-`define REG_A 0
-`define REG_B 1
-`define REG_C 2
-`define REG_D 3
-`define REG_E 4
-`define REG_F 5
-`define REG_H 6
-`define REG_L 7
-`define REG_SPH 8
-`define REG_SPL 9
-`define REG_PCH 10
-`define REG_PCL 11
-
-`define FLAG_Z 8'b10000000
-`define FLAG_N 8'b01000000
-`define FLAG_H 8'b00100000
-`define FLAG_C 8'b00010000
-
-`define STATE_FETCH 2'h0
-`define STATE_DECODE 2'h1
+`define REG_A 0
+`define REG_B 1
+`define REG_C 2
+`define REG_D 3
+`define REG_E 4
+`define REG_F 5
+`define REG_H 6
+`define REG_L 7
+`define REG_SPH 8
+`define REG_SPL 9
+`define REG_PCH 10
+`define REG_PCL 11
+
+`define _A registers[`REG_A]
+`define _B registers[`REG_B]
+`define _C registers[`REG_C]
+`define _D registers[`REG_D]
+`define _E registers[`REG_E]
+`define _F registers[`REG_F]
+`define _H registers[`REG_H]
+`define _L registers[`REG_L]
+`define _SPH registers[`REG_SPH]
+`define _SPL registers[`REG_SPL]
+`define _PCH registers[`REG_PCH]
+`define _PCL registers[`REG_PCL]
+`define _AF {`_A, `_F}
+`define _BC {`_B, `_C}
+`define _DE {`_D, `_E}
+`define _HL {`_H, `_L}
+`define _SP {`_SPH, `_SPL}
+`define _PC {`_PCH, `_PCL}
+
+`define FLAG_Z 8'b10000000
+`define FLAG_N 8'b01000000
+`define FLAG_H 8'b00100000
+`define FLAG_C 8'b00010000
+
+`define STATE_FETCH 2'h0
+`define STATE_DECODE 2'h1
`define STATE_EXECUTE 2'h2
`define STATE_WRITEBACK 2'h3
-`define INSN_LD_reg_imm8 8'b00xxx110
-`define INSN_HALT 8'b01110110
-`define INSN_LD_HL_reg 8'b01110xxx
-`define INSN_LD_reg_HL 8'b01xxx110
-`define INSN_LD_reg_reg 8'b01xxxxxx
+`define INSN_LD_reg_imm8 9'b000xxx110
+`define INSN_HALT 9'b001110110
+`define INSN_LD_HL_reg 9'b001110xxx
+`define INSN_LD_reg_HL 9'b001xxx110
+`define INSN_LD_reg_reg 9'b001xxxxxx
+`define INSN_LD_reg_imm16 9'b000xx0001
+`define INSN_LD_SP_HL 9'b011111001
+`define INSN_PUSH_reg 9'b011xx0101
+`define INSN_POP_reg 9'b011xx0001
+`define INSN_LDH_AC 9'b0111x0010 // Either LDH A,(C) or LDH (C),A
+`define INSN_LDx_AHL 9'b0001xx010 // LDD/LDI A,(HL) / (HL),A
+`define INSN_ALU8 9'b010xxxxxx // 10 xxx yyy
+`define INSN_ALU8IMM 9'b011xxx110
+`define INSN_NOP 9'b000000000
+`define INSN_RST 9'b011xxx111
+`define INSN_RET 9'b0110x1001 // 1 = RETI, 0 = RET
+`define INSN_RETCC 9'b0110xx000
+`define INSN_CALL 9'b011001101
+`define INSN_CALLCC 9'b0110xx100 // Not that call/cc.
+`define INSN_JP_imm 9'b011000011
+`define INSN_JPCC_imm 9'b0110xx010
+`define INSN_ALU_A 9'b000xxx111
+`define INSN_JP_HL 9'b011101001
+`define INSN_JR_imm 9'b000011000
+`define INSN_JRCC_imm 9'b0001xx000
+`define INSN_INCDEC16 9'b000xxx011
+`define INSN_VOP_INTR 9'b011111100 // 0xFC is grabbed by the fetch if there is an interrupt pending.
+`define INSN_DI 9'b011110011
+`define INSN_EI 9'b011111011
+`define INSN_INCDEC_HL 9'b00011010x
+`define INSN_INCDEC_reg8 9'b000xxx10x
+`define INSN_LD8M_A 9'b0111x0000 // 1111 for ld A, x; 1110 for ld x, A; bit 1 specifies 16m8 or 8m8
+`define INSN_LD16M_A 9'b0111x1010 // 1111 for ld A, x; 1110 for ld x, A; bit 1 specifies 16m8 or 8m8
+`define INSN_LDBCDE_A 9'b0000xx010
+`define INSN_TWO_BYTE 9'b011001011 // prefix for two-byte opqodes
+`define INSN_ALU_EXT 9'b100xxxxxx
+`define INSN_BIT 9'b101xxxxxx
+`define INSN_RES 9'b110xxxxxx
+`define INSN_SET 9'b111xxxxxx
+
+`define INSN_cc_NZ 2'b00
+`define INSN_cc_Z 2'b01
+`define INSN_cc_NC 2'b10
+`define INSN_cc_C 2'b11
+
`define INSN_reg_A 3'b111
`define INSN_reg_B 3'b000
`define INSN_reg_C 3'b001
`define INSN_reg_E 3'b011
`define INSN_reg_H 3'b100
`define INSN_reg_L 3'b101
-`define INSN_reg_dHL 3'b110
+`define INSN_reg_dHL 3'b110
+`define INSN_reg16_BC 2'b00
+`define INSN_reg16_DE 2'b01
+`define INSN_reg16_HL 2'b10
+`define INSN_reg16_SP 2'b11
+`define INSN_stack_AF 2'b11
+`define INSN_stack_BC 2'b00
+`define INSN_stack_DE 2'b01
+`define INSN_stack_HL 2'b10
+`define INSN_alu_ADD 3'b000
+`define INSN_alu_ADC 3'b001
+`define INSN_alu_SUB 3'b010
+`define INSN_alu_SBC 3'b011
+`define INSN_alu_AND 3'b100
+`define INSN_alu_XOR 3'b101
+`define INSN_alu_OR 3'b110
+`define INSN_alu_CP 3'b111 // Oh lawd, is dat some CP?
+`define INSN_alu_RLCA 3'b000
+`define INSN_alu_RRCA 3'b001
+`define INSN_alu_RLA 3'b010
+`define INSN_alu_RRA 3'b011
+`define INSN_alu_DAA 3'b100
+`define INSN_alu_CPL 3'b101
+`define INSN_alu_SCF 3'b110
+`define INSN_alu_CCF 3'b111
+`define INSN_alu_RLC 3'b000
+`define INSN_alu_RRC 3'b001
+`define INSN_alu_RL 3'b010
+`define INSN_alu_RR 3'b011
+`define INSN_alu_DA_SLA 3'b100
+`define INSN_alu_CPL_SRA 3'b101
+`define INSN_alu_SCF_SWAP 3'b110
+`define INSN_alu_CCF_SRL 3'b111
+
+`define EXEC_INC_PC `_PC <= `_PC + 1;
+`define EXEC_NEXTADDR_PCINC address <= `_PC + 1;
+`define EXEC_NEWCYCLE begin newcycle <= 1; rd <= 1; wr <= 0; end
+`define EXEC_NEWCYCLE_TWOBYTE begin newcycle <= 1; rd <= 1; wr <= 0; twobyte <= 1; end
+`define EXEC_WRITE(ad, da) begin address <= (ad); wdata <= (da); wr <= 1; end end
+`define EXEC_READ(ad) begin address <= (ad); rd <= 1; end end
module GBZ80Core(
input clk,
output reg [15:0] busaddress, /* BUS_* is latched on STATE_FETCH. */
inout [7:0] busdata,
- output reg buswr, output reg busrd);
-
- reg [1:0] state = 0; /* State within this bus cycle (see STATE_*). */
- reg [2:0] cycle = 0; /* Cycle for instructions. */
+ output reg buswr, output reg busrd,
+ input irq, input [7:0] jaddr,
+ output reg [1:0] state);
+
+// reg [1:0] state; /* State within this bus cycle (see STATE_*). */
+ reg [2:0] cycle; /* Cycle for instructions. */
reg [7:0] registers[11:0];
reg [15:0] address; /* Address for the next bus operation. */
- reg [7:0] opcode; /* Opcode from the current machine cycle. */
-
+ reg [8:0] opcode; /* Opcode from the current machine cycle. */
+
reg [7:0] rdata, wdata; /* Read data from this bus cycle, or write data for the next. */
- reg rd = 1, wr = 0, newcycle = 1;
+ reg rd, wr, newcycle, twobyte;
- reg [7:0] tmp; /* Generic temporary reg. */
+ reg [7:0] tmp, tmp2; /* Generic temporary regs. */
reg [7:0] buswdata;
assign busdata = buswr ? buswdata : 8'bzzzzzzzz;
-
+
+ reg ie, iedelay;
+
+ wire [7:0] rlc,rrc,rl,rr,sla,sra,swap,srl;
+ wire [3:0] rlcf,rrcf,rlf,rrf,slaf,sraf,swapf,srlf;
+ wire [7:0] alu_res;
+ wire [3:0] f_res;
+
+ assign rlc = {tmp[6:0],tmp[7]};
+ assign rlcf = {(tmp == 0 ? 1'b1 : 1'b0)
+ ,2'b0,
+ tmp[7]};
+
+ assign rrc = {tmp[0],tmp[7:1]};
+ assign rrcf = {(tmp == 0 ? 1'b1 : 1'b0),
+ 2'b0,
+ tmp[0]};
+
+ assign rl = {tmp[6:0],`_F[4]};
+ assign rlf = {({tmp[6:0],`_F[4]} == 0 ? 1'b1 : 1'b0),
+ 2'b0,
+ tmp[7]};
+
+ assign rr = {`_F[4],tmp[7:1]};
+ assign rrf = {({tmp[4],tmp[7:1]} == 0 ? 1'b1 : 1'b0),
+ 2'b0,
+ tmp[0]};
+
+ assign sla = {tmp[6:0],0};
+ assign slaf = {(tmp[6:0] == 0 ? 1'b1 : 1'b0),
+ 2'b0,
+ tmp[7]};
+
+ assign sra = {tmp[7],tmp[7:1]};
+// assign sraf = {(tmp[7:1] == 0 ? 1'b1 : 1'b0),2'b0,tmp[0]}; now in assign srlf =
+
+ assign swap = {tmp[3:0],tmp[7:4]};
+ assign swapf = {(tmp == 0 ? 1'b1 : 1'b0),
+ 3'b0};
+
+ assign srl = {0,tmp[7:1]};
+ assign srlf = {(tmp[7:1] == 0 ? 1'b1 : 1'b0),
+ 2'b0,
+ tmp[0]};
+ assign sraf = srlf;
+
+ /* Y U Q */
+ assign {alu_res,f_res} =
+ opcode[5] ? (
+ opcode[4] ? (
+ opcode[3] ? {srl,srlf} : {swap,swapf}
+ ) : (
+ opcode[3] ? {sra,sraf} : {sla,slaf}
+ )
+ ) : (
+ opcode[4] ? (
+ opcode[3] ? {rr,rrf} : {rl,rlf}
+ ) : (
+ opcode[3] ? {rrc,rrcf} : {rlc,rlcf}
+ )
+ );
+
initial begin
- registers[ 0] = 0;
- registers[ 1] = 0;
- registers[ 2] = 0;
- registers[ 3] = 0;
- registers[ 4] = 0;
- registers[ 5] = 0;
- registers[ 6] = 0;
- registers[ 7] = 0;
- registers[ 8] = 0;
- registers[ 9] = 0;
- registers[10] = 0;
- registers[11] = 0;
+ `_A <= 0;
+ `_B <= 0;
+ `_C <= 0;
+ `_D <= 0;
+ `_E <= 0;
+ `_F <= 0;
+ `_H <= 0;
+ `_L <= 0;
+ `_PCH <= 0;
+ `_PCL <= 0;
+ `_SPH <= 0;
+ `_SPL <= 0;
+ rd <= 1;
+ wr <= 0;
+ newcycle <= 1;
+ state <= 0;
+ cycle <= 0;
+ busrd <= 0;
+ buswr <= 0;
+ busaddress <= 0;
+ ie <= 0;
+ iedelay <= 0;
+ opcode <= 0;
+ state <= `STATE_WRITEBACK;
+ cycle <= 0;
+ twobyte <= 0;
end
always @(posedge clk)
case (state)
`STATE_FETCH: begin
- if (wr)
- buswdata <= wdata;
- if (newcycle)
- busaddress <= {registers[`REG_PCH], registers[`REG_PCL]};
- else
+ if (newcycle) begin
+ busaddress <= `_PC;
+ buswr <= 0;
+ busrd <= 1;
+ end else begin
busaddress <= address;
- buswr <= wr;
- busrd <= rd;
+ buswr <= wr;
+ busrd <= rd;
+ if (wr)
+ buswdata <= wdata;
+ end
state <= `STATE_DECODE;
end
`STATE_DECODE: begin
if (newcycle) begin
- opcode <= busdata;
+ if (twobyte) begin
+ opcode <= {1,busdata};
+ twobyte <= 0;
+ end else if (ie && irq)
+ opcode <= `INSN_VOP_INTR;
+ else
+ opcode <= {0,busdata};
rdata <= busdata;
newcycle <= 0;
cycle <= 0;
- end else
+ end else begin
if (rd) rdata <= busdata;
+ cycle <= cycle + 1;
+ end
+ if (iedelay) begin
+ ie <= 1;
+ iedelay <= 0;
+ end
buswr <= 0;
busrd <= 0;
+ wr <= 0;
+ rd <= 0;
+ address <= 16'bxxxxxxxxxxxxxxxx; // Make it obvious if something of type has happened.
+ wdata <= 8'bxxxxxxxx;
state <= `STATE_EXECUTE;
end
`STATE_EXECUTE: begin
-`define EXEC_INC_PC \
- {registers[`REG_PCH], registers[`REG_PCL]} <= {registers[`REG_PCH], registers[`REG_PCL]} + 1
-`define EXEC_NEXTADDR_PCINC \
- address <= {registers[`REG_PCH], registers[`REG_PCL]} + 1
-`define EXEC_NEWCYCLE \
- newcycle <= 1; rd <= 1; wr <= 0
casex (opcode)
- `INSN_LD_reg_imm8: begin
- case (cycle)
- 0: begin
- `EXEC_INC_PC;
- `EXEC_NEXTADDR_PCINC;
- rd <= 1;
- end
- 1: begin
- `EXEC_INC_PC;
- if (opcode[5:3] == `INSN_reg_dHL) begin
- address <= {registers[`REG_H], registers[`REG_L]};
- wdata <= rdata;
- rd <= 0;
- wr <= 1;
- end else begin
- `EXEC_NEWCYCLE;
- end
- end
- 2: begin
- `EXEC_NEWCYCLE;
- end
- endcase
- end
- `INSN_HALT: begin
- /* XXX UNIMP */
- end
- `INSN_LD_HL_reg: begin
- /* XXX UNIMP */
- end
- `INSN_LD_reg_HL: begin
- /* XXX UNIMP */
- end
- `INSN_LD_reg_reg: begin
- `EXEC_INC_PC;
- `EXEC_NEWCYCLE;
- case (opcode[2:0])
- `INSN_reg_A: begin tmp <= registers[`REG_A]; end
- `INSN_reg_B: begin tmp <= registers[`REG_B]; end
- `INSN_reg_C: begin tmp <= registers[`REG_C]; end
- `INSN_reg_D: begin tmp <= registers[`REG_D]; end
- `INSN_reg_E: begin tmp <= registers[`REG_E]; end
- `INSN_reg_H: begin tmp <= registers[`REG_H]; end
- `INSN_reg_L: begin tmp <= registers[`REG_L]; end
- endcase
- end
+ `define EXECUTE
+ `include "allinsns.v"
+ `undef EXECUTE
+ default:
+ $stop;
endcase
state <= `STATE_WRITEBACK;
end
`STATE_WRITEBACK: begin
casex (opcode)
- `INSN_LD_reg_imm8:
- case (cycle)
- 0: cycle <= 1;
- 1: case (opcode[5:3])
- `INSN_reg_A: begin registers[`REG_A] <= rdata; cycle <= 0; end
- `INSN_reg_B: begin registers[`REG_B] <= rdata; cycle <= 0; end
- `INSN_reg_C: begin registers[`REG_C] <= rdata; cycle <= 0; end
- `INSN_reg_D: begin registers[`REG_D] <= rdata; cycle <= 0; end
- `INSN_reg_E: begin registers[`REG_E] <= rdata; cycle <= 0; end
- `INSN_reg_H: begin registers[`REG_H] <= rdata; cycle <= 0; end
- `INSN_reg_L: begin registers[`REG_L] <= rdata; cycle <= 0; end
- `INSN_reg_dHL: cycle <= 2;
- endcase
- 2: cycle <= 0;
- endcase
- `INSN_HALT: begin
- /* XXX UNIMP */
- end
- `INSN_LD_HL_reg: begin
- /* XXX UNIMP */
- end
- `INSN_LD_reg_HL: begin
- /* XXX UNIMP */
- end
- `INSN_LD_reg_reg: begin
- case (opcode[5:3])
- `INSN_reg_A: begin registers[`REG_A] <= tmp; end
- `INSN_reg_B: begin registers[`REG_B] <= tmp; end
- `INSN_reg_C: begin registers[`REG_C] <= tmp; end
- `INSN_reg_D: begin registers[`REG_D] <= tmp; end
- `INSN_reg_E: begin registers[`REG_E] <= tmp; end
- `INSN_reg_H: begin registers[`REG_H] <= tmp; end
- `INSN_reg_L: begin registers[`REG_L] <= tmp; end
- endcase
- end
+ `define WRITEBACK
+ `include "allinsns.v"
+ `undef WRITEBACK
+ default:
+ $stop;
endcase
state <= `STATE_FETCH;
end
endcase
endmodule
-
-`timescale 1ns / 1ps
-module TestBench();
- reg clk = 0;
- wire [15:0] addr;
- wire [7:0] data;
- wire wr, rd;
- reg [7:0] rom [2047:0];
-
- initial $readmemh("rom.hex", rom);
- always #10 clk <= ~clk;
- GBZ80Core core(
- .clk(clk),
- .busaddress(addr),
- .busdata(data),
- .buswr(wr),
- .busrd(rd));
- assign data = rd ? rom[addr] : 8'bzzzzzzzz;
-endmodule
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