X-Git-Url: http://git.joshuawise.com/fpgaboy.git/blobdiff_plain/7d9d69c71187b4891b2281ab58ab8360e43290c2..06ad3a30038ac8ca45dd7b0c34213c0c8335c17c:/GBZ80Core.v

diff --git a/GBZ80Core.v b/GBZ80Core.v
index 3bc2b16..96e4dcd 100644
--- a/GBZ80Core.v
+++ b/GBZ80Core.v
@@ -36,7 +36,21 @@
 `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_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
@@ -62,6 +76,14 @@
 `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
 
 module GBZ80Core(
 	input clk,
@@ -273,7 +295,7 @@ module GBZ80Core(
 						`INSN_stack_HL:	wdata <= registers[`REG_L];
 						endcase
 					end
-				2:	begin /* TWIDDLE OUR FUCKING THUMBS! */ end
+				2:	begin /* Twiddle thumbs. */ end
 				3:	begin
 						`EXEC_NEWCYCLE;
 						`EXEC_INC_PC;
@@ -350,6 +372,10 @@ module GBZ80Core(
 					endcase
 				end
 			end
+			`INSN_ALU_A: begin
+				`EXEC_NEWCYCLE;
+				`EXEC_INC_PC;
+			end
 			`INSN_NOP: begin
 				`EXEC_NEWCYCLE;
 				`EXEC_INC_PC;
@@ -376,24 +402,35 @@ module GBZ80Core(
 					end
 				endcase
 			end
-			`INSN_RET: begin
+			`INSN_RET,`INSN_RETCC: begin
 				case (cycle)
 				0:	begin
 						rd <= 1;
 						address <= {registers[`REG_SPH],registers[`REG_SPL]};
 					end
-				1:	begin
+				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
-				2:	begin /* twiddle thumbs */ end
-				3:	begin
+				3:	begin /* twiddle thumbs */ end
+				4:	begin
 						`EXEC_NEWCYCLE;
 						// do NOT increment PC!
 					end
 				endcase
 			end
-			`INSN_CALL: begin
+			`INSN_CALL,`INSN_CALLCC: begin
 				case (cycle)
 				0:	begin
 						`EXEC_INC_PC;
@@ -407,6 +444,14 @@ module GBZ80Core(
 					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;
@@ -423,6 +468,90 @@ module GBZ80Core(
 					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
 			default:
 				$stop;
 			endcase
@@ -587,6 +716,28 @@ module GBZ80Core(
 							  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;
@@ -614,11 +765,50 @@ module GBZ80Core(
 							  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,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)
@@ -629,20 +819,22 @@ module GBZ80Core(
 						{registers[`REG_SPH],registers[`REG_SPL]}-2;
 				endcase
 			end
-			`INSN_RET: begin
+			`INSN_RET,`INSN_RETCC: begin
 				case (cycle)
-				0:	begin /* type F */ end
-				1:	registers[`REG_PCL] <= rdata;
-				2:	registers[`REG_PCH] <= rdata;
-				3:	begin
+				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])	/* RETI */
+						if (opcode[4] && opcode[0])	/* RETI */
 							ie <= 1;
 					end
 				endcase
 			end
-			`INSN_CALL: begin
+			`INSN_CALL,`INSN_CALLCC: begin
 				case (cycle)
 				0:	begin /* type F */ end
 				1:	tmp <= rdata;	// tmp contains newpcl
@@ -656,6 +848,54 @@ module GBZ80Core(
 					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
 			default:
 				$stop;
 			endcase
@@ -663,175 +903,3 @@ module GBZ80Core(
 		end
 		endcase
 endmodule
-
-`timescale 1ns / 1ps
-module ROM(
-	input [15:0] address,
-	inout [7:0] data,
-	input clk,
-	input wr, rd);
-
-	reg [7:0] rom [2047:0];
-	initial $readmemh("rom.hex", rom);
-
-	wire decode = address[15:13] == 0;
-	wire [7:0] odata = rom[address[11:0]];
-	assign data = (rd && decode) ? odata : 8'bzzzzzzzz;
-	//assign data = rd ? odata : 8'bzzzzzzzz;
-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;
-	
-	always @(negedge clk)
-	begin
-		if (decode && rd)
-			odata <= ram[address[12:0]];
-		else if (decode && wr)
-			ram[address[12:0]] <= data;
-	end
-endmodule
-
-module Switches(
-	input [15:0] address,
-	inout [7:0] data,
-	input clk,
-	input wr, rd,
-	input [7:0] switches,
-	output reg [7:0] ledout);
-	
-	wire decode = address == 16'hFF51;
-	reg [7:0] odata;
-	wire idata = data;
-	assign data = (rd && decode) ? odata : 8'bzzzzzzzz;
-	
-	always @(negedge clk)
-	begin
-		if (decode && rd)
-			odata <= switches;
-		else if (decode && wr)
-			ledout <= data;
-	end
-endmodule
-
-module CoreTop(
-	input xtal,
-	input [1:0] switches,
-	output wire [7:0] leds,
-	output serio,
-	output wire [3:0] digits,
-	output wire [7:0] seven);
-	
-	wire clk;
-	//IBUFG ibuf (.O(clk), .I(iclk));
-	
-	CPUDCM dcm (.CLKIN_IN(xtal), .CLKFX_OUT(clk));
-
-	wire [15:0] addr;
-	wire [7:0] data;
-	wire wr, rd;
-	
-	wire [7:0] ledout;
-	assign leds = switches[1] ? (switches[0]?{rd,wr,addr[5:0]}:data[7:0])
-						: ledout;
-
-	GBZ80Core core(
-		.clk(clk),
-		.busaddress(addr),
-		.busdata(data),
-		.buswr(wr),
-		.busrd(rd));
-	
-	ROM rom(
-		.address(addr),
-		.data(data),
-		.clk(clk),
-		.wr(wr),
-		.rd(rd));
-	
-	AddrMon amon(
-    .addr(addr), 
-    .clk(clk), 
-    .digit(digits), 
-    .out(seven)
-    );
-	 
-	Switches sw(
-		.address(addr),
-		.data(data),
-		.clk(clk),
-		.wr(wr),
-		.rd(rd),
-		.ledout(ledout),
-		.switches(0)
-		);
-
-	UART nouart (
-    .clk(clk), 
-    .wr(wr), 
-    .rd(rd), 
-    .addr(addr), 
-    .data(data), 
-    .serial(serio)
-    );
-endmodule
-
-module TestBench();
-	reg clk = 0;
-	wire [15:0] addr;
-	wire [7:0] data;
-	wire wr, rd;
-	
-//	wire [7:0] leds;
-//	wire [7:0] switches;
-	
-	always #10 clk <= ~clk;
-	GBZ80Core core(
-		.clk(clk),
-		.busaddress(addr),
-		.busdata(data),
-		.buswr(wr),
-		.busrd(rd));
-	
-	ROM rom(
-		.clk(clk),
-		.address(addr),
-		.data(data),
-		.wr(wr),
-		.rd(rd));
-	
-//	InternalRAM ram(
-//		.address(addr),
-//		.data(data),
-//		.clk(clk),
-//		.wr(wr),
-//		.rd(rd));
-
-//	wire serio;
-//	UART uart(
-//		.addr(addr),
-//		.data(data),
-//		.clk(clk),
-//		.wr(wr),
-//		.rd(rd),
-//		.serial(serio));
-	
-//	Switches sw(
-//		.clk(clk),
-//		.address(addr),
-//		.data(data),
-//		.wr(wr),
-//		.rd(rd),
-//		.switches(switches),
-//		.leds(leds));
-endmodule