
Save_ALU = 1'b1;
end
8'b00101111 :
// CPL
I_CPL = 1'b1;
8'b00111111 :
// CCF
I_CCF = 1'b1;
8'b00110111 :
// SCF
I_SCF = 1'b1;
8'b00000000 :
begin
if (NMICycle == 1'b1 )
begin
// NMI
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[0] :
begin
TStates = 3'b101;
IncDec_16 = 4'b1111;
Set_Addr_To = aSP;
Set_BusB_To = 4'b1101;
end
MCycle[1] :
begin
TStates = 3'b100;
Write = 1'b1;
IncDec_16 = 4'b1111;
Set_Addr_To = aSP;
Set_BusB_To = 4'b1100;
end
MCycle[2] :
begin
TStates = 3'b100;
Write = 1'b1;
end
default :;
endcase // case(MCycle)
end
else if (IntCycle == 1'b1 )
begin
// INT (IM 2)
MCycles = 3'b101;
case (1'b1) // MCycle
MCycle[0] :
begin
LDZ = 1'b1;
TStates = 3'b101;
IncDec_16 = 4'b1111;
Set_Addr_To = aSP;
Set_BusB_To = 4'b1101;
end
MCycle[1] :
begin
TStates = 3'b100;
Write = 1'b1;
IncDec_16 = 4'b1111;
Set_Addr_To = aSP;
Set_BusB_To = 4'b1100;
end
MCycle[2] :
begin
TStates = 3'b100;
Write = 1'b1;
end
MCycle[3] :
begin
Inc_PC = 1'b1;
LDZ = 1'b1;
end
MCycle[4] :
Jump = 1'b1;
default :;
endcase
end
end // case: 8'b00000000
8'b11110011 :
// DI
SetDI = 1'b1;
8'b11111011 :
// EI
SetEI = 1'b1;
// 16 BIT ARITHMETIC GROUP
8'b00zz1001 :
begin
// ADD HL,ss
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[1] :
begin
NoRead = 1'b1;
ALU_Op = 4'b0000;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
Set_BusA_To[2:0] = 3'b101;
case (IR[5:4])
0,1,2 :
begin
Set_BusB_To[2:1] = IR[5:4];
Set_BusB_To[0] = 1'b1;
end
default :
Set_BusB_To = 4'b1000;
endcase // case(IR[5:4])
TStates = 3'b100;
Arith16 = 1'b1;
end // case: 2
MCycle[2] :
begin
NoRead = 1'b1;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
ALU_Op = 4'b0001;
Set_BusA_To[2:0] = 3'b100;
case (IR[5:4])
0,1,2 :
Set_BusB_To[2:1] = IR[5:4];
default :
Set_BusB_To = 4'b1001;
endcase
Arith16 = 1'b1;
end // case: 3
default :;
endcase // case(MCycle)
end // case: 8'b00001001,8'b00011001,8'b00101001,8'b00111001
8'b00zz0011 :
begin
// INC ss
TStates = 3'b110;
IncDec_16[3:2] = 2'b01;
IncDec_16[1:0] = DPAIR;
end
8'b00zz1011 :
begin
// DEC ss
TStates = 3'b110;
IncDec_16[3:2] = 2'b11;
IncDec_16[1:0] = DPAIR;
end
// ROTATE AND SHIFT GROUP
8'b00000111,
// RLCA
8'b00010111,
// RLA
8'b00001111,
// RRCA
8'b00011111 :
// RRA
begin
Set_BusA_To[2:0] = 3'b111;
ALU_Op = 4'b1000;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
end // case: 8'b00000111,...
// JUMP GROUP
8'b11000011 :
begin
// JP nn
MCycles = 3'b011;
if (MCycle[1])
begin
Inc_PC = 1'b1;
LDZ = 1'b1;
end
if (MCycle[2])
begin
Inc_PC = 1'b1;
Jump = 1'b1;
end
end // case: 8'b11000011
8'b11zzz010 :
begin
if (IR[5] == 1'b1 && Mode == 3 )
begin
case (IR[4:3])
2'b00 :
begin
// LD ($FF00+C),A
MCycles = 3'b010;
case (1'b1) // MCycle
MCycle[0] :
begin
Set_Addr_To = aBC;
Set_BusB_To = 4'b0111;
end
MCycle[1] :
begin
Write = 1'b1;
IORQ = 1'b1;
end
default :;
endcase // case(MCycle)
end // case: 2'b00
2'b01 :
begin
// LD (nn),A
MCycles = 3'b100;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
LDZ = 1'b1;
end
MCycle[2] :
begin
Set_Addr_To = aZI;
Inc_PC = 1'b1;
Set_BusB_To = 4'b0111;
end
MCycle[3] :
Write = 1'b1;
default :;
endcase // case(MCycle)
end // case: default :...
2'b10 :
begin
// LD A,($FF00+C)
MCycles = 3'b010;
case (1'b1) // MCycle
MCycle[0] :
Set_Addr_To = aBC;
MCycle[1] :
begin
Read_To_Acc = 1'b1;
IORQ = 1'b1;
end
default :;
endcase // case(MCycle)
end // case: 2'b10
2'b11 :
begin
// LD A,(nn)
MCycles = 3'b100;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
LDZ = 1'b1;
end
MCycle[2] :
begin
Set_Addr_To = aZI;
Inc_PC = 1'b1;
end
MCycle[3] :
Read_To_Acc = 1'b1;
default :;
endcase // case(MCycle)
end
endcase
end
else
begin
// JP cc,nn
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
LDZ = 1'b1;
end
MCycle[2] :
begin
Inc_PC = 1'b1;
if (is_cc_true(F, IR[5:3]) )
begin
Jump = 1'b1;
end
end
default :;
endcase
end // else: !if(DPAIR == 2'b11 )
end // case: 8'b11000010,8'b11001010,8'b11010010,8'b11011010,8'b11100010,8'b11101010,8'b11110010,8'b11111010
8'b00011000 :
begin
if (Mode != 2 )
begin
// JR e
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[1] :
Inc_PC = 1'b1;
MCycle[2] :
begin
NoRead = 1'b1;
JumpE = 1'b1;
TStates = 3'b101;
end
default :;
endcase
end // if (Mode != 2 )
end // case: 8'b00011000
// Conditional relative jumps (JR [C/NC/Z/NZ], e)
8'b001zz000 :
begin
if (Mode != 2 )
begin
MCycles = 3'd3;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
case (IR[4:3])
0 : MCycles = (F[Flag_Z]) ? 3'd2 : 3'd3;
1 : MCycles = (!F[Flag_Z]) ? 3'd2 : 3'd3;
2 : MCycles = (F[Flag_C]) ? 3'd2 : 3'd3;
3 : MCycles = (!F[Flag_C]) ? 3'd2 : 3'd3;
endcase
end
MCycle[2] :
begin
NoRead = 1'b1;
JumpE = 1'b1;
TStates = 3'd5;
end
default :;
endcase
end // if (Mode != 2 )
end // case: 8'b00111000
8'b11101001 :
// JP (HL)
JumpXY = 1'b1;
8'b00010000 :
begin
if (Mode == 3 )
begin
I_DJNZ = 1'b1;
end
else if (Mode < 2 )
begin
// DJNZ,e
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[0] :
begin
TStates = 3'b101;
I_DJNZ = 1'b1;
Set_BusB_To = 4'b1010;
Set_BusA_To[2:0] = 3'b000;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
ALU_Op = 4'b0010;
end
MCycle[1] :
begin
I_DJNZ = 1'b1;
Inc_PC = 1'b1;
end
MCycle[2] :
begin
NoRead = 1'b1;
JumpE = 1'b1;
TStates = 3'b101;
end
default :;
endcase
end // if (Mode < 2 )
end // case: 8'b00010000
// CALL AND RETURN GROUP
8'b11001101 :
begin
// CALL nn
MCycles = 3'b101;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
LDZ = 1'b1;
end
MCycle[2] :
begin
IncDec_16 = 4'b1111;
Inc_PC = 1'b1;
TStates = 3'b100;
Set_Addr_To = aSP;
LDW = 1'b1;
Set_BusB_To = 4'b1101;
end
MCycle[3] :
begin
Write = 1'b1;
IncDec_16 = 4'b1111;
Set_Addr_To = aSP;
Set_BusB_To = 4'b1100;
end
MCycle[4] :
begin
Write = 1'b1;
Call = 1'b1;
end
default :;
endcase // case(MCycle)
end // case: 8'b11001101
8'b11zzz100 :
begin
if (IR[5] == 1'b0 || Mode != 3 )
begin
// CALL cc,nn
MCycles = 3'b101;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
LDZ = 1'b1;
end
MCycle[2] :
begin
Inc_PC = 1'b1;
LDW = 1'b1;
if (is_cc_true(F, IR[5:3]) )
begin
IncDec_16 = 4'b1111;
Set_Addr_To = aSP;
TStates = 3'b100;
Set_BusB_To = 4'b1101;
end
else
begin
MCycles = 3'b011;
end // else: !if(is_cc_true(F, IR[5:3]) )
end // case: 3
MCycle[3] :
begin
Write = 1'b1;
IncDec_16 = 4'b1111;
Set_Addr_To = aSP;
Set_BusB_To = 4'b1100;
end
MCycle[4] :
begin
Write = 1'b1;
Call = 1'b1;
end
default :;
endcase
end // if (IR[5] == 1'b0 || Mode != 3 )
end // case: 8'b11000100,8'b11001100,8'b11010100,8'b11011100,8'b11100100,8'b11101100,8'b11110100,8'b11111100
8'b11001001 :
begin
// RET
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[0] :
begin
TStates = 3'b101;
Set_Addr_To = aSP;
end
MCycle[1] :
begin
IncDec_16 = 4'b0111;
Set_Addr_To = aSP;
LDZ = 1'b1;
end
MCycle[2] :
begin
Jump = 1'b1;
IncDec_16 = 4'b0111;
end
default :;
endcase // case(MCycle)
end // case: 8'b11001001
8'b11000000,8'b11001000,8'b11010000,8'b11011000,8'b11100000,8'b11101000,8'b11110000,8'b11111000 :
begin
if (IR[5] == 1'b1 && Mode == 3 )
begin
case (IR[4:3])
2'b00 :
begin
// LD ($FF00+nn),A
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
Set_Addr_To = aIOA;
Set_BusB_To = 4'b0111;
end
MCycle[2] :
Write = 1'b1;
default :;
endcase // case(MCycle)
end // case: 2'b00
2'b01 :
begin
// ADD SP,n
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[1] :
begin
ALU_Op = 4'b0000;
Inc_PC = 1'b1;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
Set_BusA_To = 4'b1000;
Set_BusB_To = 4'b0110;
end
MCycle[2] :
begin
NoRead = 1'b1;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
ALU_Op = 4'b0001;
Set_BusA_To = 4'b1001;
Set_BusB_To = 4'b1110; // Incorrect unsigned !!!!!!!!!!!!!!!!!!!!!
end
default :;
endcase // case(MCycle)
end // case: 2'b01
2'b10 :
begin
// LD A,($FF00+nn)
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
Set_Addr_To = aIOA;
end
MCycle[2] :
Read_To_Acc = 1'b1;
default :;
endcase // case(MCycle)
end // case: 2'b10
2'b11 :
begin
// LD HL,SP+n -- Not correct !!!!!!!!!!!!!!!!!!!
MCycles = 3'b101;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
LDZ = 1'b1;
end
MCycle[2] :
begin
Set_Addr_To = aZI;
Inc_PC = 1'b1;
LDW = 1'b1;
end
MCycle[3] :
begin
Set_BusA_To[2:0] = 3'b101; // L
Read_To_Reg = 1'b1;
Inc_WZ = 1'b1;
Set_Addr_To = aZI;
end
MCycle[4] :
begin
Set_BusA_To[2:0] = 3'b100; // H
Read_To_Reg = 1'b1;
end
default :;
endcase // case(MCycle)
end // case: 2'b11
endcase // case(IR[4:3])
end
else
begin
// RET cc
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[0] :
begin
if (is_cc_true(F, IR[5:3]) )
begin
Set_Addr_To = aSP;
end
else
begin
MCycles = 3'b001;
end
TStates = 3'b101;
end // case: 1
MCycle[1] :
begin
IncDec_16 = 4'b0111;
Set_Addr_To = aSP;
LDZ = 1'b1;
end
MCycle[2] :
begin
Jump = 1'b1;
IncDec_16 = 4'b0111;
end
default :;
endcase
end // else: !if(IR[5] == 1'b1 && Mode == 3 )
end // case: 8'b11000000,8'b11001000,8'b11010000,8'b11011000,8'b11100000,8'b11101000,8'b11110000,8'b11111000
8'b11000111,8'b11001111,8'b11010111,8'b11011111,8'b11100111,8'b11101111,8'b11110111,8'b11111111 :
begin
// RST p
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[0] :
begin
TStates = 3'b101;
IncDec_16 = 4'b1111;
Set_Addr_To = aSP;
Set_BusB_To = 4'b1101;
end
MCycle[1] :
begin
Write = 1'b1;
IncDec_16 = 4'b1111;
Set_Addr_To = aSP;
Set_BusB_To = 4'b1100;
end
MCycle[2] :
begin
Write = 1'b1;
RstP = 1'b1;
end
default :;
endcase // case(MCycle)
end // case: 8'b11000111,8'b11001111,8'b11010111,8'b11011111,8'b11100111,8'b11101111,8'b11110111,8'b11111111
// INPUT AND OUTPUT GROUP
8'b11011011 :
begin
if (Mode != 3 )
begin
// IN A,(n)
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
Set_Addr_To = aIOA;
end
MCycle[2] :
begin
Read_To_Acc = 1'b1;
IORQ = 1'b1;
end
default :;
endcase
end // if (Mode != 3 )
end // case: 8'b11011011
8'b11010011 :
begin
if (Mode != 3 )
begin
// OUT (n),A
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
Set_Addr_To = aIOA;
Set_BusB_To = 4'b0111;
end
MCycle[2] :
begin
Write = 1'b1;
IORQ = 1'b1;
end
default :;
endcase
end // if (Mode != 3 )
end // case: 8'b11010011
//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
// MULTIBYTE INSTRUCTIONS
//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
8'b11001011 :
begin
if (Mode != 2 )
begin
Prefix = 2'b01;
end
end
8'b11101101 :
begin
if (Mode < 2 )
begin
Prefix = 2'b10;
end
end
8'b11011101,8'b11111101 :
begin
if (Mode < 2 )
begin
Prefix = 2'b11;
end
end
endcase // case(IR)
end // case: 2'b00
2'b01 :
begin
//----------------------------------------------------------------------------
//
// CB prefixed instructions
//
//----------------------------------------------------------------------------
Set_BusA_To[2:0] = IR[2:0];
Set_BusB_To[2:0] = IR[2:0];
casez (IR)
8'b00000000,8'b00000001,8'b00000010,8'b00000011,8'b00000100,8'b00000101,8'b00000111,
8'b00010000,8'b00010001,8'b00010010,8'b00010011,8'b00010100,8'b00010101,8'b00010111,
8'b00001000,8'b00001001,8'b00001010,8'b00001011,8'b00001100,8'b00001101,8'b00001111,
8'b00011000,8'b00011001,8'b00011010,8'b00011011,8'b00011100,8'b00011101,8'b00011111,
8'b00100000,8'b00100001,8'b00100010,8'b00100011,8'b00100100,8'b00100101,8'b00100111,
8'b00101000,8'b00101001,8'b00101010,8'b00101011,8'b00101100,8'b00101101,8'b00101111,
8'b00110000,8'b00110001,8'b00110010,8'b00110011,8'b00110100,8'b00110101,8'b00110111,
8'b00111000,8'b00111001,8'b00111010,8'b00111011,8'b00111100,8'b00111101,8'b00111111 :
begin
// RLC r
// RL r
// RRC r
// RR r
// SLA r
// SRA r
// SRL r
// SLL r (Undocumented) / SWAP r
if (MCycle[0] ) begin
ALU_Op = 4'b1000;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
end
end // case: 8'b00000000,8'b00000001,8'b00000010,8'b00000011,8'b00000100,8'b00000101,8'b00000111,...
8'b00zzz110 :
begin
// RLC (HL)
// RL (HL)
// RRC (HL)
// RR (HL)
// SRA (HL)
// SRL (HL)
// SLA (HL)
// SLL (HL) (Undocumented) / SWAP (HL)
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[0], MCycle[6] :
Set_Addr_To = aXY;
MCycle[1] :
begin
ALU_Op = 4'b1000;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
Set_Addr_To = aXY;
TStates = 3'b100;
end
MCycle[2] :
Write = 1'b1;
default :;
endcase // case(MCycle)
end // case: 8'b00000110,8'b00010110,8'b00001110,8'b00011110,8'b00101110,8'b00111110,8'b00100110,8'b00110110
8'b01000000,8'b01000001,8'b01000010,8'b01000011,8'b01000100,8'b01000101,8'b01000111,
8'b01001000,8'b01001001,8'b01001010,8'b01001011,8'b01001100,8'b01001101,8'b01001111,
8'b01010000,8'b01010001,8'b01010010,8'b01010011,8'b01010100,8'b01010101,8'b01010111,
8'b01011000,8'b01011001,8'b01011010,8'b01011011,8'b01011100,8'b01011101,8'b01011111,
8'b01100000,8'b01100001,8'b01100010,8'b01100011,8'b01100100,8'b01100101,8'b01100111,
8'b01101000,8'b01101001,8'b01101010,8'b01101011,8'b01101100,8'b01101101,8'b01101111,
8'b01110000,8'b01110001,8'b01110010,8'b01110011,8'b01110100,8'b01110101,8'b01110111,
8'b01111000,8'b01111001,8'b01111010,8'b01111011,8'b01111100,8'b01111101,8'b01111111 :
begin
// BIT b,r
if (MCycle[0] )
begin
Set_BusB_To[2:0] = IR[2:0];
ALU_Op = 4'b1001;
end
end // case: 8'b01000000,8'b01000001,8'b01000010,8'b01000011,8'b01000100,8'b01000101,8'b01000111,...
8'b01000110,8'b01001110,8'b01010110,8'b01011110,8'b01100110,8'b01101110,8'b01110110,8'b01111110 :
begin
// BIT b,(HL)
MCycles = 3'b010;
case (1'b1) // MCycle
MCycle[0], MCycle[6] :
Set_Addr_To = aXY;
MCycle[1] :
begin
ALU_Op = 4'b1001;
TStates = 3'b100;
end
default :;
endcase // case(MCycle)
end // case: 8'b01000110,8'b01001110,8'b01010110,8'b01011110,8'b01100110,8'b01101110,8'b01110110,8'b01111110
8'b11000000,8'b11000001,8'b11000010,8'b11000011,8'b11000100,8'b11000101,8'b11000111,
8'b11001000,8'b11001001,8'b11001010,8'b11001011,8'b11001100,8'b11001101,8'b11001111,
8'b11010000,8'b11010001,8'b11010010,8'b11010011,8'b11010100,8'b11010101,8'b11010111,
8'b11011000,8'b11011001,8'b11011010,8'b11011011,8'b11011100,8'b11011101,8'b11011111,
8'b11100000,8'b11100001,8'b11100010,8'b11100011,8'b11100100,8'b11100101,8'b11100111,
8'b11101000,8'b11101001,8'b11101010,8'b11101011,8'b11101100,8'b11101101,8'b11101111,
8'b11110000,8'b11110001,8'b11110010,8'b11110011,8'b11110100,8'b11110101,8'b11110111,
8'b11111000,8'b11111001,8'b11111010,8'b11111011,8'b11111100,8'b11111101,8'b11111111 :
begin
// SET b,r
if (MCycle[0] )
begin
ALU_Op = 4'b1010;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
end
end // case: 8'b11000000,8'b11000001,8'b11000010,8'b11000011,8'b11000100,8'b11000101,8'b11000111,...
8'b11000110,8'b11001110,8'b11010110,8'b11011110,8'b11100110,8'b11101110,8'b11110110,8'b11111110 :
begin
// SET b,(HL)
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[0], MCycle[6] :
Set_Addr_To = aXY;
MCycle[1] :
begin
ALU_Op = 4'b1010;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
Set_Addr_To = aXY;
TStates = 3'b100;
end
MCycle[2] :
Write = 1'b1;
default :;
endcase // case(MCycle)
end // case: 8'b11000110,8'b11001110,8'b11010110,8'b11011110,8'b11100110,8'b11101110,8'b11110110,8'b11111110
8'b10000000,8'b10000001,8'b10000010,8'b10000011,8'b10000100,8'b10000101,8'b10000111,
8'b10001000,8'b10001001,8'b10001010,8'b10001011,8'b10001100,8'b10001101,8'b10001111,
8'b10010000,8'b10010001,8'b10010010,8'b10010011,8'b10010100,8'b10010101,8'b10010111,
8'b10011000,8'b10011001,8'b10011010,8'b10011011,8'b10011100,8'b10011101,8'b10011111,
8'b10100000,8'b10100001,8'b10100010,8'b10100011,8'b10100100,8'b10100101,8'b10100111,
8'b10101000,8'b10101001,8'b10101010,8'b10101011,8'b10101100,8'b10101101,8'b10101111,
8'b10110000,8'b10110001,8'b10110010,8'b10110011,8'b10110100,8'b10110101,8'b10110111,
8'b10111000,8'b10111001,8'b10111010,8'b10111011,8'b10111100,8'b10111101,8'b10111111 :
begin
// RES b,r
if (MCycle[0] )
begin
ALU_Op = 4'b1011;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
end
end // case: 8'b10000000,8'b10000001,8'b10000010,8'b10000011,8'b10000100,8'b10000101,8'b10000111,...
8'b10000110,8'b10001110,8'b10010110,8'b10011110,8'b10100110,8'b10101110,8'b10110110,8'b10111110 :
begin
// RES b,(HL)
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[0], MCycle[6] :
Set_Addr_To = aXY;
MCycle[1] :
begin
ALU_Op = 4'b1011;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
Set_Addr_To = aXY;
TStates = 3'b100;
end
MCycle[2] :
Write = 1'b1;
default :;
endcase // case(MCycle)
end // case: 8'b10000110,8'b10001110,8'b10010110,8'b10011110,8'b10100110,8'b10101110,8'b10110110,8'b10111110
endcase // case(IR)
end // case: 2'b01
default :
begin : default_ed_block
//----------------------------------------------------------------------------
//
// ED prefixed instructions
//
//----------------------------------------------------------------------------
casez (IR)
/*
* Undocumented NOP instructions commented out to reduce size of mcode
*
8'b00000000,8'b00000001,8'b00000010,8'b00000011,8'b00000100,8'b00000101,8'b00000110,8'b00000111
,8'b00001000,8'b00001001,8'b00001010,8'b00001011,8'b00001100,8'b00001101,8'b00001110,8'b00001111
,8'b00010000,8'b00010001,8'b00010010,8'b00010011,8'b00010100,8'b00010101,8'b00010110,8'b00010111
,8'b00011000,8'b00011001,8'b00011010,8'b00011011,8'b00011100,8'b00011101,8'b00011110,8'b00011111
,8'b00100000,8'b00100001,8'b00100010,8'b00100011,8'b00100100,8'b00100101,8'b00100110,8'b00100111
,8'b00101000,8'b00101001,8'b00101010,8'b00101011,8'b00101100,8'b00101101,8'b00101110,8'b00101111
,8'b00110000,8'b00110001,8'b00110010,8'b00110011,8'b00110100,8'b00110101,8'b00110110,8'b00110111
,8'b00111000,8'b00111001,8'b00111010,8'b00111011,8'b00111100,8'b00111101,8'b00111110,8'b00111111
,8'b10000000,8'b10000001,8'b10000010,8'b10000011,8'b10000100,8'b10000101,8'b10000110,8'b10000111
,8'b10001000,8'b10001001,8'b10001010,8'b10001011,8'b10001100,8'b10001101,8'b10001110,8'b10001111
,8'b10010000,8'b10010001,8'b10010010,8'b10010011,8'b10010100,8'b10010101,8'b10010110,8'b10010111
,8'b10011000,8'b10011001,8'b10011010,8'b10011011,8'b10011100,8'b10011101,8'b10011110,8'b10011111
, 8'b10100100,8'b10100101,8'b10100110,8'b10100111
, 8'b10101100,8'b10101101,8'b10101110,8'b10101111
, 8'b10110100,8'b10110101,8'b10110110,8'b10110111
, 8'b10111100,8'b10111101,8'b10111110,8'b10111111
,8'b11000000,8'b11000001,8'b11000010,8'b11000011,8'b11000100,8'b11000101,8'b11000110,8'b11000111
,8'b11001000,8'b11001001,8'b11001010,8'b11001011,8'b11001100,8'b11001101,8'b11001110,8'b11001111
,8'b11010000,8'b11010001,8'b11010010,8'b11010011,8'b11010100,8'b11010101,8'b11010110,8'b11010111
,8'b11011000,8'b11011001,8'b11011010,8'b11011011,8'b11011100,8'b11011101,8'b11011110,8'b11011111
,8'b11100000,8'b11100001,8'b11100010,8'b11100011,8'b11100100,8'b11100101,8'b11100110,8'b11100111
,8'b11101000,8'b11101001,8'b11101010,8'b11101011,8'b11101100,8'b11101101,8'b11101110,8'b11101111
,8'b11110000,8'b11110001,8'b11110010,8'b11110011,8'b11110100,8'b11110101,8'b11110110,8'b11110111
,8'b11111000,8'b11111001,8'b11111010,8'b11111011,8'b11111100,8'b11111101,8'b11111110,8'b11111111 :
; // NOP, undocumented
8'b01111110,8'b01111111 :
// NOP, undocumented
;
*/
// 8 BIT LOAD GROUP
8'b01010111 :
begin
// LD A,I
Special_LD = 3'b100;
TStates = 3'b101;
end
8'b01011111 :
begin
// LD A,R
Special_LD = 3'b101;
TStates = 3'b101;
end
8'b01000111 :
begin
// LD I,A
Special_LD = 3'b110;
TStates = 3'b101;
end
8'b01001111 :
begin
// LD R,A
Special_LD = 3'b111;
TStates = 3'b101;
end
// 16 BIT LOAD GROUP
8'b01001011,8'b01011011,8'b01101011,8'b01111011 :
begin
// LD dd,(nn)
MCycles = 3'b101;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
LDZ = 1'b1;
end
MCycle[2] :
begin
Set_Addr_To = aZI;
Inc_PC = 1'b1;
LDW = 1'b1;
end
MCycle[3] :
begin
Read_To_Reg = 1'b1;
if (IR[5:4] == 2'b11 )
begin
Set_BusA_To = 4'b1000;
end
else
begin
Set_BusA_To[2:1] = IR[5:4];
Set_BusA_To[0] = 1'b1;
end
Inc_WZ = 1'b1;
Set_Addr_To = aZI;
end // case: 4
MCycle[4] :
begin
Read_To_Reg = 1'b1;
if (IR[5:4] == 2'b11 )
begin
Set_BusA_To = 4'b1001;
end
else
begin
Set_BusA_To[2:1] = IR[5:4];
Set_BusA_To[0] = 1'b0;
end
end // case: 5
default :;
endcase // case(MCycle)
end // case: 8'b01001011,8'b01011011,8'b01101011,8'b01111011
8'b01000011,8'b01010011,8'b01100011,8'b01110011 :
begin
// LD (nn),dd
MCycles = 3'b101;
case (1'b1) // MCycle
MCycle[1] :
begin
Inc_PC = 1'b1;
LDZ = 1'b1;
end
MCycle[2] :
begin
Set_Addr_To = aZI;
Inc_PC = 1'b1;
LDW = 1'b1;
if (IR[5:4] == 2'b11 )
begin
Set_BusB_To = 4'b1000;
end
else
begin
Set_BusB_To[2:1] = IR[5:4];
Set_BusB_To[0] = 1'b1;
Set_BusB_To[3] = 1'b0;
end
end // case: 3
MCycle[3] :
begin
Inc_WZ = 1'b1;
Set_Addr_To = aZI;
Write = 1'b1;
if (IR[5:4] == 2'b11 )
begin
Set_BusB_To = 4'b1001;
end
else
begin
Set_BusB_To[2:1] = IR[5:4];
Set_BusB_To[0] = 1'b0;
Set_BusB_To[3] = 1'b0;
end
end // case: 4
MCycle[4] :
begin
Write = 1'b1;
end
default :;
endcase // case(MCycle)
end // case: 8'b01000011,8'b01010011,8'b01100011,8'b01110011
8'b10100000 , 8'b10101000 , 8'b10110000 , 8'b10111000 :
begin
// LDI, LDD, LDIR, LDDR
MCycles = 3'b100;
case (1'b1) // MCycle
MCycle[0] :
begin
Set_Addr_To = aXY;
IncDec_16 = 4'b1100; // BC
end
MCycle[1] :
begin
Set_BusB_To = 4'b0110;
Set_BusA_To[2:0] = 3'b111;
ALU_Op = 4'b0000;
Set_Addr_To = aDE;
if (IR[3] == 1'b0 )
begin
IncDec_16 = 4'b0110; // IX
end
else
begin
IncDec_16 = 4'b1110;
end
end // case: 2
MCycle[2] :
begin
I_BT = 1'b1;
TStates = 3'b101;
Write = 1'b1;
if (IR[3] == 1'b0 )
begin
IncDec_16 = 4'b0101; // DE
end
else
begin
IncDec_16 = 4'b1101;
end
end // case: 3
MCycle[3] :
begin
NoRead = 1'b1;
TStates = 3'b101;
end
default :;
endcase // case(MCycle)
end // case: 8'b10100000 , 8'b10101000 , 8'b10110000 , 8'b10111000
8'b10100001 , 8'b10101001 , 8'b10110001 , 8'b10111001 :
begin
// CPI, CPD, CPIR, CPDR
MCycles = 3'b100;
case (1'b1) // MCycle
MCycle[0] :
begin
Set_Addr_To = aXY;
IncDec_16 = 4'b1100; // BC
end
MCycle[1] :
begin
Set_BusB_To = 4'b0110;
Set_BusA_To[2:0] = 3'b111;
ALU_Op = 4'b0111;
Save_ALU = 1'b1;
PreserveC = 1'b1;
if (IR[3] == 1'b0 )
begin
IncDec_16 = 4'b0110;
end
else
begin
IncDec_16 = 4'b1110;
end
end // case: 2
MCycle[2] :
begin
NoRead = 1'b1;
I_BC = 1'b1;
TStates = 3'b101;
end
MCycle[3] :
begin
NoRead = 1'b1;
TStates = 3'b101;
end
default :;
endcase // case(MCycle)
end // case: 8'b10100001 , 8'b10101001 , 8'b10110001 , 8'b10111001
8'b01000100,8'b01001100,8'b01010100,8'b01011100,8'b01100100,8'b01101100,8'b01110100,8'b01111100 :
begin
// NEG
ALU_Op = 4'b0010;
Set_BusB_To = 4'b0111;
Set_BusA_To = 4'b1010;
Read_To_Acc = 1'b1;
Save_ALU = 1'b1;
end
8'b01000110,8'b01001110,8'b01100110,8'b01101110 :
begin
// IM 0
IMode = 2'b00;
end
8'b01010110,8'b01110110 :
// IM 1
IMode = 2'b01;
8'b01011110,8'b01110111 :
// IM 2
IMode = 2'b10;
// 16 bit arithmetic
8'b01001010,8'b01011010,8'b01101010,8'b01111010 :
begin
// ADC HL,ss
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[1] :
begin
NoRead = 1'b1;
ALU_Op = 4'b0001;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
Set_BusA_To[2:0] = 3'b101;
case (IR[5:4])
0,1,2 :
begin
Set_BusB_To[2:1] = IR[5:4];
Set_BusB_To[0] = 1'b1;
end
default :
Set_BusB_To = 4'b1000;
endcase
TStates = 3'b100;
end // case: 2
MCycle[2] :
begin
NoRead = 1'b1;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
ALU_Op = 4'b0001;
Set_BusA_To[2:0] = 3'b100;
case (IR[5:4])
0,1,2 :
begin
Set_BusB_To[2:1] = IR[5:4];
Set_BusB_To[0] = 1'b0;
end
default :
Set_BusB_To = 4'b1001;
endcase // case(IR[5:4])
end // case: 3
default :;
endcase // case(MCycle)
end // case: 8'b01001010,8'b01011010,8'b01101010,8'b01111010
8'b01000010,8'b01010010,8'b01100010,8'b01110010 :
begin
// SBC HL,ss
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[1] :
begin
NoRead = 1'b1;
ALU_Op = 4'b0011;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
Set_BusA_To[2:0] = 3'b101;
case (IR[5:4])
0,1,2 :
begin
Set_BusB_To[2:1] = IR[5:4];
Set_BusB_To[0] = 1'b1;
end
default :
Set_BusB_To = 4'b1000;
endcase
TStates = 3'b100;
end // case: 2
MCycle[2] :
begin
NoRead = 1'b1;
ALU_Op = 4'b0011;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
Set_BusA_To[2:0] = 3'b100;
case (IR[5:4])
0,1,2 :
Set_BusB_To[2:1] = IR[5:4];
default :
Set_BusB_To = 4'b1001;
endcase
end // case: 3
default :;
endcase // case(MCycle)
end // case: 8'b01000010,8'b01010010,8'b01100010,8'b01110010
8'b01101111 :
begin
// RLD
MCycles = 3'b100;
case (1'b1) // MCycle
MCycle[1] :
begin
NoRead = 1'b1;
Set_Addr_To = aXY;
end
MCycle[2] :
begin
Read_To_Reg = 1'b1;
Set_BusB_To[2:0] = 3'b110;
Set_BusA_To[2:0] = 3'b111;
ALU_Op = 4'b1101;
TStates = 3'b100;
Set_Addr_To = aXY;
Save_ALU = 1'b1;
end
MCycle[3] :
begin
I_RLD = 1'b1;
Write = 1'b1;
end
default :;
endcase // case(MCycle)
end // case: 8'b01101111
8'b01100111 :
begin
// RRD
MCycles = 3'b100;
case (1'b1) // MCycle
MCycle[1] :
Set_Addr_To = aXY;
MCycle[2] :
begin
Read_To_Reg = 1'b1;
Set_BusB_To[2:0] = 3'b110;
Set_BusA_To[2:0] = 3'b111;
ALU_Op = 4'b1110;
TStates = 3'b100;
Set_Addr_To = aXY;
Save_ALU = 1'b1;
end
MCycle[3] :
begin
I_RRD = 1'b1;
Write = 1'b1;
end
default :;
endcase // case(MCycle)
end // case: 8'b01100111
8'b01000101,8'b01001101,8'b01010101,8'b01011101,8'b01100101,8'b01101101,8'b01110101,8'b01111101 :
begin
// RETI, RETN
MCycles = 3'b011;
case (1'b1) // MCycle
MCycle[0] :
Set_Addr_To = aSP;
MCycle[1] :
begin
IncDec_16 = 4'b0111;
Set_Addr_To = aSP;
LDZ = 1'b1;
end
MCycle[2] :
begin
Jump = 1'b1;
IncDec_16 = 4'b0111;
I_RETN = 1'b1;
end
default :;
endcase // case(MCycle)
end // case: 8'b01000101,8'b01001101,8'b01010101,8'b01011101,8'b01100101,8'b01101101,8'b01110101,8'b01111101
8'b01000000,8'b01001000,8'b01010000,8'b01011000,8'b01100000,8'b01101000,8'b01110000,8'b01111000 :
begin
// IN r,(C)
MCycles = 3'b010;
case (1'b1) // MCycle
MCycle[0] :
Set_Addr_To = aBC;
MCycle[1] :
begin
IORQ = 1'b1;
if (IR[5:3] != 3'b110 )
begin
Read_To_Reg = 1'b1;
Set_BusA_To[2:0] = IR[5:3];
end
I_INRC = 1'b1;
end
default :;
endcase // case(MCycle)
end // case: 8'b01000000,8'b01001000,8'b01010000,8'b01011000,8'b01100000,8'b01101000,8'b01110000,8'b01111000
8'b01000001,8'b01001001,8'b01010001,8'b01011001,8'b01100001,8'b01101001,8'b01110001,8'b01111001 :
begin
// OUT (C),r
// OUT (C),0
MCycles = 3'b010;
case (1'b1) // MCycle
MCycle[0] :
begin
Set_Addr_To = aBC;
Set_BusB_To[2:0] = IR[5:3];
if (IR[5:3] == 3'b110 )
begin
Set_BusB_To[3] = 1'b1;
end
end
MCycle[1] :
begin
Write = 1'b1;
IORQ = 1'b1;
end
default :;
endcase // case(MCycle)
end // case: 8'b01000001,8'b01001001,8'b01010001,8'b01011001,8'b01100001,8'b01101001,8'b01110001,8'b01111001
8'b10100010 , 8'b10101010 , 8'b10110010 , 8'b10111010 :
begin
// INI, IND, INIR, INDR
MCycles = 3'b100;
case (1'b1) // MCycle
MCycle[0] :
begin
Set_Addr_To = aBC;
Set_BusB_To = 4'b1010;
Set_BusA_To = 4'b0000;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
ALU_Op = 4'b0010;
end
MCycle[1] :
begin
IORQ = 1'b1;
Set_BusB_To = 4'b0110;
Set_Addr_To = aXY;
end
MCycle[2] :
begin
if (IR[3] == 1'b0 )
begin
IncDec_16 = 4'b0110;
end
else
begin
IncDec_16 = 4'b1110;
end
TStates = 3'b100;
Write = 1'b1;
I_BTR = 1'b1;
end // case: 3
MCycle[3] :
begin
NoRead = 1'b1;
TStates = 3'b101;
end
default :;
endcase // case(MCycle)
end // case: 8'b10100010 , 8'b10101010 , 8'b10110010 , 8'b10111010
8'b10100011 , 8'b10101011 , 8'b10110011 , 8'b10111011 :
begin
// OUTI, OUTD, OTIR, OTDR
MCycles = 3'b100;
case (1'b1) // MCycle
MCycle[0] :
begin
TStates = 3'b101;
Set_Addr_To = aXY;
Set_BusB_To = 4'b1010;
Set_BusA_To = 4'b0000;
Read_To_Reg = 1'b1;
Save_ALU = 1'b1;
ALU_Op = 4'b0010;
end
MCycle[1] :
begin
Set_BusB_To = 4'b0110;
Set_Addr_To = aBC;
if (IR[3] == 1'b0 )
begin
IncDec_16 = 4'b0110;
end
else
begin
IncDec_16 = 4'b1110;
end
end
MCycle[2] :
begin
if (IR[3] == 1'b0 )
begin
IncDec_16 = 4'b0010;
end
else
begin
IncDec_16 = 4'b1010;
end
IORQ = 1'b1;
Write = 1'b1;
I_BTR = 1'b1;
end // case: 3
MCycle[3] :
begin
NoRead = 1'b1;
TStates = 3'b101;
end
default :;
endcase // case(MCycle)
end // case: 8'b10100011 , 8'b10101011 , 8'b10110011 , 8'b10111011
default : ;
endcase // case(IR)
end // block: default_ed_block
endcase // case(ISet)
if (Mode == 1 )
begin
if (MCycle[0] )
begin
//TStates = 3'b100;
end
else
begin
TStates = 3'b011;
end
end
if (Mode == 3 )
begin
if (MCycle[0] )
begin
//TStates = 3'b100;
end
else
begin
TStates = 3'b100;
end
end
if (Mode < 2 )
begin
if (MCycle[5] )
begin
Inc_PC = 1'b1;
if (Mode == 1 )
begin
Set_Addr_To = aXY;
TStates = 3'b100;
Set_BusB_To[2:0] = SSS;
Set_BusB_To[3] = 1'b0;
end
if (IR == 8'b00110110 || IR == 8'b11001011 )
begin
Set_Addr_To = aNone;
end
end
if (MCycle[6] )
begin
if (Mode == 0 )
begin
TStates = 3'b101;
end
if (ISet != 2'b01 )
begin
Set_Addr_To = aXY;
end
Set_BusB_To[2:0] = SSS;
Set_BusB_To[3] = 1'b0;
if (IR == 8'b00110110 || ISet == 2'b01 )
begin
// LD (HL),n
Inc_PC = 1'b1;
end
else
begin
NoRead = 1'b1;
end
end
end // if (Mode < 2 )
end // always @ (IR, ISet, MCycle, F, NMICycle, IntCycle)
endmodule // T80_MCode