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/*
* LZ4 - Fast LZ compression algorithm
* Copyright (C) 2011-2012, 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://fastcompression.blogspot.com/p/lz4.html
* - LZ4 source repository : http://code.google.com/p/lz4/
*
* Changed for kernel use by:
* Chanho Min <chanho.min@lge.com>
*/
#include <linux/log2.h>
#include <linux/kernel.h>
#include <linux/lz4.h>
#include <asm/unaligned.h>
#include "lz4defs.h"
#define LZ4_HASH_VALUE(p, _table) \
__HASH_VALUE(p, MEMORY_USAGE - ilog2(sizeof(_table[0])))
struct lz4_hash_table {
const u8 *(*add)(const struct lz4_hash_table, const u8 *);
void *ctx;
const u8 *base;
};
#if __SIZEOF_POINTER__ == 4
static inline const u8 *hash_table_add32(const struct lz4_hash_table hash,
const u8 *ip)
{
const u8 **table = hash.ctx;
swap(table[LZ4_HASH_VALUE(ip, table)], ip);
return ip;
}
#else
static inline const u8 *hash_table_add32(const struct lz4_hash_table hash,
const u8 *ip)
{
u32 *table = hash.ctx;
size_t offset = ip - hash.base;
swap(table[LZ4_HASH_VALUE(ip, table)], offset);
return hash.base + offset;
}
#endif
static inline const u8 *hash_table_add16(const struct lz4_hash_table hash,
const u8 *ip)
{
u16 *table = hash.ctx;
size_t offset = ip - hash.base;
swap(table[LZ4_HASH_VALUE(ip, table)], offset);
return hash.base + offset;
}
static inline const u8 *find_match(const struct lz4_hash_table hash,
const u8 **ip, const u8 *anchor,
const u8 *start, const u8 *mflimit)
{
int findmatchattempts = (1U << SKIPSTRENGTH) + 3;
while (*ip <= mflimit) {
const u8 *ref = hash.add(hash, *ip);
if (ref >= *ip - MAX_DISTANCE && A32(ref) == A32(*ip)) {
/* found match: */
while (*ip > anchor &&
ref > start &&
unlikely((*ip)[-1] == ref[-1])) {
(*ip)--;
ref--;
}
return ref;
}
*ip += findmatchattempts++ >> SKIPSTRENGTH;
}
return NULL;
}
static inline int length_len(unsigned length)
{
return length / 255 + 1;
}
/*
* LZ4_compressCtx :
* -----------------
* Compress 'isize' bytes from 'source' into an output buffer 'dest' of
* maximum size 'maxOutputSize'. * If it cannot achieve it, compression
* will stop, and result of the function will be zero.
* return : the number of bytes written in buffer 'dest', or 0 if the
* compression fails
*/
static inline int lz4_compressctx(const struct lz4_hash_table hash,
const u8 *src, size_t src_len,
u8 *dst, size_t *dst_len)
{
const u8 *ip = src, *anchor = ip, *ref;
const u8 *const iend = ip + src_len;
const u8 *const mflimit = iend - MFLIMIT;
const u8 *const matchlimit = iend - LASTLITERALS;
u8 *op = dst, *token;
u8 *const oend = op + *dst_len;
size_t literal_len, match_len, match_offset;
/* Init */
memset(hash.ctx, 0, LZ4_MEM_COMPRESS);
hash.add(hash, ip);
/* Always start with a literal: */
ip++;
while ((ref = find_match(hash, &ip, anchor, src, mflimit))) {
/*
* We found a match; @ip now points to the match and @ref points
* to the prior part of the input we matched with. Everything up
* to @anchor has been encoded; the range from @anchor to @ip
* didn't match and now has to be encoded as a literal:
*/
literal_len = ip - anchor;
match_offset = ip - ref;
/* MINMATCH bytes already matched from find_match(): */
ip += MINMATCH;
ref += MINMATCH;
match_len = common_length(ip, ref, matchlimit);
ip += match_len;
/* check output limit */
if (unlikely(op +
1 + /* token */
2 + /* match ofset */
literal_len +
length_len(literal_len) +
length_len(match_len) +
LASTLITERALS > oend))
break;
token = op++;
*token = encode_length(&op, literal_len) << ML_BITS;
MEMCPY_ADVANCE_CHUNKED(op, anchor, literal_len);
PUT_LE16_ADVANCE(op, match_offset);
*token += encode_length(&op, match_len);
anchor = ip;
}
/* Encode remaining input as literal: */
literal_len = iend - anchor;
if (unlikely(op +
1 +
literal_len +
length_len(literal_len) > oend)) {
/* Return how much would be able to fit: */
ssize_t remaining = oend - op;
ssize_t encoded = anchor - src;
remaining -= length_len(remaining) + 1;
return -max(encoded + remaining, 1L);
}
token = op++;
*token = encode_length(&op, literal_len) << ML_BITS;
MEMCPY_ADVANCE(op, anchor, literal_len);
/* End */
BUG_ON(op > oend);
*dst_len = op - dst;
return 0;
}
__attribute__((flatten))
int lz4_compress(const unsigned char *src, size_t src_len,
unsigned char *dst, size_t *dst_len, void *wrkmem)
{
if (src_len < LZ4_64KLIMIT) {
const struct lz4_hash_table hash = {
.add = hash_table_add16,
.ctx = wrkmem,
.base = src,
};
return lz4_compressctx(hash, src, src_len, dst, dst_len);
} else {
const struct lz4_hash_table hash = {
.add = hash_table_add32,
.ctx = wrkmem,
.base = src,
};
return lz4_compressctx(hash, src, src_len, dst, dst_len);
}
}
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