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lz4.c
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/*
LZ4 - Fast LZ compression algorithm
Copyright (C) 2011-2023, 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
*/
/*-************************************
* Tuning parameters
**************************************/
/*
* LZ4_HEAPMODE :
* Select how stateless compression functions like `LZ4_compress_default()`
* allocate memory for their hash table,
* in memory stack (0:default, fastest), or in memory heap (1:requires malloc()).
*/
#ifndef LZ4_HEAPMODE
# define LZ4_HEAPMODE 0
#endif
/*
* LZ4_ACCELERATION_DEFAULT :
* Select "acceleration" for LZ4_compress_fast() when parameter value <= 0
*/
#define LZ4_ACCELERATION_DEFAULT 1
/*
* LZ4_ACCELERATION_MAX :
* Any "acceleration" value higher than this threshold
* get treated as LZ4_ACCELERATION_MAX instead (fix #876)
*/
#define LZ4_ACCELERATION_MAX 65537
/*-************************************
* CPU Feature Detection
**************************************/
/* LZ4_FORCE_MEMORY_ACCESS
* By default, access to unaligned memory is controlled by `memcpy()`, which is safe and portable.
* Unfortunately, on some target/compiler combinations, the generated assembly is sub-optimal.
* The below switch allow to select different access method for improved performance.
* Method 0 (default) : use `memcpy()`. Safe and portable.
* Method 1 : `__packed` statement. It depends on compiler extension (ie, not portable).
* This method is safe if your compiler supports it, and *generally* as fast or faster than `memcpy`.
* Method 2 : direct access. This method is portable but violate C standard.
* It can generate buggy code on targets which assembly generation depends on alignment.
* But in some circumstances, it's the only known way to get the most performance (ie GCC + ARMv6)
* See https://fastcompression.blogspot.fr/2015/08/accessing-unaligned-memory.html for details.
* Prefer these methods in priority order (0 > 1 > 2)
*/
#ifndef LZ4_FORCE_MEMORY_ACCESS /* can be defined externally */
# if defined(__GNUC__) && \
( defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) || defined(__ARM_ARCH_6K__) \
|| defined(__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__) || defined(__ARM_ARCH_6T2__) )
# define LZ4_FORCE_MEMORY_ACCESS 2
# elif (defined(__INTEL_COMPILER) && !defined(_WIN32)) || defined(__GNUC__) || defined(_MSC_VER)
# define LZ4_FORCE_MEMORY_ACCESS 1
# endif
#endif
/*
* LZ4_FORCE_SW_BITCOUNT
* Define this parameter if your target system or compiler does not support hardware bit count
*/
#if defined(_MSC_VER) && defined(_WIN32_WCE) /* Visual Studio for WinCE doesn't support Hardware bit count */
# undef LZ4_FORCE_SW_BITCOUNT /* avoid double def */
# define LZ4_FORCE_SW_BITCOUNT
#endif
/*-************************************
* Dependency
**************************************/
/*
* LZ4_SRC_INCLUDED:
* Amalgamation flag, whether lz4.c is included
*/
#ifndef LZ4_SRC_INCLUDED
# define LZ4_SRC_INCLUDED 1
#endif
#ifndef LZ4_DISABLE_DEPRECATE_WARNINGS
# define LZ4_DISABLE_DEPRECATE_WARNINGS /* due to LZ4_decompress_safe_withPrefix64k */
#endif
#ifndef LZ4_STATIC_LINKING_ONLY
# define LZ4_STATIC_LINKING_ONLY
#endif
#include "lz4.h"
/* see also "memory routines" below */
/*-************************************
* Compiler Options
**************************************/
#if defined(_MSC_VER) && (_MSC_VER >= 1400) /* Visual Studio 2005+ */
# include <intrin.h> /* only present in VS2005+ */
# pragma warning(disable : 4127) /* disable: C4127: conditional expression is constant */
# pragma warning(disable : 6237) /* disable: C6237: conditional expression is always 0 */
#endif /* _MSC_VER */
#ifndef LZ4_FORCE_INLINE
# ifdef _MSC_VER /* Visual Studio */
# define LZ4_FORCE_INLINE static __forceinline
# else
# if defined (__cplusplus) || defined (__STDC_VERSION__) && __STDC_VERSION__ >= 199901L /* C99 */
# ifdef __GNUC__
# define LZ4_FORCE_INLINE static inline __attribute__((always_inline))
# else
# define LZ4_FORCE_INLINE static inline
# endif
# else
# define LZ4_FORCE_INLINE static
# endif /* __STDC_VERSION__ */
# endif /* _MSC_VER */
#endif /* LZ4_FORCE_INLINE */
/* LZ4_FORCE_O2 and LZ4_FORCE_INLINE
* gcc on ppc64le generates an unrolled SIMDized loop for LZ4_wildCopy8,
* together with a simple 8-byte copy loop as a fall-back path.
* However, this optimization hurts the decompression speed by >30%,
* because the execution does not go to the optimized loop
* for typical compressible data, and all of the preamble checks
* before going to the fall-back path become useless overhead.
* This optimization happens only with the -O3 flag, and -O2 generates
* a simple 8-byte copy loop.
* With gcc on ppc64le, all of the LZ4_decompress_* and LZ4_wildCopy8
* functions are annotated with __attribute__((optimize("O2"))),
* and also LZ4_wildCopy8 is forcibly inlined, so that the O2 attribute
* of LZ4_wildCopy8 does not affect the compression speed.
*/
#if defined(__PPC64__) && defined(__LITTLE_ENDIAN__) && defined(__GNUC__) && !defined(__clang__)
# define LZ4_FORCE_O2 __attribute__((optimize("O2")))
# undef LZ4_FORCE_INLINE
# define LZ4_FORCE_INLINE static __inline __attribute__((optimize("O2"),always_inline))
#else
# define LZ4_FORCE_O2
#endif
#if (defined(__GNUC__) && (__GNUC__ >= 3)) || (defined(__INTEL_COMPILER) && (__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
/* Should the alignment test prove unreliable, for some reason,
* it can be disabled by setting LZ4_ALIGN_TEST to 0 */
#ifndef LZ4_ALIGN_TEST /* can be externally provided */
# define LZ4_ALIGN_TEST 1
#endif
/*-************************************
* Memory routines
**************************************/
/*! LZ4_STATIC_LINKING_ONLY_DISABLE_MEMORY_ALLOCATION :
* Disable relatively high-level LZ4/HC functions that use dynamic memory
* allocation functions (malloc(), calloc(), free()).
*
* Note that this is a compile-time switch. And since it disables
* public/stable LZ4 v1 API functions, we don't recommend using this
* symbol to generate a library for distribution.
*
* The following public functions are removed when this symbol is defined.
* - lz4 : LZ4_createStream, LZ4_freeStream,
* LZ4_createStreamDecode, LZ4_freeStreamDecode, LZ4_create (deprecated)
* - lz4hc : LZ4_createStreamHC, LZ4_freeStreamHC,
* LZ4_createHC (deprecated), LZ4_freeHC (deprecated)
* - lz4frame, lz4file : All LZ4F_* functions
*/
#if defined(LZ4_STATIC_LINKING_ONLY_DISABLE_MEMORY_ALLOCATION)
# define ALLOC(s) lz4_error_memory_allocation_is_disabled
# define ALLOC_AND_ZERO(s) lz4_error_memory_allocation_is_disabled
# define FREEMEM(p) lz4_error_memory_allocation_is_disabled
#elif defined(LZ4_USER_MEMORY_FUNCTIONS)
/* memory management functions can be customized by user project.
* Below functions must exist somewhere in the Project
* and be available at link time */
void* LZ4_malloc(size_t s);
void* LZ4_calloc(size_t n, size_t s);
void LZ4_free(void* p);
# define ALLOC(s) LZ4_malloc(s)
# define ALLOC_AND_ZERO(s) LZ4_calloc(1,s)
# define FREEMEM(p) LZ4_free(p)
#else
# include <stdlib.h> /* malloc, calloc, free */
# define ALLOC(s) malloc(s)
# define ALLOC_AND_ZERO(s) calloc(1,s)
# define FREEMEM(p) free(p)
#endif
#if ! LZ4_FREESTANDING
# include <string.h> /* memset, memcpy */
#endif
#if !defined(LZ4_memset)
# define LZ4_memset(p,v,s) memset((p),(v),(s))
#endif
#define MEM_INIT(p,v,s) LZ4_memset((p),(v),(s))
/*-************************************
* Common Constants
**************************************/
#define MINMATCH 4
#define WILDCOPYLENGTH 8
#define LASTLITERALS 5 /* see ../doc/lz4_Block_format.md#parsing-restrictions */
#define MFLIMIT 12 /* see ../doc/lz4_Block_format.md#parsing-restrictions */
#define MATCH_SAFEGUARD_DISTANCE ((2*WILDCOPYLENGTH) - MINMATCH) /* ensure it's possible to write 2 x wildcopyLength without overflowing output buffer */
#define FASTLOOP_SAFE_DISTANCE 64
static const int LZ4_minLength = (MFLIMIT+1);
#define KB *(1 <<10)
#define MB *(1 <<20)
#define GB *(1U<<30)
#define LZ4_DISTANCE_ABSOLUTE_MAX 65535
#if (LZ4_DISTANCE_MAX > LZ4_DISTANCE_ABSOLUTE_MAX) /* max supported by LZ4 format */
# error "LZ4_DISTANCE_MAX is too big : must be <= 65535"
#endif
#define ML_BITS 4
#define ML_MASK ((1U<<ML_BITS)-1)
#define RUN_BITS (8-ML_BITS)
#define RUN_MASK ((1U<<RUN_BITS)-1)
/*-************************************
* Error detection
**************************************/
#if defined(LZ4_DEBUG) && (LZ4_DEBUG>=1)
# include <assert.h>
#else
# ifndef assert
# define assert(condition) ((void)0)
# endif
#endif
#define LZ4_STATIC_ASSERT(c) { enum { LZ4_static_assert = 1/(int)(!!(c)) }; } /* use after variable declarations */
#if defined(LZ4_DEBUG) && (LZ4_DEBUG>=2)
# include <stdio.h>
static int g_debuglog_enable = 1;
# define DEBUGLOG(l, ...) { \
if ((g_debuglog_enable) && (l<=LZ4_DEBUG)) { \
fprintf(stderr, __FILE__ " %i: ", __LINE__); \
fprintf(stderr, __VA_ARGS__); \
fprintf(stderr, " \n"); \
} }
#else
# define DEBUGLOG(l, ...) {} /* disabled */
#endif
static int LZ4_isAligned(const void* ptr, size_t alignment)
{
return ((size_t)ptr & (alignment -1)) == 0;
}
/*-************************************
* Types
**************************************/
#include <limits.h>
#if defined(__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */)
# include <stdint.h>
typedef uint8_t BYTE;
typedef uint16_t U16;
typedef uint32_t U32;
typedef int32_t S32;
typedef uint64_t U64;
typedef uintptr_t uptrval;
#else
# if UINT_MAX != 4294967295UL
# error "LZ4 code (when not C++ or C99) assumes that sizeof(int) == 4"
# endif
typedef unsigned char BYTE;
typedef unsigned short U16;
typedef unsigned int U32;
typedef signed int S32;
typedef unsigned long long U64;
typedef size_t uptrval; /* generally true, except OpenVMS-64 */
#endif
#if defined(__x86_64__)
typedef U64 reg_t; /* 64-bits in x32 mode */
#else
typedef size_t reg_t; /* 32-bits in x32 mode */
#endif
typedef enum {
notLimited = 0,
limitedOutput = 1,
fillOutput = 2
} limitedOutput_directive;
/*-************************************
* Reading and writing into memory
**************************************/
/**
* LZ4 relies on memcpy with a constant size being inlined. In freestanding
* environments, the compiler can't assume the implementation of memcpy() is
* standard compliant, so it can't apply its specialized memcpy() inlining
* logic. When possible, use __builtin_memcpy() to tell the compiler to analyze
* memcpy() as if it were standard compliant, so it can inline it in freestanding
* environments. This is needed when decompressing the Linux Kernel, for example.
*/
#if !defined(LZ4_memcpy)
# if defined(__GNUC__) && (__GNUC__ >= 4)
# define LZ4_memcpy(dst, src, size) __builtin_memcpy(dst, src, size)
# else
# define LZ4_memcpy(dst, src, size) memcpy(dst, src, size)
# endif
#endif
#if !defined(LZ4_memmove)
# if defined(__GNUC__) && (__GNUC__ >= 4)
# define LZ4_memmove __builtin_memmove
# else
# define LZ4_memmove memmove
# endif
#endif
static unsigned LZ4_isLittleEndian(void)
{
const union { U32 u; BYTE c[4]; } one = { 1 }; /* don't use static : performance detrimental */
return one.c[0];
}
#if defined(__GNUC__) || defined(__INTEL_COMPILER)
#define LZ4_PACK( __Declaration__ ) __Declaration__ __attribute__((__packed__))
#elif defined(_MSC_VER)
#define LZ4_PACK( __Declaration__ ) __pragma( pack(push, 1) ) __Declaration__ __pragma( pack(pop))
#endif
#if defined(LZ4_FORCE_MEMORY_ACCESS) && (LZ4_FORCE_MEMORY_ACCESS==2)
/* lie to the compiler about data alignment; use with caution */
static U16 LZ4_read16(const void* memPtr) { return *(const U16*) memPtr; }
static U32 LZ4_read32(const void* memPtr) { return *(const U32*) memPtr; }
static reg_t LZ4_read_ARCH(const void* memPtr) { return *(const reg_t*) memPtr; }
static void LZ4_write16(void* memPtr, U16 value) { *(U16*)memPtr = value; }
static void LZ4_write32(void* memPtr, U32 value) { *(U32*)memPtr = value; }
#elif defined(LZ4_FORCE_MEMORY_ACCESS) && (LZ4_FORCE_MEMORY_ACCESS==1)
/* __pack instructions are safer, but compiler specific, hence potentially problematic for some compilers */
/* currently only defined for gcc and icc */
LZ4_PACK(typedef struct { U16 u16; }) LZ4_unalign16;
LZ4_PACK(typedef struct { U32 u32; }) LZ4_unalign32;
LZ4_PACK(typedef struct { reg_t uArch; }) LZ4_unalignST;
static U16 LZ4_read16(const void* ptr) { return ((const LZ4_unalign16*)ptr)->u16; }
static U32 LZ4_read32(const void* ptr) { return ((const LZ4_unalign32*)ptr)->u32; }
static reg_t LZ4_read_ARCH(const void* ptr) { return ((const LZ4_unalignST*)ptr)->uArch; }
static void LZ4_write16(void* memPtr, U16 value) { ((LZ4_unalign16*)memPtr)->u16 = value; }
static void LZ4_write32(void* memPtr, U32 value) { ((LZ4_unalign32*)memPtr)->u32 = value; }
#else /* safe and portable access using memcpy() */
static U16 LZ4_read16(const void* memPtr)
{
U16 val; LZ4_memcpy(&val, memPtr, sizeof(val)); return val;
}
static U32 LZ4_read32(const void* memPtr)
{
U32 val; LZ4_memcpy(&val, memPtr, sizeof(val)); return val;
}
static reg_t LZ4_read_ARCH(const void* memPtr)
{
reg_t val; LZ4_memcpy(&val, memPtr, sizeof(val)); return val;
}
static void LZ4_write16(void* memPtr, U16 value)
{
LZ4_memcpy(memPtr, &value, sizeof(value));
}
static void LZ4_write32(void* memPtr, U32 value)
{
LZ4_memcpy(memPtr, &value, sizeof(value));
}
#endif /* LZ4_FORCE_MEMORY_ACCESS */
static U16 LZ4_readLE16(const void* memPtr)
{
if (LZ4_isLittleEndian()) {
return LZ4_read16(memPtr);
} else {
const BYTE* p = (const BYTE*)memPtr;
return (U16)((U16)p[0] + (p[1]<<8));
}
}
#ifdef LZ4_STATIC_LINKING_ONLY_ENDIANNESS_INDEPENDENT_OUTPUT
static U32 LZ4_readLE32(const void* memPtr)
{
if (LZ4_isLittleEndian()) {
return LZ4_read32(memPtr);
} else {
const BYTE* p = (const BYTE*)memPtr;
return (U32)p[0] + (p[1]<<8) + (p[2]<<16) + (p[3]<<24);
}
}
#endif
static void LZ4_writeLE16(void* memPtr, U16 value)
{
if (LZ4_isLittleEndian()) {
LZ4_write16(memPtr, value);
} else {
BYTE* p = (BYTE*)memPtr;
p[0] = (BYTE) value;
p[1] = (BYTE)(value>>8);
}
}
/* customized variant of memcpy, which can overwrite up to 8 bytes beyond dstEnd */
LZ4_FORCE_INLINE
void LZ4_wildCopy8(void* dstPtr, const void* srcPtr, void* dstEnd)
{
BYTE* d = (BYTE*)dstPtr;
const BYTE* s = (const BYTE*)srcPtr;
BYTE* const e = (BYTE*)dstEnd;
do { LZ4_memcpy(d,s,8); d+=8; s+=8; } while (d<e);
}
static const unsigned inc32table[8] = {0, 1, 2, 1, 0, 4, 4, 4};
static const int dec64table[8] = {0, 0, 0, -1, -4, 1, 2, 3};
#ifndef LZ4_FAST_DEC_LOOP
# if defined __i386__ || defined _M_IX86 || defined __x86_64__ || defined _M_X64
# define LZ4_FAST_DEC_LOOP 1
# elif defined(__aarch64__) && defined(__APPLE__)
# define LZ4_FAST_DEC_LOOP 1
# elif defined(__aarch64__) && !defined(__clang__)
/* On non-Apple aarch64, we disable this optimization for clang because
* on certain mobile chipsets, performance is reduced with clang. For
* more information refer to https://github.com/lz4/lz4/pull/707 */
# define LZ4_FAST_DEC_LOOP 1
# else
# define LZ4_FAST_DEC_LOOP 0
# endif
#endif
#if LZ4_FAST_DEC_LOOP
LZ4_FORCE_INLINE void
LZ4_memcpy_using_offset_base(BYTE* dstPtr, const BYTE* srcPtr, BYTE* dstEnd, const size_t offset)
{
assert(srcPtr + offset == dstPtr);
if (offset < 8) {
LZ4_write32(dstPtr, 0); /* silence an msan warning when offset==0 */
dstPtr[0] = srcPtr[0];
dstPtr[1] = srcPtr[1];
dstPtr[2] = srcPtr[2];
dstPtr[3] = srcPtr[3];
srcPtr += inc32table[offset];
LZ4_memcpy(dstPtr+4, srcPtr, 4);
srcPtr -= dec64table[offset];
dstPtr += 8;
} else {
LZ4_memcpy(dstPtr, srcPtr, 8);
dstPtr += 8;
srcPtr += 8;
}
LZ4_wildCopy8(dstPtr, srcPtr, dstEnd);
}
/* customized variant of memcpy, which can overwrite up to 32 bytes beyond dstEnd
* this version copies two times 16 bytes (instead of one time 32 bytes)
* because it must be compatible with offsets >= 16. */
LZ4_FORCE_INLINE void
LZ4_wildCopy32(void* dstPtr, const void* srcPtr, void* dstEnd)
{
BYTE* d = (BYTE*)dstPtr;
const BYTE* s = (const BYTE*)srcPtr;
BYTE* const e = (BYTE*)dstEnd;
do { LZ4_memcpy(d,s,16); LZ4_memcpy(d+16,s+16,16); d+=32; s+=32; } while (d<e);
}
/* LZ4_memcpy_using_offset() presumes :
* - dstEnd >= dstPtr + MINMATCH
* - there is at least 8 bytes available to write after dstEnd */
LZ4_FORCE_INLINE void
LZ4_memcpy_using_offset(BYTE* dstPtr, const BYTE* srcPtr, BYTE* dstEnd, const size_t offset)
{
BYTE v[8];
assert(dstEnd >= dstPtr + MINMATCH);
switch(offset) {
case 1:
MEM_INIT(v, *srcPtr, 8);
break;
case 2:
LZ4_memcpy(v, srcPtr, 2);
LZ4_memcpy(&v[2], srcPtr, 2);
#if defined(_MSC_VER) && (_MSC_VER <= 1937) /* MSVC 2022 ver 17.7 or earlier */
# pragma warning(push)
# pragma warning(disable : 6385) /* warning C6385: Reading invalid data from 'v'. */
#endif
LZ4_memcpy(&v[4], v, 4);
#if defined(_MSC_VER) && (_MSC_VER <= 1937) /* MSVC 2022 ver 17.7 or earlier */
# pragma warning(pop)
#endif
break;
case 4:
LZ4_memcpy(v, srcPtr, 4);
LZ4_memcpy(&v[4], srcPtr, 4);
break;
default:
LZ4_memcpy_using_offset_base(dstPtr, srcPtr, dstEnd, offset);
return;
}
LZ4_memcpy(dstPtr, v, 8);
dstPtr += 8;
while (dstPtr < dstEnd) {
LZ4_memcpy(dstPtr, v, 8);
dstPtr += 8;
}
}
#endif
/*-************************************
* Common functions
**************************************/
static unsigned LZ4_NbCommonBytes (reg_t val)
{
assert(val != 0);
if (LZ4_isLittleEndian()) {
if (sizeof(val) == 8) {
# if defined(_MSC_VER) && (_MSC_VER >= 1800) && (defined(_M_AMD64) && !defined(_M_ARM64EC)) && !defined(LZ4_FORCE_SW_BITCOUNT)
/*-*************************************************************************************************
* ARM64EC is a Microsoft-designed ARM64 ABI compatible with AMD64 applications on ARM64 Windows 11.
* The ARM64EC ABI does not support AVX/AVX2/AVX512 instructions, nor their relevant intrinsics
* including _tzcnt_u64. Therefore, we need to neuter the _tzcnt_u64 code path for ARM64EC.
****************************************************************************************************/
# if defined(__clang__) && (__clang_major__ < 10)
/* Avoid undefined clang-cl intrinsics issue.
* See https://github.com/lz4/lz4/pull/1017 for details. */
return (unsigned)__builtin_ia32_tzcnt_u64(val) >> 3;
# else
/* x64 CPUS without BMI support interpret `TZCNT` as `REP BSF` */
return (unsigned)_tzcnt_u64(val) >> 3;
# endif
# elif defined(_MSC_VER) && defined(_WIN64) && !defined(LZ4_FORCE_SW_BITCOUNT)
unsigned long r = 0;
_BitScanForward64(&r, (U64)val);
return (unsigned)r >> 3;
# elif (defined(__clang__) || (defined(__GNUC__) && ((__GNUC__ > 3) || \
((__GNUC__ == 3) && (__GNUC_MINOR__ >= 4))))) && \
!defined(LZ4_FORCE_SW_BITCOUNT)
return (unsigned)__builtin_ctzll((U64)val) >> 3;
# else
const U64 m = 0x0101010101010101ULL;
val ^= val - 1;
return (unsigned)(((U64)((val & (m - 1)) * m)) >> 56);
# endif
} else /* 32 bits */ {
# if defined(_MSC_VER) && (_MSC_VER >= 1400) && !defined(LZ4_FORCE_SW_BITCOUNT)
unsigned long r;
_BitScanForward(&r, (U32)val);
return (unsigned)r >> 3;
# elif (defined(__clang__) || (defined(__GNUC__) && ((__GNUC__ > 3) || \
((__GNUC__ == 3) && (__GNUC_MINOR__ >= 4))))) && \
!defined(__TINYC__) && !defined(LZ4_FORCE_SW_BITCOUNT)
return (unsigned)__builtin_ctz((U32)val) >> 3;
# else
const U32 m = 0x01010101;
return (unsigned)((((val - 1) ^ val) & (m - 1)) * m) >> 24;
# endif
}
} else /* Big Endian CPU */ {
if (sizeof(val)==8) {
# if (defined(__clang__) || (defined(__GNUC__) && ((__GNUC__ > 3) || \
((__GNUC__ == 3) && (__GNUC_MINOR__ >= 4))))) && \
!defined(__TINYC__) && !defined(LZ4_FORCE_SW_BITCOUNT)
return (unsigned)__builtin_clzll((U64)val) >> 3;
# else
#if 1
/* this method is probably faster,
* but adds a 128 bytes lookup table */
static const unsigned char ctz7_tab[128] = {
7, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
};
U64 const mask = 0x0101010101010101ULL;
U64 const t = (((val >> 8) - mask) | val) & mask;
return ctz7_tab[(t * 0x0080402010080402ULL) >> 57];
#else
/* this method doesn't consume memory space like the previous one,
* but it contains several branches,
* that may end up slowing execution */
static const U32 by32 = sizeof(val)*4; /* 32 on 64 bits (goal), 16 on 32 bits.
Just to avoid some static analyzer complaining about shift by 32 on 32-bits target.
Note that this code path is never triggered in 32-bits mode. */
unsigned r;
if (!(val>>by32)) { r=4; } else { r=0; val>>=by32; }
if (!(val>>16)) { r+=2; val>>=8; } else { val>>=24; }
r += (!val);
return r;
#endif
# endif
} else /* 32 bits */ {
# if (defined(__clang__) || (defined(__GNUC__) && ((__GNUC__ > 3) || \
((__GNUC__ == 3) && (__GNUC_MINOR__ >= 4))))) && \
!defined(LZ4_FORCE_SW_BITCOUNT)
return (unsigned)__builtin_clz((U32)val) >> 3;
# else
val >>= 8;
val = ((((val + 0x00FFFF00) | 0x00FFFFFF) + val) |
(val + 0x00FF0000)) >> 24;
return (unsigned)val ^ 3;
# endif
}
}
}
#define STEPSIZE sizeof(reg_t)
LZ4_FORCE_INLINE
unsigned LZ4_count(const BYTE* pIn, const BYTE* pMatch, const BYTE* pInLimit)
{
const BYTE* const pStart = pIn;
if (likely(pIn < pInLimit-(STEPSIZE-1))) {
reg_t const diff = LZ4_read_ARCH(pMatch) ^ LZ4_read_ARCH(pIn);
if (!diff) {
pIn+=STEPSIZE; pMatch+=STEPSIZE;
} else {
return LZ4_NbCommonBytes(diff);
} }
while (likely(pIn < pInLimit-(STEPSIZE-1))) {
reg_t const diff = LZ4_read_ARCH(pMatch) ^ LZ4_read_ARCH(pIn);
if (!diff) { pIn+=STEPSIZE; pMatch+=STEPSIZE; continue; }
pIn += LZ4_NbCommonBytes(diff);
return (unsigned)(pIn - pStart);
}
if ((STEPSIZE==8) && (pIn<(pInLimit-3)) && (LZ4_read32(pMatch) == LZ4_read32(pIn))) { pIn+=4; pMatch+=4; }
if ((pIn<(pInLimit-1)) && (LZ4_read16(pMatch) == LZ4_read16(pIn))) { pIn+=2; pMatch+=2; }
if ((pIn<pInLimit) && (*pMatch == *pIn)) pIn++;
return (unsigned)(pIn - pStart);
}
#ifndef LZ4_COMMONDEFS_ONLY
/*-************************************
* Local Constants
**************************************/
static const int LZ4_64Klimit = ((64 KB) + (MFLIMIT-1));
static const U32 LZ4_skipTrigger = 6; /* Increase this value ==> compression run slower on incompressible data */
/*-************************************
* Local Structures and types
**************************************/
typedef enum { clearedTable = 0, byPtr, byU32, byU16 } tableType_t;
/**
* This enum distinguishes several different modes of accessing previous
* content in the stream.
*
* - noDict : There is no preceding content.
* - withPrefix64k : Table entries up to ctx->dictSize before the current blob
* blob being compressed are valid and refer to the preceding
* content (of length ctx->dictSize), which is available
* contiguously preceding in memory the content currently
* being compressed.
* - usingExtDict : Like withPrefix64k, but the preceding content is somewhere
* else in memory, starting at ctx->dictionary with length
* ctx->dictSize.
* - usingDictCtx : Everything concerning the preceding content is
* in a separate context, pointed to by ctx->dictCtx.
* ctx->dictionary, ctx->dictSize, and table entries
* in the current context that refer to positions
* preceding the beginning of the current compression are
* ignored. Instead, ctx->dictCtx->dictionary and ctx->dictCtx
* ->dictSize describe the location and size of the preceding
* content, and matches are found by looking in the ctx
* ->dictCtx->hashTable.
*/
typedef enum { noDict = 0, withPrefix64k, usingExtDict, usingDictCtx } dict_directive;
typedef enum { noDictIssue = 0, dictSmall } dictIssue_directive;
/*-************************************
* Local Utils
**************************************/
int LZ4_versionNumber (void) { return LZ4_VERSION_NUMBER; }
const char* LZ4_versionString(void) { return LZ4_VERSION_STRING; }
int LZ4_compressBound(int isize) { return LZ4_COMPRESSBOUND(isize); }
int LZ4_sizeofState(void) { return sizeof(LZ4_stream_t); }
/*-****************************************
* Internal Definitions, used only in Tests
*******************************************/
#if defined (__cplusplus)
extern "C" {
#endif
int LZ4_compress_forceExtDict (LZ4_stream_t* LZ4_dict, const char* source, char* dest, int srcSize);
int LZ4_decompress_safe_forceExtDict(const char* source, char* dest,
int compressedSize, int maxOutputSize,
const void* dictStart, size_t dictSize);
int LZ4_decompress_safe_partial_forceExtDict(const char* source, char* dest,
int compressedSize, int targetOutputSize, int dstCapacity,
const void* dictStart, size_t dictSize);
#if defined (__cplusplus)
}
#endif
/*-******************************
* Compression functions
********************************/
LZ4_FORCE_INLINE U32 LZ4_hash4(U32 sequence, tableType_t const tableType)
{
if (tableType == byU16)
return ((sequence * 2654435761U) >> ((MINMATCH*8)-(LZ4_HASHLOG+1)));
else
return ((sequence * 2654435761U) >> ((MINMATCH*8)-LZ4_HASHLOG));
}
LZ4_FORCE_INLINE U32 LZ4_hash5(U64 sequence, tableType_t const tableType)
{
const U32 hashLog = (tableType == byU16) ? LZ4_HASHLOG+1 : LZ4_HASHLOG;
if (LZ4_isLittleEndian()) {
const U64 prime5bytes = 889523592379ULL;
return (U32)(((sequence << 24) * prime5bytes) >> (64 - hashLog));
} else {
const U64 prime8bytes = 11400714785074694791ULL;
return (U32)(((sequence >> 24) * prime8bytes) >> (64 - hashLog));
}
}
LZ4_FORCE_INLINE U32 LZ4_hashPosition(const void* const p, tableType_t const tableType)
{
if ((sizeof(reg_t)==8) && (tableType != byU16)) return LZ4_hash5(LZ4_read_ARCH(p), tableType);
#ifdef LZ4_STATIC_LINKING_ONLY_ENDIANNESS_INDEPENDENT_OUTPUT
return LZ4_hash4(LZ4_readLE32(p), tableType);
#else
return LZ4_hash4(LZ4_read32(p), tableType);
#endif
}
LZ4_FORCE_INLINE void LZ4_clearHash(U32 h, void* tableBase, tableType_t const tableType)
{
switch (tableType)
{
default: /* fallthrough */
case clearedTable: { /* illegal! */ assert(0); return; }
case byPtr: { const BYTE** hashTable = (const BYTE**)tableBase; hashTable[h] = NULL; return; }
case byU32: { U32* hashTable = (U32*) tableBase; hashTable[h] = 0; return; }
case byU16: { U16* hashTable = (U16*) tableBase; hashTable[h] = 0; return; }
}
}
LZ4_FORCE_INLINE void LZ4_putIndexOnHash(U32 idx, U32 h, void* tableBase, tableType_t const tableType)
{
switch (tableType)
{
default: /* fallthrough */
case clearedTable: /* fallthrough */
case byPtr: { /* illegal! */ assert(0); return; }
case byU32: { U32* hashTable = (U32*) tableBase; hashTable[h] = idx; return; }
case byU16: { U16* hashTable = (U16*) tableBase; assert(idx < 65536); hashTable[h] = (U16)idx; return; }
}
}
/* LZ4_putPosition*() : only used in byPtr mode */
LZ4_FORCE_INLINE void LZ4_putPositionOnHash(const BYTE* p, U32 h,
void* tableBase, tableType_t const tableType)
{
const BYTE** const hashTable = (const BYTE**)tableBase;
assert(tableType == byPtr); (void)tableType;
hashTable[h] = p;
}
LZ4_FORCE_INLINE void LZ4_putPosition(const BYTE* p, void* tableBase, tableType_t tableType)
{
U32 const h = LZ4_hashPosition(p, tableType);
LZ4_putPositionOnHash(p, h, tableBase, tableType);
}
/* LZ4_getIndexOnHash() :
* Index of match position registered in hash table.
* hash position must be calculated by using base+index, or dictBase+index.
* Assumption 1 : only valid if tableType == byU32 or byU16.
* Assumption 2 : h is presumed valid (within limits of hash table)
*/
LZ4_FORCE_INLINE U32 LZ4_getIndexOnHash(U32 h, const void* tableBase, tableType_t tableType)
{
LZ4_STATIC_ASSERT(LZ4_MEMORY_USAGE > 2);
if (tableType == byU32) {
const U32* const hashTable = (const U32*) tableBase;
assert(h < (1U << (LZ4_MEMORY_USAGE-2)));
return hashTable[h];
}
if (tableType == byU16) {
const U16* const hashTable = (const U16*) tableBase;
assert(h < (1U << (LZ4_MEMORY_USAGE-1)));
return hashTable[h];
}
assert(0); return 0; /* forbidden case */
}
static const BYTE* LZ4_getPositionOnHash(U32 h, const void* tableBase, tableType_t tableType)
{
assert(tableType == byPtr); (void)tableType;
{ const BYTE* const* hashTable = (const BYTE* const*) tableBase; return hashTable[h]; }
}
LZ4_FORCE_INLINE const BYTE*
LZ4_getPosition(const BYTE* p,
const void* tableBase, tableType_t tableType)
{
U32 const h = LZ4_hashPosition(p, tableType);
return LZ4_getPositionOnHash(h, tableBase, tableType);
}
LZ4_FORCE_INLINE void
LZ4_prepareTable(LZ4_stream_t_internal* const cctx,
const int inputSize,
const tableType_t tableType) {
/* If the table hasn't been used, it's guaranteed to be zeroed out, and is
* therefore safe to use no matter what mode we're in. Otherwise, we figure
* out if it's safe to leave as is or whether it needs to be reset.
*/
if ((tableType_t)cctx->tableType != clearedTable) {
assert(inputSize >= 0);
if ((tableType_t)cctx->tableType != tableType
|| ((tableType == byU16) && cctx->currentOffset + (unsigned)inputSize >= 0xFFFFU)
|| ((tableType == byU32) && cctx->currentOffset > 1 GB)
|| tableType == byPtr
|| inputSize >= 4 KB)
{
DEBUGLOG(4, "LZ4_prepareTable: Resetting table in %p", cctx);
MEM_INIT(cctx->hashTable, 0, LZ4_HASHTABLESIZE);
cctx->currentOffset = 0;
cctx->tableType = (U32)clearedTable;
} else {
DEBUGLOG(4, "LZ4_prepareTable: Re-use hash table (no reset)");
}
}
/* Adding a gap, so all previous entries are > LZ4_DISTANCE_MAX back,
* is faster than compressing without a gap.
* However, compressing with currentOffset == 0 is faster still,
* so we preserve that case.
*/
if (cctx->currentOffset != 0 && tableType == byU32) {
DEBUGLOG(5, "LZ4_prepareTable: adding 64KB to currentOffset");
cctx->currentOffset += 64 KB;
}
/* Finally, clear history */
cctx->dictCtx = NULL;
cctx->dictionary = NULL;
cctx->dictSize = 0;
}
/** LZ4_compress_generic_validated() :
* inlined, to ensure branches are decided at compilation time.
* The following conditions are presumed already validated:
* - source != NULL
* - inputSize > 0
*/
LZ4_FORCE_INLINE int LZ4_compress_generic_validated(
LZ4_stream_t_internal* const cctx,
const char* const source,
char* const dest,
const int inputSize,
int* inputConsumed, /* only written when outputDirective == fillOutput */
const int maxOutputSize,
const limitedOutput_directive outputDirective,
const tableType_t tableType,
const dict_directive dictDirective,
const dictIssue_directive dictIssue,
const int acceleration)
{
int result;
const BYTE* ip = (const BYTE*)source;
U32 const startIndex = cctx->currentOffset;
const BYTE* base = (const BYTE*)source - startIndex;
const BYTE* lowLimit;
const LZ4_stream_t_internal* dictCtx = (const LZ4_stream_t_internal*) cctx->dictCtx;
const BYTE* const dictionary =
dictDirective == usingDictCtx ? dictCtx->dictionary : cctx->dictionary;
const U32 dictSize =
dictDirective == usingDictCtx ? dictCtx->dictSize : cctx->dictSize;
const U32 dictDelta =
(dictDirective == usingDictCtx) ? startIndex - dictCtx->currentOffset : 0; /* make indexes in dictCtx comparable with indexes in current context */
int const maybe_extMem = (dictDirective == usingExtDict) || (dictDirective == usingDictCtx);
U32 const prefixIdxLimit = startIndex - dictSize; /* used when dictDirective == dictSmall */
const BYTE* const dictEnd = dictionary ? dictionary + dictSize : dictionary;
const BYTE* anchor = (const BYTE*) source;
const BYTE* const iend = ip + inputSize;
const BYTE* const mflimitPlusOne = iend - MFLIMIT + 1;
const BYTE* const matchlimit = iend - LASTLITERALS;
/* the dictCtx currentOffset is indexed on the start of the dictionary,
* while a dictionary in the current context precedes the currentOffset */
const BYTE* dictBase = (dictionary == NULL) ? NULL :
(dictDirective == usingDictCtx) ?
dictionary + dictSize - dictCtx->currentOffset :
dictionary + dictSize - startIndex;
BYTE* op = (BYTE*) dest;
BYTE* const olimit = op + maxOutputSize;
U32 offset = 0;
U32 forwardH;
DEBUGLOG(5, "LZ4_compress_generic_validated: srcSize=%i, tableType=%u", inputSize, tableType);
assert(ip != NULL);
if (tableType == byU16) assert(inputSize<LZ4_64Klimit); /* Size too large (not within 64K limit) */
if (tableType == byPtr) assert(dictDirective==noDict); /* only supported use case with byPtr */
/* If init conditions are not met, we don't have to mark stream
* as having dirty context, since no action was taken yet */
if (outputDirective == fillOutput && maxOutputSize < 1) { return 0; } /* Impossible to store anything */
assert(acceleration >= 1);
lowLimit = (const BYTE*)source - (dictDirective == withPrefix64k ? dictSize : 0);
/* Update context state */
if (dictDirective == usingDictCtx) {
/* Subsequent linked blocks can't use the dictionary. */
/* Instead, they use the block we just compressed. */
cctx->dictCtx = NULL;
cctx->dictSize = (U32)inputSize;
} else {
cctx->dictSize += (U32)inputSize;
}
cctx->currentOffset += (U32)inputSize;
cctx->tableType = (U32)tableType;
if (inputSize<LZ4_minLength) goto _last_literals; /* Input too small, no compression (all literals) */