X-Git-Url: http://git.joshuawise.com/fpgaboy.git/blobdiff_plain/241c995cb7db3feeeb57d11625dc8fd34c166d82..6c46357c6f1bfeefc3a9f85aed03f94e923d09f1:/GBZ80Core.v diff --git a/GBZ80Core.v b/GBZ80Core.v index 968cd26..36cd76a 100644 --- a/GBZ80Core.v +++ b/GBZ80Core.v @@ -1,28 +1,47 @@ -`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 @@ -30,6 +49,31 @@ `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_JPCC_imm 8'b110xx010 +`define INSN_ALU_A 8'b00xxx111 +`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_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 @@ -37,23 +81,48 @@ `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_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 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, /* BUS_* is latched on STATE_FETCH. */ inout [7:0] busdata, - output reg buswr, output reg busrd); + output reg buswr, output reg busrd, + input irq, input [7:0] jaddr, + output reg [1:0] state); - reg [1:0] state = 0; /* State within this bus cycle (see STATE_*). */ - reg [2:0] cycle = 0; /* Cycle for instructions. */ +// reg [1:0] state; /* State within this bus cycle (see STATE_*). */ + reg [2:0] cycle; /* Cycle for instructions. */ reg [7:0] registers[11:0]; @@ -62,13 +131,15 @@ module GBZ80Core( reg [7:0] 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; - 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; + initial begin registers[ 0] <= 0; registers[ 1] <= 0; @@ -82,29 +153,54 @@ module GBZ80Core( registers[ 9] <= 0; registers[10] <= 0; registers[11] <= 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; 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 if (newcycle) begin - opcode <= busdata; + if (ie && irq) + opcode <= `INSN_VOP_INTR; + else + opcode <= 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; @@ -114,158 +210,10 @@ module GBZ80Core( 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 - `EXEC_NEWCYCLE; - /* XXX Interrupts needed for HALT. */ - end - `INSN_LD_HL_reg: begin - 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 - endcase - address <= {registers[`REG_H], registers[`REG_L]}; - wr <= 1; rd <= 0; - end - 1: begin - `EXEC_INC_PC; - `EXEC_NEWCYCLE; - end - endcase - end - `INSN_LD_reg_HL: begin - case(cycle) - 0: begin - address <= {registers[`REG_H], registers[`REG_L]}; - rd <= 1; - end - 1: begin - tmp <= rdata; - `EXEC_INC_PC; - `EXEC_NEWCYCLE; - end - endcase - 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 - `INSN_LD_reg_imm16: begin - `EXEC_INC_PC; - case (cycle) - 0: begin - `EXEC_NEXTADDR_PCINC; - rd <= 1; - end - 1: begin - `EXEC_NEXTADDR_PCINC; - rd <= 1; - end - 2: begin `EXEC_NEWCYCLE; end - endcase - end - `INSN_LD_SP_HL: begin - case (cycle) - 0: begin - tmp <= registers[`REG_H]; - end - 1: begin - `EXEC_NEWCYCLE; - `EXEC_INC_PC; - tmp <= registers[`REG_L]; - 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 + `define EXECUTE + `include "allinsns.v" + `undef EXECUTE default: $stop; endcase @@ -273,160 +221,13 @@ module GBZ80Core( 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 - /* Nothing needs happen here. */ - /* XXX Interrupts needed for HALT. */ - end - `INSN_LD_HL_reg: begin - case (cycle) - 0: cycle <= 1; - 1: cycle <= 0; - endcase - end - `INSN_LD_reg_HL: begin - case (cycle) - 0: cycle <= 1; - 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 - 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 - endcase - end - `INSN_LD_reg_imm16: begin - case (cycle) - 0: cycle <= 1; - 1: begin - case (opcode[5:4]) - `INSN_reg16_BC: registers[`REG_C] <= rdata; - `INSN_reg16_DE: registers[`REG_E] <= rdata; - `INSN_reg16_HL: registers[`REG_L] <= rdata; - `INSN_reg16_SP: registers[`REG_SPL] <= rdata; - endcase - cycle <= 2; - end - 2: begin - case (opcode[5:4]) - `INSN_reg16_BC: registers[`REG_B] <= rdata; - `INSN_reg16_DE: registers[`REG_D] <= rdata; - `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; - end - 1: begin - cycle <= 0; - registers[`REG_SPL] <= tmp; - end - endcase - end - `INSN_PUSH_reg: begin /* PUSH is 16 cycles! */ - case (cycle) - 0: begin - {registers[`REG_SPH],registers[`REG_SPL]} <= - {registers[`REG_SPH],registers[`REG_SPL]} - 1; - cycle <= 1; - end - 1: begin - {registers[`REG_SPH],registers[`REG_SPL]} <= - {registers[`REG_SPH],registers[`REG_SPL]} - 1; - cycle <= 2; - end - 2: cycle <= 3; - 3: cycle <= 0; - endcase - end - `INSN_POP_reg: begin /* POP is 12 cycles! */ - case (cycle) - 0: begin - cycle <= 1; - {registers[`REG_SPH],registers[`REG_SPL]} <= - {registers[`REG_SPH],registers[`REG_SPL]} + 1; - end - 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; - cycle <= 2; - 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 - cycle <= 0; - 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