1 // Copyright 2013 Google Inc. All Rights Reserved. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 // 15 // Macros for endianness, branch prediction and unaligned loads and stores. 16 17 #ifndef BROTLI_ENC_PORT_H_ 18 #define BROTLI_ENC_PORT_H_ 19 20 #if defined OS_LINUX || defined OS_CYGWIN 21 #include <endian.h> 22 #elif defined OS_FREEBSD 23 #include <machine/endian.h> 24 #elif defined OS_MACOSX 25 #include <machine/endian.h> 26 /* Let's try and follow the Linux convention */ 27 #define __BYTE_ORDER BYTE_ORDER 28 #define __LITTLE_ENDIAN LITTLE_ENDIAN 29 #define __BIG_ENDIAN BIG_ENDIAN 30 #endif 31 32 // define the macros IS_LITTLE_ENDIAN or IS_BIG_ENDIAN 33 // using the above endian definitions from endian.h if 34 // endian.h was included 35 #ifdef __BYTE_ORDER 36 #if __BYTE_ORDER == __LITTLE_ENDIAN 37 #define IS_LITTLE_ENDIAN 38 #endif 39 40 #if __BYTE_ORDER == __BIG_ENDIAN 41 #define IS_BIG_ENDIAN 42 #endif 43 44 #else 45 46 #if defined(__LITTLE_ENDIAN__) 47 #define IS_LITTLE_ENDIAN 48 #elif defined(__BIG_ENDIAN__) 49 #define IS_BIG_ENDIAN 50 #endif 51 #endif // __BYTE_ORDER 52 53 #if defined(COMPILER_GCC3) 54 #define PREDICT_FALSE(x) (__builtin_expect(x, 0)) 55 #define PREDICT_TRUE(x) (__builtin_expect(!!(x), 1)) 56 #else 57 #define PREDICT_FALSE(x) x 58 #define PREDICT_TRUE(x) x 59 #endif 60 61 // Portable handling of unaligned loads, stores, and copies. 62 // On some platforms, like ARM, the copy functions can be more efficient 63 // then a load and a store. 64 65 #if defined(ARCH_PIII) || defined(ARCH_ATHLON) || \ 66 defined(ARCH_K8) || defined(_ARCH_PPC) 67 68 // x86 and x86-64 can perform unaligned loads/stores directly; 69 // modern PowerPC hardware can also do unaligned integer loads and stores; 70 // but note: the FPU still sends unaligned loads and stores to a trap handler! 71 72 #define BROTLI_UNALIGNED_LOAD32(_p) (*reinterpret_cast<const uint32_t *>(_p)) 73 #define BROTLI_UNALIGNED_LOAD64(_p) (*reinterpret_cast<const uint64_t *>(_p)) 74 75 #define BROTLI_UNALIGNED_STORE32(_p, _val) \ 76 (*reinterpret_cast<uint32_t *>(_p) = (_val)) 77 #define BROTLI_UNALIGNED_STORE64(_p, _val) \ 78 (*reinterpret_cast<uint64_t *>(_p) = (_val)) 79 80 #elif defined(__arm__) && \ 81 !defined(__ARM_ARCH_5__) && \ 82 !defined(__ARM_ARCH_5T__) && \ 83 !defined(__ARM_ARCH_5TE__) && \ 84 !defined(__ARM_ARCH_5TEJ__) && \ 85 !defined(__ARM_ARCH_6__) && \ 86 !defined(__ARM_ARCH_6J__) && \ 87 !defined(__ARM_ARCH_6K__) && \ 88 !defined(__ARM_ARCH_6Z__) && \ 89 !defined(__ARM_ARCH_6ZK__) && \ 90 !defined(__ARM_ARCH_6T2__) 91 92 // ARMv7 and newer support native unaligned accesses, but only of 16-bit 93 // and 32-bit values (not 64-bit); older versions either raise a fatal signal, 94 // do an unaligned read and rotate the words around a bit, or do the reads very 95 // slowly (trip through kernel mode). 96 97 #define BROTLI_UNALIGNED_LOAD32(_p) (*reinterpret_cast<const uint32_t *>(_p)) 98 #define BROTLI_UNALIGNED_STORE32(_p, _val) \ 99 (*reinterpret_cast<uint32_t *>(_p) = (_val)) 100 101 inline uint64_t BROTLI_UNALIGNED_LOAD64(const void *p) { 102 uint64_t t; 103 memcpy(&t, p, sizeof t); 104 return t; 105 } 106 107 inline void BROTLI_UNALIGNED_STORE64(void *p, uint64_t v) { 108 memcpy(p, &v, sizeof v); 109 } 110 111 #else 112 113 // These functions are provided for architectures that don't support 114 // unaligned loads and stores. 115 116 inline uint32_t BROTLI_UNALIGNED_LOAD32(const void *p) { 117 uint32_t t; 118 memcpy(&t, p, sizeof t); 119 return t; 120 } 121 122 inline uint64_t BROTLI_UNALIGNED_LOAD64(const void *p) { 123 uint64_t t; 124 memcpy(&t, p, sizeof t); 125 return t; 126 } 127 128 inline void BROTLI_UNALIGNED_STORE32(void *p, uint32_t v) { 129 memcpy(p, &v, sizeof v); 130 } 131 132 inline void BROTLI_UNALIGNED_STORE64(void *p, uint64_t v) { 133 memcpy(p, &v, sizeof v); 134 } 135 136 #endif 137 138 #endif // BROTLI_ENC_PORT_H_ 139
