X-Git-Url: http://git.joshuawise.com/fpgaboy.git/blobdiff_plain/634ce02ca41547deda6e98f0e16a81f849bb130c..a85b19a7c7e7fecb4e71c41b37fb30dabaf8bd14:/GBZ80Core.v diff --git a/GBZ80Core.v b/GBZ80Core.v index fa9ed0b..1bc8f78 100644 --- a/GBZ80Core.v +++ b/GBZ80Core.v @@ -28,6 +28,23 @@ `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_CALL 8'b11001101 +`define INSN_JP_imm 8'b11000011 +`define INSN_JPCC_imm 8'b110xx010 + +`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 @@ -40,6 +57,19 @@ `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? + module GBZ80Core( input clk, output reg [15:0] busaddress, /* BUS_* is latched on STATE_FETCH. */ @@ -58,37 +88,48 @@ module GBZ80Core( 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 [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 = 0; + 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; + 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; + ie <= 0; + rd <= 1; + wr <= 0; + newcycle <= 1; + state <= 0; + cycle <= 0; end always @(posedge clk) case (state) `STATE_FETCH: begin - if (wr) - buswdata <= wdata; - if (newcycle) + if (newcycle) begin busaddress <= {registers[`REG_PCH], registers[`REG_PCL]}; - else + 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 @@ -97,10 +138,16 @@ module GBZ80Core( rdata <= busdata; newcycle <= 0; cycle <= 0; - end else + end else begin if (rd) rdata <= busdata; + cycle <= cycle + 1; + 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 @@ -118,7 +165,7 @@ module GBZ80Core( `EXEC_NEXTADDR_PCINC; rd <= 1; end - 1: begin + 1: begin `EXEC_INC_PC; if (opcode[5:3] == `INSN_reg_dHL) begin address <= {registers[`REG_H], registers[`REG_L]}; @@ -129,7 +176,7 @@ module GBZ80Core( `EXEC_NEWCYCLE; end end - 2: begin + 2: begin `EXEC_NEWCYCLE; end endcase @@ -142,13 +189,13 @@ module GBZ80Core( case (cycle) 0: begin case (opcode[2:0]) - `INSN_reg_A: begin wdata <= registers[`REG_A]; end - `INSN_reg_B: begin wdata <= registers[`REG_B]; end - `INSN_reg_C: begin wdata <= registers[`REG_C]; end - `INSN_reg_D: begin wdata <= registers[`REG_D]; end - `INSN_reg_E: begin wdata <= registers[`REG_E]; end - `INSN_reg_H: begin wdata <= registers[`REG_H]; end - `INSN_reg_L: begin wdata <= registers[`REG_L]; end + `INSN_reg_A: wdata <= registers[`REG_A]; + `INSN_reg_B: wdata <= registers[`REG_B]; + `INSN_reg_C: wdata <= registers[`REG_C]; + `INSN_reg_D: wdata <= registers[`REG_D]; + `INSN_reg_E: wdata <= registers[`REG_E]; + `INSN_reg_H: wdata <= registers[`REG_H]; + `INSN_reg_L: wdata <= registers[`REG_L]; endcase address <= {registers[`REG_H], registers[`REG_L]}; wr <= 1; rd <= 0; @@ -161,11 +208,11 @@ module GBZ80Core( end `INSN_LD_reg_HL: begin case(cycle) - 0: begin + 0: begin address <= {registers[`REG_H], registers[`REG_L]}; - wr <= 0; rd <= 1; + rd <= 1; end - 1: begin + 1: begin tmp <= rdata; `EXEC_INC_PC; `EXEC_NEWCYCLE; @@ -176,13 +223,13 @@ module GBZ80Core( `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 + `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]; endcase end `INSN_LD_reg_imm16: begin @@ -202,8 +249,6 @@ module GBZ80Core( `INSN_LD_SP_HL: begin case (cycle) 0: begin - rd <= 0; - address <= 16'bxxxxxxxxxxxxxxxx; tmp <= registers[`REG_H]; end 1: begin @@ -213,6 +258,206 @@ module GBZ80Core( end endcase end + `INSN_PUSH_reg: begin /* PUSH is 16 cycles! */ + case (cycle) + 0: begin + wr <= 1; + address <= {registers[`REG_SPH],registers[`REG_SPL]}-1; + case (opcode[5:4]) + `INSN_stack_AF: wdata <= registers[`REG_A]; + `INSN_stack_BC: wdata <= registers[`REG_B]; + `INSN_stack_DE: wdata <= registers[`REG_D]; + `INSN_stack_HL: wdata <= registers[`REG_H]; + endcase + end + 1: begin + wr <= 1; + address <= {registers[`REG_SPH],registers[`REG_SPL]}-1; + case (opcode[5:4]) + `INSN_stack_AF: wdata <= registers[`REG_F]; + `INSN_stack_BC: wdata <= registers[`REG_C]; + `INSN_stack_DE: wdata <= registers[`REG_E]; + `INSN_stack_HL: wdata <= registers[`REG_L]; + endcase + end + 2: begin /* TWIDDLE OUR FUCKING THUMBS! */ end + 3: begin + `EXEC_NEWCYCLE; + `EXEC_INC_PC; + end + endcase + end + `INSN_POP_reg: begin /* POP is 12 cycles! */ + case (cycle) + 0: begin + rd <= 1; + address <= {registers[`REG_SPH],registers[`REG_SPL]}; + end + 1: begin + rd <= 1; + address <= {registers[`REG_SPH],registers[`REG_SPL]}; + end + 2: begin + `EXEC_NEWCYCLE; + `EXEC_INC_PC; + end + endcase + end + `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_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: begin + case (cycle) + 0: begin + rd <= 1; + address <= {registers[`REG_SPH],registers[`REG_SPL]}; + end + 1: begin + rd <= 1; + address <= {registers[`REG_SPH],registers[`REG_SPL]} + 1; + end + 2: begin /* twiddle thumbs */ end + 3: begin + `EXEC_NEWCYCLE; + // do NOT increment PC! + end + endcase + end + `INSN_CALL: 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; + 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 + 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 default: $stop; endcase @@ -222,60 +467,56 @@ module GBZ80Core( 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; + 0: begin end + 1: case (opcode[5:3]) + `INSN_reg_A: begin registers[`REG_A] <= rdata; end + `INSN_reg_B: begin registers[`REG_B] <= rdata; end + `INSN_reg_C: begin registers[`REG_C] <= rdata; end + `INSN_reg_D: begin registers[`REG_D] <= rdata; end + `INSN_reg_E: begin registers[`REG_E] <= rdata; end + `INSN_reg_H: begin registers[`REG_H] <= rdata; end + `INSN_reg_L: begin registers[`REG_L] <= rdata; end + `INSN_reg_dHL: begin /* Go off to cycle 2 */ end endcase - 2: cycle <= 0; + 2: begin end endcase `INSN_HALT: begin /* Nothing needs happen here. */ /* XXX Interrupts needed for HALT. */ end `INSN_LD_HL_reg: begin - case (cycle) - 0: cycle <= 1; - 1: cycle <= 0; - endcase + /* Nothing of interest here */ end `INSN_LD_reg_HL: begin case (cycle) - 0: cycle <= 1; + 0: begin end 1: 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 + `INSN_reg_A: registers[`REG_A] <= tmp; + `INSN_reg_B: registers[`REG_B] <= tmp; + `INSN_reg_C: registers[`REG_C] <= tmp; + `INSN_reg_D: registers[`REG_D] <= tmp; + `INSN_reg_E: registers[`REG_E] <= tmp; + `INSN_reg_H: registers[`REG_H] <= tmp; + `INSN_reg_L: registers[`REG_L] <= tmp; endcase - cycle <= 0; end endcase 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 + `INSN_reg_A: registers[`REG_A] <= tmp; + `INSN_reg_B: registers[`REG_B] <= tmp; + `INSN_reg_C: registers[`REG_C] <= tmp; + `INSN_reg_D: registers[`REG_D] <= tmp; + `INSN_reg_E: registers[`REG_E] <= tmp; + `INSN_reg_H: registers[`REG_H] <= tmp; + `INSN_reg_L: registers[`REG_L] <= tmp; endcase end `INSN_LD_reg_imm16: begin case (cycle) - 0: cycle <= 1; + 0: begin /* */ end 1: begin case (opcode[5:4]) `INSN_reg16_BC: registers[`REG_C] <= rdata; @@ -283,7 +524,6 @@ module GBZ80Core( `INSN_reg16_HL: registers[`REG_L] <= rdata; `INSN_reg16_SP: registers[`REG_SPL] <= rdata; endcase - cycle <= 2; end 2: begin case (opcode[5:4]) @@ -292,43 +532,178 @@ module GBZ80Core( `INSN_reg16_HL: registers[`REG_H] <= rdata; `INSN_reg16_SP: registers[`REG_SPH] <= rdata; endcase - cycle <= 0; end endcase end `INSN_LD_SP_HL: begin case (cycle) - 0: begin - cycle <= 1; - registers[`REG_SPH] <= tmp; + 0: registers[`REG_SPH] <= tmp; + 1: registers[`REG_SPL] <= tmp; + endcase + end + `INSN_PUSH_reg: begin /* PUSH is 16 cycles! */ + case (cycle) + 0: {registers[`REG_SPH],registers[`REG_SPL]} <= + {registers[`REG_SPH],registers[`REG_SPL]} - 1; + 1: {registers[`REG_SPH],registers[`REG_SPL]} <= + {registers[`REG_SPH],registers[`REG_SPL]} - 1; + 2: begin /* type F */ end + 3: begin /* type F */ end + endcase + end + `INSN_POP_reg: begin /* POP is 12 cycles! */ + case (cycle) + 0: {registers[`REG_SPH],registers[`REG_SPL]} <= + {registers[`REG_SPH],registers[`REG_SPL]} + 1; + 1: begin + case (opcode[5:4]) + `INSN_stack_AF: registers[`REG_F] <= rdata; + `INSN_stack_BC: registers[`REG_C] <= rdata; + `INSN_stack_DE: registers[`REG_E] <= rdata; + `INSN_stack_HL: registers[`REG_L] <= rdata; + endcase + {registers[`REG_SPH],registers[`REG_SPL]} <= + {registers[`REG_SPH],registers[`REG_SPL]} + 1; + end + 2: begin + case (opcode[5:4]) + `INSN_stack_AF: registers[`REG_A] <= rdata; + `INSN_stack_BC: registers[`REG_B] <= rdata; + `INSN_stack_DE: registers[`REG_D] <= rdata; + `INSN_stack_HL: registers[`REG_H] <= rdata; + endcase + end + endcase + end + `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 - 1: begin - cycle <= 0; - registers[`REG_SPL] <= tmp; + `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 + default: + $stop; + endcase + end + 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: begin + case (cycle) + 0: begin /* type F */ end + 1: registers[`REG_PCL] <= rdata; + 2: registers[`REG_PCH] <= rdata; + 3: begin + {registers[`REG_SPH],registers[`REG_SPL]} <= + {registers[`REG_SPH],registers[`REG_SPL]} + 2; + if (opcode[4]) /* RETI */ + ie <= 1; + end + endcase + end + `INSN_CALL: 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 + 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