X-Git-Url: http://git.joshuawise.com/fpgaboy.git/blobdiff_plain/b85870e0cf3c61677a430559c9621a665a8bab6d..a8f4468d0cd6910eba8031e21038d76857a2c107:/GBZ80Core.v diff --git a/GBZ80Core.v b/GBZ80Core.v index e5a7d35..9db958f 100644 --- a/GBZ80Core.v +++ b/GBZ80Core.v @@ -1,31 +1,90 @@ -`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 @@ -33,185 +92,266 @@ `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 +`ifdef verilator + `define EXEC_WRITE(ad, da) begin address <= (ad); wdata <= (da); wr <= 1; end + `define EXEC_READ(ad) begin address <= (ad); rd <= 1; end +`else + `ifdef isim + `define EXEC_WRITE(ad, da) begin address <= (ad); wdata <= (da); wr <= 1; end + `define EXEC_READ(ad) begin address <= (ad); rd <= 1; end + `else +/* Work around XST's retarded bugs :\ */ + `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 + `endif +`endif 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. */ + inout [15:0] bus0address, /* BUS_* is latched on STATE_FETCH. */ + inout [7:0] bus0data, + inout bus0wr, bus0rd, + inout [15:0] bus1address, /* BUS_* is latched on STATE_FETCH. */ + inout [7:0] bus1data, + inout bus1wr, bus1rd, + 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; + wire [7:0] busdata; + + reg [15:0] busaddress; + reg buswr, busrd; + + reg bootstrap_enb; + wire bus = ((busaddress[15:8] == 8'h00) && bootstrap_enb) || ((busaddress[15:7] == 9'b111111111) && (busaddress != 16'hFFFF)); /* 0 or 1 depending on which bus */ + + assign bus0address = (bus == 0) ? busaddress : 16'bzzzzzzzzzzzzzzz; + assign bus1address = (bus == 1) ? busaddress : 16'bzzzzzzzzzzzzzzz; + assign bus0data = ((bus == 0) && buswr) ? buswdata : 8'bzzzzzzzz; + assign bus1data = ((bus == 1) && buswr) ? buswdata : 8'bzzzzzzzz; + assign busdata = (bus == 0) ? bus0data : bus1data; + assign bus0rd = (bus == 0) ? busrd : 1'bz; + assign bus1rd = (bus == 1) ? busrd : 1'bz; + assign bus0wr = (bus == 0) ? buswr : 1'bz; + assign bus1wr = (bus == 1) ? buswr : 1'bz; + + 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],1'b0}; + 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 == 1'b0 ? 1'b1 : 1'b0), + 3'b0}; + + assign srl = {1'b0,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; + bootstrap_enb <= 1; end - always @(posedge clk) + always @(negedge clk) /* Set things up at the negedge to prepare for the posedge. */ 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 + end + `STATE_DECODE: begin /* Make sure this only happens for one clock. */ + end + endcase + + always @(posedge clk) + case (state) + `STATE_FETCH: begin + /* Things are set up in negedge so that something looking on posedge will get his shit. */ state <= `STATE_DECODE; end `STATE_DECODE: begin if (newcycle) begin - opcode <= busdata; - rdata <= busdata; + if (twobyte) begin + opcode <= {1'b1,busdata}; + twobyte <= 0; + end else if (ie && irq) + opcode <= `INSN_VOP_INTR; + else + opcode <= {1'b0,busdata}; newcycle <= 0; + rdata <= busdata; cycle <= 0; - end else + end else begin if (rd) rdata <= busdata; + cycle <= cycle + 1; + end + if (iedelay) begin + ie <= 1; + iedelay <= 0; + end + wr <= 0; + rd <= 0; buswr <= 0; busrd <= 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