com.sun.squawk.vm
Class HDR

java.lang.Object
  com.sun.squawk.vm.HDR

public class HDR
extends Object

This class contains constants that describe the object header layout.

Field Summary

static int	arrayHeaderSize The size (in bytes) of an object header for an array object.
static int	arrayHeaderTag The object header format tag value specifying an array object header.
static int	basicHeaderSize The size (in bytes) of an object header for a non-array, non-method-body object.
static int	basicHeaderTag The object header format tag value specifying a non-array, non-method-body object header.
static int	BITS_PER_BYTE The number of bits per byte.
static int	BITS_PER_WORD The number of bits in a pointer.
static int	BYTES_PER_WORD The size (in bytes) of a pointer.
static int	forwardPointerBit The bit in a class pointer word that is set if the object has been forwarded.
static int	headerTagBits The number of low order bits in the first word of an object header that specify the format of the object header.
static int	headerTagMask The mask that is applied to the first word of an object header to extract the format tag.
static int	klass The offset (in words) from an object's address to the class pointer in the object's header.
static int	length The offset (in words) from an object's address to array length in the object's header.
static int	LOG2_BITS_PER_BYTE The amount by which to right shift a bit index to yield the byte in a bitmap containing the indexed bit.
static int	LOG2_BITS_PER_WORD The amount by which to right shift a bit index to yield the word in a bitmap containing the indexed bit.
static int	LOG2_BYTES_PER_WORD The amount by which to right shift a byte offset to find the offset of the word that contains the indexed byte.
static int	methodDefiningClass The offset (in words) from an method body's address to the defining class pointer in the method body's header.
static int	methodHeaderTag The object header format tag value specifying a mehod body object header.
static int	methodInfoStart The offset (in bytes) from an method body's address to the start of the info block in the method body's header.

Constructor Summary

HDR()

Method Summary

Methods inherited from class java.lang.Object

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

Field Detail

BYTES_PER_WORD

public static final int BYTES_PER_WORD

The size (in bytes) of a pointer.

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Constant Field Values

LOG2_BYTES_PER_WORD

public static final int LOG2_BYTES_PER_WORD

The amount by which to right shift a byte offset to find the offset of the word that contains the indexed byte.

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Constant Field Values

BITS_PER_BYTE

public static final int BITS_PER_BYTE

The number of bits per byte.

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Constant Field Values

BITS_PER_WORD

public static final int BITS_PER_WORD

The number of bits in a pointer.

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Constant Field Values

LOG2_BITS_PER_WORD

public static final int LOG2_BITS_PER_WORD

The amount by which to right shift a bit index to yield the word in a bitmap containing the indexed bit.

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Constant Field Values

LOG2_BITS_PER_BYTE

public static final int LOG2_BITS_PER_BYTE

The amount by which to right shift a bit index to yield the byte in a bitmap containing the indexed bit.

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Constant Field Values

klass

public static final int klass

The offset (in words) from an object's address to the class pointer in the object's header.

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Constant Field Values

length

public static final int length

The offset (in words) from an object's address to array length in the object's header.

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Constant Field Values

methodDefiningClass

public static final int methodDefiningClass

The offset (in words) from an method body's address to the defining class pointer in the method body's header.

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Constant Field Values

methodInfoStart

public static final int methodInfoStart

The offset (in bytes) from an method body's address to the start of the info block in the method body's header.

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Constant Field Values

basicHeaderSize

public static final int basicHeaderSize

The size (in bytes) of an object header for a non-array, non-method-body object.

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Constant Field Values

arrayHeaderSize

public static final int arrayHeaderSize

The size (in bytes) of an object header for an array object.

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Constant Field Values

headerTagBits

public static final int headerTagBits

The number of low order bits in the first word of an object header that specify the format of the object header.

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Constant Field Values

headerTagMask

public static final int headerTagMask

The mask that is applied to the first word of an object header to extract the format tag.

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Constant Field Values

basicHeaderTag

public static final int basicHeaderTag

The object header format tag value specifying a non-array, non-method-body object header.

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Constant Field Values

arrayHeaderTag

public static final int arrayHeaderTag

The object header format tag value specifying an array object header.

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Constant Field Values

methodHeaderTag

public static final int methodHeaderTag

The object header format tag value specifying a mehod body object header.

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Constant Field Values

forwardPointerBit

public static final int forwardPointerBit

The bit in a class pointer word that is set if the object has been forwarded.

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Constant Field Values

Constructor Detail

HDR

public HDR()