path: root/contrib/libs/zstd/lib/common/mem.h

/*
 * Copyright (c) Yann Collet, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under both the BSD-style license (found in the
 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
 * in the COPYING file in the root directory of this source tree).
 * You may select, at your option, one of the above-listed licenses.
 */
 
#ifndef MEM_H_MODULE 
#define MEM_H_MODULE 
 
#if defined (__cplusplus) 
extern "C" { 
#endif 
 
/*-**************************************** 
*  Dependencies 
******************************************/ 
#include <stddef.h>  /* size_t, ptrdiff_t */
#include "compiler.h"  /* __has_builtin */
#include "debug.h"  /* DEBUG_STATIC_ASSERT */
#include "zstd_deps.h"  /* ZSTD_memcpy */
 
 
/*-**************************************** 
*  Compiler specifics 
******************************************/ 
#if defined(_MSC_VER)   /* Visual Studio */ 
#   include <stdlib.h>  /* _byteswap_ulong */ 
#   include <intrin.h>  /* _byteswap_* */ 
#endif 
#if defined(__GNUC__) 
#  define MEM_STATIC static __inline __attribute__((unused)) 
#elif defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */) 
#  define MEM_STATIC static inline 
#elif defined(_MSC_VER) 
#  define MEM_STATIC static __inline 
#else 
#  define MEM_STATIC static  /* this version may generate warnings for unused static functions; disable the relevant warning */ 
#endif 
 
/*-************************************************************** 
*  Basic Types 
*****************************************************************/ 
#if  !defined (__VMS) && (defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */) ) 
#  if defined(_AIX)
#    include <inttypes.h>
#  else
#    include <stdint.h> /* intptr_t */
#  endif
  typedef   uint8_t BYTE;
  typedef   uint8_t U8;
  typedef    int8_t S8;
  typedef  uint16_t U16;
  typedef   int16_t S16;
  typedef  uint32_t U32;
  typedef   int32_t S32;
  typedef  uint64_t U64;
  typedef   int64_t S64;
#else 
# include <limits.h>
#if CHAR_BIT != 8
#  error "this implementation requires char to be exactly 8-bit type"
#endif
  typedef unsigned char      BYTE;
  typedef unsigned char      U8;
  typedef   signed char      S8;
#if USHRT_MAX != 65535
#  error "this implementation requires short to be exactly 16-bit type"
#endif
  typedef unsigned short      U16; 
  typedef   signed short      S16; 
#if UINT_MAX != 4294967295
#  error "this implementation requires int to be exactly 32-bit type"
#endif
  typedef unsigned int        U32; 
  typedef   signed int        S32; 
/* note : there are no limits defined for long long type in C90.
 * limits exist in C99, however, in such case, <stdint.h> is preferred */
  typedef unsigned long long  U64; 
  typedef   signed long long  S64; 
#endif 
 
 
/*-************************************************************** 
*  Memory I/O API
*****************************************************************/ 
/*=== Static platform detection ===*/
MEM_STATIC unsigned MEM_32bits(void);
MEM_STATIC unsigned MEM_64bits(void);
MEM_STATIC unsigned MEM_isLittleEndian(void);

/*=== Native unaligned read/write ===*/
MEM_STATIC U16 MEM_read16(const void* memPtr);
MEM_STATIC U32 MEM_read32(const void* memPtr);
MEM_STATIC U64 MEM_read64(const void* memPtr);
MEM_STATIC size_t MEM_readST(const void* memPtr);

MEM_STATIC void MEM_write16(void* memPtr, U16 value);
MEM_STATIC void MEM_write32(void* memPtr, U32 value);
MEM_STATIC void MEM_write64(void* memPtr, U64 value);

/*=== Little endian unaligned read/write ===*/
MEM_STATIC U16 MEM_readLE16(const void* memPtr);
MEM_STATIC U32 MEM_readLE24(const void* memPtr);
MEM_STATIC U32 MEM_readLE32(const void* memPtr);
MEM_STATIC U64 MEM_readLE64(const void* memPtr);
MEM_STATIC size_t MEM_readLEST(const void* memPtr);

MEM_STATIC void MEM_writeLE16(void* memPtr, U16 val);
MEM_STATIC void MEM_writeLE24(void* memPtr, U32 val);
MEM_STATIC void MEM_writeLE32(void* memPtr, U32 val32);
MEM_STATIC void MEM_writeLE64(void* memPtr, U64 val64);
MEM_STATIC void MEM_writeLEST(void* memPtr, size_t val);

/*=== Big endian unaligned read/write ===*/
MEM_STATIC U32 MEM_readBE32(const void* memPtr);
MEM_STATIC U64 MEM_readBE64(const void* memPtr);
MEM_STATIC size_t MEM_readBEST(const void* memPtr);

MEM_STATIC void MEM_writeBE32(void* memPtr, U32 val32);
MEM_STATIC void MEM_writeBE64(void* memPtr, U64 val64);
MEM_STATIC void MEM_writeBEST(void* memPtr, size_t val);

/*=== Byteswap ===*/
MEM_STATIC U32 MEM_swap32(U32 in);
MEM_STATIC U64 MEM_swap64(U64 in);
MEM_STATIC size_t MEM_swapST(size_t in);


/*-**************************************************************
*  Memory I/O Implementation
*****************************************************************/
/* MEM_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 (i.e., 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 depending on alignment. 
 *            In some circumstances, it's the only known way to get the most performance (i.e. GCC + ARMv6)
 * See http://fastcompression.blogspot.fr/2015/08/accessing-unaligned-memory.html for details. 
 * Prefer these methods in priority order (0 > 1 > 2) 
 */ 
#ifndef MEM_FORCE_MEMORY_ACCESS   /* can be defined externally, on command line for example */ 
#  if defined(__INTEL_COMPILER) || defined(__GNUC__) || defined(__ICCARM__)
#    define MEM_FORCE_MEMORY_ACCESS 1 
#  endif 
#endif 
 
MEM_STATIC unsigned MEM_32bits(void) { return sizeof(size_t)==4; } 
MEM_STATIC unsigned MEM_64bits(void) { return sizeof(size_t)==8; } 
 
MEM_STATIC unsigned MEM_isLittleEndian(void) 
{ 
#if defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
    return 1;
#elif defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
    return 0;
#elif defined(__clang__) && __LITTLE_ENDIAN__
    return 1;
#elif defined(__clang__) && __BIG_ENDIAN__
    return 0;
#elif defined(_MSC_VER) && (_M_AMD64 || _M_IX86)
    return 1;
#elif defined(__DMC__) && defined(_M_IX86)
    return 1;
#else
    const union { U32 u; BYTE c[4]; } one = { 1 };   /* don't use static : performance detrimental  */ 
    return one.c[0]; 
#endif
} 
 
#if defined(MEM_FORCE_MEMORY_ACCESS) && (MEM_FORCE_MEMORY_ACCESS==2) 
 
/* violates C standard, by lying on structure alignment. 
Only use if no other choice to achieve best performance on target platform */ 
MEM_STATIC U16 MEM_read16(const void* memPtr) { return *(const U16*) memPtr; } 
MEM_STATIC U32 MEM_read32(const void* memPtr) { return *(const U32*) memPtr; } 
MEM_STATIC U64 MEM_read64(const void* memPtr) { return *(const U64*) memPtr; } 
MEM_STATIC size_t MEM_readST(const void* memPtr) { return *(const size_t*) memPtr; }
 
MEM_STATIC void MEM_write16(void* memPtr, U16 value) { *(U16*)memPtr = value; } 
MEM_STATIC void MEM_write32(void* memPtr, U32 value) { *(U32*)memPtr = value; } 
MEM_STATIC void MEM_write64(void* memPtr, U64 value) { *(U64*)memPtr = value; } 
 
#elif defined(MEM_FORCE_MEMORY_ACCESS) && (MEM_FORCE_MEMORY_ACCESS==1) 
 
/* __pack instructions are safer, but compiler specific, hence potentially problematic for some compilers */ 
/* currently only defined for gcc and icc */ 
#if defined(_MSC_VER) || (defined(__INTEL_COMPILER) && defined(WIN32))
    __pragma( pack(push, 1) )
    typedef struct { U16 v; } unalign16;
    typedef struct { U32 v; } unalign32;
    typedef struct { U64 v; } unalign64;
    typedef struct { size_t v; } unalignArch;
    __pragma( pack(pop) )
#else
    typedef struct { U16 v; } __attribute__((packed)) unalign16;
    typedef struct { U32 v; } __attribute__((packed)) unalign32;
    typedef struct { U64 v; } __attribute__((packed)) unalign64;
    typedef struct { size_t v; } __attribute__((packed)) unalignArch;
#endif
 
MEM_STATIC U16 MEM_read16(const void* ptr) { return ((const unalign16*)ptr)->v; }
MEM_STATIC U32 MEM_read32(const void* ptr) { return ((const unalign32*)ptr)->v; }
MEM_STATIC U64 MEM_read64(const void* ptr) { return ((const unalign64*)ptr)->v; }
MEM_STATIC size_t MEM_readST(const void* ptr) { return ((const unalignArch*)ptr)->v; }
 
MEM_STATIC void MEM_write16(void* memPtr, U16 value) { ((unalign16*)memPtr)->v = value; }
MEM_STATIC void MEM_write32(void* memPtr, U32 value) { ((unalign32*)memPtr)->v = value; }
MEM_STATIC void MEM_write64(void* memPtr, U64 value) { ((unalign64*)memPtr)->v = value; }
 
#else 
 
/* default method, safe and standard. 
   can sometimes prove slower */ 
 
MEM_STATIC U16 MEM_read16(const void* memPtr) 
{ 
    U16 val; ZSTD_memcpy(&val, memPtr, sizeof(val)); return val;
} 
 
MEM_STATIC U32 MEM_read32(const void* memPtr) 
{ 
    U32 val; ZSTD_memcpy(&val, memPtr, sizeof(val)); return val;
} 
 
MEM_STATIC U64 MEM_read64(const void* memPtr) 
{ 
    U64 val; ZSTD_memcpy(&val, memPtr, sizeof(val)); return val;
} 
 
MEM_STATIC size_t MEM_readST(const void* memPtr) 
{ 
    size_t val; ZSTD_memcpy(&val, memPtr, sizeof(val)); return val;
} 
 
MEM_STATIC void MEM_write16(void* memPtr, U16 value) 
{ 
    ZSTD_memcpy(memPtr, &value, sizeof(value));
} 
 
MEM_STATIC void MEM_write32(void* memPtr, U32 value) 
{ 
    ZSTD_memcpy(memPtr, &value, sizeof(value));
} 
 
MEM_STATIC void MEM_write64(void* memPtr, U64 value) 
{ 
    ZSTD_memcpy(memPtr, &value, sizeof(value));
} 
 
#endif /* MEM_FORCE_MEMORY_ACCESS */ 
 
MEM_STATIC U32 MEM_swap32(U32 in) 
{ 
#if defined(_MSC_VER)     /* Visual Studio */ 
    return _byteswap_ulong(in); 
#elif (defined (__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 403)) \
  || (defined(__clang__) && __has_builtin(__builtin_bswap32))
    return __builtin_bswap32(in); 
#else 
    return  ((in << 24) & 0xff000000 ) | 
            ((in <<  8) & 0x00ff0000 ) | 
            ((in >>  8) & 0x0000ff00 ) | 
            ((in >> 24) & 0x000000ff ); 
#endif 
} 
 
MEM_STATIC U64 MEM_swap64(U64 in) 
{ 
#if defined(_MSC_VER)     /* Visual Studio */ 
    return _byteswap_uint64(in); 
#elif (defined (__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 403)) \
  || (defined(__clang__) && __has_builtin(__builtin_bswap64))
    return __builtin_bswap64(in); 
#else 
    return  ((in << 56) & 0xff00000000000000ULL) | 
            ((in << 40) & 0x00ff000000000000ULL) | 
            ((in << 24) & 0x0000ff0000000000ULL) | 
            ((in << 8)  & 0x000000ff00000000ULL) | 
            ((in >> 8)  & 0x00000000ff000000ULL) | 
            ((in >> 24) & 0x0000000000ff0000ULL) | 
            ((in >> 40) & 0x000000000000ff00ULL) | 
            ((in >> 56) & 0x00000000000000ffULL); 
#endif 
} 
 
MEM_STATIC size_t MEM_swapST(size_t in) 
{ 
    if (MEM_32bits()) 
        return (size_t)MEM_swap32((U32)in); 
    else 
        return (size_t)MEM_swap64((U64)in); 
} 
 
/*=== Little endian r/w ===*/ 
 
MEM_STATIC U16 MEM_readLE16(const void* memPtr) 
{ 
    if (MEM_isLittleEndian()) 
        return MEM_read16(memPtr); 
    else { 
        const BYTE* p = (const BYTE*)memPtr; 
        return (U16)(p[0] + (p[1]<<8)); 
    } 
} 
 
MEM_STATIC void MEM_writeLE16(void* memPtr, U16 val) 
{ 
    if (MEM_isLittleEndian()) { 
        MEM_write16(memPtr, val); 
    } else { 
        BYTE* p = (BYTE*)memPtr; 
        p[0] = (BYTE)val; 
        p[1] = (BYTE)(val>>8); 
    } 
} 
 
MEM_STATIC U32 MEM_readLE24(const void* memPtr) 
{ 
    return (U32)MEM_readLE16(memPtr) + ((U32)(((const BYTE*)memPtr)[2]) << 16);
} 
 
MEM_STATIC void MEM_writeLE24(void* memPtr, U32 val) 
{ 
    MEM_writeLE16(memPtr, (U16)val); 
    ((BYTE*)memPtr)[2] = (BYTE)(val>>16); 
} 
 
MEM_STATIC U32 MEM_readLE32(const void* memPtr) 
{ 
    if (MEM_isLittleEndian()) 
        return MEM_read32(memPtr); 
    else 
        return MEM_swap32(MEM_read32(memPtr)); 
} 
 
MEM_STATIC void MEM_writeLE32(void* memPtr, U32 val32) 
{ 
    if (MEM_isLittleEndian()) 
        MEM_write32(memPtr, val32); 
    else 
        MEM_write32(memPtr, MEM_swap32(val32)); 
} 
 
MEM_STATIC U64 MEM_readLE64(const void* memPtr) 
{ 
    if (MEM_isLittleEndian()) 
        return MEM_read64(memPtr); 
    else 
        return MEM_swap64(MEM_read64(memPtr)); 
} 
 
MEM_STATIC void MEM_writeLE64(void* memPtr, U64 val64) 
{ 
    if (MEM_isLittleEndian()) 
        MEM_write64(memPtr, val64); 
    else 
        MEM_write64(memPtr, MEM_swap64(val64)); 
} 
 
MEM_STATIC size_t MEM_readLEST(const void* memPtr) 
{ 
    if (MEM_32bits()) 
        return (size_t)MEM_readLE32(memPtr); 
    else 
        return (size_t)MEM_readLE64(memPtr); 
} 
 
MEM_STATIC void MEM_writeLEST(void* memPtr, size_t val) 
{ 
    if (MEM_32bits()) 
        MEM_writeLE32(memPtr, (U32)val); 
    else 
        MEM_writeLE64(memPtr, (U64)val); 
} 
 
/*=== Big endian r/w ===*/ 
 
MEM_STATIC U32 MEM_readBE32(const void* memPtr) 
{ 
    if (MEM_isLittleEndian()) 
        return MEM_swap32(MEM_read32(memPtr)); 
    else 
        return MEM_read32(memPtr); 
} 
 
MEM_STATIC void MEM_writeBE32(void* memPtr, U32 val32) 
{ 
    if (MEM_isLittleEndian()) 
        MEM_write32(memPtr, MEM_swap32(val32)); 
    else 
        MEM_write32(memPtr, val32); 
} 
 
MEM_STATIC U64 MEM_readBE64(const void* memPtr) 
{ 
    if (MEM_isLittleEndian()) 
        return MEM_swap64(MEM_read64(memPtr)); 
    else 
        return MEM_read64(memPtr); 
} 
 
MEM_STATIC void MEM_writeBE64(void* memPtr, U64 val64) 
{ 
    if (MEM_isLittleEndian()) 
        MEM_write64(memPtr, MEM_swap64(val64)); 
    else 
        MEM_write64(memPtr, val64); 
} 
 
MEM_STATIC size_t MEM_readBEST(const void* memPtr) 
{ 
    if (MEM_32bits()) 
        return (size_t)MEM_readBE32(memPtr); 
    else 
        return (size_t)MEM_readBE64(memPtr); 
} 
 
MEM_STATIC void MEM_writeBEST(void* memPtr, size_t val) 
{ 
    if (MEM_32bits()) 
        MEM_writeBE32(memPtr, (U32)val); 
    else 
        MEM_writeBE64(memPtr, (U64)val); 
} 
 
/* code only tested on 32 and 64 bits systems */
MEM_STATIC void MEM_check(void) { DEBUG_STATIC_ASSERT((sizeof(size_t)==4) || (sizeof(size_t)==8)); }
 

#if defined (__cplusplus) 
} 
#endif 
 
#endif /* MEM_H_MODULE */