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/*
* @(#)Instruction.java
*
* Revisions and updates (c) 2022-2023 Sandy Brownlee. alexander.brownlee@stir.ac.uk
*
* Original release:
*
* Copyright (C) 1999, 2003 D.A. Watt and D.F. Brown
* Dept. of Computing Science, University of Glasgow, Glasgow G12 8QQ Scotland
* and School of Computer and Math Sciences, The Robert Gordon University,
* St. Andrew Street, Aberdeen AB25 1HG, Scotland.
* All rights reserved.
*
* This software is provided free for educational use only. It may
* not be used for commercial purposes without the prior written permission
* of the authors.
*/
package triangle.abstractMachine;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.IOException;
public class Instruction {
// Java has no type synonyms, so the following representations are
// assumed:
//
// type
// OpCode = 0..15; {4 bits unsigned}
// Length = 0..255; {8 bits unsigned}
// Operand = -32767..+32767; {16 bits signed}
// Represents TAM instructions.
final OpCode opCode;
final Register register;
final int length;
int operand; // Not final to allow for patching jump address
public Instruction(OpCode opcode, Register register, int length, int operand) {
this.opCode = opcode;
this.register = register;
this.length = length;
this.operand = operand;
}
public void setOperand(int operand) {
this.operand = operand;
}
public void write(DataOutputStream output) throws IOException {
output.writeInt(opCode.ordinal());
output.writeInt(register.ordinal());
output.writeInt(length);
output.writeInt(operand);
}
public static Instruction read(DataInputStream input) throws IOException {
try {
var opCode = OpCode.values()[input.readInt()];
var register = Register.values()[input.readInt()];
var length = input.readInt();
var operand = input.readInt();
return new Instruction(opCode, register, length, operand);
} catch (EOFException s) {
return null;
}
}
}