soot.coffi.Instruction_bytevar Maven / Gradle / Ivy

package soot.coffi;

/*-
 * #%L
 * Soot - a J*va Optimization Framework
 * %%
 * Copyright (C) 1997 Clark Verbrugge
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 2.1 of the
 * License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Lesser Public License for more details.
 * 
 * You should have received a copy of the GNU General Lesser Public
 * License along with this program.  If not, see
 * .
 * #L%
 */

/**
 * Instruction subclasses are used to represent parsed bytecode; each bytecode operation has a corresponding subclass of
 * Instruction.
 * 
 * Each subclass is derived from one of
 * 

 * Instruction
 * Instruction_noargs (an Instruction with no embedded arguments)
 * Instruction_byte (an Instruction with a single byte data argument)
 * Instruction_bytevar (a byte argument specifying a local variable)
 * Instruction_byteindex (a byte argument specifying a constant pool index)
 * Instruction_int (an Instruction with a single short data argument)
 * Instruction_intvar (a short argument specifying a local variable)
 * Instruction_intindex (a short argument specifying a constant pool index)
 * Instruction_intbranch (a short argument specifying a code offset)
 * Instruction_longbranch (an int argument specifying a code offset)
 * 
 *
 * @author Clark Verbrugge
 * @see Instruction
 * @see Instruction_noargs
 * @see Instruction_byte
 * @see Instruction_bytevar
 * @see Instruction_byteindex
 * @see Instruction_int
 * @see Instruction_intvar
 * @see Instruction_intindex
 * @see Instruction_intbranch
 * @see Instruction_longbranch
 * @see Instruction_Unknown
 */
class Instruction_bytevar extends Instruction implements Interface_OneIntArg {
  /**
   * arg_b needs to be short in order to contain all the possible values for an unsigned byte
   */
  public int arg_b;
  public boolean isWide;

  public Instruction_bytevar(byte c) {
    super(c);
  }

  public String toString(cp_info constant_pool[]) {
    return super.toString(constant_pool) + argsep + LOCALPREFIX + arg_b;
  }

  public int nextOffset(int curr) {
    return curr + 1 + ((isWide) ? 3 : 1);
  }

  public int parse(byte bc[], int index) {
    int indexbyte1 = (bc[index]) & 0xff;

    if (isWide) {
      int indexbyte2 = (bc[index + 1]) & 0xff;

      arg_b = (indexbyte1 << 8) | indexbyte2;

      return index + 2;
    } else {
      arg_b = indexbyte1;
      return index + 1;
    }
  }

  public int compile(byte bc[], int index) {
    bc[index++] = code;
    bc[index++] = (byte) arg_b;
    return index;
  }

  public int getIntArg() {
    return arg_b;
  }
}