source/lib/byte_order.h

   1 /* Copyright (c) 2015 Wildfire Games
   2  *
   3  * Permission is hereby granted, free of charge, to any person obtaining
   4  * a copy of this software and associated documentation files (the
   5  * "Software"), to deal in the Software without restriction, including
   6  * without limitation the rights to use, copy, modify, merge, publish,
   7  * distribute, sublicense, and/or sell copies of the Software, and to
   8  * permit persons to whom the Software is furnished to do so, subject to
   9  * the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included
  12  * in all copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  15  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  16  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  17  * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
  18  * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  19  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  20  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  21  */
  22
  23 /*
  24  * byte order (endianness) support routines.
  25  */
  26
  27 #ifndef INCLUDED_BYTE_ORDER
  28 #define INCLUDED_BYTE_ORDER
  29
  30 #include "lib/sysdep/cpu.h"
  31
  32 // detect byte order via predefined macros.
  33 #ifndef BYTE_ORDER
  34 # define LITTLE_ENDIAN 0x4321
  35 # define BIG_ENDIAN    0x1234
  36 # if ARCH_IA32 || ARCH_IA64 || ARCH_AMD64 || ARCH_ALPHA || ARCH_ARM || ARCH_AARCH64 || ARCH_MIPS || defined(__LITTLE_ENDIAN__)
  37 #  define BYTE_ORDER LITTLE_ENDIAN
  38 # else
  39 #  define BYTE_ORDER BIG_ENDIAN
  40 # endif
  41 #endif
  42
  43
  44 /**
  45  * convert 4 characters to u32 (at compile time) for easy comparison.
  46  * output is in native byte order; e.g. FOURCC_LE can be used instead.
  47  **/
  48 #define FOURCC(a,b,c,d) // real definition is below
  49 #undef  FOURCC
  50
  51 // implementation rationale:
  52 // - can't pass code as string, and use s[0]..s[3], because
  53 //   VC6/7 don't realize the macro is constant
  54 //   (it should be usable as a switch{} expression)
  55 // - the casts are ugly but necessary. u32 is required because u8 << 8 == 0;
  56 //   the additional u8 cast ensures each character is treated as unsigned
  57 //   (otherwise, they'd be promoted to signed int before the u32 cast,
  58 //   which would break things).
  59
  60 /// big-endian version of FOURCC
  61 #define FOURCC_BE(a,b,c,d) ( ((u32)(u8)a) << 24 | ((u32)(u8)b) << 16 | \
  62         ((u32)(u8)c) << 8  | ((u32)(u8)d) << 0  )
  63
  64 /// little-endian version of FOURCC
  65 #define FOURCC_LE(a,b,c,d) ( ((u32)(u8)a) << 0  | ((u32)(u8)b) << 8  | \
  66         ((u32)(u8)c) << 16 | ((u32)(u8)d) << 24 )
  67
  68 #if BYTE_ORDER == BIG_ENDIAN
  69 # define FOURCC FOURCC_BE
  70 #else
  71 # define FOURCC FOURCC_LE
  72 #endif
  73
  74
  75 #if BYTE_ORDER == BIG_ENDIAN
  76 // convert a little-endian number to/from native byte order.
  77 # define to_le16(x) swap16(x)
  78 # define to_le32(x) swap32(x)
  79 # define to_le64(x) swap64(x)
  80 // convert a big-endian number to/from native byte order.
  81 # define to_be16(x) (x)
  82 # define to_be32(x) (x)
  83 # define to_be64(x) (x)
  84 #else // LITTLE_ENDIAN
  85 // convert a little-endian number to/from native byte order.
  86 # define to_le16(x) (x)
  87 # define to_le32(x) (x)
  88 # define to_le64(x) (x)
  89 // convert a big-endian number to/from native byte order.
  90 # define to_be16(x) swap16(x)
  91 # define to_be32(x) swap32(x)
  92 # define to_be64(x) swap64(x)
  93 #endif
  94
  95 /// read a little-endian number from memory into native byte order.
  96 LIB_API u16 read_le16(const void* p);
  97 LIB_API u32 read_le32(const void* p);   /// see read_le16
  98 LIB_API u64 read_le64(const void* p);   /// see read_le16
  99
 100 /// read a big-endian number from memory into native byte order.
 101 LIB_API u16 read_be16(const void* p);
 102 LIB_API u32 read_be32(const void* p);   /// see read_be16
 103 LIB_API u64 read_be64(const void* p);   /// see read_be16
 104
 105 /// write a little-endian number to memory in native byte order.
 106 LIB_API void write_le16(void* p, u16 x);
 107 LIB_API void write_le32(void* p, u32 x);        /// see write_le16
 108 LIB_API void write_le64(void* p, u64 x);        /// see write_le16
 109
 110 /// write a big-endian number to memory in native byte order.
 111 LIB_API void write_be16(void* p, u16 x);
 112 LIB_API void write_be32(void* p, u32 x);        /// see write_be16
 113 LIB_API void write_be64(void* p, u64 x);        /// see write_be16
 114
 115 /**
 116  * zero-extend \<size\> (truncated to 8) bytes of little-endian data to u64,
 117  * starting at address \<p\> (need not be aligned).
 118  **/
 119 LIB_API u64 movzx_le64(const u8* p, size_t size);
 120 LIB_API u64 movzx_be64(const u8* p, size_t size);
 121
 122 /**
 123  * sign-extend \<size\> (truncated to 8) bytes of little-endian data to i64,
 124  * starting at address \<p\> (need not be aligned).
 125  **/
 126 LIB_API i64 movsx_le64(const u8* p, size_t size);
 127 LIB_API i64 movsx_be64(const u8* p, size_t size);
 128
 129
 130 #if ICC_VERSION
 131 #define swap32 _bswap
 132 #define swap64 _bswap64
 133 #elif MSC_VERSION
 134 extern unsigned short _byteswap_ushort(unsigned short);
 135 extern unsigned long _byteswap_ulong(unsigned long);
 136 extern unsigned __int64 _byteswap_uint64(unsigned __int64);
 137 #pragma intrinsic(_byteswap_ushort)
 138 #pragma intrinsic(_byteswap_ulong)
 139 #pragma intrinsic(_byteswap_uint64)
 140 # define swap16 _byteswap_ushort
 141 # define swap32 _byteswap_ulong
 142 # define swap64 _byteswap_uint64
 143 #elif defined(linux)
 144 # include <asm/byteorder.h>
 145 # if defined(__arch__swab16) && !defined(swap16)
 146 #  define swap16 __arch__swab16
 147 # endif
 148 # if defined(__arch__swab32) && !defined(swap32)
 149 #  define swap32 __arch__swab32
 150 # endif
 151 # if defined(__arch__swab64) && !defined(swap64)
 152 #  define swap64 __arch__swab64
 153 # endif
 154 #endif
 155
 156 #ifndef swap16
 157 LIB_API u16 swap16(const u16 x);
 158 #endif
 159 #ifndef swap32
 160 LIB_API u32 swap32(const u32 x);
 161 #endif
 162 #ifndef swap64
 163 LIB_API u64 swap64(const u64 x);
 164 #endif
 165
 166 #endif  // #ifndef INCLUDED_BYTE_ORDER