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mirror_zfs/module/zfs/lz4_zfs.c
Rich Ercolani d6c1bbdd65
Updated the lz4 decompressor 
As an experiment, I stole the lz4 decompressor from
upstream lz4 (1.9.3), and landed it.

Feedback suggested that keeping the vendor lz4 code isolated and
unlinted was probably reasonable, so I lobbed it into its own file.

It also seemed reasonable to put the mostly-untouched* code into
lz4.c proper, and relegate the integrated and ZFS-specific code to
lz4_zfs.c.

Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes #12805
2022-01-07 10:36:49 -08:00

881 lines
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/*
* LZ4 - Fast LZ compression algorithm
* Header File
* Copyright (C) 2011-2013, 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/
*/
/*
* N.B. - This file seems to be based on LZ4 r85, dated Dec 10, 2012
*/
#include <sys/zfs_context.h>
#include <sys/zio_compress.h>
static int real_LZ4_compress(const char *source, char *dest, int isize,
int osize);
static int LZ4_compressCtx(void *ctx, const char *source, char *dest,
int isize, int osize);
static int LZ4_compress64kCtx(void *ctx, const char *source, char *dest,
int isize, int osize);
/* See lz4.c */
int LZ4_uncompress_unknownOutputSize(const char *source, char *dest,
int isize, int maxOutputSize);
static kmem_cache_t *lz4_cache;
size_t
lz4_compress_zfs(void *s_start, void *d_start, size_t s_len,
size_t d_len, int n)
{
(void) n;
uint32_t bufsiz;
char *dest = d_start;
ASSERT(d_len >= sizeof (bufsiz));
bufsiz = real_LZ4_compress(s_start, &dest[sizeof (bufsiz)], s_len,
d_len - sizeof (bufsiz));
/* Signal an error if the compression routine returned zero. */
if (bufsiz == 0)
return (s_len);
/*
* The exact compressed size is needed by the decompression routine,
* so it is stored at the start of the buffer. Note that this may be
* less than the compressed block size, which is rounded up to a
* multiple of 1<<ashift.
*/
*(uint32_t *)dest = BE_32(bufsiz);
return (bufsiz + sizeof (bufsiz));
}
int
lz4_decompress_zfs(void *s_start, void *d_start, size_t s_len,
size_t d_len, int n)
{
(void) n;
const char *src = s_start;
uint32_t bufsiz = BE_IN32(src);
/* invalid compressed buffer size encoded at start */
if (bufsiz + sizeof (bufsiz) > s_len)
return (1);
/*
* Returns 0 on success (decompression function returned non-negative)
* and non-zero on failure (decompression function returned negative).
*/
return (LZ4_uncompress_unknownOutputSize(&src[sizeof (bufsiz)],
d_start, bufsiz, d_len) < 0);
}
/*
* LZ4 API Description:
*
* Simple Functions:
* real_LZ4_compress() :
* isize : is the input size. Max supported value is ~1.9GB
* return : the number of bytes written in buffer dest
* or 0 if the compression fails (if LZ4_COMPRESSMIN is set).
* note : destination buffer must be already allocated.
* destination buffer must be sized to handle worst cases
* situations (input data not compressible) worst case size
* evaluation is provided by function LZ4_compressBound().
*
* real_LZ4_uncompress() :
* osize : is the output size, therefore the original size
* return : the number of bytes read in the source buffer.
* If the source stream is malformed, the function will stop
* decoding and return a negative result, indicating the byte
* position of the faulty instruction. This function never
* writes beyond dest + osize, and is therefore protected
* against malicious data packets.
* note : destination buffer must be already allocated
* note : real_LZ4_uncompress() is not used in ZFS so its code
* is not present here.
*
* Advanced Functions
*
* LZ4_compressBound() :
* Provides the maximum size that LZ4 may output in a "worst case"
* scenario (input data not compressible) primarily useful for memory
* allocation of output buffer.
*
* isize : is the input size. Max supported value is ~1.9GB
* return : maximum output size in a "worst case" scenario
* note : this function is limited by "int" range (2^31-1)
*
* LZ4_uncompress_unknownOutputSize() :
* isize : is the input size, therefore the compressed size
* maxOutputSize : is the size of the destination buffer (which must be
* already allocated)
* return : the number of bytes decoded in the destination buffer
* (necessarily <= maxOutputSize). If the source stream is
* malformed, the function will stop decoding and return a
* negative result, indicating the byte position of the faulty
* instruction. This function never writes beyond dest +
* maxOutputSize, and is therefore protected against malicious
* data packets.
* note : Destination buffer must be already allocated.
* This version is slightly slower than real_LZ4_uncompress()
*
* LZ4_compressCtx() :
* This function explicitly handles the CTX memory structure.
*
* ILLUMOS CHANGES: the CTX memory structure must be explicitly allocated
* by the caller (either on the stack or using kmem_cache_alloc). Passing
* NULL isn't valid.
*
* LZ4_compress64kCtx() :
* Same as LZ4_compressCtx(), but specific to small inputs (<64KB).
* isize *Must* be <64KB, otherwise the output will be corrupted.
*
* ILLUMOS CHANGES: the CTX memory structure must be explicitly allocated
* by the caller (either on the stack or using kmem_cache_alloc). Passing
* NULL isn't valid.
*/
/*
* Tuning parameters
*/
/*
* COMPRESSIONLEVEL: Increasing this value improves compression ratio
* Lowering this value reduces memory usage. Reduced memory usage
* typically improves speed, due to cache effect (ex: L1 32KB for Intel,
* L1 64KB for AMD). Memory usage formula : N->2^(N+2) Bytes
* (examples : 12 -> 16KB ; 17 -> 512KB)
*/
#define COMPRESSIONLEVEL 12
/*
* NOTCOMPRESSIBLE_CONFIRMATION: Decreasing this value will make the
* algorithm skip faster data segments considered "incompressible".
* This may decrease compression ratio dramatically, but will be
* faster on incompressible data. Increasing this value will make
* the algorithm search more before declaring a segment "incompressible".
* This could improve compression a bit, but will be slower on
* incompressible data. The default value (6) is recommended.
*/
#define NOTCOMPRESSIBLE_CONFIRMATION 6
/*
* BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE: This will provide a boost to
* performance for big endian cpu, but the resulting compressed stream
* will be incompatible with little-endian CPU. You can set this option
* to 1 in situations where data will stay within closed environment.
* This option is useless on Little_Endian CPU (such as x86).
*/
/* #define BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE 1 */
/*
* CPU Feature Detection
*/
/* 32 or 64 bits ? */
#if defined(_LP64)
#define LZ4_ARCH64 1
#else
#define LZ4_ARCH64 0
#endif
/*
* Little Endian or Big Endian?
* Note: overwrite the below #define if you know your architecture endianness.
*/
#if defined(_ZFS_BIG_ENDIAN)
#define LZ4_BIG_ENDIAN 1
#else
/*
* Little Endian assumed. PDP Endian and other very rare endian format
* are unsupported.
*/
#undef LZ4_BIG_ENDIAN
#endif
/*
* Unaligned memory access is automatically enabled for "common" CPU,
* such as x86. For others CPU, the compiler will be more cautious, and
* insert extra code to ensure aligned access is respected. If you know
* your target CPU supports unaligned memory access, you may want to
* force this option manually to improve performance
*/
#if defined(__ARM_FEATURE_UNALIGNED)
#define LZ4_FORCE_UNALIGNED_ACCESS 1
#endif
/*
* Illumos : we can't use GCC's __builtin_ctz family of builtins in the
* kernel
* Linux : we can use GCC's __builtin_ctz family of builtins in the
* kernel
*/
#undef LZ4_FORCE_SW_BITCOUNT
#if defined(__sparc)
#define LZ4_FORCE_SW_BITCOUNT
#endif
/*
* Compiler Options
*/
/* Disable restrict */
#define restrict
/*
* Linux : GCC_VERSION is defined as of 3.9-rc1, so undefine it.
* torvalds/linux@3f3f8d2f48acfd8ed3b8e6b7377935da57b27b16
*/
#ifdef GCC_VERSION
#undef GCC_VERSION
#endif
#define GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)
#if (GCC_VERSION >= 302) || (__INTEL_COMPILER >= 800) || defined(__clang__)
#define expect(expr, value) (__builtin_expect((expr), (value)))
#else
#define expect(expr, value) (expr)
#endif
#ifndef likely
#define likely(expr) expect((expr) != 0, 1)
#endif
#ifndef unlikely
#define unlikely(expr) expect((expr) != 0, 0)
#endif
#define lz4_bswap16(x) ((unsigned short int) ((((x) >> 8) & 0xffu) | \
(((x) & 0xffu) << 8)))
/* Basic types */
#define BYTE uint8_t
#define U16 uint16_t
#define U32 uint32_t
#define S32 int32_t
#define U64 uint64_t
#ifndef LZ4_FORCE_UNALIGNED_ACCESS
#pragma pack(1)
#endif
typedef struct _U16_S {
U16 v;
} U16_S;
typedef struct _U32_S {
U32 v;
} U32_S;
typedef struct _U64_S {
U64 v;
} U64_S;
#ifndef LZ4_FORCE_UNALIGNED_ACCESS
#pragma pack()
#endif
#define A64(x) (((U64_S *)(x))->v)
#define A32(x) (((U32_S *)(x))->v)
#define A16(x) (((U16_S *)(x))->v)
/*
* Constants
*/
#define MINMATCH 4
#define HASH_LOG COMPRESSIONLEVEL
#define HASHTABLESIZE (1 << HASH_LOG)
#define HASH_MASK (HASHTABLESIZE - 1)
#define SKIPSTRENGTH (NOTCOMPRESSIBLE_CONFIRMATION > 2 ? \
NOTCOMPRESSIBLE_CONFIRMATION : 2)
#define COPYLENGTH 8
#define LASTLITERALS 5
#define MFLIMIT (COPYLENGTH + MINMATCH)
#define MINLENGTH (MFLIMIT + 1)
#define MAXD_LOG 16
#define MAX_DISTANCE ((1 << MAXD_LOG) - 1)
#define ML_BITS 4
#define ML_MASK ((1U<<ML_BITS)-1)
#define RUN_BITS (8-ML_BITS)
#define RUN_MASK ((1U<<RUN_BITS)-1)
/*
* Architecture-specific macros
*/
#if LZ4_ARCH64
#define STEPSIZE 8
#define UARCH U64
#define AARCH A64
#define LZ4_COPYSTEP(s, d) A64(d) = A64(s); d += 8; s += 8;
#define LZ4_COPYPACKET(s, d) LZ4_COPYSTEP(s, d)
#define LZ4_SECURECOPY(s, d, e) if (d < e) LZ4_WILDCOPY(s, d, e)
#define HTYPE U32
#define INITBASE(base) const BYTE* const base = ip
#else /* !LZ4_ARCH64 */
#define STEPSIZE 4
#define UARCH U32
#define AARCH A32
#define LZ4_COPYSTEP(s, d) A32(d) = A32(s); d += 4; s += 4;
#define LZ4_COPYPACKET(s, d) LZ4_COPYSTEP(s, d); LZ4_COPYSTEP(s, d);
#define LZ4_SECURECOPY LZ4_WILDCOPY
#define HTYPE const BYTE *
#define INITBASE(base) const int base = 0
#endif /* !LZ4_ARCH64 */
#if (defined(LZ4_BIG_ENDIAN) && !defined(BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE))
#define LZ4_READ_LITTLEENDIAN_16(d, s, p) \
{ U16 v = A16(p); v = lz4_bswap16(v); d = (s) - v; }
#define LZ4_WRITE_LITTLEENDIAN_16(p, i) \
{ U16 v = (U16)(i); v = lz4_bswap16(v); A16(p) = v; p += 2; }
#else
#define LZ4_READ_LITTLEENDIAN_16(d, s, p) { d = (s) - A16(p); }
#define LZ4_WRITE_LITTLEENDIAN_16(p, v) { A16(p) = v; p += 2; }
#endif
/* Local structures */
struct refTables {
HTYPE hashTable[HASHTABLESIZE];
};
/* Macros */
#define LZ4_HASH_FUNCTION(i) (((i) * 2654435761U) >> ((MINMATCH * 8) - \
HASH_LOG))
#define LZ4_HASH_VALUE(p) LZ4_HASH_FUNCTION(A32(p))
#define LZ4_WILDCOPY(s, d, e) do { LZ4_COPYPACKET(s, d) } while (d < e);
#define LZ4_BLINDCOPY(s, d, l) { BYTE* e = (d) + l; LZ4_WILDCOPY(s, d, e); \
d = e; }
/* Private functions */
#if LZ4_ARCH64
static inline int
LZ4_NbCommonBytes(register U64 val)
{
#if defined(LZ4_BIG_ENDIAN)
#if ((defined(__GNUC__) && (GCC_VERSION >= 304)) || defined(__clang__)) && \
!defined(LZ4_FORCE_SW_BITCOUNT)
return (__builtin_clzll(val) >> 3);
#else
int r;
if (!(val >> 32)) {
r = 4;
} else {
r = 0;
val >>= 32;
}
if (!(val >> 16)) {
r += 2;
val >>= 8;
} else {
val >>= 24;
}
r += (!val);
return (r);
#endif
#else
#if ((defined(__GNUC__) && (GCC_VERSION >= 304)) || defined(__clang__)) && \
!defined(LZ4_FORCE_SW_BITCOUNT)
return (__builtin_ctzll(val) >> 3);
#else
static const int DeBruijnBytePos[64] =
{ 0, 0, 0, 0, 0, 1, 1, 2, 0, 3, 1, 3, 1, 4, 2, 7, 0, 2, 3, 6, 1, 5,
3, 5, 1, 3, 4, 4, 2, 5, 6, 7, 7, 0, 1, 2, 3, 3, 4, 6, 2, 6, 5,
5, 3, 4, 5, 6, 7, 1, 2, 4, 6, 4,
4, 5, 7, 2, 6, 5, 7, 6, 7, 7
};
return DeBruijnBytePos[((U64) ((val & -val) * 0x0218A392CDABBD3F)) >>
58];
#endif
#endif
}
#else
static inline int
LZ4_NbCommonBytes(register U32 val)
{
#if defined(LZ4_BIG_ENDIAN)
#if ((defined(__GNUC__) && (GCC_VERSION >= 304)) || defined(__clang__)) && \
!defined(LZ4_FORCE_SW_BITCOUNT)
return (__builtin_clz(val) >> 3);
#else
int r;
if (!(val >> 16)) {
r = 2;
val >>= 8;
} else {
r = 0;
val >>= 24;
}
r += (!val);
return (r);
#endif
#else
#if defined(__GNUC__) && (GCC_VERSION >= 304) && \
!defined(LZ4_FORCE_SW_BITCOUNT)
return (__builtin_ctz(val) >> 3);
#else
static const int DeBruijnBytePos[32] = {
0, 0, 3, 0, 3, 1, 3, 0,
3, 2, 2, 1, 3, 2, 0, 1,
3, 3, 1, 2, 2, 2, 2, 0,
3, 1, 2, 0, 1, 0, 1, 1
};
return DeBruijnBytePos[((U32) ((val & -(S32) val) * 0x077CB531U)) >>
27];
#endif
#endif
}
#endif
/* Compression functions */
static int
LZ4_compressCtx(void *ctx, const char *source, char *dest, int isize,
int osize)
{
struct refTables *srt = (struct refTables *)ctx;
HTYPE *HashTable = (HTYPE *) (srt->hashTable);
const BYTE *ip = (BYTE *) source;
INITBASE(base);
const BYTE *anchor = ip;
const BYTE *const iend = ip + isize;
const BYTE *const oend = (BYTE *) dest + osize;
const BYTE *const mflimit = iend - MFLIMIT;
#define matchlimit (iend - LASTLITERALS)
BYTE *op = (BYTE *) dest;
int len, length;
const int skipStrength = SKIPSTRENGTH;
U32 forwardH;
/* Init */
if (isize < MINLENGTH)
goto _last_literals;
/* First Byte */
HashTable[LZ4_HASH_VALUE(ip)] = ip - base;
ip++;
forwardH = LZ4_HASH_VALUE(ip);
/* Main Loop */
for (;;) {
int findMatchAttempts = (1U << skipStrength) + 3;
const BYTE *forwardIp = ip;
const BYTE *ref;
BYTE *token;
/* Find a match */
do {
U32 h = forwardH;
int step = findMatchAttempts++ >> skipStrength;
ip = forwardIp;
forwardIp = ip + step;
if (unlikely(forwardIp > mflimit)) {
goto _last_literals;
}
forwardH = LZ4_HASH_VALUE(forwardIp);
ref = base + HashTable[h];
HashTable[h] = ip - base;
} while ((ref < ip - MAX_DISTANCE) || (A32(ref) != A32(ip)));
/* Catch up */
while ((ip > anchor) && (ref > (BYTE *) source) &&
unlikely(ip[-1] == ref[-1])) {
ip--;
ref--;
}
/* Encode Literal length */
length = ip - anchor;
token = op++;
/* Check output limit */
if (unlikely(op + length + (2 + 1 + LASTLITERALS) +
(length >> 8) > oend))
return (0);
if (length >= (int)RUN_MASK) {
*token = (RUN_MASK << ML_BITS);
len = length - RUN_MASK;
for (; len > 254; len -= 255)
*op++ = 255;
*op++ = (BYTE)len;
} else
*token = (length << ML_BITS);
/* Copy Literals */
LZ4_BLINDCOPY(anchor, op, length);
_next_match:
/* Encode Offset */
LZ4_WRITE_LITTLEENDIAN_16(op, ip - ref);
/* Start Counting */
ip += MINMATCH;
ref += MINMATCH; /* MinMatch verified */
anchor = ip;
while (likely(ip < matchlimit - (STEPSIZE - 1))) {
UARCH diff = AARCH(ref) ^ AARCH(ip);
if (!diff) {
ip += STEPSIZE;
ref += STEPSIZE;
continue;
}
ip += LZ4_NbCommonBytes(diff);
goto _endCount;
}
#if LZ4_ARCH64
if ((ip < (matchlimit - 3)) && (A32(ref) == A32(ip))) {
ip += 4;
ref += 4;
}
#endif
if ((ip < (matchlimit - 1)) && (A16(ref) == A16(ip))) {
ip += 2;
ref += 2;
}
if ((ip < matchlimit) && (*ref == *ip))
ip++;
_endCount:
/* Encode MatchLength */
len = (ip - anchor);
/* Check output limit */
if (unlikely(op + (1 + LASTLITERALS) + (len >> 8) > oend))
return (0);
if (len >= (int)ML_MASK) {
*token += ML_MASK;
len -= ML_MASK;
for (; len > 509; len -= 510) {
*op++ = 255;
*op++ = 255;
}
if (len > 254) {
len -= 255;
*op++ = 255;
}
*op++ = (BYTE)len;
} else
*token += len;
/* Test end of chunk */
if (ip > mflimit) {
anchor = ip;
break;
}
/* Fill table */
HashTable[LZ4_HASH_VALUE(ip - 2)] = ip - 2 - base;
/* Test next position */
ref = base + HashTable[LZ4_HASH_VALUE(ip)];
HashTable[LZ4_HASH_VALUE(ip)] = ip - base;
if ((ref > ip - (MAX_DISTANCE + 1)) && (A32(ref) == A32(ip))) {
token = op++;
*token = 0;
goto _next_match;
}
/* Prepare next loop */
anchor = ip++;
forwardH = LZ4_HASH_VALUE(ip);
}
_last_literals:
/* Encode Last Literals */
{
int lastRun = iend - anchor;
if (op + lastRun + 1 + ((lastRun + 255 - RUN_MASK) / 255) >
oend)
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++ = (lastRun << ML_BITS);
(void) memcpy(op, anchor, iend - anchor);
op += iend - anchor;
}
/* End */
return (int)(((char *)op) - dest);
}
/* Note : this function is valid only if isize < LZ4_64KLIMIT */
#define LZ4_64KLIMIT ((1 << 16) + (MFLIMIT - 1))
#define HASHLOG64K (HASH_LOG + 1)
#define HASH64KTABLESIZE (1U << HASHLOG64K)
#define LZ4_HASH64K_FUNCTION(i) (((i) * 2654435761U) >> ((MINMATCH*8) - \
HASHLOG64K))
#define LZ4_HASH64K_VALUE(p) LZ4_HASH64K_FUNCTION(A32(p))
static int
LZ4_compress64kCtx(void *ctx, const char *source, char *dest, int isize,
int osize)
{
struct refTables *srt = (struct refTables *)ctx;
U16 *HashTable = (U16 *) (srt->hashTable);
const BYTE *ip = (BYTE *) source;
const BYTE *anchor = ip;
const BYTE *const base = ip;
const BYTE *const iend = ip + isize;
const BYTE *const oend = (BYTE *) dest + osize;
const BYTE *const mflimit = iend - MFLIMIT;
#define matchlimit (iend - LASTLITERALS)
BYTE *op = (BYTE *) dest;
int len, length;
const int skipStrength = SKIPSTRENGTH;
U32 forwardH;
/* Init */
if (isize < MINLENGTH)
goto _last_literals;
/* First Byte */
ip++;
forwardH = LZ4_HASH64K_VALUE(ip);
/* Main Loop */
for (;;) {
int findMatchAttempts = (1U << skipStrength) + 3;
const BYTE *forwardIp = ip;
const BYTE *ref;
BYTE *token;
/* Find a match */
do {
U32 h = forwardH;
int step = findMatchAttempts++ >> skipStrength;
ip = forwardIp;
forwardIp = ip + step;
if (forwardIp > mflimit) {
goto _last_literals;
}
forwardH = LZ4_HASH64K_VALUE(forwardIp);
ref = base + HashTable[h];
HashTable[h] = ip - base;
} while (A32(ref) != A32(ip));
/* Catch up */
while ((ip > anchor) && (ref > (BYTE *) source) &&
(ip[-1] == ref[-1])) {
ip--;
ref--;
}
/* Encode Literal length */
length = ip - anchor;
token = op++;
/* Check output limit */
if (unlikely(op + length + (2 + 1 + LASTLITERALS) +
(length >> 8) > oend))
return (0);
if (length >= (int)RUN_MASK) {
*token = (RUN_MASK << ML_BITS);
len = length - RUN_MASK;
for (; len > 254; len -= 255)
*op++ = 255;
*op++ = (BYTE)len;
} else
*token = (length << ML_BITS);
/* Copy Literals */
LZ4_BLINDCOPY(anchor, op, length);
_next_match:
/* Encode Offset */
LZ4_WRITE_LITTLEENDIAN_16(op, ip - ref);
/* Start Counting */
ip += MINMATCH;
ref += MINMATCH; /* MinMatch verified */
anchor = ip;
while (ip < matchlimit - (STEPSIZE - 1)) {
UARCH diff = AARCH(ref) ^ AARCH(ip);
if (!diff) {
ip += STEPSIZE;
ref += STEPSIZE;
continue;
}
ip += LZ4_NbCommonBytes(diff);
goto _endCount;
}
#if LZ4_ARCH64
if ((ip < (matchlimit - 3)) && (A32(ref) == A32(ip))) {
ip += 4;
ref += 4;
}
#endif
if ((ip < (matchlimit - 1)) && (A16(ref) == A16(ip))) {
ip += 2;
ref += 2;
}
if ((ip < matchlimit) && (*ref == *ip))
ip++;
_endCount:
/* Encode MatchLength */
len = (ip - anchor);
/* Check output limit */
if (unlikely(op + (1 + LASTLITERALS) + (len >> 8) > oend))
return (0);
if (len >= (int)ML_MASK) {
*token += ML_MASK;
len -= ML_MASK;
for (; len > 509; len -= 510) {
*op++ = 255;
*op++ = 255;
}
if (len > 254) {
len -= 255;
*op++ = 255;
}
*op++ = (BYTE)len;
} else
*token += len;
/* Test end of chunk */
if (ip > mflimit) {
anchor = ip;
break;
}
/* Fill table */
HashTable[LZ4_HASH64K_VALUE(ip - 2)] = ip - 2 - base;
/* Test next position */
ref = base + HashTable[LZ4_HASH64K_VALUE(ip)];
HashTable[LZ4_HASH64K_VALUE(ip)] = ip - base;
if (A32(ref) == A32(ip)) {
token = op++;
*token = 0;
goto _next_match;
}
/* Prepare next loop */
anchor = ip++;
forwardH = LZ4_HASH64K_VALUE(ip);
}
_last_literals:
/* Encode Last Literals */
{
int lastRun = iend - anchor;
if (op + lastRun + 1 + ((lastRun + 255 - RUN_MASK) / 255) >
oend)
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++ = (lastRun << ML_BITS);
(void) memcpy(op, anchor, iend - anchor);
op += iend - anchor;
}
/* End */
return (int)(((char *)op) - dest);
}
static int
real_LZ4_compress(const char *source, char *dest, int isize, int osize)
{
void *ctx;
int result;
ASSERT(lz4_cache != NULL);
ctx = kmem_cache_alloc(lz4_cache, KM_SLEEP);
/*
* out of kernel memory, gently fall through - this will disable
* compression in zio_compress_data
*/
if (ctx == NULL)
return (0);
memset(ctx, 0, sizeof (struct refTables));
if (isize < LZ4_64KLIMIT)
result = LZ4_compress64kCtx(ctx, source, dest, isize, osize);
else
result = LZ4_compressCtx(ctx, source, dest, isize, osize);
kmem_cache_free(lz4_cache, ctx);
return (result);
}
void
lz4_init(void)
{
lz4_cache = kmem_cache_create("lz4_cache",
sizeof (struct refTables), 0, NULL, NULL, NULL, NULL, NULL, 0);
}
void
lz4_fini(void)
{
if (lz4_cache) {
kmem_cache_destroy(lz4_cache);
lz4_cache = NULL;
}
}
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