@Override
public int compare(byte[] left, byte[] right) {
int minLength = Math.min(left.length, right.length);
int minWords = minLength / Longs.BYTES;
/*
* Compare 8 bytes at a time. Benchmarking shows comparing 8 bytes at a
* time is no slower than comparing 4 bytes at a time even on 32-bit.
* On the other hand, it is substantially faster on 64-bit.
*/
for (int i = 0; i < minWords * Longs.BYTES; i += Longs.BYTES) {
long lw = theUnsafe.getLong(left, BYTE_ARRAY_BASE_OFFSET + (long) i);
long rw = theUnsafe.getLong(right, BYTE_ARRAY_BASE_OFFSET + (long) i);
long diff = lw ^ rw;
if (diff != 0) {
if (!littleEndian) {
return UnsignedLongs.compare(lw, rw);
}
// Use binary search
int n = 0;
int y;
int x = (int) diff;
if (x == 0) {
x = (int) (diff >>> 32);
n = 32;
}
y = x << 16;
if (y == 0) {
n += 16;
} else {
x = y;
}
y = x << 8;
if (y == 0) {
n += 8;
}
return (int) (((lw >>> n) & UNSIGNED_MASK) - ((rw >>> n) & UNSIGNED_MASK));
}
}
// The epilogue to cover the last (minLength % 8) elements.
for (int i = minWords * Longs.BYTES; i < minLength; i++) {
int result = UnsignedBytes.compare(left[i], right[i]);
if (result != 0) {
return result;
}
}
return left.length - right.length;
}
private static int compare(
@NotNull final Buffer left,
long leftFrom,
final long leftLength,
@NotNull final Buffer right,
long rightFrom,
final long rightLength) {
assert leftLength > 0;
assert rightLength > 0;
// Adapted from Guava UnsignedBytes
long length = Math.min(leftLength, rightLength);
for (;
length >= Longs.BYTES;
leftFrom += Longs.BYTES, rightFrom += Longs.BYTES, length -= Longs.BYTES) {
final long lw = left.getLong(leftFrom);
final long rw = right.getLong(rightFrom);
if (lw != rw) {
return UnsignedLongs.compare(lw, rw);
}
}
if (length >= Ints.BYTES) {
final int lw = left.getInt(leftFrom);
final int rw = right.getInt(rightFrom);
if (lw != rw) {
return UnsignedInts.compare(lw, rw);
}
leftFrom += Ints.BYTES;
rightFrom += Ints.BYTES;
length -= Ints.BYTES;
}
for (; length > 0; leftFrom++, rightFrom++, length--) {
final int result = UnsignedBytes.compare(left.get(leftFrom), right.get(rightFrom));
if (result != 0) {
return result;
}
}
return (leftLength < rightLength) ? -1 : ((leftLength == rightLength) ? 0 : 1);
}
