/**

 * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.

 * All rights reserved.

 *

 * This source code is licensed under the BSD-style license found in the

 * LICENSE file in the root directory of this source tree. An additional grant

 * of patent rights can be found in the PATENTS file in the same directory.

 */

#ifndef MEM_H_MODULE

#define MEM_H_MODULE

#if defined (__cplusplus)

extern "C" {

#endif

/*-****************************************

*  Dependencies

******************************************/

#include <stddef.h>     /* size_t, ptrdiff_t */

#include <string.h>     /* 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

/* code only tested on 32 and 64 bits systems */

MEM_STATIC void MEM_check(void) { MEM_STATIC_ASSERT((sizeof(size_t)==4) || (sizeof(size_t)==8)); }

/*-**************************************************************

*  Basic Types

*****************************************************************/

#if  !defined (__VMS) && (defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */) )

# include <stdint.h>

  typedef  uint8_t BYTE;

  typedef uint16_t U16;

  typedef  int16_t S16;

  typedef uint32_t U32;

  typedef  int32_t S32;

  typedef uint64_t U64;

  typedef  int64_t S64;

  typedef intptr_t iPtrDiff;

#else

  typedef unsigned char      BYTE;

  typedef unsigned short      U16;

  typedef   signed short      S16;

  typedef unsigned int        U32;

  typedef   signed int        S32;

  typedef unsigned long long  U64;

  typedef   signed long long  S64;

  typedef ptrdiff_t      iPtrDiff;

#endif

/*-**************************************************************

*  Memory I/O

*****************************************************************/

/* 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 (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 depending on alignment.

 *            In some circumstances, it's the only known way to get the most performance (ie 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(__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 MEM_FORCE_MEMORY_ACCESS 2

#  elif defined(__INTEL_COMPILER) /*|| defined(_MSC_VER)*/ || \

  (defined(__GNUC__) && ( defined(__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__) || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7S__) ))

#    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)

{

    const union { U32 u; BYTE c[4]; } one = { 1 };   /* don't use static : performance detrimental  */

    return one.c[0];

}

#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 U64 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 union { U16 u16; U32 u32; U64 u64; size_t st; } unalign;

    __pragma( pack(pop) )

#else

    typedef union { U16 u16; U32 u32; U64 u64; size_t st; } __attribute__((packed)) unalign;

#endif

MEM_STATIC U16 MEM_read16(const void* ptr) { return ((const unalign*)ptr)->u16; }

MEM_STATIC U32 MEM_read32(const void* ptr) { return ((const unalign*)ptr)->u32; }

MEM_STATIC U64 MEM_read64(const void* ptr) { return ((const unalign*)ptr)->u64; }

MEM_STATIC U64 MEM_readST(const void* ptr) { return ((const unalign*)ptr)->st; }

MEM_STATIC void MEM_write16(void* memPtr, U16 value) { ((unalign*)memPtr)->u16 = value; }

MEM_STATIC void MEM_write32(void* memPtr, U32 value) { ((unalign*)memPtr)->u32 = value; }

MEM_STATIC void MEM_write64(void* memPtr, U64 value) { ((unalign*)memPtr)->u64 = value; }

#else

/* default method, safe and standard.

   can sometimes prove slower */

MEM_STATIC U16 MEM_read16(const void* memPtr)

{

    U16 val; memcpy(&val, memPtr, sizeof(val)); return val;

}

MEM_STATIC U32 MEM_read32(const void* memPtr)

{

    U32 val; memcpy(&val, memPtr, sizeof(val)); return val;

}

MEM_STATIC U64 MEM_read64(const void* memPtr)

{

    U64 val; memcpy(&val, memPtr, sizeof(val)); return val;

}

MEM_STATIC size_t MEM_readST(const void* memPtr)

{

    size_t val; memcpy(&val, memPtr, sizeof(val)); return val;

}

MEM_STATIC void MEM_write16(void* memPtr, U16 value)

{

    memcpy(memPtr, &value, sizeof(value));

}

MEM_STATIC void MEM_write32(void* memPtr, U32 value)

{

    memcpy(memPtr, &value, sizeof(value));

}

MEM_STATIC void MEM_write64(void* memPtr, U64 value)

{

    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__)

    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__)

    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 MEM_readLE16(memPtr) + (((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);

}

/* function safe only for comparisons */

MEM_STATIC U32 MEM_readMINMATCH(const void* memPtr, U32 length)

{

    switch (length)

    {

    default :

    case 4 : return MEM_read32(memPtr);

    case 3 : if (MEM_isLittleEndian())

                return MEM_read32(memPtr)<<8;

             else

                return MEM_read32(memPtr)>>8;

    }

}

#if defined (__cplusplus)

}

#endif

#endif /* MEM_H_MODULE */