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 101inline uint64_t BROTLI_UNALIGNED_LOAD64(const void *p) { 102 uint64_t t; 103 memcpy(&t, p, sizeof t); 104 return t; 105} 106 107inline 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 116inline uint32_t BROTLI_UNALIGNED_LOAD32(const void *p) { 117 uint32_t t; 118 memcpy(&t, p, sizeof t); 119 return t; 120} 121 122inline uint64_t BROTLI_UNALIGNED_LOAD64(const void *p) { 123 uint64_t t; 124 memcpy(&t, p, sizeof t); 125 return t; 126} 127 128inline void BROTLI_UNALIGNED_STORE32(void *p, uint32_t v) { 129 memcpy(p, &v, sizeof v); 130} 131 132inline 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