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net.jpountz.lz4.LZ4UnsafeUtils Maven / Gradle / Ivy
package net.jpountz.lz4;
/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import static net.jpountz.lz4.LZ4Constants.COPY_LENGTH;
import static net.jpountz.lz4.LZ4Constants.LAST_LITERALS;
import static net.jpountz.lz4.LZ4Constants.ML_BITS;
import static net.jpountz.lz4.LZ4Constants.ML_MASK;
import static net.jpountz.lz4.LZ4Constants.RUN_MASK;
import static net.jpountz.util.UnsafeUtils.readByte;
import static net.jpountz.util.UnsafeUtils.readInt;
import static net.jpountz.util.UnsafeUtils.readLong;
import static net.jpountz.util.UnsafeUtils.readShort;
import static net.jpountz.util.UnsafeUtils.writeByte;
import static net.jpountz.util.UnsafeUtils.writeInt;
import static net.jpountz.util.UnsafeUtils.writeLong;
import static net.jpountz.util.UnsafeUtils.writeShort;
import static net.jpountz.util.Utils.NATIVE_BYTE_ORDER;
import java.nio.ByteOrder;
enum LZ4UnsafeUtils {
;
static void safeArraycopy(byte[] src, int srcOff, byte[] dest, int destOff, int len) {
final int fastLen = len & 0xFFFFFFF8;
wildArraycopy(src, srcOff, dest, destOff, fastLen);
for (int i = 0, slowLen = len & 0x7; i < slowLen; i += 1) {
writeByte(dest, destOff + fastLen + i, readByte(src, srcOff + fastLen + i));
}
}
static void wildArraycopy(byte[] src, int srcOff, byte[] dest, int destOff, int len) {
for (int i = 0; i < len; i += 8) {
writeLong(dest, destOff + i, readLong(src, srcOff + i));
}
}
static void wildIncrementalCopy(byte[] dest, int matchOff, int dOff, int matchCopyEnd) {
if (dOff - matchOff < 4) {
for (int i = 0; i < 4; ++i) {
writeByte(dest, dOff+i, readByte(dest, matchOff+i));
}
dOff += 4;
matchOff += 4;
int dec = 0;
assert dOff >= matchOff && dOff - matchOff < 8;
switch (dOff - matchOff) {
case 1:
matchOff -= 3;
break;
case 2:
matchOff -= 2;
break;
case 3:
matchOff -= 3;
dec = -1;
break;
case 5:
dec = 1;
break;
case 6:
dec = 2;
break;
case 7:
dec = 3;
break;
default:
break;
}
writeInt(dest, dOff, readInt(dest, matchOff));
dOff += 4;
matchOff -= dec;
} else if (dOff - matchOff < COPY_LENGTH) {
writeLong(dest, dOff, readLong(dest, matchOff));
dOff += dOff - matchOff;
}
while (dOff < matchCopyEnd) {
writeLong(dest, dOff, readLong(dest, matchOff));
dOff += 8;
matchOff += 8;
}
}
static void safeIncrementalCopy(byte[] dest, int matchOff, int dOff, int matchLen) {
for (int i = 0; i < matchLen; ++i) {
dest[dOff + i] = dest[matchOff + i];
writeByte(dest, dOff + i, readByte(dest, matchOff + i));
}
}
static int readShortLittleEndian(byte[] src, int srcOff) {
short s = readShort(src, srcOff);
if (NATIVE_BYTE_ORDER == ByteOrder.BIG_ENDIAN) {
s = Short.reverseBytes(s);
}
return s & 0xFFFF;
}
static void writeShortLittleEndian(byte[] dest, int destOff, int value) {
short s = (short) value;
if (NATIVE_BYTE_ORDER == ByteOrder.BIG_ENDIAN) {
s = Short.reverseBytes(s);
}
writeShort(dest, destOff, s);
}
static boolean readIntEquals(byte[] src, int ref, int sOff) {
return readInt(src, ref) == readInt(src, sOff);
}
static int commonBytes(byte[] src, int ref, int sOff, int srcLimit) {
int matchLen = 0;
while (sOff <= srcLimit - 8) {
if (readLong(src, sOff) == readLong(src, ref)) {
matchLen += 8;
ref += 8;
sOff += 8;
} else {
final int zeroBits;
if (NATIVE_BYTE_ORDER == ByteOrder.BIG_ENDIAN) {
zeroBits = Long.numberOfLeadingZeros(readLong(src, sOff) ^ readLong(src, ref));
} else {
zeroBits = Long.numberOfTrailingZeros(readLong(src, sOff) ^ readLong(src, ref));
}
return matchLen + (zeroBits >>> 3);
}
}
while (sOff < srcLimit && readByte(src, ref++) == readByte(src, sOff++)) {
++matchLen;
}
return matchLen;
}
static int writeLen(int len, byte[] dest, int dOff) {
while (len >= 0xFF) {
writeByte(dest, dOff++, 0xFF);
len -= 0xFF;
}
writeByte(dest, dOff++, len);
return dOff;
}
static int encodeSequence(byte[] src, int anchor, int matchOff, int matchRef, int matchLen, byte[] dest, int dOff, int destEnd) {
final int runLen = matchOff - anchor;
final int tokenOff = dOff++;
int token;
if (runLen >= RUN_MASK) {
token = (byte) (RUN_MASK << ML_BITS);
dOff = writeLen(runLen - RUN_MASK, dest, dOff);
} else {
token = runLen << ML_BITS;
}
// copy literals
wildArraycopy(src, anchor, dest, dOff, runLen);
dOff += runLen;
// encode offset
final int matchDec = matchOff - matchRef;
dest[dOff++] = (byte) matchDec;
dest[dOff++] = (byte) (matchDec >>> 8);
// encode match len
matchLen -= 4;
if (dOff + (1 + LAST_LITERALS) + (matchLen >>> 8) > destEnd) {
throw new LZ4Exception("maxDestLen is too small");
}
if (matchLen >= ML_MASK) {
token |= ML_MASK;
dOff = writeLen(matchLen - RUN_MASK, dest, dOff);
} else {
token |= matchLen;
}
dest[tokenOff] = (byte) token;
return dOff;
}
static int commonBytesBackward(byte[] b, int o1, int o2, int l1, int l2) {
int count = 0;
while (o1 > l1 && o2 > l2 && readByte(b, --o1) == readByte(b, --o2)) {
++count;
}
return count;
}
static int lastLiterals(byte[] src, int sOff, int srcLen, byte[] dest, int dOff, int destEnd) {
return LZ4SafeUtils.lastLiterals(src, sOff, srcLen, dest, dOff, destEnd);
}
}
