BytecodeStream (Jikes RVM API)

java.lang.Object
- org.jikesrvm.classloader.BytecodeStream

```
public class BytecodeStream
extends Object
```
Provides minimal abstraction layer to a stream of bytecodes from the code attribute of a method.

Field Summary

Fields
Modifier and Type	Field and Description
`private int`	`bcIndex`
`private int`	`bcLength`
`private byte[]`	`bcodes`
`private NormalMethod`	`method`
`private int`	`opcode`
`private boolean`	`wide`

Constructor Summary

Constructors
Constructor and Description

BytecodeStream(NormalMethod m, byte[] bc)

Constructors
Constructor and Description
`BytecodeStream(NormalMethod m, byte[] bc)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`alignInvokeInterface()` Skips the extra stuff after an invokeinterface instruction.
`void`	`alignSwitch()` Skips the padding of a switch instruction.
`int`	`computeLookupSwitchOffset(int value, int num)` Returns the offset for a given value of the lookupswitch (as a signed int) or 0 if the value is not in the table..
`int`	`computeTableSwitchOffset(int value, int low, int high)` Returns the offset for a given value of the tableswitch (as a signed int) or 0 if the value is out of range..
`int`	`getArrayDimension()` Returns the dimension of the array (as an unsigned byte).
`int`	`getArrayElementType()` Returns the element type (primitive) of the array (as an unsigned byte).
`int`	`getBranchOffset()` Returns the offset of the branch (as a signed short).
`int`	`getByteValue()` Returns a signed byte value Used for bipush
`int`	`getConstantIndex()` Returns the constant pool index of a constant (as an unsigned byte).
`byte`	`getConstantType(int index)` Returns the type of a constant at a given constant pool index (as a byte).
`RVMClass`	`getDeclaringClass()` Returns the declaring class that this bytecode stream is from
`int`	`getDefaultSwitchOffset()` Returns the default offset of the switch (as a signed int).
`double`	`getDoubleConstant(int index)` Returns the constant at a given constant pool index (as a double).
`FieldReference`	`getFieldReference()` Returns a reference to a field.
`FieldReference`	`getFieldReference(int[] constantPool)` Returns a reference to a field, for use prior to the class being loaded.
`float`	`getFloatConstant(int index)` Returns the constant at a given constant pool index (as a float).
`int`	`getHighSwitchValue()` Returns the highest value of the tableswitch (as a signed int).
`int`	`getIncrement()` Returns an increment value (as a signed byte).
`int`	`getIntConstant(int index)` Returns the constant at a given constant pool index (as an int).
`int`	`getLocalNumber()` Returns the number of the local (as an unsigned byte) Used for iload, lload, fload, dload, aload, istore, lstore, fstore, dstore, astore, iinc, ret
`long`	`getLongConstant(int index)` Returns the constant at a given constant pool index (as a long).
`int`	`getLookupSwitchOffset(int num)` Returns the numbered offset of the lookupswitch (as a signed int).
`int`	`getLookupSwitchValue(int num)` Returns the numbered value of the lookupswitch (as a signed int).
`int`	`getLowSwitchValue()` Returns the lowest value of the tableswitch (as a signed int).
`NormalMethod`	`getMethod()` Returns the method that this bytecode stream is from
`MethodReference`	`getMethodReference()` Returns a reference to a field.
`MethodReference`	`getMethodReference(int[] constantPool)` Returns a reference to a field, for use prior to the class being loaded.
`TypeReference`	`getObjectArrayType()` Returns the type of the object array (as a RVMType).
`RVMType`	`getObjectArrayType(RVMType klass)` Returns the type of the array of given object type (as a RVMType).
`int`	`getOpcode()` Returns the opcode of the current instruction in the sequence.
`RVMType`	`getPrimitiveArrayType()` Returns the type of the primitive array (as a RVMType).
`RVMArray`	`getPrimitiveArrayType(int etype)` Returns the type of the array of given primitive type (as a RVMType).
`int`	`getShortValue()` Returns a signed short value Used for sipush
`private int`	`getSignedInt(int index)`
`String`	`getStringConstant(int index)` Returns the constant at a given constant pool index (as a String).
`int`	`getSwitchLength()` Returns the number of match-offset pairs in the lookupswitch (as a signed int).
`int`	`getTableSwitchOffset(int num)` Returns the numbered offset of the tableswitch (as a signed int).
`TypeReference`	`getTypeReference()` Returns the type reference (as a RVMType).
`private int`	`getUnsignedByte(int index)`
`int`	`getWideBranchOffset()` Returns the wide offset of the branch (as a signed int).
`int`	`getWideConstantIndex()` Returns the wide constant pool index of a constant (as an unsigned short).
`int`	`getWideIncrement()` Returns an increment value (as a signed short).
`int`	`getWideLocalNumber()` Returns the wide number of the local (as an unsigned short) Used for iload, lload, fload, dload, aload, istore, lstore, fstore, dstore, astore, iinc prefixed by wide
`int`	`getWideOpcode()` Returns the opcode of the wide instruction.
`boolean`	`hasMoreBytecodes()` Does the stream have more bytecodes in it?
`int`	`index()` Returns the current bytecode index
`boolean`	`isWide()` Are we currently processing a wide instruction?
`int`	`length()` Returns the length of the bytecode stream Returns 0 if the method doesn't have any bytecodes (i.e. is abstract or native)
`int`	`nextInstruction()` Sets up the next instruction in the sequence
`int`	`nextPseudoInstruction()`
`int`	`peekNextOpcode()` Returns the opcode of the next instruction in the sequence without advancing to it
`int`	`readIntConst()`
`private long`	`readLong()`
`long`	`readLongConst()`
`private byte`	`readSignedByte()`
`private int`	`readSignedInt()`
`private int`	`readSignedShort()`
`private int`	`readUnsignedByte()`
`private int`	`readUnsignedShort()`
`void`	`reset()` Resets the stream to the beginning
`void`	`reset(int index)` Resets the stream to a given position Use with caution
`void`	`skipInstruction()` Skips the current instruction
`void`	`skipInstruction(int opcode, boolean wide)` Skips the current instruction (without using the opcode field) A slightly optimized version of skipInstruction()
`void`	`skipLookupSwitchPairs(int num)` Skips the match-offset pairs of a lookupswitch instruction.
`private void`	`skipSpecialInstruction(int opcode)`
`void`	`skipTableSwitchOffsets(int num)` Skips the offsets of a tableswitch instruction.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - method
```
private final NormalMethod method
```
  - bcLength
```
private final int bcLength
```
  - bcodes
```
private final byte[] bcodes
```
  - bcIndex
```
private int bcIndex
```
  - opcode
```
private int opcode
```
  - wide
```
private boolean wide
```
- Constructor Detail
  - BytecodeStream
```
public BytecodeStream(NormalMethod m,
                      byte[] bc)
```
    Parameters:
    
    m - the method containing the bytecodes
    
    bc - the array of bytecodes
- Method Detail
  - getMethod
```
public final NormalMethod getMethod()
```
    Returns the method that this bytecode stream is from
    
    Returns:
    
    method
  - getDeclaringClass
```
public final RVMClass getDeclaringClass()
```
    Returns the declaring class that this bytecode stream is from
    
    Returns:
    
    method
  - length
```
public final int length()
```
    Returns the length of the bytecode stream Returns 0 if the method doesn't have any bytecodes (i.e. is abstract or native)
    
    Returns:
    
    bytecode stream length
  - index
```
public final int index()
```
    Returns the current bytecode index
    
    Returns:
    
    the current bytecode index
  - reset
```
public final void reset()
```
    Resets the stream to the beginning
    
    See Also:
    
    reset(int)
  - reset
```
public final void reset(int index)
```
    Resets the stream to a given position Use with caution
    
    Parameters:
    
    index - the position to reset the stream to
    
    See Also:
    
    reset()
  - hasMoreBytecodes
```
public final boolean hasMoreBytecodes()
```
    Does the stream have more bytecodes in it?
    
    Returns:
    
    whether there are more bytecodes
  - peekNextOpcode
```
public final int peekNextOpcode()
```
    Returns the opcode of the next instruction in the sequence without advancing to it
    
    Returns:
    
    the opcode of the next instruction
    
    See Also:
    
    nextInstruction()
  - nextInstruction
```
public final int nextInstruction()
```
    Sets up the next instruction in the sequence
    
    Returns:
    
    the opcode of the next instruction
    
    See Also:
    
    peekNextOpcode()
  - getOpcode
```
public final int getOpcode()
```
    Returns the opcode of the current instruction in the sequence.
    Note: if skipInstruction has been called, but nextInstruction has not, this method will return the opcode of the skipped instruction!
    
    Returns:
    
    the opcode of the current instruction
    
    See Also:
    
    nextInstruction(), isWide()
  - isWide
```
public final boolean isWide()
```
    Are we currently processing a wide instruction?
    
    Returns:
    
    true if current instruction is wide
    
    See Also:
    
    nextInstruction(), getOpcode()
  - skipInstruction
```
public final void skipInstruction()
```
    Skips the current instruction
    
    See Also:
    
    skipInstruction(int,boolean)
  - skipInstruction
```
public final void skipInstruction(int opcode,
                                  boolean wide)
```
    Skips the current instruction (without using the opcode field) A slightly optimized version of skipInstruction()
    
    Parameters:
    
    opcode - current opcode
    
    wide - whether current instruction follows wide
    
    See Also:
    
    skipInstruction()
  - getByteValue
```
public final int getByteValue()
```
    Returns a signed byte value Used for bipush
    
    Returns:
    
    signed byte value
  - getShortValue
```
public final int getShortValue()
```
    Returns a signed short value Used for sipush
    
    Returns:
    
    signed short value
  - getLocalNumber
```
public final int getLocalNumber()
```
    Returns the number of the local (as an unsigned byte) Used for iload, lload, fload, dload, aload, istore, lstore, fstore, dstore, astore, iinc, ret
    
    Returns:
    
    local number
    
    See Also:
    
    getWideLocalNumber()
  - getWideLocalNumber
```
public final int getWideLocalNumber()
```
    Returns the wide number of the local (as an unsigned short) Used for iload, lload, fload, dload, aload, istore, lstore, fstore, dstore, astore, iinc prefixed by wide
    
    Returns:
    
    wide local number
    
    See Also:
    
    getLocalNumber()
  - getIncrement
```
public final int getIncrement()
```
    Returns an increment value (as a signed byte).
    Used for iinc
    
    Returns:
    
    increment
    
    See Also:
    
    getWideIncrement()
  - getWideIncrement
```
public final int getWideIncrement()
```
    Returns an increment value (as a signed short).
    Used for iinc prefixed by wide
    
    Returns:
    
    wide increment
    
    See Also:
    
    getIncrement()
  - getBranchOffset
```
public final int getBranchOffset()
```
    Returns the offset of the branch (as a signed short).
    Used for if<cond>, ificmp<cond>, ifacmp<cond>, goto, jsr
    
    Returns:
    
    branch offset
    
    See Also:
    
    getWideBranchOffset()
  - getWideBranchOffset
```
public final int getWideBranchOffset()
```
    Returns the wide offset of the branch (as a signed int).
    Used for goto_w, jsr_w
    
    Returns:
    
    wide branch offset
    
    See Also:
    
    getBranchOffset()
  - alignSwitch
```
public final void alignSwitch()
```
    Skips the padding of a switch instruction.
    Used for tableswitch, lookupswitch
  - getDefaultSwitchOffset
```
public final int getDefaultSwitchOffset()
```
    Returns the default offset of the switch (as a signed int).
    Used for tableswitch, lookupswitch
    
    Returns:
    
    default switch offset
  - getLowSwitchValue
```
public final int getLowSwitchValue()
```
    Returns the lowest value of the tableswitch (as a signed int).
    Used for tableswitch
    
    Returns:
    
    lowest switch value
    
    See Also:
    
    getHighSwitchValue()
  - getHighSwitchValue
```
public final int getHighSwitchValue()
```
    Returns the highest value of the tableswitch (as a signed int).
    Used for tableswitch
    
    Returns:
    
    highest switch value
    
    See Also:
    
    getLowSwitchValue()
  - skipTableSwitchOffsets
```
public final void skipTableSwitchOffsets(int num)
```
    Skips the offsets of a tableswitch instruction.
    Used for tableswitch
    
    Parameters:
    
    num - the number of offsets to skip
    
    See Also:
    
    getTableSwitchOffset(int)
  - getTableSwitchOffset
```
public final int getTableSwitchOffset(int num)
```
    Returns the numbered offset of the tableswitch (as a signed int).
    Used for tableswitch.
    The "cursor" has to be positioned at the start of the offset table.
    NOTE: Will NOT advance cursor
    
    Parameters:
    
    num - the number of the offset to retrieve
    
    Returns:
    
    switch offset
  - computeTableSwitchOffset
```
public final int computeTableSwitchOffset(int value,
                                          int low,
                                          int high)
```
    Returns the offset for a given value of the tableswitch (as a signed int) or 0 if the value is out of range..
    Used for tableswitch.
    The "cursor" has to be positioned at the start of the offset table.
    NOTE: Will NOT advance cursor
    
    Parameters:
    
    value - the value to retrieve offset for
    
    low - the lowest value of the tableswitch
    
    high - the highest value of the tableswitch
    
    Returns:
    
    switch offset
  - getSwitchLength
```
public final int getSwitchLength()
```
    Returns the number of match-offset pairs in the lookupswitch (as a signed int).
    Used for lookupswitch
    
    Returns:
    
    number of switch pairs
  - skipLookupSwitchPairs
```
public final void skipLookupSwitchPairs(int num)
```
    Skips the match-offset pairs of a lookupswitch instruction.
    Used for lookupswitch
    
    Parameters:
    
    num - the number of match-offset pairs to skip
    
    See Also:
    
    getLookupSwitchValue(int), getLookupSwitchOffset(int)
  - getLookupSwitchOffset
```
public final int getLookupSwitchOffset(int num)
```
    Returns the numbered offset of the lookupswitch (as a signed int).
    Used for lookupswitch.
    The "cursor" has to be positioned at the start of the pair table.
    NOTE: Will NOT advance cursor
    
    Parameters:
    
    num - the number of the offset to retrieve
    
    Returns:
    
    switch offset
    
    See Also:
    
    getLookupSwitchValue(int)
  - getLookupSwitchValue
```
public final int getLookupSwitchValue(int num)
```
    Returns the numbered value of the lookupswitch (as a signed int).
    Used for lookupswitch.
    The "cursor" has to be positioned at the start of the pair table.
    NOTE: Will NOT advance cursor
    
    Parameters:
    
    num - the number of the value to retrieve
    
    Returns:
    
    switch value
    
    See Also:
    
    getLookupSwitchOffset(int)
  - computeLookupSwitchOffset
```
public final int computeLookupSwitchOffset(int value,
                                           int num)
```
    Returns the offset for a given value of the lookupswitch (as a signed int) or 0 if the value is not in the table..
    Used for lookupswitch.
    The "cursor" has to be positioned at the start of the offset table.
    NOTE: Will NOT advance cursor.
    WARNING: Uses LINEAR search.
    XXX Whoever has time on their hands can re-implement this as a binary search.
    
    Parameters:
    
    value - the value to retrieve offset for
    
    num - the number of match-offset pairs in the lookupswitch
    
    Returns:
    
    switch offset
  - getFieldReference
```
public final FieldReference getFieldReference()
```
    Returns a reference to a field.
    Used for getstatic, putstatic, getfield, putfield
    
    Returns:
    
    field reference
  - getFieldReference
```
public final FieldReference getFieldReference(int[] constantPool)
```
    Returns a reference to a field, for use prior to the class being loaded.
    Used for getstatic, putstatic, getfield, putfield
    
    Parameters:
    
    constantPool - the constant pool for the class
    
    Returns:
    
    field reference
  - getMethodReference
```
public final MethodReference getMethodReference()
```
    Returns a reference to a field.
    Used for invokevirtual, invokespecial, invokestatic, invokeinterface
    
    Returns:
    
    method reference
  - getMethodReference
```
public final MethodReference getMethodReference(int[] constantPool)
```
    Returns a reference to a field, for use prior to the class being loaded.
    Used for invokevirtual, invokespecial, invokestatic, invokeinterface
    
    Parameters:
    
    constantPool - the constant pool for the class
    
    Returns:
    
    method reference
  - alignInvokeInterface
```
public final void alignInvokeInterface()
```
    Skips the extra stuff after an invokeinterface instruction.
    Used for invokeinterface
  - getTypeReference
```
public final TypeReference getTypeReference()
```
    Returns the type reference (as a RVMType).
    Used for new, anewarray, checkcast, instanceof, multianewarray
    
    Returns:
    
    type reference
  - getArrayElementType
```
public final int getArrayElementType()
```
    Returns the element type (primitive) of the array (as an unsigned byte).
    Used for newarray
    
    Returns:
    
    array element type
    
    See Also:
    
    getPrimitiveArrayType(), getPrimitiveArrayType(int)
  - getPrimitiveArrayType
```
public final RVMArray getPrimitiveArrayType(int etype)
```
    Returns the type of the array of given primitive type (as a RVMType).
    Used for newarray
    
    Parameters:
    
    etype - element type
    
    Returns:
    
    array type
    
    See Also:
    
    getArrayElementType(), getPrimitiveArrayType()
  - getPrimitiveArrayType
```
public final RVMType getPrimitiveArrayType()
```
    Returns the type of the primitive array (as a RVMType).
    Used for newarray
    
    Returns:
    
    array type
    
    See Also:
    
    getArrayElementType(), getPrimitiveArrayType(int)
  - getObjectArrayType
```
public final RVMType getObjectArrayType(RVMType klass)
```
    Returns the type of the array of given object type (as a RVMType).
    Used for anewarray
    
    Parameters:
    
    klass - element type
    
    Returns:
    
    array type
    
    See Also:
    
    getTypeReference(), getObjectArrayType()
  - getObjectArrayType
```
public final TypeReference getObjectArrayType()
```
    Returns the type of the object array (as a RVMType).
    Used for anewarray
    
    Returns:
    
    array type
    
    See Also:
    
    getObjectArrayType(RVMType)
  - getArrayDimension
```
public final int getArrayDimension()
```
    Returns the dimension of the array (as an unsigned byte).
    Used for multianewarray
    
    Returns:
    
    array dimension
  - getWideOpcode
```
public final int getWideOpcode()
```
    Returns the opcode of the wide instruction.
    Used for wide.
    Can be one of iload, lload, fload, dload, aload, istore, lstore, fstore, dstore, astore, iinc
    
    Returns:
    
    the opcode of the wide instruction
  - getConstantIndex
```
public final int getConstantIndex()
```
    Returns the constant pool index of a constant (as an unsigned byte).
    Used for ldc
    
    Returns:
    
    constant index
    
    See Also:
    
    getWideConstantIndex(), getConstantType(int), getIntConstant(int), getLongConstant(int), getFloatConstant(int), getDoubleConstant(int), getStringConstant(int)
  - getWideConstantIndex
```
public final int getWideConstantIndex()
```
    Returns the wide constant pool index of a constant (as an unsigned short).
    Used for ldc_w, ldc2_w
    
    Returns:
    
    wide constant index
    
    See Also:
    
    getConstantIndex(), getConstantType(int), getIntConstant(int), getLongConstant(int), getFloatConstant(int), getDoubleConstant(int), getStringConstant(int)
  - getConstantType
```
public final byte getConstantType(int index)
```
    Returns the type of a constant at a given constant pool index (as a byte).
    Used for ldc, ldc_w, ldc2_w
    
    Parameters:
    
    index - index into constant pool
    
    Returns:
    
    constant type
    
    See Also:
    
    getConstantIndex(), getWideConstantIndex(), getIntConstant(int), getLongConstant(int), getFloatConstant(int), getDoubleConstant(int), getStringConstant(int)
  - getIntConstant
```
public final int getIntConstant(int index)
```
    Returns the constant at a given constant pool index (as an int).
    Used for ldc, ldc_w
    
    Parameters:
    
    index - index into constant pool
    
    Returns:
    
    int constant
    
    See Also:
    
    getConstantIndex(), getWideConstantIndex(), getConstantType(int), getLongConstant(int), getFloatConstant(int), getDoubleConstant(int), getStringConstant(int)
  - getLongConstant
```
public final long getLongConstant(int index)
```
    Returns the constant at a given constant pool index (as a long).
    Used for ldc2_w
    
    Parameters:
    
    index - index into constant pool
    
    Returns:
    
    long constant
    
    See Also:
    
    getConstantIndex(), getWideConstantIndex(), getConstantType(int), getIntConstant(int), getFloatConstant(int), getDoubleConstant(int), getStringConstant(int)
  - getFloatConstant
```
public final float getFloatConstant(int index)
```
    Returns the constant at a given constant pool index (as a float).
    Used for ldc, ldc_w
    
    Parameters:
    
    index - index into constant pool
    
    Returns:
    
    float constant
    
    See Also:
    
    getConstantIndex(), getWideConstantIndex(), getConstantType(int), getIntConstant(int), getLongConstant(int), getDoubleConstant(int), getStringConstant(int)
  - getDoubleConstant
```
public final double getDoubleConstant(int index)
```
    Returns the constant at a given constant pool index (as a double).
    Used for ldc2_w
    
    Parameters:
    
    index - index into constant pool
    
    Returns:
    
    double constant
    
    See Also:
    
    getConstantIndex(), getWideConstantIndex(), getConstantType(int), getIntConstant(int), getLongConstant(int), getFloatConstant(int), getStringConstant(int)
  - getStringConstant
```
public final String getStringConstant(int index)
```
    Returns the constant at a given constant pool index (as a String).
    Used for ldc, ldc_w
    
    Parameters:
    
    index - index into constant pool
    
    Returns:
    
    String constant
    
    See Also:
    
    getConstantIndex(), getWideConstantIndex(), getConstantType(int), getIntConstant(int), getLongConstant(int), getFloatConstant(int), getDoubleConstant(int)
  - skipSpecialInstruction
```
private void skipSpecialInstruction(int opcode)
```
  - nextPseudoInstruction
```
public final int nextPseudoInstruction()
```
  - readIntConst
```
public final int readIntConst()
```
  - readLongConst
```
public final long readLongConst()
```
  - readLong
```
private long readLong()
```
  - readSignedByte
```
private byte readSignedByte()
```
  - readUnsignedByte
```
private int readUnsignedByte()
```
  - getUnsignedByte
```
private int getUnsignedByte(int index)
```
  - readSignedShort
```
private int readSignedShort()
```
  - readUnsignedShort
```
private int readUnsignedShort()
```
  - readSignedInt
```
private int readSignedInt()
```
  - getSignedInt
```
private int getSignedInt(int index)
```

Class BytecodeStream

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

method

bcLength

bcodes

bcIndex

opcode

wide

Constructor Detail

BytecodeStream

Method Detail

getMethod

getDeclaringClass

length

index

reset

reset

hasMoreBytecodes

peekNextOpcode

nextInstruction

getOpcode

isWide

skipInstruction

skipInstruction

getByteValue

getShortValue

getLocalNumber

getWideLocalNumber

getIncrement

getWideIncrement

getBranchOffset

getWideBranchOffset

alignSwitch

getDefaultSwitchOffset

getLowSwitchValue

getHighSwitchValue

skipTableSwitchOffsets

getTableSwitchOffset

computeTableSwitchOffset

getSwitchLength

skipLookupSwitchPairs

getLookupSwitchOffset

getLookupSwitchValue

computeLookupSwitchOffset

getFieldReference

getFieldReference

getMethodReference

getMethodReference

alignInvokeInterface

getTypeReference

getArrayElementType

getPrimitiveArrayType

getPrimitiveArrayType

getObjectArrayType

getObjectArrayType

getArrayDimension

getWideOpcode

getConstantIndex

getWideConstantIndex

getConstantType

getIntConstant

getLongConstant

getFloatConstant

getDoubleConstant

getStringConstant

skipSpecialInstruction

nextPseudoInstruction

readIntConst

readLongConst

readLong

readSignedByte

readUnsignedByte

getUnsignedByte

readSignedShort

readUnsignedShort

readSignedInt