X-Git-Url: http://git.joshuawise.com/fpgaboy.git/blobdiff_plain/241c995cb7db3feeeb57d11625dc8fd34c166d82..9a1369ad8a7a1178b06cf2a37bf0530b818e7f3e:/GBZ80Core.v

diff --git a/GBZ80Core.v b/GBZ80Core.v
index 968cd26..1aaa01c 100644
--- a/GBZ80Core.v
+++ b/GBZ80Core.v
@@ -29,7 +29,11 @@
 `define INSN_LD_reg_imm16	8'b00xx0001
 `define INSN_LD_SP_HL		8'b11111001
 `define INSN_PUSH_reg		8'b11xx0101
-`define INSN_POP_reg		8'b11xx0001
+`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_reg_A		3'b111
 `define INSN_reg_B		3'b000
 `define INSN_reg_C		3'b001
@@ -46,6 +50,15 @@
 `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?
+
 module GBZ80Core(
 	input clk,
 	output reg [15:0] busaddress,	/* BUS_* is latched on STATE_FETCH. */
@@ -266,6 +279,60 @@ module GBZ80Core(
 					end
 				endcase
 			end
+			`INSN_LDH_AC: begin
+				case (cycle)
+				0:	begin
+						address <= {8'hFF,registers[`REG_C]};
+						if (opcode[4]) begin	// LD A,(C)
+							rd <= 1;
+						end else begin
+							wr <= 1;
+							wdata <= registers[`REG_A];
+						end
+					end
+				1: begin
+						`EXEC_NEWCYCLE;
+						`EXEC_INC_PC;
+					end
+				endcase
+			end
+			`INSN_LDx_AHL: begin
+				case (cycle)
+				0: begin
+						address <= {registers[`REG_H],registers[`REG_L]};
+						if (opcode[3]) begin	// LDx A, (HL)
+							rd <= 1;
+						end else begin
+							wr <= 1;
+							wdata <= registers[`REG_A];
+						end
+					end
+				1:	begin
+						`EXEC_NEWCYCLE;
+						`EXEC_INC_PC;
+					end
+				endcase
+			end
+			`INSN_ALU8: begin
+				if ((opcode[2:0] == `INSN_reg_dHL) && (cycle == 0)) begin
+					// fffffffff fuck your shit, read from (HL) :(
+					rd <= 1;
+					address <= {registers[`REG_H], registers[`REG_L]};
+				end else begin
+					`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
+					endcase
+				end
+			end
 			default:
 				$stop;
 			endcase
@@ -405,7 +472,91 @@ module GBZ80Core(
 						cycle <= 0;
 					end
 				endcase
-			end	
+			end
+			`INSN_LDH_AC: begin
+				case (cycle)
+				0:	cycle <= 1;
+				1: begin
+						cycle <= 0;
+						if (opcode[4])
+							registers[`REG_A] <= rdata;
+					end
+				endcase
+			end
+			`INSN_LDx_AHL: begin
+				case (cycle)
+				0:	cycle <= 1;
+				1:	begin
+						cycle <= 0;
+						if (opcode[3])
+							registers[`REG_A] <= rdata;
+						{registers[`REG_H],registers[`REG_L]} <=
+							opcode[4] ? // if set, LDD, else LDI
+							({registers[`REG_H],registers[`REG_L]} - 1) :
+							({registers[`REG_H],registers[`REG_L]} + 1);
+					end
+				endcase
+			end
+			`INSN_ALU8: begin
+				if ((opcode[2:0] == `INSN_reg_dHL) && (cycle == 0)) begin
+					/* Sit on our asses. */
+					cycle <= 1;
+				end else begin		/* Actually do the computation! */
+					case (opcode[5:3])
+					`INSN_alu_ADD: begin
+						registers[`REG_A] <=
+							registers[`REG_A] + tmp;
+						registers[`REG_F] <=
+							{ /* Z */ ((registers[`REG_A] + tmp) == 0) ? 1'b1 : 1'b0,
+							  /* N */ 0,
+							  /* 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_ADC: 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 */ 0,
+							  /* 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;
+						registers[`REG_F] <=
+							{ /* Z */ ((registers[`REG_A] & tmp) == 0) ? 1'b1 : 1'b0,
+							  0,1,0,
+							  registers[`REG_F][3:0]
+							};
+					end
+					`INSN_alu_OR: begin
+						registers[`REG_A] <=
+							registers[`REG_A] | tmp;
+						registers[`REG_F] <=
+							{ /* Z */ ((registers[`REG_A] | tmp) == 0) ? 1'b1 : 1'b0,
+							  0,0,0,
+							  registers[`REG_F][3:0]
+							};
+					end
+					`INSN_alu_XOR: begin
+						registers[`REG_A] <=
+							registers[`REG_A] ^ tmp;
+						registers[`REG_F] <=
+							{ /* Z */ ((registers[`REG_A] ^ tmp) == 0) ? 1'b1 : 1'b0,
+							  0,0,0,
+							  registers[`REG_F][3:0]
+							};
+					end
+					default:
+						$stop;
+					endcase
+				end
+			end
 			endcase
 			state <= `STATE_FETCH;
 		end