jminusminus

Class CLInstruction

java.lang.Object

jminusminus.CLInstruction

Direct Known Subclasses:

CLArithmeticInstruction, CLArrayInstruction, CLBitInstruction, CLComparisonInstruction, CLConversionInstruction, CLFieldInstruction, CLFlowControlInstruction, CLLoadStoreInstruction, CLMethodInstruction, CLMiscInstruction, CLObjectInstruction, CLStackInstruction

abstract class CLInstruction
extends Object

Representation of a JVM instruction. It stores the opcode and mnenomic of an instruction, its operand count (DYNAMIC if the instruction has variable number operands), pc (location counter), stack units (words produced - words consumed from the operand stack), and local variable index (IRRELEVANT if the instruction does not operate on local variables).

Field Summary

Fields

Modifier and Type	Field and Description
static CLInsInfo[]	instructionInfo For each JVM instruction, this array stores its opcode, mnemonic, number of operands (DYNAMIC for instructions with variable attribute count), local variable index (IRRELEVANT where not applicable), stack units, and instruction category.
protected int	localVariableIndex Index of the local variable that this instruction refers to; applies only to instructions that operate on local variables.
protected String	mnemonic Mnemonic for this instruction.
protected int	opcode Opcode for this instruction.
protected int	operandCount Number of operands for this instruction; determined statically for all instructions except TABLESWITCH and LOOKUPSWITCH.
protected int	pc Location counter; index of this instruction within the code array of a method.
protected int	stackUnits Stack units; words produced - words consumed from the operand stack by this instruction.

Constructor Summary

Constructors

Constructor and Description
CLInstruction()

Method Summary

Methods

Modifier and Type	Method and Description
protected int	byteAt(int i, int byteNum) Return the byte from i at position byteNum.
static boolean	isValid(int opcode) Return true if the opcode is valid; false otherwise.
int	localVariableIndex() Return the local variable index for this instruction.
String	mnemonic() Return the mnemonic for this instruction.
int	opcode() Return the opcode for this instruction.
int	operandCount() Return the number of operands for this instruction.
int	pc() Return the pc for this instruction.
int	stackUnits() Return the stack units for this instruction.
abstract ArrayList<Integer>	toBytes() Return the bytecode for this instruction.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

opcode

protected int opcode

Opcode for this instruction.

mnemonic

protected String mnemonic

Mnemonic for this instruction.

operandCount

protected int operandCount

Number of operands for this instruction; determined statically for all instructions except TABLESWITCH and LOOKUPSWITCH.

pc

protected int pc

Location counter; index of this instruction within the code array of a method.

stackUnits

protected int stackUnits

Stack units; words produced - words consumed from the operand stack by this instruction.

localVariableIndex

protected int localVariableIndex

Index of the local variable that this instruction refers to; applies only to instructions that operate on local variables.

instructionInfo

public static final CLInsInfo[] instructionInfo

For each JVM instruction, this array stores its opcode, mnemonic, number of operands (DYNAMIC for instructions with variable attribute count), local variable index (IRRELEVANT where not applicable), stack units, and instruction category. For example, for IMUL, these parameters are IMUL, "imul", 0, IRRELEVANT, -1, ARITHMETIC1.

Constructor Detail

CLInstruction

CLInstruction()

Method Detail

isValid

public static boolean isValid(int opcode)

Return true if the opcode is valid; false otherwise.

Parameters:

opcode - instruction opcode.

Returns:

true or false.

opcode

public int opcode()

Return the opcode for this instruction.

Returns:

the opcode.

mnemonic

public String mnemonic()

Return the mnemonic for this instruction.

Returns:

the mnemonic.

operandCount

public int operandCount()

Return the number of operands for this instruction.

Returns:

number of operands.

pc

public int pc()

Return the pc for this instruction.

Returns:

the pc.

stackUnits

public int stackUnits()

Return the stack units for this instruction.

Returns:

the stack units.

localVariableIndex

public int localVariableIndex()

Return the local variable index for this instruction.

Returns:

the local variable index.

toBytes

public abstract ArrayList<Integer> toBytes()

Return the bytecode for this instruction.

Returns:

bytecode.

byteAt

protected int byteAt(int i,
         int byteNum)

Return the byte from i at position byteNum.

Parameters:

i - number whose individual byte is required.

byteNum - the byte to return; 1 (lower) - 4 (higher) instructions.

Returns:

the byte at the specified position.