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 "../dsp/dsp.h"
  20 #include "../webp/types.h"
  21
  22 // some endian fix (e.g.: mips-gcc doesn't define __BIG_ENDIAN__)
  23 #if !defined(WORDS_BIGENDIAN) && \
  24     (defined(__BIG_ENDIAN__) || defined(_M_PPC) || \
  25      (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)))
  26 #define WORDS_BIGENDIAN
  27 #endif
  28
  29 #if defined(WORDS_BIGENDIAN)
  30 #define HToLE32 BSwap32
  31 #define HToLE16 BSwap16
  32 #else
  33 #define HToLE32(x) (x)
  34 #define HToLE16(x) (x)
  35 #endif
  36
  37 #if !defined(HAVE_CONFIG_H)
  38 // clang-3.3 and gcc-4.3 have builtin functions for swap32/swap64
  39 #if LOCAL_GCC_PREREQ(4,3) || LOCAL_CLANG_PREREQ(3,3)
  40 #define HAVE_BUILTIN_BSWAP32
  41 #define HAVE_BUILTIN_BSWAP64
  42 #endif
  43 // clang-3.3 and gcc-4.8 have a builtin function for swap16
  44 #if LOCAL_GCC_PREREQ(4,8) || LOCAL_CLANG_PREREQ(3,3)
  45 #define HAVE_BUILTIN_BSWAP16
  46 #endif
  47 #endif  // !HAVE_CONFIG_H
  48
  49 static WEBP_INLINE uint16_t BSwap16(uint16_t x) {
  50 #if defined(HAVE_BUILTIN_BSWAP16)
  51   return __builtin_bswap16(x);
  52 #elif defined(_MSC_VER)
  53   return _byteswap_ushort(x);
  54 #else
  55   // gcc will recognize a 'rorw $8, ...' here:
  56   return (x >> 8) | ((x & 0xff) << 8);
  57 #endif  // HAVE_BUILTIN_BSWAP16
  58 }
  59
  60 static WEBP_INLINE uint32_t BSwap32(uint32_t x) {
  61 #if defined(WEBP_USE_MIPS32_R2)
  62   uint32_t ret;
  63   __asm__ volatile (
  64     "wsbh   %[ret], %[x]          \n\t"
  65     "rotr   %[ret], %[ret],  16   \n\t"
  66     : [ret]"=r"(ret)
  67     : [x]"r"(x)
  68   );
  69   return ret;
  70 #elif defined(HAVE_BUILTIN_BSWAP32)
  71   return __builtin_bswap32(x);
  72 #elif defined(__i386__) || defined(__x86_64__)
  73   uint32_t swapped_bytes;
  74   __asm__ volatile("bswap %0" : "=r"(swapped_bytes) : "0"(x));
  75   return swapped_bytes;
  76 #elif defined(_MSC_VER)
  77   return (uint32_t)_byteswap_ulong(x);
  78 #else
  79   return (x >> 24) | ((x >> 8) & 0xff00) | ((x << 8) & 0xff0000) | (x << 24);
  80 #endif  // HAVE_BUILTIN_BSWAP32
  81 }
  82
  83 static WEBP_INLINE uint64_t BSwap64(uint64_t x) {
  84 #if defined(HAVE_BUILTIN_BSWAP64)
  85   return __builtin_bswap64(x);
  86 #elif defined(__x86_64__)
  87   uint64_t swapped_bytes;
  88   __asm__ volatile("bswapq %0" : "=r"(swapped_bytes) : "0"(x));
  89   return swapped_bytes;
  90 #elif defined(_MSC_VER)
  91   return (uint64_t)_byteswap_uint64(x);
  92 #else  // generic code for swapping 64-bit values (suggested by bdb@)
  93   x = ((x & 0xffffffff00000000ull) >> 32) | ((x & 0x00000000ffffffffull) << 32);
  94   x = ((x & 0xffff0000ffff0000ull) >> 16) | ((x & 0x0000ffff0000ffffull) << 16);
  95   x = ((x & 0xff00ff00ff00ff00ull) >>  8) | ((x & 0x00ff00ff00ff00ffull) <<  8);
  96   return x;
  97 #endif  // HAVE_BUILTIN_BSWAP64
  98 }
  99
 100 #endif  // WEBP_UTILS_ENDIAN_INL_H_