X-Git-Url: http://git.joshuawise.com/fpgaboy.git/blobdiff_plain/2f55f80959676970f85a02a9a968668ae2113dda..bc75fc673a7453cb5b9077d70695d3525d13366d:/GBZ80Core.v?ds=inline

diff --git a/GBZ80Core.v b/GBZ80Core.v
index 9bc60a8..053df4a 100644
--- a/GBZ80Core.v
+++ b/GBZ80Core.v
@@ -1,169 +1,370 @@
-`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_imm8_reg_A		3'b111
-`define INSN_imm8_reg_B		3'b000
-`define INSN_imm8_reg_C		3'b001
-`define INSN_imm8_reg_D		3'b010
-`define INSN_imm8_reg_E		3'b011
-`define INSN_imm8_reg_H		3'b100
-`define INSN_imm8_reg_L		3'b101
-`define INSN_imm8_reg_dHL	3'b110
+`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_ADD_HL		9'b000xx1001
+
+`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
+`define INSN_reg_D		3'b010
+`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_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, output reg irqack, 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, 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 */
+		`ifdef isim
+			|| (busaddress === 16'hxxxx) /* To avoid simulator glomulation. */
+		`endif
+			;
+		
+	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'b0;
+	assign bus1rd = (bus == 1) ? busrd : 1'b0;
+	assign bus0wr = (bus == 0) ? buswr : 1'b0;
+	assign bus1wr = (bus == 1) ? buswr : 1'b0;
+
+	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;
+		irqack <= 0;
 	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) begin
+					buswdata <= wdata;
+					if (address == 16'hFF50)
+						bootstrap_enb <= 0;
+				end
+			end
+		end
+		`STATE_DECODE: begin	/* Make sure this only happens for one clock. */
+			buswr <= 0;
+			busrd <= 0;
+		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;
+				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
-				if (rd) rdata <= busdata;
-			buswr <= 0;
-			busrd <= 0;
+			end else begin
+				if (rd) rdata <= busdata;	/* Still valid because peripherals are now expected to keep it held valid. */
+				cycle <= cycle + 1;
+			end
+			if (iedelay) begin
+				ie <= 1;
+				iedelay <= 0;
+			end
+			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
-`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
+		`ifdef isim
+			if (opcode[7:0] === 8'bxxxxxxxx)
+				$stop;
+		`endif
 			casex (opcode)
-			`INSN_LD_reg_imm8: begin
-				case (cycle)
-				0:	begin
-						`EXEC_INC_PC;
-						`EXEC_NEXTADDR_PCINC;
-						newcycle <= 0;
-						rd <= 1;
-					end
-				1: begin
-						`EXEC_INC_PC;
-						if (opcode[5:3] == `INSN_imm8_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
+			`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_imm8_reg_A:	begin registers[`REG_A] <= rdata; cycle <= 0; end
-						`INSN_imm8_reg_B:	begin registers[`REG_B] <= rdata; cycle <= 0; end
-						`INSN_imm8_reg_C:	begin registers[`REG_C] <= rdata; cycle <= 0; end
-						`INSN_imm8_reg_D:	begin registers[`REG_D] <= rdata; cycle <= 0; end
-						`INSN_imm8_reg_E:	begin registers[`REG_E] <= rdata; cycle <= 0; end
-						`INSN_imm8_reg_H:	begin registers[`REG_H] <= rdata; cycle <= 0; end
-						`INSN_imm8_reg_L:	begin registers[`REG_L] <= rdata; cycle <= 0; end
-						`INSN_imm8_reg_dHL:	cycle <= 2;
-						endcase
-					2: cycle <= 0;
-					endcase
+			`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