third_party/libwebp/utils/endian_inl.h

   1 // Copyright 2014 Google Inc. All Rights Reserved.
   2 //
   3 // Use of this source code is governed by a BSD-style license
   4 // that can be found in the COPYING file in the root of the source
   5 // tree. An additional intellectual property rights grant can be found
   6 // in the file PATENTS. All contributing project authors may
   7 // be found in the AUTHORS file in the root of the source tree.
   8 // -----------------------------------------------------------------------------
   9 //
  10 // Endian related functions.
  11
  12 #ifndef WEBP_UTILS_ENDIAN_INL_H_
  13 #define WEBP_UTILS_ENDIAN_INL_H_
  14
  15 #ifdef HAVE_CONFIG_H
  16 #include "../webp/config.h"
  17 #endif
  18
  19 #include "../webp/types.h"
  20
  21 // some endian fix (e.g.: mips-gcc doesn't define __BIG_ENDIAN__)
  22 #if !defined(WORDS_BIGENDIAN) && \
  23     (defined(__BIG_ENDIAN__) || defined(_M_PPC) || \
  24      (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)))
  25 #define WORDS_BIGENDIAN
  26 #endif
  27
  28 #if defined(WORDS_BIGENDIAN)
  29 #define HToLE32 BSwap32
  30 #define HToLE16 BSwap16
  31 #else
  32 #define HToLE32(x) (x)
  33 #define HToLE16(x) (x)
  34 #endif
  35
  36 #if !defined(HAVE_CONFIG_H)
  37 #ifdef __GNUC__
  38 # define LOCAL_GCC_VERSION ((__GNUC__ << 8) | __GNUC_MINOR__)
  39 #else
  40 # define LOCAL_GCC_VERSION 0
  41 #endif  // __GNUC__
  42
  43 #ifdef __clang__
  44 # define LOCAL_CLANG_VERSION ((__clang_major__ << 8) | __clang_minor__)
  45 #else
  46 # define LOCAL_CLANG_VERSION 0
  47 #endif  // __clang__
  48
  49 // clang-3.3 and gcc-4.3 have builtin functions for swap32/swap64
  50 #if LOCAL_GCC_VERSION >= 0x403 || LOCAL_CLANG_VERSION >= 0x303
  51 #define HAVE_BUILTIN_BSWAP32
  52 #define HAVE_BUILTIN_BSWAP64
  53 #endif
  54 // clang-3.3 and gcc-4.8 have a builtin function for swap16
  55 #if LOCAL_GCC_VERSION >= 0x408 || LOCAL_CLANG_VERSION >= 0x303
  56 #define HAVE_BUILTIN_BSWAP16
  57 #endif
  58 #endif  // !HAVE_CONFIG_H
  59
  60 static WEBP_INLINE uint16_t BSwap16(uint16_t x) {
  61 #if defined(HAVE_BUILTIN_BSWAP16)
  62   return __builtin_bswap16(x);
  63 #elif defined(_MSC_VER)
  64   return _byteswap_ushort(x);
  65 #else
  66   // gcc will recognize a 'rorw $8, ...' here:
  67   return (x >> 8) | ((x & 0xff) << 8);
  68 #endif  // HAVE_BUILTIN_BSWAP16
  69 }
  70
  71 static WEBP_INLINE uint32_t BSwap32(uint32_t x) {
  72 #if defined(HAVE_BUILTIN_BSWAP32)
  73   return __builtin_bswap32(x);
  74 #elif defined(__i386__) || defined(__x86_64__)
  75   uint32_t swapped_bytes;
  76   __asm__ volatile("bswap %0" : "=r"(swapped_bytes) : "0"(x));
  77   return swapped_bytes;
  78 #elif defined(_MSC_VER)
  79   return (uint32_t)_byteswap_ulong(x);
  80 #else
  81   return (x >> 24) | ((x >> 8) & 0xff00) | ((x << 8) & 0xff0000) | (x << 24);
  82 #endif  // HAVE_BUILTIN_BSWAP32
  83 }
  84
  85 static WEBP_INLINE uint64_t BSwap64(uint64_t x) {
  86 #if defined(HAVE_BUILTIN_BSWAP64)
  87   return __builtin_bswap64(x);
  88 #elif defined(__x86_64__)
  89   uint64_t swapped_bytes;
  90   __asm__ volatile("bswapq %0" : "=r"(swapped_bytes) : "0"(x));
  91   return swapped_bytes;
  92 #elif defined(_MSC_VER)
  93   return (uint64_t)_byteswap_uint64(x);
  94 #else  // generic code for swapping 64-bit values (suggested by bdb@)
  95   x = ((x & 0xffffffff00000000ull) >> 32) | ((x & 0x00000000ffffffffull) << 32);
  96   x = ((x & 0xffff0000ffff0000ull) >> 16) | ((x & 0x0000ffff0000ffffull) << 16);
  97   x = ((x & 0xff00ff00ff00ff00ull) >>  8) | ((x & 0x00ff00ff00ff00ffull) <<  8);
  98   return x;
  99 #endif  // HAVE_BUILTIN_BSWAP64
 100 }
 101
 102 #endif  // WEBP_UTILS_ENDIAN_INL_H_