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Diffstat (limited to 'lib/lz4/lz4hc_compress.c')
| -rw-r--r-- | lib/lz4/lz4hc_compress.c | 768 |
1 files changed, 768 insertions, 0 deletions
diff --git a/lib/lz4/lz4hc_compress.c b/lib/lz4/lz4hc_compress.c new file mode 100644 index 0000000000..e7ac8694b7 --- /dev/null +++ b/lib/lz4/lz4hc_compress.c @@ -0,0 +1,768 @@ +/* + * LZ4 HC - High Compression Mode of LZ4 + * Copyright (C) 2011-2015, Yann Collet. + * + * BSD 2 - Clause License (http://www.opensource.org/licenses/bsd - license.php) + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following disclaimer + * in the documentation and/or other materials provided with the + * distribution. + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * You can contact the author at : + * - LZ4 homepage : http://www.lz4.org + * - LZ4 source repository : https://github.com/lz4/lz4 + * + * Changed for kernel usage by: + * Sven Schmidt <4sschmid@informatik.uni-hamburg.de> + */ + +/*-************************************ + * Dependencies + **************************************/ +#include <linux/lz4.h> +#include "lz4defs.h" +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/string.h> /* memset */ + +/* ************************************* + * Local Constants and types + ***************************************/ + +#define OPTIMAL_ML (int)((ML_MASK - 1) + MINMATCH) + +#define HASH_FUNCTION(i) (((i) * 2654435761U) \ + >> ((MINMATCH*8) - LZ4HC_HASH_LOG)) +#define DELTANEXTU16(p) chainTable[(U16)(p)] /* faster */ + +static U32 LZ4HC_hashPtr(const void *ptr) +{ + return HASH_FUNCTION(LZ4_read32(ptr)); +} + +/************************************** + * HC Compression + **************************************/ +static void LZ4HC_init(LZ4HC_CCtx_internal *hc4, const BYTE *start) +{ + memset((void *)hc4->hashTable, 0, sizeof(hc4->hashTable)); + memset(hc4->chainTable, 0xFF, sizeof(hc4->chainTable)); + hc4->nextToUpdate = 64 * KB; + hc4->base = start - 64 * KB; + hc4->end = start; + hc4->dictBase = start - 64 * KB; + hc4->dictLimit = 64 * KB; + hc4->lowLimit = 64 * KB; +} + +/* Update chains up to ip (excluded) */ +static FORCE_INLINE void LZ4HC_Insert(LZ4HC_CCtx_internal *hc4, + const BYTE *ip) +{ + U16 * const chainTable = hc4->chainTable; + U32 * const hashTable = hc4->hashTable; + const BYTE * const base = hc4->base; + U32 const target = (U32)(ip - base); + U32 idx = hc4->nextToUpdate; + + while (idx < target) { + U32 const h = LZ4HC_hashPtr(base + idx); + size_t delta = idx - hashTable[h]; + + if (delta > MAX_DISTANCE) + delta = MAX_DISTANCE; + + DELTANEXTU16(idx) = (U16)delta; + + hashTable[h] = idx; + idx++; + } + + hc4->nextToUpdate = target; +} + +static FORCE_INLINE int LZ4HC_InsertAndFindBestMatch( + LZ4HC_CCtx_internal *hc4, /* Index table will be updated */ + const BYTE *ip, + const BYTE * const iLimit, + const BYTE **matchpos, + const int maxNbAttempts) +{ + U16 * const chainTable = hc4->chainTable; + U32 * const HashTable = hc4->hashTable; + const BYTE * const base = hc4->base; + const BYTE * const dictBase = hc4->dictBase; + const U32 dictLimit = hc4->dictLimit; + const U32 lowLimit = (hc4->lowLimit + 64 * KB > (U32)(ip - base)) + ? hc4->lowLimit + : (U32)(ip - base) - (64 * KB - 1); + U32 matchIndex; + int nbAttempts = maxNbAttempts; + size_t ml = 0; + + /* HC4 match finder */ + LZ4HC_Insert(hc4, ip); + matchIndex = HashTable[LZ4HC_hashPtr(ip)]; + + while ((matchIndex >= lowLimit) + && (nbAttempts)) { + nbAttempts--; + if (matchIndex >= dictLimit) { + const BYTE * const match = base + matchIndex; + + if (*(match + ml) == *(ip + ml) + && (LZ4_read32(match) == LZ4_read32(ip))) { + size_t const mlt = LZ4_count(ip + MINMATCH, + match + MINMATCH, iLimit) + MINMATCH; + + if (mlt > ml) { + ml = mlt; + *matchpos = match; + } + } + } else { + const BYTE * const match = dictBase + matchIndex; + + if (LZ4_read32(match) == LZ4_read32(ip)) { + size_t mlt; + const BYTE *vLimit = ip + + (dictLimit - matchIndex); + + if (vLimit > iLimit) + vLimit = iLimit; + mlt = LZ4_count(ip + MINMATCH, + match + MINMATCH, vLimit) + MINMATCH; + if ((ip + mlt == vLimit) + && (vLimit < iLimit)) + mlt += LZ4_count(ip + mlt, + base + dictLimit, + iLimit); + if (mlt > ml) { + /* virtual matchpos */ + ml = mlt; + *matchpos = base + matchIndex; + } + } + } + matchIndex -= DELTANEXTU16(matchIndex); + } + + return (int)ml; +} + +static FORCE_INLINE int LZ4HC_InsertAndGetWiderMatch( + LZ4HC_CCtx_internal *hc4, + const BYTE * const ip, + const BYTE * const iLowLimit, + const BYTE * const iHighLimit, + int longest, + const BYTE **matchpos, + const BYTE **startpos, + const int maxNbAttempts) +{ + U16 * const chainTable = hc4->chainTable; + U32 * const HashTable = hc4->hashTable; + const BYTE * const base = hc4->base; + const U32 dictLimit = hc4->dictLimit; + const BYTE * const lowPrefixPtr = base + dictLimit; + const U32 lowLimit = (hc4->lowLimit + 64 * KB > (U32)(ip - base)) + ? hc4->lowLimit + : (U32)(ip - base) - (64 * KB - 1); + const BYTE * const dictBase = hc4->dictBase; + U32 matchIndex; + int nbAttempts = maxNbAttempts; + int delta = (int)(ip - iLowLimit); + + /* First Match */ + LZ4HC_Insert(hc4, ip); + matchIndex = HashTable[LZ4HC_hashPtr(ip)]; + + while ((matchIndex >= lowLimit) + && (nbAttempts)) { + nbAttempts--; + if (matchIndex >= dictLimit) { + const BYTE *matchPtr = base + matchIndex; + + if (*(iLowLimit + longest) + == *(matchPtr - delta + longest)) { + if (LZ4_read32(matchPtr) == LZ4_read32(ip)) { + int mlt = MINMATCH + LZ4_count( + ip + MINMATCH, + matchPtr + MINMATCH, + iHighLimit); + int back = 0; + + while ((ip + back > iLowLimit) + && (matchPtr + back > lowPrefixPtr) + && (ip[back - 1] == matchPtr[back - 1])) + back--; + + mlt -= back; + + if (mlt > longest) { + longest = (int)mlt; + *matchpos = matchPtr + back; + *startpos = ip + back; + } + } + } + } else { + const BYTE * const matchPtr = dictBase + matchIndex; + + if (LZ4_read32(matchPtr) == LZ4_read32(ip)) { + size_t mlt; + int back = 0; + const BYTE *vLimit = ip + (dictLimit - matchIndex); + + if (vLimit > iHighLimit) + vLimit = iHighLimit; + + mlt = LZ4_count(ip + MINMATCH, + matchPtr + MINMATCH, vLimit) + MINMATCH; + + if ((ip + mlt == vLimit) && (vLimit < iHighLimit)) + mlt += LZ4_count(ip + mlt, base + dictLimit, + iHighLimit); + while ((ip + back > iLowLimit) + && (matchIndex + back > lowLimit) + && (ip[back - 1] == matchPtr[back - 1])) + back--; + + mlt -= back; + + if ((int)mlt > longest) { + longest = (int)mlt; + *matchpos = base + matchIndex + back; + *startpos = ip + back; + } + } + } + + matchIndex -= DELTANEXTU16(matchIndex); + } + + return longest; +} + +static FORCE_INLINE int LZ4HC_encodeSequence( + const BYTE **ip, + BYTE **op, + const BYTE **anchor, + int matchLength, + const BYTE * const match, + limitedOutput_directive limitedOutputBuffer, + BYTE *oend) +{ + int length; + BYTE *token; + + /* Encode Literal length */ + length = (int)(*ip - *anchor); + token = (*op)++; + + if ((limitedOutputBuffer) + && ((*op + (length>>8) + + length + (2 + 1 + LASTLITERALS)) > oend)) { + /* Check output limit */ + return 1; + } + if (length >= (int)RUN_MASK) { + int len; + + *token = (RUN_MASK<<ML_BITS); + len = length - RUN_MASK; + for (; len > 254 ; len -= 255) + *(*op)++ = 255; + *(*op)++ = (BYTE)len; + } else + *token = (BYTE)(length<<ML_BITS); + + /* Copy Literals */ + LZ4_wildCopy(*op, *anchor, (*op) + length); + *op += length; + + /* Encode Offset */ + LZ4_writeLE16(*op, (U16)(*ip - match)); + *op += 2; + + /* Encode MatchLength */ + length = (int)(matchLength - MINMATCH); + + if ((limitedOutputBuffer) + && (*op + (length>>8) + + (1 + LASTLITERALS) > oend)) { + /* Check output limit */ + return 1; + } + + if (length >= (int)ML_MASK) { + *token += ML_MASK; + length -= ML_MASK; + + for (; length > 509 ; length -= 510) { + *(*op)++ = 255; + *(*op)++ = 255; + } + + if (length > 254) { + length -= 255; + *(*op)++ = 255; + } + + *(*op)++ = (BYTE)length; + } else + *token += (BYTE)(length); + + /* Prepare next loop */ + *ip += matchLength; + *anchor = *ip; + + return 0; +} + +static int LZ4HC_compress_generic( + LZ4HC_CCtx_internal *const ctx, + const char * const source, + char * const dest, + int const inputSize, + int const maxOutputSize, + int compressionLevel, + limitedOutput_directive limit + ) +{ + const BYTE *ip = (const BYTE *) source; + const BYTE *anchor = ip; + const BYTE * const iend = ip + inputSize; + const BYTE * const mflimit = iend - MFLIMIT; + const BYTE * const matchlimit = (iend - LASTLITERALS); + + BYTE *op = (BYTE *) dest; + BYTE * const oend = op + maxOutputSize; + + unsigned int maxNbAttempts; + int ml, ml2, ml3, ml0; + const BYTE *ref = NULL; + const BYTE *start2 = NULL; + const BYTE *ref2 = NULL; + const BYTE *start3 = NULL; + const BYTE *ref3 = NULL; + const BYTE *start0; + const BYTE *ref0; + + /* init */ + if (compressionLevel > LZ4HC_MAX_CLEVEL) + compressionLevel = LZ4HC_MAX_CLEVEL; + if (compressionLevel < 1) + compressionLevel = LZ4HC_DEFAULT_CLEVEL; + maxNbAttempts = 1 << (compressionLevel - 1); + ctx->end += inputSize; + + ip++; + + /* Main Loop */ + while (ip < mflimit) { + ml = LZ4HC_InsertAndFindBestMatch(ctx, ip, + matchlimit, (&ref), maxNbAttempts); + if (!ml) { + ip++; + continue; + } + + /* saved, in case we would skip too much */ + start0 = ip; + ref0 = ref; + ml0 = ml; + +_Search2: + if (ip + ml < mflimit) + ml2 = LZ4HC_InsertAndGetWiderMatch(ctx, + ip + ml - 2, ip + 0, + matchlimit, ml, &ref2, + &start2, maxNbAttempts); + else + ml2 = ml; + + if (ml2 == ml) { + /* No better match */ + if (LZ4HC_encodeSequence(&ip, &op, + &anchor, ml, ref, limit, oend)) + return 0; + continue; + } + + if (start0 < ip) { + if (start2 < ip + ml0) { + /* empirical */ + ip = start0; + ref = ref0; + ml = ml0; + } + } + + /* Here, start0 == ip */ + if ((start2 - ip) < 3) { + /* First Match too small : removed */ + ml = ml2; + ip = start2; + ref = ref2; + goto _Search2; + } + +_Search3: + /* + * Currently we have : + * ml2 > ml1, and + * ip1 + 3 <= ip2 (usually < ip1 + ml1) + */ + if ((start2 - ip) < OPTIMAL_ML) { + int correction; + int new_ml = ml; + + if (new_ml > OPTIMAL_ML) + new_ml = OPTIMAL_ML; + if (ip + new_ml > start2 + ml2 - MINMATCH) + new_ml = (int)(start2 - ip) + ml2 - MINMATCH; + + correction = new_ml - (int)(start2 - ip); + + if (correction > 0) { + start2 += correction; + ref2 += correction; + ml2 -= correction; + } + } + /* + * Now, we have start2 = ip + new_ml, + * with new_ml = min(ml, OPTIMAL_ML = 18) + */ + + if (start2 + ml2 < mflimit) + ml3 = LZ4HC_InsertAndGetWiderMatch(ctx, + start2 + ml2 - 3, start2, + matchlimit, ml2, &ref3, &start3, + maxNbAttempts); + else + ml3 = ml2; + + if (ml3 == ml2) { + /* No better match : 2 sequences to encode */ + /* ip & ref are known; Now for ml */ + if (start2 < ip + ml) + ml = (int)(start2 - ip); + /* Now, encode 2 sequences */ + if (LZ4HC_encodeSequence(&ip, &op, &anchor, + ml, ref, limit, oend)) + return 0; + ip = start2; + if (LZ4HC_encodeSequence(&ip, &op, &anchor, + ml2, ref2, limit, oend)) + return 0; + continue; + } + + if (start3 < ip + ml + 3) { + /* Not enough space for match 2 : remove it */ + if (start3 >= (ip + ml)) { + /* can write Seq1 immediately + * ==> Seq2 is removed, + * so Seq3 becomes Seq1 + */ + if (start2 < ip + ml) { + int correction = (int)(ip + ml - start2); + + start2 += correction; + ref2 += correction; + ml2 -= correction; + if (ml2 < MINMATCH) { + start2 = start3; + ref2 = ref3; + ml2 = ml3; + } + } + + if (LZ4HC_encodeSequence(&ip, &op, &anchor, + ml, ref, limit, oend)) + return 0; + ip = start3; + ref = ref3; + ml = ml3; + + start0 = start2; + ref0 = ref2; + ml0 = ml2; + goto _Search2; + } + + start2 = start3; + ref2 = ref3; + ml2 = ml3; + goto _Search3; + } + + /* + * OK, now we have 3 ascending matches; + * let's write at least the first one + * ip & ref are known; Now for ml + */ + if (start2 < ip + ml) { + if ((start2 - ip) < (int)ML_MASK) { + int correction; + + if (ml > OPTIMAL_ML) + ml = OPTIMAL_ML; + if (ip + ml > start2 + ml2 - MINMATCH) + ml = (int)(start2 - ip) + ml2 - MINMATCH; + correction = ml - (int)(start2 - ip); + if (correction > 0) { + start2 += correction; + ref2 += correction; + ml2 -= correction; + } + } else + ml = (int)(start2 - ip); + } + if (LZ4HC_encodeSequence(&ip, &op, &anchor, ml, + ref, limit, oend)) + return 0; + + ip = start2; + ref = ref2; + ml = ml2; + + start2 = start3; + ref2 = ref3; + ml2 = ml3; + + goto _Search3; + } + + /* Encode Last Literals */ + { + int lastRun = (int)(iend - anchor); + + if ((limit) + && (((char *)op - dest) + lastRun + 1 + + ((lastRun + 255 - RUN_MASK)/255) + > (U32)maxOutputSize)) { + /* Check output limit */ + return 0; + } + if (lastRun >= (int)RUN_MASK) { + *op++ = (RUN_MASK<<ML_BITS); + lastRun -= RUN_MASK; + for (; lastRun > 254 ; lastRun -= 255) + *op++ = 255; + *op++ = (BYTE) lastRun; + } else + *op++ = (BYTE)(lastRun<<ML_BITS); + LZ4_memcpy(op, anchor, iend - anchor); + op += iend - anchor; + } + + /* End */ + return (int) (((char *)op) - dest); +} + +static int LZ4_compress_HC_extStateHC( + void *state, + const char *src, + char *dst, + int srcSize, + int maxDstSize, + int compressionLevel) +{ + LZ4HC_CCtx_internal *ctx = &((LZ4_streamHC_t *)state)->internal_donotuse; + + if (((size_t)(state)&(sizeof(void *) - 1)) != 0) { + /* Error : state is not aligned + * for pointers (32 or 64 bits) + */ + return 0; + } + + LZ4HC_init(ctx, (const BYTE *)src); + + if (maxDstSize < LZ4_compressBound(srcSize)) + return LZ4HC_compress_generic(ctx, src, dst, + srcSize, maxDstSize, compressionLevel, limitedOutput); + else + return LZ4HC_compress_generic(ctx, src, dst, + srcSize, maxDstSize, compressionLevel, noLimit); +} + +int LZ4_compress_HC(const char *src, char *dst, int srcSize, + int maxDstSize, int compressionLevel, void *wrkmem) +{ + return LZ4_compress_HC_extStateHC(wrkmem, src, dst, + srcSize, maxDstSize, compressionLevel); +} +EXPORT_SYMBOL(LZ4_compress_HC); + +/************************************** + * Streaming Functions + **************************************/ +void LZ4_resetStreamHC(LZ4_streamHC_t *LZ4_streamHCPtr, int compressionLevel) +{ + LZ4_streamHCPtr->internal_donotuse.base = NULL; + LZ4_streamHCPtr->internal_donotuse.compressionLevel = (unsigned int)compressionLevel; +} + +int LZ4_loadDictHC(LZ4_streamHC_t *LZ4_streamHCPtr, + const char *dictionary, + int dictSize) +{ + LZ4HC_CCtx_internal *ctxPtr = &LZ4_streamHCPtr->internal_donotuse; + + if (dictSize > 64 * KB) { + dictionary += dictSize - 64 * KB; + dictSize = 64 * KB; + } + LZ4HC_init(ctxPtr, (const BYTE *)dictionary); + if (dictSize >= 4) + LZ4HC_Insert(ctxPtr, (const BYTE *)dictionary + (dictSize - 3)); + ctxPtr->end = (const BYTE *)dictionary + dictSize; + return dictSize; +} +EXPORT_SYMBOL(LZ4_loadDictHC); + +/* compression */ + +static void LZ4HC_setExternalDict( + LZ4HC_CCtx_internal *ctxPtr, + const BYTE *newBlock) +{ + if (ctxPtr->end >= ctxPtr->base + 4) { + /* Referencing remaining dictionary content */ + LZ4HC_Insert(ctxPtr, ctxPtr->end - 3); + } + + /* + * Only one memory segment for extDict, + * so any previous extDict is lost at this stage + */ + ctxPtr->lowLimit = ctxPtr->dictLimit; + ctxPtr->dictLimit = (U32)(ctxPtr->end - ctxPtr->base); + ctxPtr->dictBase = ctxPtr->base; + ctxPtr->base = newBlock - ctxPtr->dictLimit; + ctxPtr->end = newBlock; + /* match referencing will resume from there */ + ctxPtr->nextToUpdate = ctxPtr->dictLimit; +} + +static int LZ4_compressHC_continue_generic( + LZ4_streamHC_t *LZ4_streamHCPtr, + const char *source, + char *dest, + int inputSize, + int maxOutputSize, + limitedOutput_directive limit) +{ + LZ4HC_CCtx_internal *ctxPtr = &LZ4_streamHCPtr->internal_donotuse; + + /* auto - init if forgotten */ + if (ctxPtr->base == NULL) + LZ4HC_init(ctxPtr, (const BYTE *) source); + + /* Check overflow */ + if ((size_t)(ctxPtr->end - ctxPtr->base) > 2 * GB) { + size_t dictSize = (size_t)(ctxPtr->end - ctxPtr->base) + - ctxPtr->dictLimit; + if (dictSize > 64 * KB) + dictSize = 64 * KB; + LZ4_loadDictHC(LZ4_streamHCPtr, + (const char *)(ctxPtr->end) - dictSize, (int)dictSize); + } + + /* Check if blocks follow each other */ + if ((const BYTE *)source != ctxPtr->end) + LZ4HC_setExternalDict(ctxPtr, (const BYTE *)source); + + /* Check overlapping input/dictionary space */ + { + const BYTE *sourceEnd = (const BYTE *) source + inputSize; + const BYTE * const dictBegin = ctxPtr->dictBase + ctxPtr->lowLimit; + const BYTE * const dictEnd = ctxPtr->dictBase + ctxPtr->dictLimit; + + if ((sourceEnd > dictBegin) + && ((const BYTE *)source < dictEnd)) { + if (sourceEnd > dictEnd) + sourceEnd = dictEnd; + ctxPtr->lowLimit = (U32)(sourceEnd - ctxPtr->dictBase); + + if (ctxPtr->dictLimit - ctxPtr->lowLimit < 4) + ctxPtr->lowLimit = ctxPtr->dictLimit; + } + } + + return LZ4HC_compress_generic(ctxPtr, source, dest, + inputSize, maxOutputSize, ctxPtr->compressionLevel, limit); +} + +int LZ4_compress_HC_continue( + LZ4_streamHC_t *LZ4_streamHCPtr, + const char *source, + char *dest, + int inputSize, + int maxOutputSize) +{ + if (maxOutputSize < LZ4_compressBound(inputSize)) + return LZ4_compressHC_continue_generic(LZ4_streamHCPtr, + source, dest, inputSize, maxOutputSize, limitedOutput); + else + return LZ4_compressHC_continue_generic(LZ4_streamHCPtr, + source, dest, inputSize, maxOutputSize, noLimit); +} +EXPORT_SYMBOL(LZ4_compress_HC_continue); + +/* dictionary saving */ + +int LZ4_saveDictHC( + LZ4_streamHC_t *LZ4_streamHCPtr, + char *safeBuffer, + int dictSize) +{ + LZ4HC_CCtx_internal *const streamPtr = &LZ4_streamHCPtr->internal_donotuse; + int const prefixSize = (int)(streamPtr->end + - (streamPtr->base + streamPtr->dictLimit)); + + if (dictSize > 64 * KB) + dictSize = 64 * KB; + if (dictSize < 4) + dictSize = 0; + if (dictSize > prefixSize) + dictSize = prefixSize; + + memmove(safeBuffer, streamPtr->end - dictSize, dictSize); + + { + U32 const endIndex = (U32)(streamPtr->end - streamPtr->base); + + streamPtr->end = (const BYTE *)safeBuffer + dictSize; + streamPtr->base = streamPtr->end - endIndex; + streamPtr->dictLimit = endIndex - dictSize; + streamPtr->lowLimit = endIndex - dictSize; + + if (streamPtr->nextToUpdate < streamPtr->dictLimit) + streamPtr->nextToUpdate = streamPtr->dictLimit; + } + return dictSize; +} +EXPORT_SYMBOL(LZ4_saveDictHC); + +MODULE_LICENSE("Dual BSD/GPL"); +MODULE_DESCRIPTION("LZ4 HC compressor"); |