com.sun.squawk
Class Unsafe

java.lang.Object
  com.sun.squawk.Unsafe

public final class Unsafe
extends Object

A collection of methods for performing peek and poke operations on memory addresses.

The Unsafe class is primarily concerned with accessing memory ouside of the Java heap, but improper use of the Unsafe class can corrupt the Java heap (hence the name).

Only "trusted" Isolates may use the methods of this class. Calls to Any memory accessor methods by an untrusted Isolate will throw a SecurityException.

Author:

Nik Shaylor, Doug Simon, Derek White

See Also:

Isolate

Method Summary

static Address	getAddress(Address base, int offset) Gets a pointer from memory as an Address.
static int	getByte(Address base, int offset) Gets a signed 8 bit value from memory.
static void	getBytes(Address src, int boffset, byte[] bytes, int low, int number) Copy from memory to byte array.
static int	getChar(Address base, int offset) Gets an unsigned 16 bit value from memory.
static int	getInt(Address base, int offset) Gets a signed 32 bit value from memory.
static void	getInts(Address src, int boffset, int[] ints, int low, int number) Copy from memory to int array.
static long	getLong(Address base, int offset) Gets a 64 bit value from memory using a 64 bit word offset.
static long	getLongAtWord(Address base, int offset) Gets a 64 bit value from memory using a 32 bit word offset.
static void	getLongs(Address src, int boffset, long[] longs, int low, int number) Copy from memory to long array.
static int	getShort(Address base, int offset) Gets a signed 16 bit value from memory.
static void	getShorts(Address src, int boffset, short[] shorts, int low, int number) Copy from memory to short array.
static int	getUByte(Address base, int offset) Gets an unsigned 8 bit value from memory.
static UWord	getUWord(Address base, int offset) Gets an unsigned 32 or 64 bit value from memory.
static void	setAddress(Address base, int offset, Address value) Sets a pointer value in memory without updating the write barrier.
static void	setByte(Address base, int offset, int value) Sets an 8 bit value in memory.
static void	setBytes(Address dst, int boffset, byte[] bytes, int low, int number) Copy from byte array to memory.
static void	setChar(Address base, int offset, int value) Sets an unsigned 16 bit value in memory.
static void	setInt(Address base, int offset, int value) Sets a 32 bit value in memory.
static void	setInts(Address dst, int boffset, int[] ints, int low, int number) Copy from int array to memory.
static void	setLong(Address base, int offset, long value) Sets a 64 bit value in memory.
static void	setLongAtWord(Address base, int offset, long value) Sets a 64 bit value in memory at a 32 bit word offset.
static void	setLongs(Address dst, int boffset, long[] longs, int low, int number) Copy from long array to memory.
static void	setShort(Address base, int offset, int value) Sets a signed 16 bit value in memory.
static void	setShorts(Address dst, int boffset, short[] shorts, int low, int number) Copy from short array to memory.
static void	setUWord(Address base, int offset, UWord value) Sets a UWord value in memory.

Methods inherited from class java.lang.Object

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

Method Detail

getAddress

public static Address getAddress(Address base,
                                 int offset)

Gets a pointer from memory as an Address.

Parameters:

base - the base address

offset - the offset (in UWords) from base from which to load

Returns:

the value

getByte

public static int getByte(Address base,
                          int offset)

Gets a signed 8 bit value from memory.

Parameters:

base - the base address

offset - the offset (in bytes) from base from which to load

Returns:

the value

getBytes

public static void getBytes(Address src,
                            int boffset,
                            byte[] bytes,
                            int low,
                            int number)

Copy from memory to byte array. Copy number bytes from the memory location specified by the address dst and byte offset boffset to the byte array bytes starting at position low.

Parameters:

src - the base memory address

boffset - the byte offset to add to the base memory address

bytes - the destination byte array

low - the offset in the destination array

number - the number of bytes to copy

Throws:

ArrayIndexOutOfBoundsException - if the range specified by low and number does not fit within the dst array

getChar

public static int getChar(Address base,
                          int offset)

Gets an unsigned 16 bit value from memory.

Parameters:

base - the base address

offset - the offset (in 16 bit words) from base from which to load

Returns:

the value

getInt

public static int getInt(Address base,
                         int offset)

Gets a signed 32 bit value from memory.

Parameters:

base - the base address

offset - the offset (in 32 bit words) from base from which to load

Returns:

the value

getInts

public static void getInts(Address src,
                           int boffset,
                           int[] ints,
                           int low,
                           int number)

Copy from memory to int array. Copy number ints from the memory location specified by the address dst and byte offset boffset to the int array ints starting at position low.

Parameters:

src - the base memory address

boffset - the byte offset to add to the base memory address

ints - the destination int array

low - the offset in the destination array

number - the number of ints to copy

Throws:

ArrayIndexOutOfBoundsException - if the range specified by low and number does not fit within the dst array

getLong

public static long getLong(Address base,
                           int offset)

Gets a 64 bit value from memory using a 64 bit word offset.

Parameters:

base - the base address

offset - the offset (in 64 bit words) from base from which to load

Returns:

the value

getLongAtWord

public static long getLongAtWord(Address base,
                                 int offset)

Gets a 64 bit value from memory using a 32 bit word offset.

Parameters:

base - the base address

offset - the offset (in 32 bit words) from base from which to load

Returns:

the value

getLongs

public static void getLongs(Address src,
                            int boffset,
                            long[] longs,
                            int low,
                            int number)

Copy from memory to long array. Copy number longs from the memory location specified by the address dst and byte offset boffset to the long array longs starting at position low.

Parameters:

src - the base memory address

boffset - the byte offset to add to the base memory address

longs - the destination long array

low - the offset in the destination array

number - the number of ints to copy

Throws:

ArrayIndexOutOfBoundsException - if the range specified by low and number does not fit within the dst array

getShort

public static int getShort(Address base,
                           int offset)

Gets a signed 16 bit value from memory.

Parameters:

base - the base address

offset - the offset (in 16 bit words) from base from which to load

Returns:

the value

getShorts

public static void getShorts(Address src,
                             int boffset,
                             short[] shorts,
                             int low,
                             int number)

Copy from memory to short array. Copy number shorts from the memory location specified by the address dst and byte offset boffset to the short array shorts starting at position low.

Parameters:

src - the base memory address

boffset - the byte offset to add to the base memory address

shorts - the destination short array

low - the offset in the destination array

number - the number of shorts to copy

Throws:

ArrayIndexOutOfBoundsException - if the range specified by low and number does not fit within the dst array

getUByte

public static int getUByte(Address base,
                           int offset)

Gets an unsigned 8 bit value from memory.

Parameters:

base - the base address

offset - the offset (in bytes) from base from which to load

Returns:

the value

getUWord

public static UWord getUWord(Address base,
                             int offset)

Gets an unsigned 32 or 64 bit value from memory.

Parameters:

base - the base address

offset - the offset (in UWords) from base from which to load

Returns:

the value

setAddress

public static void setAddress(Address base,
                              int offset,
                              Address value)

Sets a pointer value in memory without updating the write barrier. If this method is being called in a hosted environment then the corresponding bit in the oop map (if any) is also set.

Parameters:

base - the base address

offset - the offset (in UWords) from base at which to write

value - the value to write

setByte

public static void setByte(Address base,
                           int offset,
                           int value)

Sets an 8 bit value in memory.

Parameters:

base - the base address

offset - the offset (in bytes) from base at which to write

value - the value to write

setBytes

public static void setBytes(Address dst,
                            int boffset,
                            byte[] bytes,
                            int low,
                            int number)

Copy from byte array to memory. Copy number bytes from byte array bytes starting at position low.to the memory location specified by the address dst and byte offset boffset.

Parameters:

dst - the base memory address

boffset - the byte offset to add to the base memory address

bytes - the src byte array

low - the offset in the src array

number - the number of bytes to copy

Throws:

ArrayIndexOutOfBoundsException - if the range specified by low and number does not fit within the src array

setChar

public static void setChar(Address base,
                           int offset,
                           int value)

Sets an unsigned 16 bit value in memory.

Parameters:

base - the base address

offset - the offset (in 16 bit words) from base at which to write

value - the value to write

setInt

public static void setInt(Address base,
                          int offset,
                          int value)

Sets a 32 bit value in memory.

Parameters:

base - the base address

offset - the offset (in 32 bit words) from base at which to write

value - the value to write

setInts

public static void setInts(Address dst,
                           int boffset,
                           int[] ints,
                           int low,
                           int number)

Copy from int array to memory. Copy number int from int array ints starting at position low.to the memory location specified by the address dst and byte offset boffset.

Parameters:

dst - the base memory address

boffset - the byte offset to add to the base memory address

ints - the src int array

low - the offset in the src array

number - the number of bytes to copy

Throws:

ArrayIndexOutOfBoundsException - if the range specified by low and number does not fit within the src array

setLong

public static void setLong(Address base,
                           int offset,
                           long value)

Sets a 64 bit value in memory.

Parameters:

base - the base address

offset - the offset (in 64 bit words) from base at which to write

value - the value to write

setLongAtWord

public static void setLongAtWord(Address base,
                                 int offset,
                                 long value)

Sets a 64 bit value in memory at a 32 bit word offset.

Parameters:

base - the base address

offset - the offset (in 32 bit words) from base at which to write

value - the value to write

setLongs

public static void setLongs(Address dst,
                            int boffset,
                            long[] longs,
                            int low,
                            int number)

Copy from long array to memory. Copy number longs from long array longs starting at position low.to the memory location specified by the address dst and byte offset boffset.

Parameters:

dst - the base memory address

boffset - the byte offset to add to the base memory address

longs - the src long array

low - the offset in the src array

number - the number of bytes to copy

Throws:

ArrayIndexOutOfBoundsException - if the range specified by low and number does not fit within the src array

setShort

public static void setShort(Address base,
                            int offset,
                            int value)

Sets a signed 16 bit value in memory.

Parameters:

base - the base address

offset - the offset (in 16 bit words) from base at which to write

value - the value to write

setShorts

public static void setShorts(Address dst,
                             int boffset,
                             short[] shorts,
                             int low,
                             int number)

Copy from short array to memory. Copy number shorts from short array shorts starting at position low.to the memory location specified by the address dst and byte offset boffset.

Parameters:

dst - the base memory address

boffset - the byte offset to add to the base memory address

shorts - the src short array

low - the offset in the src array

number - the number of bytes to copy

Throws:

ArrayIndexOutOfBoundsException - if the range specified by low and number does not fit within the src array

setUWord

public static void setUWord(Address base,
                            int offset,
                            UWord value)

Sets a UWord value in memory.

Parameters:

base - the base address

offset - the offset (in UWords) from base at which to write

value - the value to write