Cleanups to make code nicer looking. ALU subtraction fixes.

[fpgaboy.git] / insn_pop_reg.v

`ifdef EXECUTE
	`INSN_POP_reg: begin	/* POP is 12 cycles! */
		case (cycle)
		0:	begin
				rd <= 1;
				address <= {registers[`REG_SPH],registers[`REG_SPL]};
			end
		1:	begin
				rd <= 1;
				address <= {registers[`REG_SPH],registers[`REG_SPL]} + 1;
			end
		2:	begin
				`EXEC_NEWCYCLE;
				`EXEC_INC_PC;
			end
		endcase
	end
`endif

`ifdef WRITEBACK
	`INSN_POP_reg: begin	/* POP is 12 cycles! */
		case (cycle)
		0:	begin end
		1:	begin
				case (opcode[5:4])
				`INSN_stack_AF:	registers[`REG_F] <= rdata;
				`INSN_stack_BC:	registers[`REG_C] <= rdata;
				`INSN_stack_DE:	registers[`REG_E] <= rdata;
				`INSN_stack_HL:	registers[`REG_L] <= rdata;
				endcase
			end
		2:	begin
				case (opcode[5:4])
				`INSN_stack_AF:	registers[`REG_A] <= rdata;
				`INSN_stack_BC:	registers[`REG_B] <= rdata;
				`INSN_stack_DE:	registers[`REG_D] <= rdata;
				`INSN_stack_HL:	registers[`REG_H] <= rdata;
				endcase
				{registers[`REG_SPH],registers[`REG_SPL]} <=
					{registers[`REG_SPH],registers[`REG_SPL]} + 2;
			end
		endcase
	end
`endif