443 lines
10 KiB
C
443 lines
10 KiB
C
/*
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* LZ4 - Fast LZ compression algorithm
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* Copyright (C) 2011-2012, Yann Collet.
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* BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* You can contact the author at :
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* - LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
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* - LZ4 source repository : http://code.google.com/p/lz4/
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*
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* Changed for kernel use by:
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* Chanho Min <chanho.min@lge.com>
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/lz4.h>
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#include <asm/unaligned.h>
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#include "lz4defs.h"
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/*
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* LZ4_compressCtx :
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* -----------------
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* Compress 'isize' bytes from 'source' into an output buffer 'dest' of
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* maximum size 'maxOutputSize'. * If it cannot achieve it, compression
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* will stop, and result of the function will be zero.
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* return : the number of bytes written in buffer 'dest', or 0 if the
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* compression fails
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*/
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static inline int lz4_compressctx(void *ctx,
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const char *source,
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char *dest,
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int isize,
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int maxoutputsize)
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{
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HTYPE *hashtable = (HTYPE *)ctx;
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const u8 *ip = (u8 *)source;
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#if LZ4_ARCH64
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const BYTE * const base = ip;
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#else
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const int base = 0;
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#endif
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const u8 *anchor = ip;
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const u8 *const iend = ip + isize;
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const u8 *const mflimit = iend - MFLIMIT;
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#define MATCHLIMIT (iend - LASTLITERALS)
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u8 *op = (u8 *) dest;
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u8 *const oend = op + maxoutputsize;
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int length;
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const int skipstrength = SKIPSTRENGTH;
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u32 forwardh;
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int lastrun;
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/* Init */
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if (isize < MINLENGTH)
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goto _last_literals;
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memset((void *)hashtable, 0, LZ4_MEM_COMPRESS);
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/* First Byte */
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hashtable[LZ4_HASH_VALUE(ip)] = ip - base;
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ip++;
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forwardh = LZ4_HASH_VALUE(ip);
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/* Main Loop */
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for (;;) {
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int findmatchattempts = (1U << skipstrength) + 3;
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const u8 *forwardip = ip;
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const u8 *ref;
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u8 *token;
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/* Find a match */
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do {
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u32 h = forwardh;
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int step = findmatchattempts++ >> skipstrength;
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ip = forwardip;
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forwardip = ip + step;
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if (unlikely(forwardip > mflimit))
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goto _last_literals;
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forwardh = LZ4_HASH_VALUE(forwardip);
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ref = base + hashtable[h];
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hashtable[h] = ip - base;
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} while ((ref < ip - MAX_DISTANCE) || (A32(ref) != A32(ip)));
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/* Catch up */
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while ((ip > anchor) && (ref > (u8 *)source) &&
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unlikely(ip[-1] == ref[-1])) {
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ip--;
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ref--;
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}
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/* Encode Literal length */
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length = (int)(ip - anchor);
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token = op++;
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/* check output limit */
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if (unlikely(op + length + (2 + 1 + LASTLITERALS) +
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(length >> 8) > oend))
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return 0;
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if (length >= (int)RUN_MASK) {
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int len;
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*token = (RUN_MASK << ML_BITS);
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len = length - RUN_MASK;
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for (; len > 254 ; len -= 255)
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*op++ = 255;
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*op++ = (u8)len;
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} else
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*token = (length << ML_BITS);
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/* Copy Literals */
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LZ4_BLINDCOPY(anchor, op, length);
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_next_match:
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/* Encode Offset */
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LZ4_WRITE_LITTLEENDIAN_16(op, (u16)(ip - ref));
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/* Start Counting */
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ip += MINMATCH;
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/* MinMatch verified */
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ref += MINMATCH;
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anchor = ip;
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while (likely(ip < MATCHLIMIT - (STEPSIZE - 1))) {
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#if LZ4_ARCH64
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u64 diff = A64(ref) ^ A64(ip);
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#else
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u32 diff = A32(ref) ^ A32(ip);
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#endif
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if (!diff) {
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ip += STEPSIZE;
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ref += STEPSIZE;
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continue;
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}
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ip += LZ4_NBCOMMONBYTES(diff);
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goto _endcount;
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}
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#if LZ4_ARCH64
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if ((ip < (MATCHLIMIT - 3)) && (A32(ref) == A32(ip))) {
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ip += 4;
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ref += 4;
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}
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#endif
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if ((ip < (MATCHLIMIT - 1)) && (A16(ref) == A16(ip))) {
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ip += 2;
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ref += 2;
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}
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if ((ip < MATCHLIMIT) && (*ref == *ip))
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ip++;
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_endcount:
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/* Encode MatchLength */
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length = (int)(ip - anchor);
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/* Check output limit */
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if (unlikely(op + (1 + LASTLITERALS) + (length >> 8) > oend))
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return 0;
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if (length >= (int)ML_MASK) {
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*token += ML_MASK;
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length -= ML_MASK;
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for (; length > 509 ; length -= 510) {
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*op++ = 255;
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*op++ = 255;
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}
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if (length > 254) {
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length -= 255;
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*op++ = 255;
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}
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*op++ = (u8)length;
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} else
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*token += length;
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/* Test end of chunk */
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if (ip > mflimit) {
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anchor = ip;
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break;
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}
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/* Fill table */
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hashtable[LZ4_HASH_VALUE(ip-2)] = ip - 2 - base;
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/* Test next position */
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ref = base + hashtable[LZ4_HASH_VALUE(ip)];
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hashtable[LZ4_HASH_VALUE(ip)] = ip - base;
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if ((ref > ip - (MAX_DISTANCE + 1)) && (A32(ref) == A32(ip))) {
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token = op++;
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*token = 0;
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goto _next_match;
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}
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/* Prepare next loop */
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anchor = ip++;
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forwardh = LZ4_HASH_VALUE(ip);
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}
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_last_literals:
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/* Encode Last Literals */
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lastrun = (int)(iend - anchor);
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if (((char *)op - dest) + lastrun + 1
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+ ((lastrun + 255 - RUN_MASK) / 255) > (u32)maxoutputsize)
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return 0;
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if (lastrun >= (int)RUN_MASK) {
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*op++ = (RUN_MASK << ML_BITS);
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lastrun -= RUN_MASK;
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for (; lastrun > 254 ; lastrun -= 255)
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*op++ = 255;
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*op++ = (u8)lastrun;
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} else
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*op++ = (lastrun << ML_BITS);
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memcpy(op, anchor, iend - anchor);
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op += iend - anchor;
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/* End */
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return (int)(((char *)op) - dest);
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}
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static inline int lz4_compress64kctx(void *ctx,
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const char *source,
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char *dest,
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int isize,
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int maxoutputsize)
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{
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u16 *hashtable = (u16 *)ctx;
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const u8 *ip = (u8 *) source;
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const u8 *anchor = ip;
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const u8 *const base = ip;
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const u8 *const iend = ip + isize;
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const u8 *const mflimit = iend - MFLIMIT;
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#define MATCHLIMIT (iend - LASTLITERALS)
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u8 *op = (u8 *) dest;
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u8 *const oend = op + maxoutputsize;
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int len, length;
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const int skipstrength = SKIPSTRENGTH;
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u32 forwardh;
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int lastrun;
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/* Init */
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if (isize < MINLENGTH)
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goto _last_literals;
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memset((void *)hashtable, 0, LZ4_MEM_COMPRESS);
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/* First Byte */
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ip++;
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forwardh = LZ4_HASH64K_VALUE(ip);
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/* Main Loop */
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for (;;) {
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int findmatchattempts = (1U << skipstrength) + 3;
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const u8 *forwardip = ip;
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const u8 *ref;
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u8 *token;
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/* Find a match */
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do {
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u32 h = forwardh;
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int step = findmatchattempts++ >> skipstrength;
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ip = forwardip;
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forwardip = ip + step;
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if (forwardip > mflimit)
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goto _last_literals;
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forwardh = LZ4_HASH64K_VALUE(forwardip);
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ref = base + hashtable[h];
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hashtable[h] = (u16)(ip - base);
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} while (A32(ref) != A32(ip));
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/* Catch up */
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while ((ip > anchor) && (ref > (u8 *)source)
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&& (ip[-1] == ref[-1])) {
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ip--;
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ref--;
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}
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/* Encode Literal length */
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length = (int)(ip - anchor);
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token = op++;
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/* Check output limit */
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if (unlikely(op + length + (2 + 1 + LASTLITERALS)
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+ (length >> 8) > oend))
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return 0;
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if (length >= (int)RUN_MASK) {
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*token = (RUN_MASK << ML_BITS);
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len = length - RUN_MASK;
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for (; len > 254 ; len -= 255)
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*op++ = 255;
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*op++ = (u8)len;
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} else
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*token = (length << ML_BITS);
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/* Copy Literals */
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LZ4_BLINDCOPY(anchor, op, length);
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_next_match:
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/* Encode Offset */
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LZ4_WRITE_LITTLEENDIAN_16(op, (u16)(ip - ref));
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/* Start Counting */
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ip += MINMATCH;
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/* MinMatch verified */
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ref += MINMATCH;
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anchor = ip;
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while (ip < MATCHLIMIT - (STEPSIZE - 1)) {
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#if LZ4_ARCH64
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u64 diff = A64(ref) ^ A64(ip);
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#else
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u32 diff = A32(ref) ^ A32(ip);
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#endif
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if (!diff) {
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ip += STEPSIZE;
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ref += STEPSIZE;
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continue;
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}
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ip += LZ4_NBCOMMONBYTES(diff);
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goto _endcount;
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}
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#if LZ4_ARCH64
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if ((ip < (MATCHLIMIT - 3)) && (A32(ref) == A32(ip))) {
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ip += 4;
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ref += 4;
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}
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#endif
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if ((ip < (MATCHLIMIT - 1)) && (A16(ref) == A16(ip))) {
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ip += 2;
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ref += 2;
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}
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if ((ip < MATCHLIMIT) && (*ref == *ip))
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ip++;
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_endcount:
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/* Encode MatchLength */
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len = (int)(ip - anchor);
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/* Check output limit */
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if (unlikely(op + (1 + LASTLITERALS) + (len >> 8) > oend))
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return 0;
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if (len >= (int)ML_MASK) {
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*token += ML_MASK;
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len -= ML_MASK;
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for (; len > 509 ; len -= 510) {
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*op++ = 255;
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*op++ = 255;
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}
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if (len > 254) {
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len -= 255;
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*op++ = 255;
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}
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*op++ = (u8)len;
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} else
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*token += len;
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/* Test end of chunk */
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if (ip > mflimit) {
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anchor = ip;
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break;
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}
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/* Fill table */
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hashtable[LZ4_HASH64K_VALUE(ip-2)] = (u16)(ip - 2 - base);
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/* Test next position */
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ref = base + hashtable[LZ4_HASH64K_VALUE(ip)];
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hashtable[LZ4_HASH64K_VALUE(ip)] = (u16)(ip - base);
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if (A32(ref) == A32(ip)) {
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token = op++;
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*token = 0;
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goto _next_match;
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}
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/* Prepare next loop */
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anchor = ip++;
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forwardh = LZ4_HASH64K_VALUE(ip);
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}
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_last_literals:
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/* Encode Last Literals */
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lastrun = (int)(iend - anchor);
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if (op + lastrun + 1 + (lastrun - RUN_MASK + 255) / 255 > oend)
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return 0;
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if (lastrun >= (int)RUN_MASK) {
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*op++ = (RUN_MASK << ML_BITS);
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lastrun -= RUN_MASK;
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for (; lastrun > 254 ; lastrun -= 255)
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*op++ = 255;
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*op++ = (u8)lastrun;
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} else
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*op++ = (lastrun << ML_BITS);
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memcpy(op, anchor, iend - anchor);
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op += iend - anchor;
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/* End */
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return (int)(((char *)op) - dest);
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}
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int lz4_compress(const unsigned char *src, size_t src_len,
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unsigned char *dst, size_t *dst_len, void *wrkmem)
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{
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int ret = -1;
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int out_len = 0;
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if (src_len < LZ4_64KLIMIT)
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out_len = lz4_compress64kctx(wrkmem, src, dst, src_len,
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lz4_compressbound(src_len));
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else
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out_len = lz4_compressctx(wrkmem, src, dst, src_len,
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lz4_compressbound(src_len));
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if (out_len < 0)
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goto exit;
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*dst_len = out_len;
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return 0;
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exit:
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return ret;
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}
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EXPORT_SYMBOL(lz4_compress);
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MODULE_LICENSE("Dual BSD/GPL");
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MODULE_DESCRIPTION("LZ4 compressor");
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