src/java.base/share/classes/sun/misc/Unsafe.java
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@@ -923,6 +923,343 @@
* @since 1.8
*/
private static void throwIllegalAccessError() {
throw new IllegalAccessError();
}
+
+ /**
+ * @return Returns true if the native byte ordering of this
+ * machine is big-endian, false if it is little-endian.
+ */
+ public final boolean isBigEndian() { return BE; }
+
+ /**
+ * @return Returns true if this machine is capable of performing
+ * accesses at addresses which are not aligned for the type of the
+ * primitive type being accessed, false otherwise.
+ */
+ public final boolean unalignedAccess() { return unalignedAccess; }
+
+ /**
+ * Fetches a value at some byte offset into a given Java object.
+ * More specifically, fetches a value within the given object
+ * <code>o</code> at the given offset, or (if <code>o</code> is
+ * null) from the memory address whose numerical value is the
+ * given offset. <p>
+ *
+ * The specification of this method is the same as {@link
+ * #getLong(Object, long)} except that the offset does not need to
+ * have been obtained from {@link #objectFieldOffset} on the
+ * {@link java.lang.reflect.Field} of some Java field. The value
+ * in memory is raw data, and need not correspond to any Java
+ * variable. Unless <code>o</code> is null, the value accessed
+ * must be entirely within the allocated object. The endianness
+ * of the value in memory is the endianness of the native machine.
+ *
+ * <p> The read will be atomic with respect to the largest power
+ * of two that divides the GCD of the offset and the storage size.
+ * For example, getLongUnaligned will make atomic reads of 2-, 4-,
+ * or 8-byte storage units if the offset is zero mod 2, 4, or 8,
+ * respectively. There are no other guarantees of atomicity.
+ *
+ * @param o Java heap object in which the value resides, if any, else
+ * null
+ * @param offset The offset in bytes from the start of the object
+ * @return the value fetched from the indicated object
+ * @throws RuntimeException No defined exceptions are thrown, not even
+ * {@link NullPointerException}
+ * @since 1.9
+ */
+ public final long getLongUnaligned(Object o, long offset) {
+ if ((offset & 7) == 0) {
+ return getLong(o, offset);
+ } else if ((offset & 3) == 0) {
+ return makeLong(getInt(o, offset),
+ getInt(o, offset + 4));
+ } else if ((offset & 1) == 0) {
+ return makeLong(getShort(o, offset),
+ getShort(o, offset + 2),
+ getShort(o, offset + 4),
+ getShort(o, offset + 6));
+ } else {
+ return makeLong(getByte(o, offset),
+ getByte(o, offset + 1),
+ getByte(o, offset + 2),
+ getByte(o, offset + 3),
+ getByte(o, offset + 4),
+ getByte(o, offset + 5),
+ getByte(o, offset + 6),
+ getByte(o, offset + 7));
+ }
+ }
+ /**
+ * As {@link #getLongUnaligned(Object, long)} but with an
+ * additional argument which specifies the endianness of the value
+ * as stored in memory.
+ *
+ * @param o Java heap object in which the variable resides
+ * @param offset The offset in bytes from the start of the object
+ * @param bigEndian The endianness of the value
+ * @return the value fetched from the indicated object
+ * @since 1.9
+ */
+ public final long getLongUnaligned(Object o, long offset, boolean bigEndian) {
+ return convEndian(bigEndian, getLongUnaligned(o, offset));
+ }
+
+ /** @see #getLongUnaligned(Object, long) */
+ public final int getIntUnaligned(Object o, long offset) {
+ if ((offset & 3) == 0) {
+ return getInt(o, offset);
+ } else if ((offset & 1) == 0) {
+ return makeInt(getShort(o, offset),
+ getShort(o, offset + 2));
+ } else {
+ return makeInt(getByte(o, offset),
+ getByte(o, offset + 1),
+ getByte(o, offset + 2),
+ getByte(o, offset + 3));
+ }
+ }
+ /** @see #getLongUnaligned(Object, long, boolean) */
+ public final int getIntUnaligned(Object o, long offset, boolean bigEndian) {
+ return convEndian(bigEndian, getIntUnaligned(o, offset));
+ }
+
+ /** @see #getLongUnaligned(Object, long) */
+ public final short getShortUnaligned(Object o, long offset) {
+ if ((offset & 1) == 0) {
+ return getShort(o, offset);
+ } else {
+ return makeShort(getByte(o, offset),
+ getByte(o, offset + 1));
+ }
+ }
+ /** @see #getLongUnaligned(Object, long, boolean) */
+ public final short getShortUnaligned(Object o, long offset, boolean bigEndian) {
+ return convEndian(bigEndian, getShortUnaligned(o, offset));
+ }
+
+ /** @see #getLongUnaligned(Object, long) */
+ public final char getCharUnaligned(Object o, long offset) {
+ return (char)getShortUnaligned(o, offset);
+ }
+ /** @see #getLongUnaligned(Object, long, boolean) */
+ public final char getCharUnaligned(Object o, long offset, boolean bigEndian) {
+ return convEndian(bigEndian, getCharUnaligned(o, offset));
+ }
+
+ /**
+ * Stores a value at some byte offset into a given Java object.
+ * <p>
+ * The specification of this method is the same as {@link
+ * #getLong(Object, long)} except that the offset does not need to
+ * have been obtained from {@link #objectFieldOffset} on the
+ * {@link java.lang.reflect.Field} of some Java field. The value
+ * in memory is raw data, and need not correspond to any Java
+ * variable. The endianness of the value in memory is the
+ * endianness of the native machine.
+ * <p>
+ * The write will be atomic with respect to the largest power of
+ * two that divides the GCD of the offset and the storage size.
+ * For example, getLongUnaligned will make atomic reads of 2-, 4-,
+ * or 8-byte storage units if the offset is zero mod 2, 4, or 8,
+ * respectively. There are no other guarantees of atomicity.
+ * <p>
+ *
+ * @param o Java heap object in which the value resides, if any, else
+ * null
+ * @param offset The offset in bytes from the start of the object
+ * @param x the value to store
+ * @throws RuntimeException No defined exceptions are thrown, not even
+ * {@link NullPointerException}
+ * @since 1.9
+ */
+ public final void putLongUnaligned(Object o, long offset, long x) {
+ if ((offset & 7) == 0) {
+ putLong(o, offset, x);
+ } else if ((offset & 3) == 0) {
+ putLongParts(o, offset,
+ (int)(x >> 0),
+ (int)(x >>> 32));
+ } else if ((offset & 1) == 0) {
+ putLongParts(o, offset,
+ (short)(x >>> 0),
+ (short)(x >>> 16),
+ (short)(x >>> 32),
+ (short)(x >>> 48));
+ } else {
+ putLongParts(o, offset,
+ (byte)(x >>> 0),
+ (byte)(x >>> 8),
+ (byte)(x >>> 16),
+ (byte)(x >>> 24),
+ (byte)(x >>> 32),
+ (byte)(x >>> 40),
+ (byte)(x >>> 48),
+ (byte)(x >>> 56));
+ }
+ }
+ /**
+ * As {@link #putLongUnaligned(Object, long, long)} but with an additional
+ * argument which specifies the endianness of the value as stored in memory.
+ * @param o Java heap object in which the value resides
+ * @param offset The offset in bytes from the start of the object
+ * @param x the value to store
+ * @param bigEndian The endianness of the value
+ * @throws RuntimeException No defined exceptions are thrown, not even
+ * {@link NullPointerException}
+ * @since 1.9
+ */
+ public final void putLongUnaligned(Object o, long offset, long x, boolean bigEndian) {
+ putLongUnaligned(o, offset, convEndian(bigEndian, x));
+ }
+
+ /** @see #putLongUnaligned(Object, long, long) */
+ public final void putIntUnaligned(Object o, long offset, int x) {
+ if ((offset & 3) == 0) {
+ putInt(o, offset, x);
+ } else if ((offset & 1) == 0) {
+ putIntParts(o, offset,
+ (short)(x >> 0),
+ (short)(x >>> 16));
+ } else {
+ putIntParts(o, offset,
+ (byte)(x >>> 0),
+ (byte)(x >>> 8),
+ (byte)(x >>> 16),
+ (byte)(x >>> 24));
+ }
+ }
+ /** @see #putLongUnaligned(Object, long, long, boolean) */
+ public final void putIntUnaligned(Object o, long offset, int x, boolean bigEndian) {
+ putIntUnaligned(o, offset, convEndian(bigEndian, x));
+ }
+
+ /** @see #putLongUnaligned(Object, long, long) */
+ public final void putShortUnaligned(Object o, long offset, short x) {
+ if ((offset & 1) == 0) {
+ putShort(o, offset, x);
+ } else {
+ putShortParts(o, offset,
+ (byte)(x >>> 0),
+ (byte)(x >>> 8));
+ }
+ }
+ /** @see #putLongUnaligned(Object, long, long, boolean) */
+ public final void putShortUnaligned(Object o, long offset, short x, boolean bigEndian) {
+ putShortUnaligned(o, offset, convEndian(bigEndian, x));
+ }
+
+ /** @see #putLongUnaligned(Object, long, long) */
+ public final void putCharUnaligned(Object o, long offset, char x) {
+ putShortUnaligned(o, offset, (short)x);
+ }
+ /** @see #putLongUnaligned(Object, long, long, boolean) */
+ public final void putCharUnaligned(Object o, long offset, char x, boolean bigEndian) {
+ putCharUnaligned(o, offset, convEndian(bigEndian, x));
+ }
+
+ // JVM interface methods
+ private native boolean unalignedAccess0();
+ private native boolean isBigEndian0();
+
+ // BE is true iff the native endianness of this machine is big.
+ private static final boolean BE = theUnsafe.isBigEndian0();
+
+ // unalignedAccess is true iff this machine can perform unaligned accesses.
+ private static final boolean unalignedAccess = theUnsafe.unalignedAccess0();
+
+ private static int pickPos(int top, int pos) { return BE ? top - pos : pos; }
+
+ // These methods construct integers from bytes. The byte ordering
+ // is the native endianness of this machine.
+ private static long makeLong(byte i0, byte i1, byte i2, byte i3, byte i4, byte i5, byte i6, byte i7) {
+ return ((toUnsignedLong(i0) << pickPos(56, 0))
+ | (toUnsignedLong(i1) << pickPos(56, 8))
+ | (toUnsignedLong(i2) << pickPos(56, 16))
+ | (toUnsignedLong(i3) << pickPos(56, 24))
+ | (toUnsignedLong(i4) << pickPos(56, 32))
+ | (toUnsignedLong(i5) << pickPos(56, 40))
+ | (toUnsignedLong(i6) << pickPos(56, 48))
+ | (toUnsignedLong(i7) << pickPos(56, 56)));
+ }
+ private static long makeLong(short i0, short i1, short i2, short i3) {
+ return ((toUnsignedLong(i0) << pickPos(48, 0))
+ | (toUnsignedLong(i1) << pickPos(48, 16))
+ | (toUnsignedLong(i2) << pickPos(48, 32))
+ | (toUnsignedLong(i3) << pickPos(48, 48)));
+ }
+ private static long makeLong(int i0, int i1) {
+ return (toUnsignedLong(i0) << pickPos(32, 0))
+ | (toUnsignedLong(i1) << pickPos(32, 32));
+ }
+ private static int makeInt(short i0, short i1) {
+ return (toUnsignedInt(i0) << pickPos(16, 0))
+ | (toUnsignedInt(i1) << pickPos(16, 16));
+ }
+ private static int makeInt(byte i0, byte i1, byte i2, byte i3) {
+ return ((toUnsignedInt(i0) << pickPos(24, 0))
+ | (toUnsignedInt(i1) << pickPos(24, 8))
+ | (toUnsignedInt(i2) << pickPos(24, 16))
+ | (toUnsignedInt(i3) << pickPos(24, 24)));
+ }
+ private static short makeShort(byte i0, byte i1) {
+ return (short)((toUnsignedInt(i0) << pickPos(8, 0))
+ | (toUnsignedInt(i1) << pickPos(8, 8)));
+ }
+
+ private static byte pick(byte le, byte be) { return BE ? be : le; }
+ private static short pick(short le, short be) { return BE ? be : le; }
+ private static int pick(int le, int be) { return BE ? be : le; }
+
+ // These methods write integers to memory from smaller parts
+ // provided by their caller. The ordering in which these parts
+ // are written is the native endianness of this machine.
+ private void putLongParts(Object o, long offset, byte i0, byte i1, byte i2, byte i3, byte i4, byte i5, byte i6, byte i7) {
+ putByte(o, offset + 0, pick(i0, i7));
+ putByte(o, offset + 1, pick(i1, i6));
+ putByte(o, offset + 2, pick(i2, i5));
+ putByte(o, offset + 3, pick(i3, i4));
+ putByte(o, offset + 4, pick(i4, i3));
+ putByte(o, offset + 5, pick(i5, i2));
+ putByte(o, offset + 6, pick(i6, i1));
+ putByte(o, offset + 7, pick(i7, i0));
+ }
+ private void putLongParts(Object o, long offset, short i0, short i1, short i2, short i3) {
+ putShort(o, offset + 0, pick(i0, i3));
+ putShort(o, offset + 2, pick(i1, i2));
+ putShort(o, offset + 4, pick(i2, i1));
+ putShort(o, offset + 6, pick(i3, i0));
+ }
+ private void putLongParts(Object o, long offset, int i0, int i1) {
+ putInt(o, offset + 0, pick(i0, i1));
+ putInt(o, offset + 4, pick(i1, i0));
+ }
+ private void putIntParts(Object o, long offset, short i0, short i1) {
+ putShort(o, offset + 0, pick(i0, i1));
+ putShort(o, offset + 2, pick(i1, i0));
+ }
+ private void putIntParts(Object o, long offset, byte i0, byte i1, byte i2, byte i3) {
+ putByte(o, offset + 0, pick(i0, i3));
+ putByte(o, offset + 1, pick(i1, i2));
+ putByte(o, offset + 2, pick(i2, i1));
+ putByte(o, offset + 3, pick(i3, i0));
+ }
+ private void putShortParts(Object o, long offset, byte i0, byte i1) {
+ putByte(o, offset + 0, pick(i0, i1));
+ putByte(o, offset + 1, pick(i1, i0));
+ }
+
+ // Zero-extend an integer
+ private static int toUnsignedInt(byte n) { return n & 0xff; }
+ private static int toUnsignedInt(short n) { return n & 0xffff; }
+ private static long toUnsignedLong(byte n) { return n & 0xffl; }
+ private static long toUnsignedLong(short n) { return n & 0xffffl; }
+ private static long toUnsignedLong(int n) { return n & 0xffffffffl; }
+
+ // Maybe byte-reverse an integer
+ private static char convEndian(boolean big, char n) { return big == BE ? n : Character.reverseBytes(n); }
+ private static short convEndian(boolean big, short n) { return big == BE ? n : Short.reverseBytes(n) ; }
+ private static int convEndian(boolean big, int n) { return big == BE ? n : Integer.reverseBytes(n) ; }
+ private static long convEndian(boolean big, long n) { return big == BE ? n : Long.reverseBytes(n) ; }
}