in src/main/java/org/apache/bcel/classfile/Utility.java [284:537]
public static String codeToString(final ByteSequence bytes, final ConstantPool constantPool, final boolean verbose) throws IOException {
final short opcode = (short) bytes.readUnsignedByte();
int defaultOffset = 0;
final int low;
final int high;
final int npairs;
final int index;
final int vindex;
final int constant;
final int[] match;
final int[] jumpTable;
int noPadBytes = 0;
final int offset;
final StringBuilder buf = new StringBuilder(Const.getOpcodeName(opcode));
/*
* Special case: Skip (0-3) padding bytes, i.e., the following bytes are 4-byte-aligned
*/
if (opcode == Const.TABLESWITCH || opcode == Const.LOOKUPSWITCH) {
final int remainder = bytes.getIndex() % 4;
noPadBytes = remainder == 0 ? 0 : 4 - remainder;
for (int i = 0; i < noPadBytes; i++) {
final byte b;
if ((b = bytes.readByte()) != 0) {
System.err.println("Warning: Padding byte != 0 in " + Const.getOpcodeName(opcode) + ":" + b);
}
}
// Both cases have a field default_offset in common
defaultOffset = bytes.readInt();
}
switch (opcode) {
/*
* Table switch has variable length arguments.
*/
case Const.TABLESWITCH:
low = bytes.readInt();
high = bytes.readInt();
offset = bytes.getIndex() - 12 - noPadBytes - 1;
defaultOffset += offset;
buf.append("\tdefault = ").append(defaultOffset).append(", low = ").append(low).append(", high = ").append(high).append("(");
jumpTable = new int[high - low + 1];
for (int i = 0; i < jumpTable.length; i++) {
jumpTable[i] = offset + bytes.readInt();
buf.append(jumpTable[i]);
if (i < jumpTable.length - 1) {
buf.append(", ");
}
}
buf.append(")");
break;
/*
* Lookup switch has variable length arguments.
*/
case Const.LOOKUPSWITCH: {
npairs = bytes.readInt();
offset = bytes.getIndex() - 8 - noPadBytes - 1;
match = new int[npairs];
jumpTable = new int[npairs];
defaultOffset += offset;
buf.append("\tdefault = ").append(defaultOffset).append(", npairs = ").append(npairs).append(" (");
for (int i = 0; i < npairs; i++) {
match[i] = bytes.readInt();
jumpTable[i] = offset + bytes.readInt();
buf.append("(").append(match[i]).append(", ").append(jumpTable[i]).append(")");
if (i < npairs - 1) {
buf.append(", ");
}
}
buf.append(")");
}
break;
/*
* Two address bytes + offset from start of byte stream form the jump target
*/
case Const.GOTO:
case Const.IFEQ:
case Const.IFGE:
case Const.IFGT:
case Const.IFLE:
case Const.IFLT:
case Const.JSR:
case Const.IFNE:
case Const.IFNONNULL:
case Const.IFNULL:
case Const.IF_ACMPEQ:
case Const.IF_ACMPNE:
case Const.IF_ICMPEQ:
case Const.IF_ICMPGE:
case Const.IF_ICMPGT:
case Const.IF_ICMPLE:
case Const.IF_ICMPLT:
case Const.IF_ICMPNE:
buf.append("\t\t#").append(bytes.getIndex() - 1 + bytes.readShort());
break;
/*
* 32-bit wide jumps
*/
case Const.GOTO_W:
case Const.JSR_W:
buf.append("\t\t#").append(bytes.getIndex() - 1 + bytes.readInt());
break;
/*
* Index byte references local variable (register)
*/
case Const.ALOAD:
case Const.ASTORE:
case Const.DLOAD:
case Const.DSTORE:
case Const.FLOAD:
case Const.FSTORE:
case Const.ILOAD:
case Const.ISTORE:
case Const.LLOAD:
case Const.LSTORE:
case Const.RET:
if (wide) {
vindex = bytes.readUnsignedShort();
wide = false; // Clear flag
} else {
vindex = bytes.readUnsignedByte();
}
buf.append("\t\t%").append(vindex);
break;
/*
* Remember wide byte which is used to form a 16-bit address in the following instruction. Relies on that the method is
* called again with the following opcode.
*/
case Const.WIDE:
wide = true;
buf.append("\t(wide)");
break;
/*
* Array of basic type.
*/
case Const.NEWARRAY:
buf.append("\t\t<").append(Const.getTypeName(bytes.readByte())).append(">");
break;
/*
* Access object/class fields.
*/
case Const.GETFIELD:
case Const.GETSTATIC:
case Const.PUTFIELD:
case Const.PUTSTATIC:
index = bytes.readUnsignedShort();
buf.append("\t\t").append(constantPool.constantToString(index, Const.CONSTANT_Fieldref)).append(verbose ? " (" + index + ")" : "");
break;
/*
* Operands are references to classes in constant pool
*/
case Const.NEW:
case Const.CHECKCAST:
buf.append("\t");
index = bytes.readUnsignedShort();
buf.append("\t<").append(constantPool.constantToString(index, Const.CONSTANT_Class)).append(">").append(verbose ? " (" + index + ")" : "");
break;
case Const.INSTANCEOF:
index = bytes.readUnsignedShort();
buf.append("\t<").append(constantPool.constantToString(index, Const.CONSTANT_Class)).append(">").append(verbose ? " (" + index + ")" : "");
break;
/*
* Operands are references to methods in constant pool
*/
case Const.INVOKESPECIAL:
case Const.INVOKESTATIC:
index = bytes.readUnsignedShort();
final Constant c = constantPool.getConstant(index);
// With Java8 operand may be either a CONSTANT_Methodref
// or a CONSTANT_InterfaceMethodref. (markro)
buf.append("\t").append(constantPool.constantToString(index, c.getTag())).append(verbose ? " (" + index + ")" : "");
break;
case Const.INVOKEVIRTUAL:
index = bytes.readUnsignedShort();
buf.append("\t").append(constantPool.constantToString(index, Const.CONSTANT_Methodref)).append(verbose ? " (" + index + ")" : "");
break;
case Const.INVOKEINTERFACE:
index = bytes.readUnsignedShort();
final int nargs = bytes.readUnsignedByte(); // historical, redundant
buf.append("\t").append(constantPool.constantToString(index, Const.CONSTANT_InterfaceMethodref)).append(verbose ? " (" + index + ")\t" : "")
.append(nargs).append("\t").append(bytes.readUnsignedByte()); // Last byte is a reserved space
break;
case Const.INVOKEDYNAMIC:
index = bytes.readUnsignedShort();
buf.append("\t").append(constantPool.constantToString(index, Const.CONSTANT_InvokeDynamic)).append(verbose ? " (" + index + ")\t" : "")
.append(bytes.readUnsignedByte()) // Thrid byte is a reserved space
.append(bytes.readUnsignedByte()); // Last byte is a reserved space
break;
/*
* Operands are references to items in constant pool
*/
case Const.LDC_W:
case Const.LDC2_W:
index = bytes.readUnsignedShort();
buf.append("\t\t").append(constantPool.constantToString(index, constantPool.getConstant(index).getTag()))
.append(verbose ? " (" + index + ")" : "");
break;
case Const.LDC:
index = bytes.readUnsignedByte();
buf.append("\t\t").append(constantPool.constantToString(index, constantPool.getConstant(index).getTag()))
.append(verbose ? " (" + index + ")" : "");
break;
/*
* Array of references.
*/
case Const.ANEWARRAY:
index = bytes.readUnsignedShort();
buf.append("\t\t<").append(compactClassName(constantPool.getConstantString(index, Const.CONSTANT_Class), false)).append(">")
.append(verbose ? " (" + index + ")" : "");
break;
/*
* Multidimensional array of references.
*/
case Const.MULTIANEWARRAY: {
index = bytes.readUnsignedShort();
final int dimensions = bytes.readUnsignedByte();
buf.append("\t<").append(compactClassName(constantPool.getConstantString(index, Const.CONSTANT_Class), false)).append(">\t").append(dimensions)
.append(verbose ? " (" + index + ")" : "");
}
break;
/*
* Increment local variable.
*/
case Const.IINC:
if (wide) {
vindex = bytes.readUnsignedShort();
constant = bytes.readShort();
wide = false;
} else {
vindex = bytes.readUnsignedByte();
constant = bytes.readByte();
}
buf.append("\t\t%").append(vindex).append("\t").append(constant);
break;
default:
if (Const.getNoOfOperands(opcode) > 0) {
for (int i = 0; i < Const.getOperandTypeCount(opcode); i++) {
buf.append("\t\t");
switch (Const.getOperandType(opcode, i)) {
case Const.T_BYTE:
buf.append(bytes.readByte());
break;
case Const.T_SHORT:
buf.append(bytes.readShort());
break;
case Const.T_INT:
buf.append(bytes.readInt());
break;
default: // Never reached
throw new IllegalStateException("Unreachable default case reached!");
}
}
}
}
return buf.toString();
}