1 /* 2 * Copyright (c) 2016-present, Yann Collet, Facebook, Inc. 3 * All rights reserved. 4 * 5 * This source code is licensed under both the BSD-style license (found in the 6 * LICENSE file in the root directory of this source tree) and the GPLv2 (found 7 * in the COPYING file in the root directory of this source tree). 8 * You may select, at your option, one of the above-listed licenses. 9 */ 10 11 #ifndef MEM_H_MODULE 12 #define MEM_H_MODULE 13 14 #if defined (__cplusplus) 15 extern "C" { 16 #endif 17 18 /*-**************************************** 19 * Dependencies 20 ******************************************/ 21 #include <stddef.h> /* size_t, ptrdiff_t */ 22 #include <string.h> /* memcpy */ 23 24 25 /*-**************************************** 26 * Compiler specifics 27 ******************************************/ 28 #if defined(_MSC_VER) /* Visual Studio */ 29 # include <stdlib.h> /* _byteswap_ulong */ 30 # include <intrin.h> /* _byteswap_* */ 31 #endif 32 #if defined(__GNUC__) 33 # define MEM_STATIC static __inline __attribute__((unused)) 34 #elif defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */) 35 # define MEM_STATIC static inline 36 #elif defined(_MSC_VER) 37 # define MEM_STATIC static __inline 38 #else 39 # define MEM_STATIC static /* this version may generate warnings for unused static functions; disable the relevant warning */ 40 #endif 41 42 /* code only tested on 32 and 64 bits systems */ 43 #define MEM_STATIC_ASSERT(c) { enum { MEM_static_assert = 1/(int)(!!(c)) }; } 44 MEM_STATIC void MEM_check(void) { MEM_STATIC_ASSERT((sizeof(size_t)==4) || (sizeof(size_t)==8)); } 45 46 47 /*-************************************************************** 48 * Basic Types 49 *****************************************************************/ 50 #if !defined (__VMS) && (defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */) ) 51 # include <stdint.h> 52 typedef uint8_t BYTE; 53 typedef uint16_t U16; 54 typedef int16_t S16; 55 typedef uint32_t U32; 56 typedef int32_t S32; 57 typedef uint64_t U64; 58 typedef int64_t S64; 59 #else 60 typedef unsigned char BYTE; 61 typedef unsigned short U16; 62 typedef signed short S16; 63 typedef unsigned int U32; 64 typedef signed int S32; 65 typedef unsigned long long U64; 66 typedef signed long long S64; 67 #endif 68 69 70 /*-************************************************************** 71 * Memory I/O 72 *****************************************************************/ 73 /* MEM_FORCE_MEMORY_ACCESS : 74 * By default, access to unaligned memory is controlled by `memcpy()`, which is safe and portable. 75 * Unfortunately, on some target/compiler combinations, the generated assembly is sub-optimal. 76 * The below switch allow to select different access method for improved performance. 77 * Method 0 (default) : use `memcpy()`. Safe and portable. 78 * Method 1 : `__packed` statement. It depends on compiler extension (i.e., not portable). 79 * This method is safe if your compiler supports it, and *generally* as fast or faster than `memcpy`. 80 * Method 2 : direct access. This method is portable but violate C standard. 81 * It can generate buggy code on targets depending on alignment. 82 * In some circumstances, it's the only known way to get the most performance (i.e. GCC + ARMv6) 83 * See http://fastcompression.blogspot.fr/2015/08/accessing-unaligned-memory.html for details. 84 * Prefer these methods in priority order (0 > 1 > 2) 85 */ 86 #ifndef MEM_FORCE_MEMORY_ACCESS /* can be defined externally, on command line for example */ 87 # if defined(__GNUC__) && ( defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) || defined(__ARM_ARCH_6K__) || defined(__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__) || defined(__ARM_ARCH_6T2__) ) 88 # define MEM_FORCE_MEMORY_ACCESS 2 89 # elif defined(__INTEL_COMPILER) || defined(__GNUC__) 90 # define MEM_FORCE_MEMORY_ACCESS 1 91 # endif 92 #endif 93 94 MEM_STATIC unsigned MEM_32bits(void) { return sizeof(size_t)==4; } 95 MEM_STATIC unsigned MEM_64bits(void) { return sizeof(size_t)==8; } 96 97 MEM_STATIC unsigned MEM_isLittleEndian(void) 98 { 99 const union { U32 u; BYTE c[4]; } one = { 1 }; /* don't use static : performance detrimental */ 100 return one.c[0]; 101 } 102 103 #if defined(MEM_FORCE_MEMORY_ACCESS) && (MEM_FORCE_MEMORY_ACCESS==2) 104 105 /* violates C standard, by lying on structure alignment. 106 Only use if no other choice to achieve best performance on target platform */ 107 MEM_STATIC U16 MEM_read16(const void* memPtr) { return *(const U16*) memPtr; } 108 MEM_STATIC U32 MEM_read32(const void* memPtr) { return *(const U32*) memPtr; } 109 MEM_STATIC U64 MEM_read64(const void* memPtr) { return *(const U64*) memPtr; } 110 MEM_STATIC size_t MEM_readST(const void* memPtr) { return *(const size_t*) memPtr; } 111 112 MEM_STATIC void MEM_write16(void* memPtr, U16 value) { *(U16*)memPtr = value; } 113 MEM_STATIC void MEM_write32(void* memPtr, U32 value) { *(U32*)memPtr = value; } 114 MEM_STATIC void MEM_write64(void* memPtr, U64 value) { *(U64*)memPtr = value; } 115 116 #elif defined(MEM_FORCE_MEMORY_ACCESS) && (MEM_FORCE_MEMORY_ACCESS==1) 117 118 /* __pack instructions are safer, but compiler specific, hence potentially problematic for some compilers */ 119 /* currently only defined for gcc and icc */ 120 #if defined(_MSC_VER) || (defined(__INTEL_COMPILER) && defined(WIN32)) 121 __pragma( pack(push, 1) ) 122 typedef struct { U16 v; } unalign16; 123 typedef struct { U32 v; } unalign32; 124 typedef struct { U64 v; } unalign64; 125 typedef struct { size_t v; } unalignArch; 126 __pragma( pack(pop) ) 127 #else 128 typedef struct { U16 v; } __attribute__((packed)) unalign16; 129 typedef struct { U32 v; } __attribute__((packed)) unalign32; 130 typedef struct { U64 v; } __attribute__((packed)) unalign64; 131 typedef struct { size_t v; } __attribute__((packed)) unalignArch; 132 #endif 133 134 MEM_STATIC U16 MEM_read16(const void* ptr) { return ((const unalign16*)ptr)->v; } 135 MEM_STATIC U32 MEM_read32(const void* ptr) { return ((const unalign32*)ptr)->v; } 136 MEM_STATIC U64 MEM_read64(const void* ptr) { return ((const unalign64*)ptr)->v; } 137 MEM_STATIC size_t MEM_readST(const void* ptr) { return ((const unalignArch*)ptr)->v; } 138 139 MEM_STATIC void MEM_write16(void* memPtr, U16 value) { ((unalign16*)memPtr)->v = value; } 140 MEM_STATIC void MEM_write32(void* memPtr, U32 value) { ((unalign32*)memPtr)->v = value; } 141 MEM_STATIC void MEM_write64(void* memPtr, U64 value) { ((unalign64*)memPtr)->v = value; } 142 143 #else 144 145 /* default method, safe and standard. 146 can sometimes prove slower */ 147 148 MEM_STATIC U16 MEM_read16(const void* memPtr) 149 { 150 U16 val; memcpy(&val, memPtr, sizeof(val)); return val; 151 } 152 153 MEM_STATIC U32 MEM_read32(const void* memPtr) 154 { 155 U32 val; memcpy(&val, memPtr, sizeof(val)); return val; 156 } 157 158 MEM_STATIC U64 MEM_read64(const void* memPtr) 159 { 160 U64 val; memcpy(&val, memPtr, sizeof(val)); return val; 161 } 162 163 MEM_STATIC size_t MEM_readST(const void* memPtr) 164 { 165 size_t val; memcpy(&val, memPtr, sizeof(val)); return val; 166 } 167 168 MEM_STATIC void MEM_write16(void* memPtr, U16 value) 169 { 170 memcpy(memPtr, &value, sizeof(value)); 171 } 172 173 MEM_STATIC void MEM_write32(void* memPtr, U32 value) 174 { 175 memcpy(memPtr, &value, sizeof(value)); 176 } 177 178 MEM_STATIC void MEM_write64(void* memPtr, U64 value) 179 { 180 memcpy(memPtr, &value, sizeof(value)); 181 } 182 183 #endif /* MEM_FORCE_MEMORY_ACCESS */ 184 185 MEM_STATIC U32 MEM_swap32(U32 in) 186 { 187 #if defined(_MSC_VER) /* Visual Studio */ 188 return _byteswap_ulong(in); 189 #elif defined (__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 403) 190 return __builtin_bswap32(in); 191 #else 192 return ((in << 24) & 0xff000000 ) | 193 ((in << 8) & 0x00ff0000 ) | 194 ((in >> 8) & 0x0000ff00 ) | 195 ((in >> 24) & 0x000000ff ); 196 #endif 197 } 198 199 MEM_STATIC U64 MEM_swap64(U64 in) 200 { 201 #if defined(_MSC_VER) /* Visual Studio */ 202 return _byteswap_uint64(in); 203 #elif defined (__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 403) 204 return __builtin_bswap64(in); 205 #else 206 return ((in << 56) & 0xff00000000000000ULL) | 207 ((in << 40) & 0x00ff000000000000ULL) | 208 ((in << 24) & 0x0000ff0000000000ULL) | 209 ((in << 8) & 0x000000ff00000000ULL) | 210 ((in >> 8) & 0x00000000ff000000ULL) | 211 ((in >> 24) & 0x0000000000ff0000ULL) | 212 ((in >> 40) & 0x000000000000ff00ULL) | 213 ((in >> 56) & 0x00000000000000ffULL); 214 #endif 215 } 216 217 MEM_STATIC size_t MEM_swapST(size_t in) 218 { 219 if (MEM_32bits()) 220 return (size_t)MEM_swap32((U32)in); 221 else 222 return (size_t)MEM_swap64((U64)in); 223 } 224 225 /*=== Little endian r/w ===*/ 226 227 MEM_STATIC U16 MEM_readLE16(const void* memPtr) 228 { 229 if (MEM_isLittleEndian()) 230 return MEM_read16(memPtr); 231 else { 232 const BYTE* p = (const BYTE*)memPtr; 233 return (U16)(p[0] + (p[1]<<8)); 234 } 235 } 236 237 MEM_STATIC void MEM_writeLE16(void* memPtr, U16 val) 238 { 239 if (MEM_isLittleEndian()) { 240 MEM_write16(memPtr, val); 241 } else { 242 BYTE* p = (BYTE*)memPtr; 243 p[0] = (BYTE)val; 244 p[1] = (BYTE)(val>>8); 245 } 246 } 247 248 MEM_STATIC U32 MEM_readLE24(const void* memPtr) 249 { 250 return MEM_readLE16(memPtr) + (((const BYTE*)memPtr)[2] << 16); 251 } 252 253 MEM_STATIC void MEM_writeLE24(void* memPtr, U32 val) 254 { 255 MEM_writeLE16(memPtr, (U16)val); 256 ((BYTE*)memPtr)[2] = (BYTE)(val>>16); 257 } 258 259 MEM_STATIC U32 MEM_readLE32(const void* memPtr) 260 { 261 if (MEM_isLittleEndian()) 262 return MEM_read32(memPtr); 263 else 264 return MEM_swap32(MEM_read32(memPtr)); 265 } 266 267 MEM_STATIC void MEM_writeLE32(void* memPtr, U32 val32) 268 { 269 if (MEM_isLittleEndian()) 270 MEM_write32(memPtr, val32); 271 else 272 MEM_write32(memPtr, MEM_swap32(val32)); 273 } 274 275 MEM_STATIC U64 MEM_readLE64(const void* memPtr) 276 { 277 if (MEM_isLittleEndian()) 278 return MEM_read64(memPtr); 279 else 280 return MEM_swap64(MEM_read64(memPtr)); 281 } 282 283 MEM_STATIC void MEM_writeLE64(void* memPtr, U64 val64) 284 { 285 if (MEM_isLittleEndian()) 286 MEM_write64(memPtr, val64); 287 else 288 MEM_write64(memPtr, MEM_swap64(val64)); 289 } 290 291 MEM_STATIC size_t MEM_readLEST(const void* memPtr) 292 { 293 if (MEM_32bits()) 294 return (size_t)MEM_readLE32(memPtr); 295 else 296 return (size_t)MEM_readLE64(memPtr); 297 } 298 299 MEM_STATIC void MEM_writeLEST(void* memPtr, size_t val) 300 { 301 if (MEM_32bits()) 302 MEM_writeLE32(memPtr, (U32)val); 303 else 304 MEM_writeLE64(memPtr, (U64)val); 305 } 306 307 /*=== Big endian r/w ===*/ 308 309 MEM_STATIC U32 MEM_readBE32(const void* memPtr) 310 { 311 if (MEM_isLittleEndian()) 312 return MEM_swap32(MEM_read32(memPtr)); 313 else 314 return MEM_read32(memPtr); 315 } 316 317 MEM_STATIC void MEM_writeBE32(void* memPtr, U32 val32) 318 { 319 if (MEM_isLittleEndian()) 320 MEM_write32(memPtr, MEM_swap32(val32)); 321 else 322 MEM_write32(memPtr, val32); 323 } 324 325 MEM_STATIC U64 MEM_readBE64(const void* memPtr) 326 { 327 if (MEM_isLittleEndian()) 328 return MEM_swap64(MEM_read64(memPtr)); 329 else 330 return MEM_read64(memPtr); 331 } 332 333 MEM_STATIC void MEM_writeBE64(void* memPtr, U64 val64) 334 { 335 if (MEM_isLittleEndian()) 336 MEM_write64(memPtr, MEM_swap64(val64)); 337 else 338 MEM_write64(memPtr, val64); 339 } 340 341 MEM_STATIC size_t MEM_readBEST(const void* memPtr) 342 { 343 if (MEM_32bits()) 344 return (size_t)MEM_readBE32(memPtr); 345 else 346 return (size_t)MEM_readBE64(memPtr); 347 } 348 349 MEM_STATIC void MEM_writeBEST(void* memPtr, size_t val) 350 { 351 if (MEM_32bits()) 352 MEM_writeBE32(memPtr, (U32)val); 353 else 354 MEM_writeBE64(memPtr, (U64)val); 355 } 356 357 358 #if defined (__cplusplus) 359 } 360 #endif 361 362 #endif /* MEM_H_MODULE */ 363