X-Git-Url: http://git.joshuawise.com/fpgaboy.git/blobdiff_plain/abae5818eeec14c040361b5181ff1a31cad79868..4f9c2edfd1242be9e98667d39393c829fcd826c8:/GBZ80Core.v diff --git a/GBZ80Core.v b/GBZ80Core.v index c0c2b26..ec1756e 100644 --- a/GBZ80Core.v +++ b/GBZ80Core.v @@ -36,6 +36,7 @@ `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_reg_A 3'b111 `define INSN_reg_B 3'b000 @@ -80,7 +81,7 @@ 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; @@ -146,7 +147,7 @@ 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]}; @@ -157,7 +158,7 @@ module GBZ80Core( `EXEC_NEWCYCLE; end end - 2: begin + 2: begin `EXEC_NEWCYCLE; end endcase @@ -170,13 +171,13 @@ 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; @@ -189,11 +190,11 @@ module GBZ80Core( end `INSN_LD_reg_HL: begin case(cycle) - 0: begin + 0: begin address <= {registers[`REG_H], registers[`REG_L]}; rd <= 1; end - 1: begin + 1: begin tmp <= rdata; `EXEC_INC_PC; `EXEC_NEWCYCLE; @@ -204,13 +205,13 @@ 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 @@ -241,7 +242,7 @@ module GBZ80Core( end `INSN_PUSH_reg: begin /* PUSH is 16 cycles! */ case (cycle) - 0: begin + 0: begin wr <= 1; address <= {registers[`REG_SPH],registers[`REG_SPL]}-1; case (opcode[5:4]) @@ -251,7 +252,7 @@ module GBZ80Core( `INSN_stack_HL: wdata <= registers[`REG_H]; endcase end - 1: begin + 1: begin wr <= 1; address <= {registers[`REG_SPH],registers[`REG_SPL]}-1; case (opcode[5:4]) @@ -262,7 +263,7 @@ module GBZ80Core( endcase end 2: begin /* TWIDDLE OUR FUCKING THUMBS! */ end - 3: begin + 3: begin `EXEC_NEWCYCLE; `EXEC_INC_PC; end @@ -270,15 +271,15 @@ module GBZ80Core( end `INSN_POP_reg: begin /* POP is 12 cycles! */ case (cycle) - 0: begin + 0: begin rd <= 1; address <= {registers[`REG_SPH],registers[`REG_SPL]}; end - 1: begin + 1: begin rd <= 1; address <= {registers[`REG_SPH],registers[`REG_SPL]}; end - 2: begin + 2: begin `EXEC_NEWCYCLE; `EXEC_INC_PC; end @@ -295,7 +296,7 @@ module GBZ80Core( wdata <= registers[`REG_A]; end end - 1: begin + 1: begin `EXEC_NEWCYCLE; `EXEC_INC_PC; end @@ -303,7 +304,7 @@ module GBZ80Core( end `INSN_LDx_AHL: begin case (cycle) - 0: begin + 0: begin address <= {registers[`REG_H],registers[`REG_L]}; if (opcode[3]) begin // LDx A, (HL) rd <= 1; @@ -327,14 +328,14 @@ module GBZ80Core( `EXEC_NEWCYCLE; `EXEC_INC_PC; 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_dHL: begin tmp <= rdata; 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]; + `INSN_reg_dHL: tmp <= rdata; endcase end end @@ -345,19 +346,19 @@ module GBZ80Core( `INSN_RST: begin case (cycle) 0: begin - `EXEC_INC_PC; // This goes FIRST + `EXEC_INC_PC; // This goes FIRST in RST end - 1: begin + 1: begin wr <= 1; address <= {registers[`REG_SPH],registers[`REG_SPL]}-1; wdata <= registers[`REG_PCH]; end - 2: begin + 2: begin wr <= 1; address <= {registers[`REG_SPH],registers[`REG_SPL]}-2; wdata <= registers[`REG_PCL]; end - 3: begin + 3: begin `EXEC_NEWCYCLE; {registers[`REG_PCH],registers[`REG_PCL]} <= {10'b0,opcode[5:3],3'b0}; @@ -381,6 +382,36 @@ module GBZ80Core( 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 default: $stop; endcase @@ -390,8 +421,8 @@ module GBZ80Core( casex (opcode) `INSN_LD_reg_imm8: case (cycle) - 0: cycle <= 1; - 1: case (opcode[5:3]) + 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 @@ -401,7 +432,7 @@ module GBZ80Core( `INSN_reg_L: begin registers[`REG_L] <= rdata; cycle <= 0; end `INSN_reg_dHL: cycle <= 2; endcase - 2: cycle <= 0; + 2: cycle <= 0; endcase `INSN_HALT: begin /* Nothing needs happen here. */ @@ -409,8 +440,8 @@ module GBZ80Core( end `INSN_LD_HL_reg: begin case (cycle) - 0: cycle <= 1; - 1: cycle <= 0; + 0: cycle <= 1; + 1: cycle <= 0; endcase end `INSN_LD_reg_HL: begin @@ -418,13 +449,13 @@ module GBZ80Core( 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 + `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 @@ -432,13 +463,13 @@ module GBZ80Core( 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 @@ -610,7 +641,7 @@ module GBZ80Core( case (cycle) 0: cycle <= 1; 1: cycle <= 2; - 2: cycle <= 3; + 2: cycle <= 3; 3: begin cycle <= 0; {registers[`REG_SPH],registers[`REG_SPL]} <= @@ -638,6 +669,34 @@ module GBZ80Core( end endcase end + `INSN_CALL: begin + case (cycle) + 0: cycle <= 1; + 1: begin + cycle <= 2; + tmp <= rdata; // tmp contains newpcl + end + 2: begin + cycle <= 3; + tmp2 <= rdata; // tmp2 contains newpch + end + 3: begin + cycle <= 4; + end + 4: begin + cycle <= 5; + registers[`REG_PCH] <= tmp2; + end + 5: begin + {registers[`REG_SPH],registers[`REG_SPL]} <= + {registers[`REG_SPH],registers[`REG_SPL]} - 2; + registers[`REG_PCL] <= tmp; + cycle <= 0; + end + endcase + end + default: + $stop; endcase state <= `STATE_FETCH; end @@ -645,14 +704,57 @@ module GBZ80Core( endmodule `timescale 1ns / 1ps +module ROM( + input [15:0] address, + inout [7:0] data, + input wr, rd); + + reg [7:0] rom [2047:0]; + initial $readmemh("rom.hex", rom); + + wire decode = address[15:13] == 0; + reg [7:0] odata; + wire idata = data; + assign data = (rd && decode) ? odata : 8'bzzzzzzzz; + + always @(posedge rd) + if (decode) + odata <= rom[address]; +endmodule + +module InternalRAM( + input [15:0] address, + inout [7:0] data, + input clk, + input wr, rd); + + reg [7:0] ram [8191:0]; + + wire decode = (address >= 16'hC000) && (address < 16'hFE00); + reg [7:0] odata; + wire idata = data; + assign data = (rd && decode) ? odata : 8'bzzzzzzzz; + + reg [13:0] diq; + initial + for (diq = 0; diq < 8191; diq = diq + 1) + ram[diq] = 8'h43; + + always @(negedge clk) + begin + if (decode && rd) + odata <= ram[address[12:0]]; + if (decode && wr) + ram[address[12:0]] <= data; + end +endmodule + 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), @@ -660,5 +762,17 @@ module TestBench(); .busdata(data), .buswr(wr), .busrd(rd)); - assign data = rd ? rom[addr] : 8'bzzzzzzzz; + + ROM rom( + .address(addr), + .data(data), + .wr(wr), + .rd(rd)); + + InternalRAM ram( + .address(addr), + .data(data), + .clk(clk), + .wr(wr), + .rd(rd)); endmodule