-`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 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 _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 STATE_FETCH 2'h0
-`define STATE_DECODE 2'h1
+`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_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_imm16 8'b00xx0001
`define INSN_LD_SP_HL 8'b11111001
`define INSN_PUSH_reg 8'b11xx0101
-`define INSN_POP_reg 8'b11xx0001
-`define INSN_LDH_AC 8'b111x0010 // Either LDH A,(C) or LDH (C),A
-`define INSN_LDx_AHL 8'b001xx010 // LDD/LDI A,(HL) / (HL),A
-`define INSN_ALU8 8'b10xxxxxx // 10 xxx yyy
-`define INSN_NOP 8'b00000000
-`define INSN_RST 8'b11xxx111
-`define INSN_RET 8'b110x1001 // 1 = RETI, 0 = RET
-`define INSN_RETCC 8'b110xx000
-`define INSN_CALL 8'b11001101
-`define INSN_CALLCC 8'b110xx100 // Not that call/cc.
-`define INSN_JP_imm 8'b11000011
+`define INSN_POP_reg 8'b11xx0001
+`define INSN_LDH_AC 8'b111x0010 // Either LDH A,(C) or LDH (C),A
+`define INSN_LDx_AHL 8'b001xx010 // LDD/LDI A,(HL) / (HL),A
+`define INSN_ALU8 8'b10xxxxxx // 10 xxx yyy
+`define INSN_ALU8IMM 8'b11xxx110
+`define INSN_NOP 8'b00000000
+`define INSN_RST 8'b11xxx111
+`define INSN_RET 8'b110x1001 // 1 = RETI, 0 = RET
+`define INSN_RETCC 8'b110xx000
+`define INSN_CALL 8'b11001101
+`define INSN_CALLCC 8'b110xx100 // Not that call/cc.
+`define INSN_JP_imm 8'b11000011
`define INSN_JPCC_imm 8'b110xx010
`define INSN_ALU_A 8'b00xxx111
-`define INSN_JP_HL 8'b11101001
-`define INSN_JR_imm 8'b00011000
+`define INSN_JP_HL 8'b11101001
+`define INSN_JR_imm 8'b00011000
`define INSN_JRCC_imm 8'b001xx000
`define INSN_INCDEC16 8'b00xxx011
`define INSN_VOP_INTR 8'b11111100 // 0xFC is grabbed by the fetch if there is an interrupt pending.
-`define INSN_DI 8'b11110011
-`define INSN_EI 8'b11111011
+`define INSN_DI 8'b11110011
+`define INSN_EI 8'b11111011
-`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_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_E 3'b011
`define INSN_reg_H 3'b100
`define INSN_reg_L 3'b101
-`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_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_SCF 3'b110
`define INSN_alu_CCF 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_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 = 0, /* BUS_* is latched on STATE_FETCH. */
+ output reg [15:0] busaddress, /* BUS_* is latched on STATE_FETCH. */
inout [7:0] busdata,
- output reg buswr = 0, output reg busrd = 0,
- input irq, input [7:0] jaddr);
+ 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 [1:0] state; /* State within this bus cycle (see STATE_*). */
reg [2:0] cycle; /* Cycle for instructions. */
reg [7:0] registers[11:0];
reg [7:0] buswdata;
assign busdata = buswr ? buswdata : 8'bzzzzzzzz;
- reg ie = 0, iedelay = 0;
+ reg ie, iedelay;
initial begin
registers[ 0] <= 0;
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)
`define EXECUTE
`include "allinsns.v"
`undef EXECUTE
- `INSN_LDH_AC: begin
- case (cycle)
- 0: begin
- address <= {8'hFF,registers[`REG_C]};
- if (opcode[4]) begin // LD A,(C)
- rd <= 1;
- end else begin
- wr <= 1;
- wdata <= registers[`REG_A];
- end
- end
- 1: begin
- `EXEC_NEWCYCLE;
- `EXEC_INC_PC;
- end
- endcase
- end
- `INSN_LDx_AHL: begin
- case (cycle)
- 0: begin
- address <= {registers[`REG_H],registers[`REG_L]};
- if (opcode[3]) begin // LDx A, (HL)
- rd <= 1;
- end else begin
- wr <= 1;
- wdata <= registers[`REG_A];
- end
- end
- 1: begin
- `EXEC_NEWCYCLE;
- `EXEC_INC_PC;
- end
- endcase
- end
- `INSN_ALU8: begin
- if ((opcode[2:0] == `INSN_reg_dHL) && (cycle == 0)) begin
- // fffffffff fuck your shit, read from (HL) :(
- rd <= 1;
- address <= {registers[`REG_H], registers[`REG_L]};
- end else begin
- `EXEC_NEWCYCLE;
- `EXEC_INC_PC;
- case (opcode[2:0])
- `INSN_reg_A: tmp <= registers[`REG_A];
- `INSN_reg_B: tmp <= registers[`REG_B];
- `INSN_reg_C: tmp <= registers[`REG_C];
- `INSN_reg_D: tmp <= registers[`REG_D];
- `INSN_reg_E: tmp <= registers[`REG_E];
- `INSN_reg_H: tmp <= registers[`REG_H];
- `INSN_reg_L: tmp <= registers[`REG_L];
- `INSN_reg_dHL: tmp <= rdata;
- endcase
- end
- end
- `INSN_ALU_A: begin
- `EXEC_NEWCYCLE;
- `EXEC_INC_PC;
- end
- `INSN_NOP: begin
- `EXEC_NEWCYCLE;
- `EXEC_INC_PC;
- end
- `INSN_RST: begin
- case (cycle)
- 0: begin
- `EXEC_INC_PC; // This goes FIRST in RST
- end
- 1: begin
- wr <= 1;
- address <= {registers[`REG_SPH],registers[`REG_SPL]}-1;
- wdata <= registers[`REG_PCH];
- end
- 2: begin
- wr <= 1;
- address <= {registers[`REG_SPH],registers[`REG_SPL]}-2;
- wdata <= registers[`REG_PCL];
- end
- 3: begin
- `EXEC_NEWCYCLE;
- {registers[`REG_PCH],registers[`REG_PCL]} <=
- {10'b0,opcode[5:3],3'b0};
- end
- endcase
- end
- `INSN_RET,`INSN_RETCC: begin
- case (cycle)
- 0: begin
- rd <= 1;
- address <= {registers[`REG_SPH],registers[`REG_SPL]};
- end
- 1: begin // SPECIAL CASE: cycle does NOT increase linearly with ret!
- `EXEC_INC_PC; // cycle 1 is skipped if we are not retcc
- case (opcode[4:3])
- `INSN_cc_NZ: if (registers[`REG_F][7]) begin `EXEC_NEWCYCLE; end
- `INSN_cc_Z: if (~registers[`REG_F][7]) begin `EXEC_NEWCYCLE; end
- `INSN_cc_NC: if (registers[`REG_F][4]) begin `EXEC_NEWCYCLE; end
- `INSN_cc_C: if (~registers[`REG_F][4]) begin `EXEC_NEWCYCLE; end
- endcase
- rd <= 1;
- address <= {registers[`REG_SPH],registers[`REG_SPL]};
- end
- 2: begin
- rd <= 1;
- address <= {registers[`REG_SPH],registers[`REG_SPL]} + 1;
- end
- 3: begin /* twiddle thumbs */ end
- 4: begin
- `EXEC_NEWCYCLE;
- // do NOT increment PC!
- end
- endcase
- end
- `INSN_CALL,`INSN_CALLCC: begin
- case (cycle)
- 0: begin
- `EXEC_INC_PC;
- `EXEC_NEXTADDR_PCINC;
- rd <= 1;
- end
- 1: begin
- `EXEC_INC_PC;
- `EXEC_NEXTADDR_PCINC;
- rd <= 1;
- end
- 2: begin
- `EXEC_INC_PC;
- if (!opcode[0]) // i.e., is callcc
- /* We need to check the condition code to bail out. */
- case (opcode[4:3])
- `INSN_cc_NZ: if (registers[`REG_F][7]) begin `EXEC_NEWCYCLE; end
- `INSN_cc_Z: if (~registers[`REG_F][7]) begin `EXEC_NEWCYCLE; end
- `INSN_cc_NC: if (registers[`REG_F][4]) begin `EXEC_NEWCYCLE; end
- `INSN_cc_C: if (~registers[`REG_F][4]) begin `EXEC_NEWCYCLE; end
- endcase
- end
- 3: begin
- address <= {registers[`REG_SPH],registers[`REG_SPL]} - 1;
- wdata <= registers[`REG_PCH];
- wr <= 1;
- end
- 4: begin
- address <= {registers[`REG_SPH],registers[`REG_SPL]} - 2;
- wdata <= registers[`REG_PCL];
- wr <= 1;
- end
- 5: begin
- `EXEC_NEWCYCLE; /* do NOT increment the PC */
- end
- endcase
- end
- `INSN_JP_imm,`INSN_JPCC_imm: begin
- case (cycle)
- 0: begin
- `EXEC_INC_PC;
- `EXEC_NEXTADDR_PCINC;
- rd <= 1;
- end
- 1: begin
- `EXEC_INC_PC;
- `EXEC_NEXTADDR_PCINC;
- rd <= 1;
- end
- 2: begin
- `EXEC_INC_PC;
- if (!opcode[0]) begin // i.e., JP cc,nn
- /* We need to check the condition code to bail out. */
- case (opcode[4:3])
- `INSN_cc_NZ: if (registers[`REG_F][7]) begin `EXEC_NEWCYCLE; end
- `INSN_cc_Z: if (~registers[`REG_F][7]) begin `EXEC_NEWCYCLE; end
- `INSN_cc_NC: if (registers[`REG_F][4]) begin `EXEC_NEWCYCLE; end
- `INSN_cc_C: if (~registers[`REG_F][4]) begin `EXEC_NEWCYCLE; end
- endcase
- end
- end
- 3: begin
- `EXEC_NEWCYCLE;
- end
- endcase
- end
- `INSN_JP_HL: begin
- `EXEC_NEWCYCLE;
- end
- `INSN_JR_imm,`INSN_JRCC_imm: begin
- case (cycle)
- 0: begin
- `EXEC_INC_PC;
- `EXEC_NEXTADDR_PCINC;
- rd <= 1;
- end
- 1: begin
- `EXEC_INC_PC;
- if (opcode[5]) begin // i.e., JP cc,nn
- /* We need to check the condition code to bail out. */
- case (opcode[4:3])
- `INSN_cc_NZ: if (registers[`REG_F][7]) begin `EXEC_NEWCYCLE; end
- `INSN_cc_Z: if (~registers[`REG_F][7]) begin `EXEC_NEWCYCLE; end
- `INSN_cc_NC: if (registers[`REG_F][4]) begin `EXEC_NEWCYCLE; end
- `INSN_cc_C: if (~registers[`REG_F][4]) begin `EXEC_NEWCYCLE; end
- endcase
- end
- end
- 2: begin
- `EXEC_NEWCYCLE;
- end
- endcase
- end
- `INSN_INCDEC16: begin
- case (cycle)
- 0: begin
- case (opcode[5:4])
- `INSN_reg16_BC: begin
- tmp <= registers[`REG_B];
- tmp2 <= registers[`REG_C];
- end
- `INSN_reg16_DE: begin
- tmp <= registers[`REG_D];
- tmp2 <= registers[`REG_E];
- end
- `INSN_reg16_HL: begin
- tmp <= registers[`REG_H];
- tmp2 <= registers[`REG_L];
- end
- `INSN_reg16_SP: begin
- tmp <= registers[`REG_SPH];
- tmp2 <= registers[`REG_SPL];
- end
- endcase
- end
- 1: begin
- `EXEC_INC_PC;
- `EXEC_NEWCYCLE;
- end
- endcase
- end
- `INSN_VOP_INTR: begin
- case (cycle)
- 0: begin
- address <= {registers[`REG_SPH],registers[`REG_SPL]} - 1;
- wdata <= registers[`REG_PCH];
- wr <= 1;
- end
- 1: begin
- address <= {registers[`REG_SPH],registers[`REG_SPL]} - 2;
- wdata <= registers[`REG_PCL];
- wr <= 1;
- end
- 2: begin
- `EXEC_NEWCYCLE;
- end
- endcase
- end
- `INSN_DI: begin
- `EXEC_NEWCYCLE;
- `EXEC_INC_PC;
- end
- `INSN_EI: begin
- `EXEC_NEWCYCLE;
- `EXEC_INC_PC;
- end
default:
$stop;
endcase
`define WRITEBACK
`include "allinsns.v"
`undef WRITEBACK
- `INSN_LDH_AC: begin
- case (cycle)
- 0: begin /* Type F */ end
- 1: if (opcode[4])
- registers[`REG_A] <= rdata;
- endcase
- end
- `INSN_LDx_AHL: begin
- case (cycle)
- 0: begin /* Type F */ end
- 1: begin
- if (opcode[3])
- registers[`REG_A] <= rdata;
- {registers[`REG_H],registers[`REG_L]} <=
- opcode[4] ? // if set, LDD, else LDI
- ({registers[`REG_H],registers[`REG_L]} - 1) :
- ({registers[`REG_H],registers[`REG_L]} + 1);
- end
- endcase
- end
- `INSN_ALU8: begin
- if ((opcode[2:0] == `INSN_reg_dHL) && (cycle == 0)) begin
- /* Sit on our asses. */
- end else begin /* Actually do the computation! */
- case (opcode[5:3])
- `INSN_alu_ADD: begin
- registers[`REG_A] <=
- registers[`REG_A] + tmp;
- registers[`REG_F] <=
- { /* Z */ ((registers[`REG_A] + tmp) == 0) ? 1'b1 : 1'b0,
- /* N */ 1'b0,
- /* H */ (({1'b0,registers[`REG_A][3:0]} + {1'b0,tmp[3:0]}) >> 4 == 1) ? 1'b1 : 1'b0,
- /* C */ (({1'b0,registers[`REG_A]} + {1'b0,tmp}) >> 8 == 1) ? 1'b1 : 1'b0,
- registers[`REG_F][3:0]
- };
- end
- `INSN_alu_ADC: begin
- registers[`REG_A] <=
- registers[`REG_A] + tmp + {7'b0,registers[`REG_F][4]};
- registers[`REG_F] <=
- { /* Z */ ((registers[`REG_A] + tmp + {7'b0,registers[`REG_F][4]}) == 0) ? 1'b1 : 1'b0,
- /* N */ 1'b0,
- /* H */ (({1'b0,registers[`REG_A][3:0]} + {1'b0,tmp[3:0]} + {4'b0,registers[`REG_F][4]}) >> 4 == 1) ? 1'b1 : 1'b0,
- /* C */ (({1'b0,registers[`REG_A]} + {1'b0,tmp} + {8'b0,registers[`REG_F][4]}) >> 8 == 1) ? 1'b1 : 1'b0,
- registers[`REG_F][3:0]
- };
- end
- `INSN_alu_SUB: begin
- registers[`REG_A] <=
- registers[`REG_A] - tmp;
- registers[`REG_F] <=
- { /* Z */ ((registers[`REG_A] - tmp) == 0) ? 1'b1 : 1'b0,
- /* N */ 1'b1,
- /* H */ (({1'b0,registers[`REG_A][3:0]} - {1'b0,tmp[3:0]}) >> 4 == 1) ? 1'b1 : 1'b0,
- /* C */ (({1'b0,registers[`REG_A]} - {1'b0,tmp}) >> 8 == 1) ? 1'b1 : 1'b0,
- registers[`REG_F][3:0]
- };
- end
- `INSN_alu_SBC: begin
- registers[`REG_A] <=
- registers[`REG_A] - (tmp + {7'b0,registers[`REG_F][4]});
- registers[`REG_F] <=
- { /* Z */ ((registers[`REG_A] - (tmp + {7'b0,registers[`REG_F][4]})) == 0) ? 1'b1 : 1'b0,
- /* N */ 1'b1,
- /* H */ (({1'b0,registers[`REG_A][3:0]} - ({1'b0,tmp[3:0]} + {4'b0,registers[`REG_F][4]})) >> 4 == 1) ? 1'b1 : 1'b0,
- /* C */ (({1'b0,registers[`REG_A]} - ({1'b0,tmp} + {8'b0,registers[`REG_F][4]})) >> 8 == 1) ? 1'b1 : 1'b0,
- registers[`REG_F][3:0]
- };
- end
- `INSN_alu_AND: begin
- registers[`REG_A] <=
- registers[`REG_A] & tmp;
- registers[`REG_F] <=
- { /* Z */ ((registers[`REG_A] & tmp) == 0) ? 1'b1 : 1'b0,
- 3'b010,
- registers[`REG_F][3:0]
- };
- end
- `INSN_alu_OR: begin
- registers[`REG_A] <=
- registers[`REG_A] | tmp;
- registers[`REG_F] <=
- { /* Z */ ((registers[`REG_A] | tmp) == 0) ? 1'b1 : 1'b0,
- 3'b000,
- registers[`REG_F][3:0]
- };
- end
- `INSN_alu_XOR: begin
- registers[`REG_A] <=
- registers[`REG_A] ^ tmp;
- registers[`REG_F] <=
- { /* Z */ ((registers[`REG_A] ^ tmp) == 0) ? 1'b1 : 1'b0,
- 3'b000,
- registers[`REG_F][3:0]
- };
- end
- `INSN_alu_CP: begin
- registers[`REG_F] <=
- { /* Z */ ((registers[`REG_A] - tmp) == 0) ? 1'b1 : 1'b0,
- /* N */ 1'b1,
- /* H */ (({1'b0,registers[`REG_A][3:0]} - {1'b0,tmp[3:0]}) >> 4 == 1) ? 1'b1 : 1'b0,
- /* C */ (({1'b0,registers[`REG_A]} - {1'b0,tmp}) >> 8 == 1) ? 1'b1 : 1'b0,
- registers[`REG_F][3:0]
- };
- end
- default:
- $stop;
- endcase
- end
- end
- `INSN_ALU_A: begin
- case(opcode[5:3])
- `INSN_alu_RLCA: begin
- registers[`REG_A] <= {registers[`REG_A][6:0],registers[`REG_A][7]};
- registers[`REG_F] <= {registers[`REG_F][7:5],registers[`REG_A][7],registers[`REG_F][3:0]};
- end
- `INSN_alu_RRCA: begin
- registers[`REG_A] <= {registers[`REG_A][0],registers[`REG_A][7:1]};
- registers[`REG_F] <= {registers[`REG_F][7:5],registers[`REG_A][0],registers[`REG_F][3:0]};
- end
- `INSN_alu_RLA: begin
- registers[`REG_A] <= {registers[`REG_A][6:0],registers[`REG_F][4]};
- registers[`REG_F] <= {registers[`REG_F][7:5],registers[`REG_A][7],registers[`REG_F][3:0]};
- end
- `INSN_alu_RRA: begin
- registers[`REG_A] <= {registers[`REG_A][4],registers[`REG_A][7:1]};
- registers[`REG_F] <= {registers[`REG_F][7:5],registers[`REG_A][0],registers[`REG_F][3:0]};
- end
- `INSN_alu_CPL: begin
- registers[`REG_A] <= ~registers[`REG_A];
- registers[`REG_F] <= {registers[`REG_F][7],1'b1,1'b1,registers[`REG_F][4:0]};
- end
- `INSN_alu_SCF: begin
- registers[`REG_F] <= {registers[`REG_F][7:5],1'b1,registers[`REG_F][3:0]};
- end
- `INSN_alu_CCF: begin
- registers[`REG_F] <= {registers[`REG_F][7:5],~registers[`REG_F][4],registers[`REG_F][3:0]};
- end
- endcase
- end
- `INSN_NOP: begin /* NOP! */ end
- `INSN_RST: begin
- case (cycle)
- 0: begin /* type F */ end
- 1: begin /* type F */ end
- 2: begin /* type F */ end
- 3: {registers[`REG_SPH],registers[`REG_SPL]} <=
- {registers[`REG_SPH],registers[`REG_SPL]}-2;
- endcase
- end
- `INSN_RET,`INSN_RETCC: begin
- case (cycle)
- 0: if (opcode[0]) // i.e., not RETCC
- cycle <= 1; // Skip cycle 1; it gets incremented on the next round.
- 1: begin /* Nothing need happen here. */ end
- 2: registers[`REG_PCL] <= rdata;
- 3: registers[`REG_PCH] <= rdata;
- 4: begin
- {registers[`REG_SPH],registers[`REG_SPL]} <=
- {registers[`REG_SPH],registers[`REG_SPL]} + 2;
- if (opcode[4] && opcode[0]) /* RETI */
- ie <= 1;
- end
- endcase
- end
- `INSN_CALL,`INSN_CALLCC: begin
- case (cycle)
- 0: begin /* type F */ end
- 1: tmp <= rdata; // tmp contains newpcl
- 2: tmp2 <= rdata; // tmp2 contains newpch
- 3: begin /* type F */ end
- 4: registers[`REG_PCH] <= tmp2;
- 5: begin
- {registers[`REG_SPH],registers[`REG_SPL]} <=
- {registers[`REG_SPH],registers[`REG_SPL]} - 2;
- registers[`REG_PCL] <= tmp;
- end
- endcase
- end
- `INSN_JP_imm,`INSN_JPCC_imm: begin
- case (cycle)
- 0: begin /* type F */ end
- 1: tmp <= rdata; // tmp contains newpcl
- 2: tmp2 <= rdata; // tmp2 contains newpch
- 3: {registers[`REG_PCH],registers[`REG_PCL]} <=
- {tmp2,tmp};
- endcase
- end
- `INSN_JP_HL: begin
- {registers[`REG_PCH],registers[`REG_PCL]} <=
- {registers[`REG_H],registers[`REG_L]};
- end
- `INSN_JR_imm,`INSN_JRCC_imm: begin
- case (cycle)
- 0: begin /* type F */ end
- 1: tmp <= rdata;
- 2: {registers[`REG_PCH],registers[`REG_PCL]} <=
- {registers[`REG_PCH],registers[`REG_PCL]} +
- {tmp[7]?8'hFF:8'h00,tmp};
- endcase
- end
- `INSN_INCDEC16: begin
- case (cycle)
- 0: {tmp,tmp2} <= {tmp,tmp2} +
- (opcode[3] ? 16'hFFFF : 16'h0001);
- 1: begin
- case (opcode[5:4])
- `INSN_reg16_BC: begin
- registers[`REG_B] <= tmp;
- registers[`REG_C] <= tmp2;
- end
- `INSN_reg16_DE: begin
- registers[`REG_D] <= tmp;
- registers[`REG_E] <= tmp2;
- end
- `INSN_reg16_HL: begin
- registers[`REG_H] <= tmp;
- registers[`REG_L] <= tmp2;
- end
- `INSN_reg16_SP: begin
- registers[`REG_SPH] <= tmp;
- registers[`REG_SPL] <= tmp2;
- end
- endcase
- end
- endcase
- end
- `INSN_VOP_INTR: begin
- case (cycle)
- 0: begin end
- 1: begin end
- 2: begin
- ie <= 0;
- {registers[`REG_PCH],registers[`REG_PCL]} <=
- {8'b0,jaddr};
- {registers[`REG_SPH],registers[`REG_SPL]} <=
- {registers[`REG_SPH],registers[`REG_SPL]} - 2;
- end
- endcase
- end
- `INSN_DI: ie <= 0;
- `INSN_EI: iedelay <= 1;
default:
$stop;
endcase
git.joshuawise.com / fpgaboy.git / blobdiff