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tv80_core.v
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tv80_core.v
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//
// TV80 8-Bit Microprocessor Core
// Based on the VHDL T80 core by Daniel Wallner (jesus@opencores.org)
//
// Copyright (c) 2004 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_core (/*AUTOARG*/
// Outputs
m1_n, iorq, no_read, write, rfsh_n, halt_n, busak_n, A, dout, mc,
ts, intcycle_n, IntE, stop,
// Inputs
reset_n, clk, cen, wait_n, int_n, nmi_n, busrq_n, dinst, di
);
// Beginning of automatic inputs (from unused autoinst inputs)
// End of automatics
parameter Mode = 1; // 0 => Z80, 1 => Fast Z80, 2 => 8080, 3 => GB
parameter IOWait = 1; // 0 => Single cycle I/O, 1 => Std I/O cycle
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 reset_n;
input clk;
input cen;
input wait_n;
input int_n;
input nmi_n;
input busrq_n;
output m1_n;
output iorq;
output no_read;
output write;
output rfsh_n;
output halt_n;
output busak_n;
output [15:0] A;
input [7:0] dinst;
input [7:0] di;
output [7:0] dout;
output [6:0] mc;
output [6:0] ts;
output intcycle_n;
output IntE;
output stop;
reg m1_n;
reg iorq;
`ifdef TV80_REFRESH
reg rfsh_n;
`endif
reg halt_n;
reg busak_n;
reg [15:0] A;
reg [7:0] dout;
reg [6:0] mc;
reg [6:0] ts;
reg intcycle_n;
reg IntE;
reg stop;
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;
// Registers
reg [7:0] ACC, F;
reg [7:0] Ap, Fp;
reg [7:0] I;
`ifdef TV80_REFRESH
reg [7:0] R;
`endif
reg [15:0] SP, PC;
reg [7:0] RegDIH;
reg [7:0] RegDIL;
wire [15:0] RegBusA;
wire [15:0] RegBusB;
wire [15:0] RegBusC;
reg [2:0] RegAddrA_r;
reg [2:0] RegAddrA;
reg [2:0] RegAddrB_r;
reg [2:0] RegAddrB;
reg [2:0] RegAddrC;
reg RegWEH;
reg RegWEL;
reg Alternate;
// Help Registers
reg [15:0] TmpAddr; // Temporary address register
reg [7:0] IR; // Instruction register
reg [1:0] ISet; // Instruction set selector
reg [15:0] RegBusA_r;
reg [15:0] ID16;
reg [7:0] Save_Mux;
reg [6:0] tstate;
reg [6:0] mcycle;
reg last_mcycle, last_tstate;
reg IntE_FF1;
reg IntE_FF2;
reg Halt_FF;
reg BusReq_s;
reg BusAck;
reg ClkEn;
reg NMI_s;
reg INT_s;
reg [1:0] IStatus;
reg [7:0] DI_Reg;
reg T_Res;
reg [1:0] XY_State;
reg [2:0] Pre_XY_F_M;
reg NextIs_XY_Fetch;
reg XY_Ind;
reg No_BTR;
reg BTR_r;
reg Auto_Wait;
reg Auto_Wait_t1;
reg Auto_Wait_t2;
reg IncDecZ;
// ALU signals
reg [7:0] BusB;
reg [7:0] BusA;
wire [7:0] ALU_Q;
wire [7:0] F_Out;
// Registered micro code outputs
reg [4:0] Read_To_Reg_r;
reg Arith16_r;
reg Z16_r;
reg [3:0] ALU_Op_r;
reg Save_ALU_r;
reg PreserveC_r;
reg [2:0] mcycles;
// Micro code outputs
wire [2:0] mcycles_d;
wire [2:0] tstates;
reg IntCycle;
reg NMICycle;
wire Inc_PC;
wire Inc_WZ;
wire [3:0] IncDec_16;
wire [1:0] Prefix;
wire Read_To_Acc;
wire Read_To_Reg;
wire [3:0] Set_BusB_To;
wire [3:0] Set_BusA_To;
wire [3:0] ALU_Op;
wire Save_ALU;
wire PreserveC;
wire Arith16;
wire [2:0] Set_Addr_To;
wire Jump;
wire JumpE;
wire JumpXY;
wire Call;
wire RstP;
wire LDZ;
wire LDW;
wire LDSPHL;
wire iorq_i;
wire [2:0] Special_LD;
wire ExchangeDH;
wire ExchangeRp;
wire ExchangeAF;
wire ExchangeRS;
wire I_DJNZ;
wire I_CPL;
wire I_CCF;
wire I_SCF;
wire I_RETN;
wire I_BT;
wire I_BC;
wire I_BTR;
wire I_RLD;
wire I_RRD;
wire I_INRC;
wire SetDI;
wire SetEI;
wire [1:0] IMode;
wire Halt;
reg [15:0] PC16;
reg [15:0] PC16_B;
reg [15:0] SP16, SP16_A, SP16_B;
reg [15:0] ID16_B;
reg Oldnmi_n;
tv80_mcode #(Mode, Flag_C, Flag_N, Flag_P, Flag_X, Flag_H, Flag_Y, Flag_Z, Flag_S) i_mcode
(
.IR (IR),
.ISet (ISet),
.MCycle (mcycle),
.F (F),
.NMICycle (NMICycle),
.IntCycle (IntCycle),
.MCycles (mcycles_d),
.TStates (tstates),
.Prefix (Prefix),
.Inc_PC (Inc_PC),
.Inc_WZ (Inc_WZ),
.IncDec_16 (IncDec_16),
.Read_To_Acc (Read_To_Acc),
.Read_To_Reg (Read_To_Reg),
.Set_BusB_To (Set_BusB_To),
.Set_BusA_To (Set_BusA_To),
.ALU_Op (ALU_Op),
.Save_ALU (Save_ALU),
.PreserveC (PreserveC),
.Arith16 (Arith16),
.Set_Addr_To (Set_Addr_To),
.IORQ (iorq_i),
.Jump (Jump),
.JumpE (JumpE),
.JumpXY (JumpXY),
.Call (Call),
.RstP (RstP),
.LDZ (LDZ),
.LDW (LDW),
.LDSPHL (LDSPHL),
.Special_LD (Special_LD),
.ExchangeDH (ExchangeDH),
.ExchangeRp (ExchangeRp),
.ExchangeAF (ExchangeAF),
.ExchangeRS (ExchangeRS),
.I_DJNZ (I_DJNZ),
.I_CPL (I_CPL),
.I_CCF (I_CCF),
.I_SCF (I_SCF),
.I_RETN (I_RETN),
.I_BT (I_BT),
.I_BC (I_BC),
.I_BTR (I_BTR),
.I_RLD (I_RLD),
.I_RRD (I_RRD),
.I_INRC (I_INRC),
.SetDI (SetDI),
.SetEI (SetEI),
.IMode (IMode),
.Halt (Halt),
.NoRead (no_read),
.Write (write)
);
tv80_alu #(Mode, Flag_C, Flag_N, Flag_P, Flag_X, Flag_H, Flag_Y, Flag_Z, Flag_S) i_alu
(
.Arith16 (Arith16_r),
.Z16 (Z16_r),
.ALU_Op (ALU_Op_r),
.IR (IR[5:0]),
.ISet (ISet),
.BusA (BusA),
.BusB (BusB),
.F_In (F),
.Q (ALU_Q),
.F_Out (F_Out)
);
function [6:0] number_to_bitvec;
input [2:0] num;
begin
case (num)
1 : number_to_bitvec = 7'b0000001;
2 : number_to_bitvec = 7'b0000010;
3 : number_to_bitvec = 7'b0000100;
4 : number_to_bitvec = 7'b0001000;
5 : number_to_bitvec = 7'b0010000;
6 : number_to_bitvec = 7'b0100000;
7 : number_to_bitvec = 7'b1000000;
default : number_to_bitvec = 7'bx;
endcase // case(num)
end
endfunction // number_to_bitvec
function [2:0] mcyc_to_number;
input [6:0] mcyc;
begin
casez (mcyc)
7'b1zzzzzz : mcyc_to_number = 3'h7;
7'b01zzzzz : mcyc_to_number = 3'h6;
7'b001zzzz : mcyc_to_number = 3'h5;
7'b0001zzz : mcyc_to_number = 3'h4;
7'b00001zz : mcyc_to_number = 3'h3;
7'b000001z : mcyc_to_number = 3'h2;
7'b0000001 : mcyc_to_number = 3'h1;
default : mcyc_to_number = 3'h1;
endcase
end
endfunction
always @(/*AUTOSENSE*/mcycle or mcycles or tstate or tstates)
begin
case (mcycles)
1 : last_mcycle = mcycle[0];
2 : last_mcycle = mcycle[1];
3 : last_mcycle = mcycle[2];
4 : last_mcycle = mcycle[3];
5 : last_mcycle = mcycle[4];
6 : last_mcycle = mcycle[5];
7 : last_mcycle = mcycle[6];
default : last_mcycle = 1'bx;
endcase // case(mcycles)
case (tstates)
0 : last_tstate = tstate[0];
1 : last_tstate = tstate[1];
2 : last_tstate = tstate[2];
3 : last_tstate = tstate[3];
4 : last_tstate = tstate[4];
5 : last_tstate = tstate[5];
6 : last_tstate = tstate[6];
default : last_tstate = 1'bx;
endcase
end // always @ (...
always @(/*AUTOSENSE*/ALU_Q or BusAck or BusB or DI_Reg
or ExchangeRp or IR or Save_ALU_r or Set_Addr_To or XY_Ind
or XY_State or cen or last_tstate or mcycle)
begin
ClkEn = cen && ~ BusAck;
if (last_tstate)
T_Res = 1'b1;
else T_Res = 1'b0;
if (XY_State != 2'b00 && XY_Ind == 1'b0 &&
((Set_Addr_To == aXY) ||
(mcycle[0] && IR == 8'b11001011) ||
(mcycle[0] && IR == 8'b00110110)))
NextIs_XY_Fetch = 1'b1;
else
NextIs_XY_Fetch = 1'b0;
if (ExchangeRp)
Save_Mux = BusB;
else if (!Save_ALU_r)
Save_Mux = DI_Reg;
else
Save_Mux = ALU_Q;
end // always @ *
always @ (posedge clk or negedge reset_n)
begin
if (reset_n == 1'b0 )
begin
PC <= #1 0; // Program Counter
A <= #1 0;
TmpAddr <= #1 0;
IR <= #1 8'b00000000;
ISet <= #1 2'b00;
XY_State <= #1 2'b00;
IStatus <= #1 2'b00;
mcycles <= #1 3'b000;
dout <= #1 8'b00000000;
ACC <= #1 8'hFF;
F <= #1 8'hFF;
Ap <= #1 8'hFF;
Fp <= #1 8'hFF;
I <= #1 0;
`ifdef TV80_REFRESH
R <= #1 0;
`endif
SP <= #1 16'hFFFF;
Alternate <= #1 1'b0;
Read_To_Reg_r <= #1 5'b00000;
Arith16_r <= #1 1'b0;
BTR_r <= #1 1'b0;
Z16_r <= #1 1'b0;
ALU_Op_r <= #1 4'b0000;
Save_ALU_r <= #1 1'b0;
PreserveC_r <= #1 1'b0;
XY_Ind <= #1 1'b0;
end
else
begin
if (ClkEn == 1'b1 )
begin
ALU_Op_r <= #1 4'b0000;
Save_ALU_r <= #1 1'b0;
Read_To_Reg_r <= #1 5'b00000;
mcycles <= #1 mcycles_d;
if (IMode != 2'b11 )
begin
IStatus <= #1 IMode;
end
Arith16_r <= #1 Arith16;
PreserveC_r <= #1 PreserveC;
if (ISet == 2'b10 && ALU_Op[2] == 1'b0 && ALU_Op[0] == 1'b1 && mcycle[2] )
begin
Z16_r <= #1 1'b1;
end
else
begin
Z16_r <= #1 1'b0;
end
if (mcycle[0] && (tstate[1] | tstate[2] | tstate[3] ))
begin
// mcycle == 1 && tstate == 1, 2, || 3
if (tstate[2] && wait_n == 1'b1 )
begin
`ifdef TV80_REFRESH
if (Mode < 2 )
begin
A[7:0] <= #1 R;
A[15:8] <= #1 I;
R[6:0] <= #1 R[6:0] + 1;
end
`endif
if (Jump == 1'b0 && Call == 1'b0 && NMICycle == 1'b0 && IntCycle == 1'b0 && ~ (Halt_FF == 1'b1 || Halt == 1'b1) )
begin
PC <= #1 PC16;
end
if (IntCycle == 1'b1 && IStatus == 2'b01 )
begin
IR <= #1 8'b11111111;
end
else if (Halt_FF == 1'b1 || (IntCycle == 1'b1 && IStatus == 2'b10) || NMICycle == 1'b1 )
begin
IR <= #1 8'b00000000;
TmpAddr[7:0] <= #1 dinst; // Special M1 vector fetch
end
else
begin
IR <= #1 dinst;
end
ISet <= #1 2'b00;
if (Prefix != 2'b00 )
begin
if (Prefix == 2'b11 )
begin
if (IR[5] == 1'b1 )
begin
XY_State <= #1 2'b10;
end
else
begin
XY_State <= #1 2'b01;
end
end
else
begin
if (Prefix == 2'b10 )
begin
XY_State <= #1 2'b00;
XY_Ind <= #1 1'b0;
end
ISet <= #1 Prefix;
end
end
else
begin
XY_State <= #1 2'b00;
XY_Ind <= #1 1'b0;
end
end // if (tstate == 2 && wait_n == 1'b1 )
end
else
begin
// either (mcycle > 1) OR (mcycle == 1 AND tstate > 3)
if (mcycle[5] )
begin
XY_Ind <= #1 1'b1;
if (Prefix == 2'b01 )
begin
ISet <= #1 2'b01;
end
end
if (T_Res == 1'b1 )
begin
BTR_r <= #1 (I_BT || I_BC || I_BTR) && ~ No_BTR;
if (Jump == 1'b1 )
begin
A[15:8] <= #1 DI_Reg;
A[7:0] <= #1 TmpAddr[7:0];
PC[15:8] <= #1 DI_Reg;
PC[7:0] <= #1 TmpAddr[7:0];
end
else if (JumpXY == 1'b1 )
begin
A <= #1 RegBusC;
PC <= #1 RegBusC;
end else if (Call == 1'b1 || RstP == 1'b1 )
begin
A <= #1 TmpAddr;
PC <= #1 TmpAddr;
end
else if (last_mcycle && NMICycle == 1'b1 )
begin
A <= #1 16'b0000000001100110;
PC <= #1 16'b0000000001100110;
end
else if (mcycle[2] && IntCycle == 1'b1 && IStatus == 2'b10 )
begin
A[15:8] <= #1 I;
A[7:0] <= #1 TmpAddr[7:0];
PC[15:8] <= #1 I;
PC[7:0] <= #1 TmpAddr[7:0];
end
else
begin
case (Set_Addr_To)
aXY :
begin
if (XY_State == 2'b00 )
begin
A <= #1 RegBusC;
end
else
begin
if (NextIs_XY_Fetch == 1'b1 )
begin
A <= #1 PC;
end
else
begin
A <= #1 TmpAddr;
end
end // else: !if(XY_State == 2'b00 )
end // case: aXY
aIOA :
begin
if (Mode == 3 )
begin
// Memory map I/O on GBZ80
A[15:8] <= #1 8'hFF;
end
else if (Mode == 2 )
begin
// Duplicate I/O address on 8080
A[15:8] <= #1 DI_Reg;
end
else
begin
A[15:8] <= #1 ACC;
end
A[7:0] <= #1 DI_Reg;
end // case: aIOA
aSP :
begin
A <= #1 SP;
end
aBC :
begin
if (Mode == 3 && iorq_i == 1'b1 )
begin
// Memory map I/O on GBZ80
A[15:8] <= #1 8'hFF;
A[7:0] <= #1 RegBusC[7:0];
end
else
begin
A <= #1 RegBusC;
end
end // case: aBC
aDE :
begin
A <= #1 RegBusC;
end
aZI :
begin
if (Inc_WZ == 1'b1 )
begin
A <= #1 TmpAddr + 1;
end
else
begin
A[15:8] <= #1 DI_Reg;
A[7:0] <= #1 TmpAddr[7:0];
end
end // case: aZI
default :
begin
A <= #1 PC;
end
endcase // case(Set_Addr_To)
end // else: !if(mcycle[2] && IntCycle == 1'b1 && IStatus == 2'b10 )
Save_ALU_r <= #1 Save_ALU;
ALU_Op_r <= #1 ALU_Op;
if (I_CPL == 1'b1 )
begin
// CPL
ACC <= #1 ~ ACC;
F[Flag_Y] <= #1 ~ ACC[5];
F[Flag_H] <= #1 1'b1;
F[Flag_X] <= #1 ~ ACC[3];
F[Flag_N] <= #1 1'b1;
end
if (I_CCF == 1'b1 )
begin
// CCF
F[Flag_C] <= #1 ~ F[Flag_C];
F[Flag_Y] <= #1 ACC[5];
F[Flag_H] <= #1 F[Flag_C];
F[Flag_X] <= #1 ACC[3];
F[Flag_N] <= #1 1'b0;
end
if (I_SCF == 1'b1 )
begin
// SCF
F[Flag_C] <= #1 1'b1;
F[Flag_Y] <= #1 ACC[5];
F[Flag_H] <= #1 1'b0;
F[Flag_X] <= #1 ACC[3];
F[Flag_N] <= #1 1'b0;
end
end // if (T_Res == 1'b1 )
if (tstate[2] && wait_n == 1'b1 )
begin
if (ISet == 2'b01 && mcycle[6] )
begin
IR <= #1 dinst;
end
if (JumpE == 1'b1 )
begin
PC <= #1 PC16;
end
else if (Inc_PC == 1'b1 )
begin
//PC <= #1 PC + 1;
PC <= #1 PC16;
end
if (BTR_r == 1'b1 )
begin
//PC <= #1 PC - 2;
PC <= #1 PC16;
end
if (RstP == 1'b1 )
begin
TmpAddr <= #1 { 10'h0, IR[5:3], 3'h0 };
//TmpAddr <= #1 (others =>1'b0);
//TmpAddr[5:3] <= #1 IR[5:3];
end
end
if (tstate[3] && mcycle[5] )
begin
TmpAddr <= #1 SP16;
end
if ((tstate[2] && wait_n == 1'b1) || (tstate[4] && mcycle[0]) )
begin
if (IncDec_16[2:0] == 3'b111 )
begin
SP <= #1 SP16;
end
end
if (LDSPHL == 1'b1 )
begin
SP <= #1 RegBusC;
end
if (ExchangeAF == 1'b1 )
begin
Ap <= #1 ACC;
ACC <= #1 Ap;
Fp <= #1 F;
F <= #1 Fp;
end
if (ExchangeRS == 1'b1 )
begin
Alternate <= #1 ~ Alternate;
end
end // else: !if(mcycle == 3'b001 && tstate(2) == 1'b0 )
if (tstate[3] )
begin
if (LDZ == 1'b1 )
begin
TmpAddr[7:0] <= #1 DI_Reg;
end
if (LDW == 1'b1 )
begin
TmpAddr[15:8] <= #1 DI_Reg;
end
if (Special_LD[2] == 1'b1 )
begin
case (Special_LD[1:0])
2'b00 :
begin
ACC <= #1 I;
F[Flag_P] <= #1 IntE_FF2;
F[Flag_Z] <= (I == 0);
F[Flag_S] <= I[7];
F[Flag_H] <= 0;
F[Flag_N] <= 0;
end
2'b01 :
begin
`ifdef TV80_REFRESH
ACC <= #1 R;
`else
ACC <= #1 0;
`endif
F[Flag_P] <= #1 IntE_FF2;
F[Flag_Z] <= (I == 0);
F[Flag_S] <= I[7];
F[Flag_H] <= 0;
F[Flag_N] <= 0;
end
2'b10 :
I <= #1 ACC;
`ifdef TV80_REFRESH
default :
R <= #1 ACC;
`else
default : ;
`endif
endcase
end
end // if (tstate == 3 )
if ((I_DJNZ == 1'b0 && Save_ALU_r == 1'b1) || ALU_Op_r == 4'b1001 )
begin
if (Mode == 3 )
begin
F[6] <= #1 F_Out[6];
F[5] <= #1 F_Out[5];
F[7] <= #1 F_Out[7];
if (PreserveC_r == 1'b0 )
begin
F[4] <= #1 F_Out[4];
end
end
else
begin
F[7:1] <= #1 F_Out[7:1];
if (PreserveC_r == 1'b0 )
begin
F[Flag_C] <= #1 F_Out[0];
end
end
end // if ((I_DJNZ == 1'b0 && Save_ALU_r == 1'b1) || ALU_Op_r == 4'b1001 )
if (T_Res == 1'b1 && I_INRC == 1'b1 )
begin
F[Flag_H] <= #1 1'b0;
F[Flag_N] <= #1 1'b0;
if (DI_Reg[7:0] == 8'b00000000 )
begin
F[Flag_Z] <= #1 1'b1;
end
else
begin
F[Flag_Z] <= #1 1'b0;
end
F[Flag_S] <= #1 DI_Reg[7];
F[Flag_P] <= #1 ~ (^DI_Reg[7:0]);
end // if (T_Res == 1'b1 && I_INRC == 1'b1 )
if (tstate[1] && Auto_Wait_t1 == 1'b0 )
begin
dout <= #1 BusB;
if (I_RLD == 1'b1 )
begin
dout[3:0] <= #1 BusA[3:0];
dout[7:4] <= #1 BusB[3:0];
end
if (I_RRD == 1'b1 )
begin
dout[3:0] <= #1 BusB[7:4];
dout[7:4] <= #1 BusA[3:0];
end
end
if (T_Res == 1'b1 )
begin
Read_To_Reg_r[3:0] <= #1 Set_BusA_To;
Read_To_Reg_r[4] <= #1 Read_To_Reg;
if (Read_To_Acc == 1'b1 )
begin
Read_To_Reg_r[3:0] <= #1 4'b0111;
Read_To_Reg_r[4] <= #1 1'b1;
end
end
if (tstate[1] && I_BT == 1'b1 )
begin
F[Flag_X] <= #1 ALU_Q[3];
F[Flag_Y] <= #1 ALU_Q[1];
F[Flag_H] <= #1 1'b0;
F[Flag_N] <= #1 1'b0;
end
if (I_BC == 1'b1 || I_BT == 1'b1 )
begin
F[Flag_P] <= #1 IncDecZ;
end
if ((tstate[1] && Save_ALU_r == 1'b0 && Auto_Wait_t1 == 1'b0) ||
(Save_ALU_r == 1'b1 && ALU_Op_r != 4'b0111) )
begin
case (Read_To_Reg_r)
5'b10111 :
ACC <= #1 Save_Mux;
5'b10110 :
dout <= #1 Save_Mux;
5'b11000 :
SP[7:0] <= #1 Save_Mux;
5'b11001 :
SP[15:8] <= #1 Save_Mux;
5'b11011 :
F <= #1 Save_Mux;
default : ;
endcase
end // if ((tstate == 1 && Save_ALU_r == 1'b0 && Auto_Wait_t1 == 1'b0) ||...
end // if (ClkEn == 1'b1 )
end // else: !if(reset_n == 1'b0 )
end
//-------------------------------------------------------------------------
//
// BC('), DE('), HL('), IX && IY
//
//-------------------------------------------------------------------------
always @ (posedge clk)
begin
if (ClkEn == 1'b1 )
begin
// Bus A / Write
RegAddrA_r <= #1 { Alternate, Set_BusA_To[2:1] };
if (XY_Ind == 1'b0 && XY_State != 2'b00 && Set_BusA_To[2:1] == 2'b10 )
begin
RegAddrA_r <= #1 { XY_State[1], 2'b11 };
end
// Bus B
RegAddrB_r <= #1 { Alternate, Set_BusB_To[2:1] };
if (XY_Ind == 1'b0 && XY_State != 2'b00 && Set_BusB_To[2:1] == 2'b10 )
begin
RegAddrB_r <= #1 { XY_State[1], 2'b11 };
end
// Address from register
RegAddrC <= #1 { Alternate, Set_Addr_To[1:0] };
// Jump (HL), LD SP,HL
if ((JumpXY == 1'b1 || LDSPHL == 1'b1) )
begin
RegAddrC <= #1 { Alternate, 2'b10 };
end
if (((JumpXY == 1'b1 || LDSPHL == 1'b1) && XY_State != 2'b00) || (mcycle[5]) )
begin
RegAddrC <= #1 { XY_State[1], 2'b11 };
end
if (I_DJNZ == 1'b1 && Save_ALU_r == 1'b1 && Mode < 2 )
begin
IncDecZ <= #1 F_Out[Flag_Z];
end
if ((tstate[2] || (tstate[3] && mcycle[0])) && IncDec_16[2:0] == 3'b100 )
begin
if (ID16 == 0 )
begin
IncDecZ <= #1 1'b0;
end
else
begin
IncDecZ <= #1 1'b1;
end
end
RegBusA_r <= #1 RegBusA;
end
end // always @ (posedge clk)
always @(/*AUTOSENSE*/Alternate or ExchangeDH or IncDec_16
or RegAddrA_r or RegAddrB_r or XY_State or mcycle or tstate)
begin
if ((tstate[2] || (tstate[3] && mcycle[0] && IncDec_16[2] == 1'b1)) && XY_State == 2'b00)
RegAddrA = { Alternate, IncDec_16[1:0] };
else if ((tstate[2] || (tstate[3] && mcycle[0] && IncDec_16[2] == 1'b1)) && IncDec_16[1:0] == 2'b10)
RegAddrA = { XY_State[1], 2'b11 };
else if (ExchangeDH == 1'b1 && tstate[3])
RegAddrA = { Alternate, 2'b10 };
else if (ExchangeDH == 1'b1 && tstate[4])
RegAddrA = { Alternate, 2'b01 };
else
RegAddrA = RegAddrA_r;
if (ExchangeDH == 1'b1 && tstate[3])
RegAddrB = { Alternate, 2'b01 };
else
RegAddrB = RegAddrB_r;
end // always @ *
always @(/*AUTOSENSE*/ALU_Op_r or Auto_Wait_t1 or ExchangeDH
or IncDec_16 or Read_To_Reg_r or Save_ALU_r or mcycle
or tstate or wait_n)
begin
RegWEH = 1'b0;
RegWEL = 1'b0;
if ((tstate[1] && ~Save_ALU_r && ~Auto_Wait_t1) ||
(Save_ALU_r && (ALU_Op_r != 4'b0111)) )
begin
case (Read_To_Reg_r)
5'b10000 , 5'b10001 , 5'b10010 , 5'b10011 , 5'b10100 , 5'b10101 :
begin
RegWEH = ~ Read_To_Reg_r[0];
RegWEL = Read_To_Reg_r[0];
end // UNMATCHED !!
default : ;
endcase // case(Read_To_Reg_r)
end // if ((tstate == 1 && Save_ALU_r == 1'b0 && Auto_Wait_t1 == 1'b0) ||...
if (ExchangeDH && (tstate[3] || tstate[4]) )
begin
RegWEH = 1'b1;
RegWEL = 1'b1;
end
if (IncDec_16[2] && ((tstate[2] && wait_n && ~mcycle[0]) || (tstate[3] && mcycle[0])) )
begin
case (IncDec_16[1:0])
2'b00 , 2'b01 , 2'b10 :
begin
RegWEH = 1'b1;
RegWEL = 1'b1;
end // UNMATCHED !!
default : ;
endcase
end
end // always @ *
always @(/*AUTOSENSE*/ExchangeDH or ID16 or IncDec_16 or RegBusA_r
or RegBusB or Save_Mux or mcycle or tstate)
begin
RegDIH = Save_Mux;
RegDIL = Save_Mux;
if (ExchangeDH == 1'b1 && tstate[3] )
begin