Java example source code file (Bits.java)
The Bits.java Java example source code/*
* Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.nio;
import java.security.AccessController;
import sun.misc.Unsafe;
import sun.misc.VM;
/**
* Access to bits, native and otherwise.
*/
class Bits { // package-private
private Bits() { }
// -- Swapping --
static short swap(short x) {
return Short.reverseBytes(x);
}
static char swap(char x) {
return Character.reverseBytes(x);
}
static int swap(int x) {
return Integer.reverseBytes(x);
}
static long swap(long x) {
return Long.reverseBytes(x);
}
// -- get/put char --
static private char makeChar(byte b1, byte b0) {
return (char)((b1 << 8) | (b0 & 0xff));
}
static char getCharL(ByteBuffer bb, int bi) {
return makeChar(bb._get(bi + 1),
bb._get(bi ));
}
static char getCharL(long a) {
return makeChar(_get(a + 1),
_get(a ));
}
static char getCharB(ByteBuffer bb, int bi) {
return makeChar(bb._get(bi ),
bb._get(bi + 1));
}
static char getCharB(long a) {
return makeChar(_get(a ),
_get(a + 1));
}
static char getChar(ByteBuffer bb, int bi, boolean bigEndian) {
return bigEndian ? getCharB(bb, bi) : getCharL(bb, bi);
}
static char getChar(long a, boolean bigEndian) {
return bigEndian ? getCharB(a) : getCharL(a);
}
private static byte char1(char x) { return (byte)(x >> 8); }
private static byte char0(char x) { return (byte)(x ); }
static void putCharL(ByteBuffer bb, int bi, char x) {
bb._put(bi , char0(x));
bb._put(bi + 1, char1(x));
}
static void putCharL(long a, char x) {
_put(a , char0(x));
_put(a + 1, char1(x));
}
static void putCharB(ByteBuffer bb, int bi, char x) {
bb._put(bi , char1(x));
bb._put(bi + 1, char0(x));
}
static void putCharB(long a, char x) {
_put(a , char1(x));
_put(a + 1, char0(x));
}
static void putChar(ByteBuffer bb, int bi, char x, boolean bigEndian) {
if (bigEndian)
putCharB(bb, bi, x);
else
putCharL(bb, bi, x);
}
static void putChar(long a, char x, boolean bigEndian) {
if (bigEndian)
putCharB(a, x);
else
putCharL(a, x);
}
// -- get/put short --
static private short makeShort(byte b1, byte b0) {
return (short)((b1 << 8) | (b0 & 0xff));
}
static short getShortL(ByteBuffer bb, int bi) {
return makeShort(bb._get(bi + 1),
bb._get(bi ));
}
static short getShortL(long a) {
return makeShort(_get(a + 1),
_get(a ));
}
static short getShortB(ByteBuffer bb, int bi) {
return makeShort(bb._get(bi ),
bb._get(bi + 1));
}
static short getShortB(long a) {
return makeShort(_get(a ),
_get(a + 1));
}
static short getShort(ByteBuffer bb, int bi, boolean bigEndian) {
return bigEndian ? getShortB(bb, bi) : getShortL(bb, bi);
}
static short getShort(long a, boolean bigEndian) {
return bigEndian ? getShortB(a) : getShortL(a);
}
private static byte short1(short x) { return (byte)(x >> 8); }
private static byte short0(short x) { return (byte)(x ); }
static void putShortL(ByteBuffer bb, int bi, short x) {
bb._put(bi , short0(x));
bb._put(bi + 1, short1(x));
}
static void putShortL(long a, short x) {
_put(a , short0(x));
_put(a + 1, short1(x));
}
static void putShortB(ByteBuffer bb, int bi, short x) {
bb._put(bi , short1(x));
bb._put(bi + 1, short0(x));
}
static void putShortB(long a, short x) {
_put(a , short1(x));
_put(a + 1, short0(x));
}
static void putShort(ByteBuffer bb, int bi, short x, boolean bigEndian) {
if (bigEndian)
putShortB(bb, bi, x);
else
putShortL(bb, bi, x);
}
static void putShort(long a, short x, boolean bigEndian) {
if (bigEndian)
putShortB(a, x);
else
putShortL(a, x);
}
// -- get/put int --
static private int makeInt(byte b3, byte b2, byte b1, byte b0) {
return (((b3 ) << 24) |
((b2 & 0xff) << 16) |
((b1 & 0xff) << 8) |
((b0 & 0xff) ));
}
static int getIntL(ByteBuffer bb, int bi) {
return makeInt(bb._get(bi + 3),
bb._get(bi + 2),
bb._get(bi + 1),
bb._get(bi ));
}
static int getIntL(long a) {
return makeInt(_get(a + 3),
_get(a + 2),
_get(a + 1),
_get(a ));
}
static int getIntB(ByteBuffer bb, int bi) {
return makeInt(bb._get(bi ),
bb._get(bi + 1),
bb._get(bi + 2),
bb._get(bi + 3));
}
static int getIntB(long a) {
return makeInt(_get(a ),
_get(a + 1),
_get(a + 2),
_get(a + 3));
}
static int getInt(ByteBuffer bb, int bi, boolean bigEndian) {
return bigEndian ? getIntB(bb, bi) : getIntL(bb, bi) ;
}
static int getInt(long a, boolean bigEndian) {
return bigEndian ? getIntB(a) : getIntL(a) ;
}
private static byte int3(int x) { return (byte)(x >> 24); }
private static byte int2(int x) { return (byte)(x >> 16); }
private static byte int1(int x) { return (byte)(x >> 8); }
private static byte int0(int x) { return (byte)(x ); }
static void putIntL(ByteBuffer bb, int bi, int x) {
bb._put(bi + 3, int3(x));
bb._put(bi + 2, int2(x));
bb._put(bi + 1, int1(x));
bb._put(bi , int0(x));
}
static void putIntL(long a, int x) {
_put(a + 3, int3(x));
_put(a + 2, int2(x));
_put(a + 1, int1(x));
_put(a , int0(x));
}
static void putIntB(ByteBuffer bb, int bi, int x) {
bb._put(bi , int3(x));
bb._put(bi + 1, int2(x));
bb._put(bi + 2, int1(x));
bb._put(bi + 3, int0(x));
}
static void putIntB(long a, int x) {
_put(a , int3(x));
_put(a + 1, int2(x));
_put(a + 2, int1(x));
_put(a + 3, int0(x));
}
static void putInt(ByteBuffer bb, int bi, int x, boolean bigEndian) {
if (bigEndian)
putIntB(bb, bi, x);
else
putIntL(bb, bi, x);
}
static void putInt(long a, int x, boolean bigEndian) {
if (bigEndian)
putIntB(a, x);
else
putIntL(a, x);
}
// -- get/put long --
static private long makeLong(byte b7, byte b6, byte b5, byte b4,
byte b3, byte b2, byte b1, byte b0)
{
return ((((long)b7 ) << 56) |
(((long)b6 & 0xff) << 48) |
(((long)b5 & 0xff) << 40) |
(((long)b4 & 0xff) << 32) |
(((long)b3 & 0xff) << 24) |
(((long)b2 & 0xff) << 16) |
(((long)b1 & 0xff) << 8) |
(((long)b0 & 0xff) ));
}
static long getLongL(ByteBuffer bb, int bi) {
return makeLong(bb._get(bi + 7),
bb._get(bi + 6),
bb._get(bi + 5),
bb._get(bi + 4),
bb._get(bi + 3),
bb._get(bi + 2),
bb._get(bi + 1),
bb._get(bi ));
}
static long getLongL(long a) {
return makeLong(_get(a + 7),
_get(a + 6),
_get(a + 5),
_get(a + 4),
_get(a + 3),
_get(a + 2),
_get(a + 1),
_get(a ));
}
static long getLongB(ByteBuffer bb, int bi) {
return makeLong(bb._get(bi ),
bb._get(bi + 1),
bb._get(bi + 2),
bb._get(bi + 3),
bb._get(bi + 4),
bb._get(bi + 5),
bb._get(bi + 6),
bb._get(bi + 7));
}
static long getLongB(long a) {
return makeLong(_get(a ),
_get(a + 1),
_get(a + 2),
_get(a + 3),
_get(a + 4),
_get(a + 5),
_get(a + 6),
_get(a + 7));
}
static long getLong(ByteBuffer bb, int bi, boolean bigEndian) {
return bigEndian ? getLongB(bb, bi) : getLongL(bb, bi);
}
static long getLong(long a, boolean bigEndian) {
return bigEndian ? getLongB(a) : getLongL(a);
}
private static byte long7(long x) { return (byte)(x >> 56); }
private static byte long6(long x) { return (byte)(x >> 48); }
private static byte long5(long x) { return (byte)(x >> 40); }
private static byte long4(long x) { return (byte)(x >> 32); }
private static byte long3(long x) { return (byte)(x >> 24); }
private static byte long2(long x) { return (byte)(x >> 16); }
private static byte long1(long x) { return (byte)(x >> 8); }
private static byte long0(long x) { return (byte)(x ); }
static void putLongL(ByteBuffer bb, int bi, long x) {
bb._put(bi + 7, long7(x));
bb._put(bi + 6, long6(x));
bb._put(bi + 5, long5(x));
bb._put(bi + 4, long4(x));
bb._put(bi + 3, long3(x));
bb._put(bi + 2, long2(x));
bb._put(bi + 1, long1(x));
bb._put(bi , long0(x));
}
static void putLongL(long a, long x) {
_put(a + 7, long7(x));
_put(a + 6, long6(x));
_put(a + 5, long5(x));
_put(a + 4, long4(x));
_put(a + 3, long3(x));
_put(a + 2, long2(x));
_put(a + 1, long1(x));
_put(a , long0(x));
}
static void putLongB(ByteBuffer bb, int bi, long x) {
bb._put(bi , long7(x));
bb._put(bi + 1, long6(x));
bb._put(bi + 2, long5(x));
bb._put(bi + 3, long4(x));
bb._put(bi + 4, long3(x));
bb._put(bi + 5, long2(x));
bb._put(bi + 6, long1(x));
bb._put(bi + 7, long0(x));
}
static void putLongB(long a, long x) {
_put(a , long7(x));
_put(a + 1, long6(x));
_put(a + 2, long5(x));
_put(a + 3, long4(x));
_put(a + 4, long3(x));
_put(a + 5, long2(x));
_put(a + 6, long1(x));
_put(a + 7, long0(x));
}
static void putLong(ByteBuffer bb, int bi, long x, boolean bigEndian) {
if (bigEndian)
putLongB(bb, bi, x);
else
putLongL(bb, bi, x);
}
static void putLong(long a, long x, boolean bigEndian) {
if (bigEndian)
putLongB(a, x);
else
putLongL(a, x);
}
// -- get/put float --
static float getFloatL(ByteBuffer bb, int bi) {
return Float.intBitsToFloat(getIntL(bb, bi));
}
static float getFloatL(long a) {
return Float.intBitsToFloat(getIntL(a));
}
static float getFloatB(ByteBuffer bb, int bi) {
return Float.intBitsToFloat(getIntB(bb, bi));
}
static float getFloatB(long a) {
return Float.intBitsToFloat(getIntB(a));
}
static float getFloat(ByteBuffer bb, int bi, boolean bigEndian) {
return bigEndian ? getFloatB(bb, bi) : getFloatL(bb, bi);
}
static float getFloat(long a, boolean bigEndian) {
return bigEndian ? getFloatB(a) : getFloatL(a);
}
static void putFloatL(ByteBuffer bb, int bi, float x) {
putIntL(bb, bi, Float.floatToRawIntBits(x));
}
static void putFloatL(long a, float x) {
putIntL(a, Float.floatToRawIntBits(x));
}
static void putFloatB(ByteBuffer bb, int bi, float x) {
putIntB(bb, bi, Float.floatToRawIntBits(x));
}
static void putFloatB(long a, float x) {
putIntB(a, Float.floatToRawIntBits(x));
}
static void putFloat(ByteBuffer bb, int bi, float x, boolean bigEndian) {
if (bigEndian)
putFloatB(bb, bi, x);
else
putFloatL(bb, bi, x);
}
static void putFloat(long a, float x, boolean bigEndian) {
if (bigEndian)
putFloatB(a, x);
else
putFloatL(a, x);
}
// -- get/put double --
static double getDoubleL(ByteBuffer bb, int bi) {
return Double.longBitsToDouble(getLongL(bb, bi));
}
static double getDoubleL(long a) {
return Double.longBitsToDouble(getLongL(a));
}
static double getDoubleB(ByteBuffer bb, int bi) {
return Double.longBitsToDouble(getLongB(bb, bi));
}
static double getDoubleB(long a) {
return Double.longBitsToDouble(getLongB(a));
}
static double getDouble(ByteBuffer bb, int bi, boolean bigEndian) {
return bigEndian ? getDoubleB(bb, bi) : getDoubleL(bb, bi);
}
static double getDouble(long a, boolean bigEndian) {
return bigEndian ? getDoubleB(a) : getDoubleL(a);
}
static void putDoubleL(ByteBuffer bb, int bi, double x) {
putLongL(bb, bi, Double.doubleToRawLongBits(x));
}
static void putDoubleL(long a, double x) {
putLongL(a, Double.doubleToRawLongBits(x));
}
static void putDoubleB(ByteBuffer bb, int bi, double x) {
putLongB(bb, bi, Double.doubleToRawLongBits(x));
}
static void putDoubleB(long a, double x) {
putLongB(a, Double.doubleToRawLongBits(x));
}
static void putDouble(ByteBuffer bb, int bi, double x, boolean bigEndian) {
if (bigEndian)
putDoubleB(bb, bi, x);
else
putDoubleL(bb, bi, x);
}
static void putDouble(long a, double x, boolean bigEndian) {
if (bigEndian)
putDoubleB(a, x);
else
putDoubleL(a, x);
}
// -- Unsafe access --
private static final Unsafe unsafe = Unsafe.getUnsafe();
private static byte _get(long a) {
return unsafe.getByte(a);
}
private static void _put(long a, byte b) {
unsafe.putByte(a, b);
}
static Unsafe unsafe() {
return unsafe;
}
// -- Processor and memory-system properties --
private static final ByteOrder byteOrder;
static ByteOrder byteOrder() {
if (byteOrder == null)
throw new Error("Unknown byte order");
return byteOrder;
}
static {
long a = unsafe.allocateMemory(8);
try {
unsafe.putLong(a, 0x0102030405060708L);
byte b = unsafe.getByte(a);
switch (b) {
case 0x01: byteOrder = ByteOrder.BIG_ENDIAN; break;
case 0x08: byteOrder = ByteOrder.LITTLE_ENDIAN; break;
default:
assert false;
byteOrder = null;
}
} finally {
unsafe.freeMemory(a);
}
}
private static int pageSize = -1;
static int pageSize() {
if (pageSize == -1)
pageSize = unsafe().pageSize();
return pageSize;
}
static int pageCount(long size) {
return (int)(size + (long)pageSize() - 1L) / pageSize();
}
private static boolean unaligned;
private static boolean unalignedKnown = false;
static boolean unaligned() {
if (unalignedKnown)
return unaligned;
String arch = AccessController.doPrivileged(
new sun.security.action.GetPropertyAction("os.arch"));
unaligned = arch.equals("i386") || arch.equals("x86")
|| arch.equals("amd64") || arch.equals("x86_64");
unalignedKnown = true;
return unaligned;
}
// -- Direct memory management --
// A user-settable upper limit on the maximum amount of allocatable
// direct buffer memory. This value may be changed during VM
// initialization if it is launched with "-XX:MaxDirectMemorySize=<size>".
private static volatile long maxMemory = VM.maxDirectMemory();
private static volatile long reservedMemory;
private static volatile long totalCapacity;
private static volatile long count;
private static boolean memoryLimitSet = false;
// These methods should be called whenever direct memory is allocated or
// freed. They allow the user to control the amount of direct memory
// which a process may access. All sizes are specified in bytes.
static void reserveMemory(long size, int cap) {
synchronized (Bits.class) {
if (!memoryLimitSet && VM.isBooted()) {
maxMemory = VM.maxDirectMemory();
memoryLimitSet = true;
}
// -XX:MaxDirectMemorySize limits the total capacity rather than the
// actual memory usage, which will differ when buffers are page
// aligned.
if (cap <= maxMemory - totalCapacity) {
reservedMemory += size;
totalCapacity += cap;
count++;
return;
}
}
System.gc();
try {
Thread.sleep(100);
} catch (InterruptedException x) {
// Restore interrupt status
Thread.currentThread().interrupt();
}
synchronized (Bits.class) {
if (totalCapacity + cap > maxMemory)
throw new OutOfMemoryError("Direct buffer memory");
reservedMemory += size;
totalCapacity += cap;
count++;
}
}
static synchronized void unreserveMemory(long size, int cap) {
if (reservedMemory > 0) {
reservedMemory -= size;
totalCapacity -= cap;
count--;
assert (reservedMemory > -1);
}
}
// -- Monitoring of direct buffer usage --
static {
// setup access to this package in SharedSecrets
sun.misc.SharedSecrets.setJavaNioAccess(
new sun.misc.JavaNioAccess() {
@Override
public sun.misc.JavaNioAccess.BufferPool getDirectBufferPool() {
return new sun.misc.JavaNioAccess.BufferPool() {
@Override
public String getName() {
return "direct";
}
@Override
public long getCount() {
return Bits.count;
}
@Override
public long getTotalCapacity() {
return Bits.totalCapacity;
}
@Override
public long getMemoryUsed() {
return Bits.reservedMemory;
}
};
}
@Override
public ByteBuffer newDirectByteBuffer(long addr, int cap, Object ob) {
return new DirectByteBuffer(addr, cap, ob);
}
@Override
public void truncate(Buffer buf) {
buf.truncate();
}
});
}
// -- Bulk get/put acceleration --
// These numbers represent the point at which we have empirically
// determined that the average cost of a JNI call exceeds the expense
// of an element by element copy. These numbers may change over time.
static final int JNI_COPY_TO_ARRAY_THRESHOLD = 6;
static final int JNI_COPY_FROM_ARRAY_THRESHOLD = 6;
// This number limits the number of bytes to copy per call to Unsafe's
// copyMemory method. A limit is imposed to allow for safepoint polling
// during a large copy
static final long UNSAFE_COPY_THRESHOLD = 1024L * 1024L;
// These methods do no bounds checking. Verification that the copy will not
// result in memory corruption should be done prior to invocation.
// All positions and lengths are specified in bytes.
/**
* Copy from given source array to destination address.
*
* @param src
* source array
* @param srcBaseOffset
* offset of first element of storage in source array
* @param srcPos
* offset within source array of the first element to read
* @param dstAddr
* destination address
* @param length
* number of bytes to copy
*/
static void copyFromArray(Object src, long srcBaseOffset, long srcPos,
long dstAddr, long length)
{
long offset = srcBaseOffset + srcPos;
while (length > 0) {
long size = (length > UNSAFE_COPY_THRESHOLD) ? UNSAFE_COPY_THRESHOLD : length;
unsafe.copyMemory(src, offset, null, dstAddr, size);
length -= size;
offset += size;
dstAddr += size;
}
}
/**
* Copy from source address into given destination array.
*
* @param srcAddr
* source address
* @param dst
* destination array
* @param dstBaseOffset
* offset of first element of storage in destination array
* @param dstPos
* offset within destination array of the first element to write
* @param length
* number of bytes to copy
*/
static void copyToArray(long srcAddr, Object dst, long dstBaseOffset, long dstPos,
long length)
{
long offset = dstBaseOffset + dstPos;
while (length > 0) {
long size = (length > UNSAFE_COPY_THRESHOLD) ? UNSAFE_COPY_THRESHOLD : length;
unsafe.copyMemory(null, srcAddr, dst, offset, size);
length -= size;
srcAddr += size;
offset += size;
}
}
static void copyFromCharArray(Object src, long srcPos, long dstAddr,
long length)
{
copyFromShortArray(src, srcPos, dstAddr, length);
}
static void copyToCharArray(long srcAddr, Object dst, long dstPos,
long length)
{
copyToShortArray(srcAddr, dst, dstPos, length);
}
static native void copyFromShortArray(Object src, long srcPos, long dstAddr,
long length);
static native void copyToShortArray(long srcAddr, Object dst, long dstPos,
long length);
static native void copyFromIntArray(Object src, long srcPos, long dstAddr,
long length);
static native void copyToIntArray(long srcAddr, Object dst, long dstPos,
long length);
static native void copyFromLongArray(Object src, long srcPos, long dstAddr,
long length);
static native void copyToLongArray(long srcAddr, Object dst, long dstPos,
long length);
}
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