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396 lines
13 KiB
C
396 lines
13 KiB
C
/* ******************************************************************
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mem.h
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low-level memory access routines
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Copyright (C) 2013-2015, 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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* 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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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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You can contact the author at :
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- FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy
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- Public forum : https://groups.google.com/forum/#!forum/lz4c
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****************************************************************** */
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#ifndef MEM_H_MODULE
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#define MEM_H_MODULE
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#if defined (__cplusplus)
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extern "C" {
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#endif
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/*-****************************************
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* Dependencies
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******************************************/
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#include <stddef.h> /* size_t, ptrdiff_t */
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#include <string.h> /* memcpy */
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/*-****************************************
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* Compiler specifics
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******************************************/
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#if defined(_MSC_VER) /* Visual Studio */
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# include <stdlib.h> /* _byteswap_ulong */
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# include <intrin.h> /* _byteswap_* */
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#endif
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#if defined(__GNUC__)
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# define MEM_STATIC static __inline __attribute__((unused))
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#elif defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */)
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# define MEM_STATIC static inline
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#elif defined(_MSC_VER)
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# define MEM_STATIC static __inline
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#else
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# define MEM_STATIC static /* this version may generate warnings for unused static functions; disable the relevant warning */
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#endif
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/* code only tested on 32 and 64 bits systems */
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#define MEM_STATIC_ASSERT(c) { enum { XXH_static_assert = 1/(int)(!!(c)) }; }
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MEM_STATIC void MEM_check(void) { MEM_STATIC_ASSERT((sizeof(size_t)==4) || (sizeof(size_t)==8)); }
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/*-**************************************************************
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* Basic Types
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*****************************************************************/
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#if !defined (__VMS) && (defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */) )
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# include <stdint.h>
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typedef uint8_t BYTE;
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typedef uint16_t U16;
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typedef int16_t S16;
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typedef uint32_t U32;
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typedef int32_t S32;
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typedef uint64_t U64;
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typedef int64_t S64;
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#else
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typedef unsigned char BYTE;
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typedef unsigned short U16;
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typedef signed short S16;
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typedef unsigned int U32;
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typedef signed int S32;
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typedef unsigned long long U64;
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typedef signed long long S64;
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#endif
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/*-**************************************************************
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* Memory I/O
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*****************************************************************/
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/* MEM_FORCE_MEMORY_ACCESS :
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* By default, access to unaligned memory is controlled by `memcpy()`, which is safe and portable.
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* Unfortunately, on some target/compiler combinations, the generated assembly is sub-optimal.
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* The below switch allow to select different access method for improved performance.
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* Method 0 (default) : use `memcpy()`. Safe and portable.
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* Method 1 : `__packed` statement. It depends on compiler extension (ie, not portable).
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* This method is safe if your compiler supports it, and *generally* as fast or faster than `memcpy`.
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* Method 2 : direct access. This method is portable but violate C standard.
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* It can generate buggy code on targets depending on alignment.
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* In some circumstances, it's the only known way to get the most performance (ie GCC + ARMv6)
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* See http://fastcompression.blogspot.fr/2015/08/accessing-unaligned-memory.html for details.
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* Prefer these methods in priority order (0 > 1 > 2)
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*/
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#ifndef MEM_FORCE_MEMORY_ACCESS /* can be defined externally, on command line for example */
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# 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__) )
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# define MEM_FORCE_MEMORY_ACCESS 2
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# elif defined(__INTEL_COMPILER) /*|| defined(_MSC_VER)*/ || \
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(defined(__GNUC__) && ( defined(__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__) || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7S__) ))
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# define MEM_FORCE_MEMORY_ACCESS 1
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# endif
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#endif
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MEM_STATIC unsigned MEM_32bits(void) { return sizeof(size_t)==4; }
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MEM_STATIC unsigned MEM_64bits(void) { return sizeof(size_t)==8; }
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MEM_STATIC unsigned MEM_isLittleEndian(void)
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{
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const union { U32 u; BYTE c[4]; } one = { 1 }; /* don't use static : performance detrimental */
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return one.c[0];
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}
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#if defined(MEM_FORCE_MEMORY_ACCESS) && (MEM_FORCE_MEMORY_ACCESS==2)
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/* violates C standard, by lying on structure alignment.
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Only use if no other choice to achieve best performance on target platform */
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MEM_STATIC U16 MEM_read16(const void* memPtr) { return *(const U16*) memPtr; }
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MEM_STATIC U32 MEM_read32(const void* memPtr) { return *(const U32*) memPtr; }
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MEM_STATIC U64 MEM_read64(const void* memPtr) { return *(const U64*) memPtr; }
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MEM_STATIC U64 MEM_readST(const void* memPtr) { return *(const size_t*) memPtr; }
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MEM_STATIC void MEM_write16(void* memPtr, U16 value) { *(U16*)memPtr = value; }
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MEM_STATIC void MEM_write32(void* memPtr, U32 value) { *(U32*)memPtr = value; }
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MEM_STATIC void MEM_write64(void* memPtr, U64 value) { *(U64*)memPtr = value; }
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#elif defined(MEM_FORCE_MEMORY_ACCESS) && (MEM_FORCE_MEMORY_ACCESS==1)
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/* __pack instructions are safer, but compiler specific, hence potentially problematic for some compilers */
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/* currently only defined for gcc and icc */
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#if defined(_MSC_VER) || (defined(__INTEL_COMPILER) && defined(WIN32))
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__pragma( pack(push, 1) )
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typedef union { U16 u16; U32 u32; U64 u64; size_t st; } unalign;
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__pragma( pack(pop) )
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#else
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typedef union { U16 u16; U32 u32; U64 u64; size_t st; } __attribute__((packed)) unalign;
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#endif
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MEM_STATIC U16 MEM_read16(const void* ptr) { return ((const unalign*)ptr)->u16; }
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MEM_STATIC U32 MEM_read32(const void* ptr) { return ((const unalign*)ptr)->u32; }
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MEM_STATIC U64 MEM_read64(const void* ptr) { return ((const unalign*)ptr)->u64; }
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MEM_STATIC U64 MEM_readST(const void* ptr) { return ((const unalign*)ptr)->st; }
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MEM_STATIC void MEM_write16(void* memPtr, U16 value) { ((unalign*)memPtr)->u16 = value; }
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MEM_STATIC void MEM_write32(void* memPtr, U32 value) { ((unalign*)memPtr)->u32 = value; }
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MEM_STATIC void MEM_write64(void* memPtr, U64 value) { ((unalign*)memPtr)->u64 = value; }
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#else
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/* default method, safe and standard.
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can sometimes prove slower */
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MEM_STATIC U16 MEM_read16(const void* memPtr)
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{
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U16 val; memcpy(&val, memPtr, sizeof(val)); return val;
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}
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MEM_STATIC U32 MEM_read32(const void* memPtr)
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{
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U32 val; memcpy(&val, memPtr, sizeof(val)); return val;
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}
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MEM_STATIC U64 MEM_read64(const void* memPtr)
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{
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U64 val; memcpy(&val, memPtr, sizeof(val)); return val;
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}
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MEM_STATIC size_t MEM_readST(const void* memPtr)
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{
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size_t val; memcpy(&val, memPtr, sizeof(val)); return val;
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}
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MEM_STATIC void MEM_write16(void* memPtr, U16 value)
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{
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memcpy(memPtr, &value, sizeof(value));
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}
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MEM_STATIC void MEM_write32(void* memPtr, U32 value)
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{
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memcpy(memPtr, &value, sizeof(value));
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}
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MEM_STATIC void MEM_write64(void* memPtr, U64 value)
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{
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memcpy(memPtr, &value, sizeof(value));
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}
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#endif /* MEM_FORCE_MEMORY_ACCESS */
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MEM_STATIC U32 MEM_swap32(U32 in)
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{
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#if defined(_MSC_VER) /* Visual Studio */
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return _byteswap_ulong(in);
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#elif defined (__GNUC__)
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return __builtin_bswap32(in);
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#else
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return ((in << 24) & 0xff000000 ) |
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((in << 8) & 0x00ff0000 ) |
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((in >> 8) & 0x0000ff00 ) |
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((in >> 24) & 0x000000ff );
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#endif
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}
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MEM_STATIC U64 MEM_swap64(U64 in)
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{
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#if defined(_MSC_VER) /* Visual Studio */
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return _byteswap_uint64(in);
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#elif defined (__GNUC__)
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return __builtin_bswap64(in);
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#else
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return ((in << 56) & 0xff00000000000000ULL) |
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((in << 40) & 0x00ff000000000000ULL) |
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((in << 24) & 0x0000ff0000000000ULL) |
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((in << 8) & 0x000000ff00000000ULL) |
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((in >> 8) & 0x00000000ff000000ULL) |
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((in >> 24) & 0x0000000000ff0000ULL) |
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((in >> 40) & 0x000000000000ff00ULL) |
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((in >> 56) & 0x00000000000000ffULL);
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#endif
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}
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MEM_STATIC size_t MEM_swapST(size_t in)
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{
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if (MEM_32bits())
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return (size_t)MEM_swap32((U32)in);
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else
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return (size_t)MEM_swap64((U64)in);
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}
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/*=== Little endian r/w ===*/
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MEM_STATIC U16 MEM_readLE16(const void* memPtr)
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{
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if (MEM_isLittleEndian())
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return MEM_read16(memPtr);
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else {
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const BYTE* p = (const BYTE*)memPtr;
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return (U16)(p[0] + (p[1]<<8));
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}
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}
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MEM_STATIC void MEM_writeLE16(void* memPtr, U16 val)
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{
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if (MEM_isLittleEndian()) {
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MEM_write16(memPtr, val);
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} else {
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BYTE* p = (BYTE*)memPtr;
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p[0] = (BYTE)val;
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p[1] = (BYTE)(val>>8);
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}
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}
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MEM_STATIC U32 MEM_readLE24(const void* memPtr)
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{
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return MEM_readLE16(memPtr) + (((const BYTE*)memPtr)[2] << 16);
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}
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MEM_STATIC void MEM_writeLE24(void* memPtr, U32 val)
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{
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MEM_writeLE16(memPtr, (U16)val);
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((BYTE*)memPtr)[2] = (BYTE)(val>>16);
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}
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MEM_STATIC U32 MEM_readLE32(const void* memPtr)
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{
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if (MEM_isLittleEndian())
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return MEM_read32(memPtr);
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else
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return MEM_swap32(MEM_read32(memPtr));
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}
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MEM_STATIC void MEM_writeLE32(void* memPtr, U32 val32)
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{
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if (MEM_isLittleEndian())
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MEM_write32(memPtr, val32);
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else
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MEM_write32(memPtr, MEM_swap32(val32));
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}
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MEM_STATIC U64 MEM_readLE64(const void* memPtr)
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{
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if (MEM_isLittleEndian())
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return MEM_read64(memPtr);
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else
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return MEM_swap64(MEM_read64(memPtr));
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}
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MEM_STATIC void MEM_writeLE64(void* memPtr, U64 val64)
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{
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if (MEM_isLittleEndian())
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MEM_write64(memPtr, val64);
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else
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MEM_write64(memPtr, MEM_swap64(val64));
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}
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MEM_STATIC size_t MEM_readLEST(const void* memPtr)
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{
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if (MEM_32bits())
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return (size_t)MEM_readLE32(memPtr);
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else
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return (size_t)MEM_readLE64(memPtr);
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}
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MEM_STATIC void MEM_writeLEST(void* memPtr, size_t val)
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{
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if (MEM_32bits())
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MEM_writeLE32(memPtr, (U32)val);
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else
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MEM_writeLE64(memPtr, (U64)val);
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}
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/*=== Big endian r/w ===*/
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MEM_STATIC U32 MEM_readBE32(const void* memPtr)
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{
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if (MEM_isLittleEndian())
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return MEM_swap32(MEM_read32(memPtr));
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else
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return MEM_read32(memPtr);
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}
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MEM_STATIC void MEM_writeBE32(void* memPtr, U32 val32)
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{
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if (MEM_isLittleEndian())
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MEM_write32(memPtr, MEM_swap32(val32));
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else
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MEM_write32(memPtr, val32);
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}
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MEM_STATIC U64 MEM_readBE64(const void* memPtr)
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{
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if (MEM_isLittleEndian())
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return MEM_swap64(MEM_read64(memPtr));
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else
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return MEM_read64(memPtr);
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}
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MEM_STATIC void MEM_writeBE64(void* memPtr, U64 val64)
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{
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if (MEM_isLittleEndian())
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MEM_write64(memPtr, MEM_swap64(val64));
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else
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MEM_write64(memPtr, val64);
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}
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MEM_STATIC size_t MEM_readBEST(const void* memPtr)
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{
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if (MEM_32bits())
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return (size_t)MEM_readBE32(memPtr);
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else
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return (size_t)MEM_readBE64(memPtr);
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}
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MEM_STATIC void MEM_writeBEST(void* memPtr, size_t val)
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{
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if (MEM_32bits())
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MEM_writeBE32(memPtr, (U32)val);
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else
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MEM_writeBE64(memPtr, (U64)val);
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}
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/* function safe only for comparisons */
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MEM_STATIC U32 MEM_readMINMATCH(const void* memPtr, U32 length)
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{
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switch (length)
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{
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default :
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case 4 : return MEM_read32(memPtr);
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case 3 : if (MEM_isLittleEndian())
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return MEM_read32(memPtr)<<8;
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else
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return MEM_read32(memPtr)>>8;
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}
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}
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#if defined (__cplusplus)
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}
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#endif
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#endif /* MEM_H_MODULE */
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