aom_util/endian_inl.h

/*
 * Copyright (c) 2016, Alliance for Open Media. All rights reserved
 *
 * This source code is subject to the terms of the BSD 2 Clause License and
 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
 * was not distributed with this source code in the LICENSE file, you can
 * obtain it at www.aomedia.org/license/software. If the Alliance for Open
 * Media Patent License 1.0 was not distributed with this source code in the
 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
 */
//
// Endian related functions.

#ifndef AOM_AOM_UTIL_ENDIAN_INL_H_
#define AOM_AOM_UTIL_ENDIAN_INL_H_

#include <stdlib.h>

#include "config/aom_config.h"

#include "aom/aom_integer.h"

#if defined(__GNUC__)
#define LOCAL_GCC_VERSION ((__GNUC__ << 8) | __GNUC_MINOR__)
#define LOCAL_GCC_PREREQ(maj, min) (LOCAL_GCC_VERSION >= (((maj) << 8) | (min)))
#else
#define LOCAL_GCC_VERSION 0
#define LOCAL_GCC_PREREQ(maj, min) 0
#endif

// handle clang compatibility
#ifndef __has_builtin
#define __has_builtin(x) 0
#endif

// some endian fix (e.g.: mips-gcc doesn't define __BIG_ENDIAN__)
#if !defined(WORDS_BIGENDIAN) &&                   \
    (defined(__BIG_ENDIAN__) || defined(_M_PPC) || \
     (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)))
#define WORDS_BIGENDIAN
#endif

#if defined(WORDS_BIGENDIAN)
#define HToLE32 BSwap32
#define HToLE16 BSwap16
#define HToBE64(x) (x)
#define HToBE32(x) (x)
#else
#define HToLE32(x) (x)
#define HToLE16(x) (x)
#define HToBE64(X) BSwap64(X)
#define HToBE32(X) BSwap32(X)
#endif

#if LOCAL_GCC_PREREQ(4, 8) || __has_builtin(__builtin_bswap16)
#define HAVE_BUILTIN_BSWAP16
#endif

#if LOCAL_GCC_PREREQ(4, 3) || __has_builtin(__builtin_bswap32)
#define HAVE_BUILTIN_BSWAP32
#endif

#if LOCAL_GCC_PREREQ(4, 3) || __has_builtin(__builtin_bswap64)
#define HAVE_BUILTIN_BSWAP64
#endif

static INLINE uint16_t BSwap16(uint16_t x) {
#if defined(HAVE_BUILTIN_BSWAP16)
  return __builtin_bswap16(x);
#elif defined(_MSC_VER)
  return _byteswap_ushort(x);
#else
  // gcc will recognize a 'rorw $8, ...' here:
  return (x >> 8) | ((x & 0xff) << 8);
#endif  // HAVE_BUILTIN_BSWAP16
}

static INLINE uint32_t BSwap32(uint32_t x) {
#if defined(HAVE_BUILTIN_BSWAP32)
  return __builtin_bswap32(x);
#elif defined(__i386__) || defined(__x86_64__)
  uint32_t swapped_bytes;
  __asm__ volatile("bswap %0" : "=r"(swapped_bytes) : "0"(x));
  return swapped_bytes;
#elif defined(_MSC_VER)
  return (uint32_t)_byteswap_ulong(x);
#else
  return (x >> 24) | ((x >> 8) & 0xff00) | ((x << 8) & 0xff0000) | (x << 24);
#endif  // HAVE_BUILTIN_BSWAP32
}

static INLINE uint64_t BSwap64(uint64_t x) {
#if defined(HAVE_BUILTIN_BSWAP64)
  return __builtin_bswap64(x);
#elif defined(__x86_64__)
  uint64_t swapped_bytes;
  __asm__ volatile("bswapq %0" : "=r"(swapped_bytes) : "0"(x));
  return swapped_bytes;
#elif defined(_MSC_VER)
  return (uint64_t)_byteswap_uint64(x);
#else   // generic code for swapping 64-bit values (suggested by bdb@)
  x = ((x & 0xffffffff00000000ull) >> 32) | ((x & 0x00000000ffffffffull) << 32);
  x = ((x & 0xffff0000ffff0000ull) >> 16) | ((x & 0x0000ffff0000ffffull) << 16);
  x = ((x & 0xff00ff00ff00ff00ull) >> 8) | ((x & 0x00ff00ff00ff00ffull) << 8);
  return x;
#endif  // HAVE_BUILTIN_BSWAP64
}

#endif  // AOM_AOM_UTIL_ENDIAN_INL_H_