Start refactoring instructions.

[fpgaboy.git] / insn_push_reg.v

`ifdef EXECUTE
	`INSN_PUSH_reg: begin	/* PUSH is 16 cycles! */
		case (cycle)
		0:	begin
				wr <= 1;
				address <= {registers[`REG_SPH],registers[`REG_SPL]}-1;
				case (opcode[5:4])
				`INSN_stack_AF:	wdata <= registers[`REG_A];
				`INSN_stack_BC:	wdata <= registers[`REG_B];
				`INSN_stack_DE:	wdata <= registers[`REG_D];
				`INSN_stack_HL:	wdata <= registers[`REG_H];
				endcase
			end
		1:	begin
				wr <= 1;
				address <= {registers[`REG_SPH],registers[`REG_SPL]}-2;
				case (opcode[5:4])
				`INSN_stack_AF:	wdata <= registers[`REG_F];
				`INSN_stack_BC:	wdata <= registers[`REG_C];
				`INSN_stack_DE:	wdata <= registers[`REG_E];
				`INSN_stack_HL:	wdata <= registers[`REG_L];
				endcase
			end
		2:	begin /* Twiddle thumbs. */ end
		3:	begin
				`EXEC_NEWCYCLE;
				`EXEC_INC_PC;
			end
		endcase
	end
`endif

`ifdef WRITEBACK
	`INSN_PUSH_reg: begin	/* PUSH is 16 cycles! */
		case (cycle)
		0:	begin /* type F */ end
		1:	begin /* type F */ end
		2:	begin /* type F */ end
		3:	{registers[`REG_SPH],registers[`REG_SPL]} <=
				{registers[`REG_SPH],registers[`REG_SPL]} - 2;
		endcase
	end
`endif