Yann Collet | b1f3f4b | 2015-10-18 22:18:32 +0100 | [diff] [blame] | 1 | /* ****************************************************************** |
| 2 | mem.h |
| 3 | low-level memory access routines |
| 4 | Copyright (C) 2013-2015, Yann Collet. |
| 5 | |
| 6 | BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php) |
| 7 | |
| 8 | Redistribution and use in source and binary forms, with or without |
| 9 | modification, are permitted provided that the following conditions are |
| 10 | met: |
| 11 | |
| 12 | * Redistributions of source code must retain the above copyright |
| 13 | notice, this list of conditions and the following disclaimer. |
| 14 | * Redistributions in binary form must reproduce the above |
| 15 | copyright notice, this list of conditions and the following disclaimer |
| 16 | in the documentation and/or other materials provided with the |
| 17 | distribution. |
| 18 | |
| 19 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 20 | "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 21 | LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 22 | A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 23 | OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 24 | SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 25 | LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 26 | DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 27 | THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 28 | (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 29 | OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 30 | |
| 31 | You can contact the author at : |
| 32 | - FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy |
| 33 | - Public forum : https://groups.google.com/forum/#!forum/lz4c |
| 34 | ****************************************************************** */ |
| 35 | #ifndef MEM_H_MODULE |
| 36 | #define MEM_H_MODULE |
| 37 | |
| 38 | #if defined (__cplusplus) |
| 39 | extern "C" { |
| 40 | #endif |
| 41 | |
| 42 | /****************************************** |
| 43 | * Includes |
| 44 | ******************************************/ |
| 45 | #include <stddef.h> /* size_t, ptrdiff_t */ |
| 46 | #include <string.h> /* memcpy */ |
| 47 | |
| 48 | |
| 49 | /****************************************** |
| 50 | * Compiler-specific |
| 51 | ******************************************/ |
Yann Collet | 89db5e0 | 2015-11-13 11:27:46 +0100 | [diff] [blame] | 52 | #if defined(__GNUC__) |
| 53 | # define MEM_STATIC static __attribute__((unused)) |
| 54 | #elif defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */) |
Yann Collet | b1f3f4b | 2015-10-18 22:18:32 +0100 | [diff] [blame] | 55 | # define MEM_STATIC static inline |
| 56 | #elif defined(_MSC_VER) |
| 57 | # define MEM_STATIC static __inline |
Yann Collet | b1f3f4b | 2015-10-18 22:18:32 +0100 | [diff] [blame] | 58 | #else |
| 59 | # define MEM_STATIC static /* this version may generate warnings for unused static functions; disable the relevant warning */ |
| 60 | #endif |
| 61 | |
| 62 | |
| 63 | /**************************************************************** |
| 64 | * Basic Types |
| 65 | *****************************************************************/ |
| 66 | #if defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */) |
| 67 | # include <stdint.h> |
| 68 | typedef uint8_t BYTE; |
| 69 | typedef uint16_t U16; |
| 70 | typedef int16_t S16; |
| 71 | typedef uint32_t U32; |
| 72 | typedef int32_t S32; |
| 73 | typedef uint64_t U64; |
| 74 | typedef int64_t S64; |
| 75 | #else |
| 76 | typedef unsigned char BYTE; |
| 77 | typedef unsigned short U16; |
| 78 | typedef signed short S16; |
| 79 | typedef unsigned int U32; |
| 80 | typedef signed int S32; |
| 81 | typedef unsigned long long U64; |
| 82 | typedef signed long long S64; |
| 83 | #endif |
| 84 | |
| 85 | |
| 86 | /**************************************************************** |
| 87 | * Memory I/O |
| 88 | *****************************************************************/ |
| 89 | /* MEM_FORCE_MEMORY_ACCESS |
| 90 | * By default, access to unaligned memory is controlled by `memcpy()`, which is safe and portable. |
| 91 | * Unfortunately, on some target/compiler combinations, the generated assembly is sub-optimal. |
| 92 | * The below switch allow to select different access method for improved performance. |
| 93 | * Method 0 (default) : use `memcpy()`. Safe and portable. |
| 94 | * Method 1 : `__packed` statement. It depends on compiler extension (ie, not portable). |
| 95 | * This method is safe if your compiler supports it, and *generally* as fast or faster than `memcpy`. |
| 96 | * Method 2 : direct access. This method is portable but violate C standard. |
| 97 | * It can generate buggy code on targets generating assembly depending on alignment. |
| 98 | * But in some circumstances, it's the only known way to get the most performance (ie GCC + ARMv6) |
| 99 | * See http://fastcompression.blogspot.fr/2015/08/accessing-unaligned-memory.html for details. |
| 100 | * Prefer these methods in priority order (0 > 1 > 2) |
| 101 | */ |
| 102 | #ifndef MEM_FORCE_MEMORY_ACCESS /* can be defined externally, on command line for example */ |
| 103 | # 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__) ) |
| 104 | # define MEM_FORCE_MEMORY_ACCESS 2 |
| 105 | # elif defined(__INTEL_COMPILER) || \ |
| 106 | (defined(__GNUC__) && ( defined(__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__) || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7S__) )) |
| 107 | # define MEM_FORCE_MEMORY_ACCESS 1 |
| 108 | # endif |
| 109 | #endif |
| 110 | |
| 111 | MEM_STATIC unsigned MEM_32bits(void) { return sizeof(void*)==4; } |
| 112 | MEM_STATIC unsigned MEM_64bits(void) { return sizeof(void*)==8; } |
| 113 | |
| 114 | MEM_STATIC unsigned MEM_isLittleEndian(void) |
| 115 | { |
| 116 | const union { U32 u; BYTE c[4]; } one = { 1 }; /* don't use static : performance detrimental */ |
| 117 | return one.c[0]; |
| 118 | } |
| 119 | |
| 120 | #if defined(MEM_FORCE_MEMORY_ACCESS) && (MEM_FORCE_MEMORY_ACCESS==2) |
| 121 | |
| 122 | /* violates C standard on structure alignment. |
| 123 | Only use if no other choice to achieve best performance on target platform */ |
| 124 | MEM_STATIC U16 MEM_read16(const void* memPtr) { return *(const U16*) memPtr; } |
| 125 | MEM_STATIC U32 MEM_read32(const void* memPtr) { return *(const U32*) memPtr; } |
| 126 | MEM_STATIC U64 MEM_read64(const void* memPtr) { return *(const U64*) memPtr; } |
| 127 | |
| 128 | MEM_STATIC void MEM_write16(void* memPtr, U16 value) { *(U16*)memPtr = value; } |
| 129 | MEM_STATIC void MEM_write32(void* memPtr, U32 value) { *(U32*)memPtr = value; } |
| 130 | MEM_STATIC void MEM_write64(void* memPtr, U64 value) { *(U64*)memPtr = value; } |
| 131 | |
| 132 | #elif defined(MEM_FORCE_MEMORY_ACCESS) && (MEM_FORCE_MEMORY_ACCESS==1) |
| 133 | |
| 134 | /* __pack instructions are safer, but compiler specific, hence potentially problematic for some compilers */ |
| 135 | /* currently only defined for gcc and icc */ |
| 136 | typedef union { U16 u16; U32 u32; U64 u64; } __attribute__((packed)) unalign; |
| 137 | |
| 138 | MEM_STATIC U16 MEM_read16(const void* ptr) { return ((const unalign*)ptr)->u16; } |
| 139 | MEM_STATIC U32 MEM_read32(const void* ptr) { return ((const unalign*)ptr)->u32; } |
| 140 | MEM_STATIC U64 MEM_read64(const void* ptr) { return ((const unalign*)ptr)->u64; } |
| 141 | |
| 142 | MEM_STATIC void MEM_write16(void* memPtr, U16 value) { ((unalign*)memPtr)->u16 = value; } |
| 143 | MEM_STATIC void MEM_write32(void* memPtr, U32 value) { ((unalign*)memPtr)->u32 = value; } |
| 144 | MEM_STATIC void MEM_write64(void* memPtr, U64 value) { ((unalign*)memPtr)->u64 = value; } |
| 145 | |
| 146 | #else |
| 147 | |
| 148 | /* default method, safe and standard. |
| 149 | can sometimes prove slower */ |
| 150 | |
| 151 | MEM_STATIC U16 MEM_read16(const void* memPtr) |
| 152 | { |
| 153 | U16 val; memcpy(&val, memPtr, sizeof(val)); return val; |
| 154 | } |
| 155 | |
| 156 | MEM_STATIC U32 MEM_read32(const void* memPtr) |
| 157 | { |
| 158 | U32 val; memcpy(&val, memPtr, sizeof(val)); return val; |
| 159 | } |
| 160 | |
| 161 | MEM_STATIC U64 MEM_read64(const void* memPtr) |
| 162 | { |
| 163 | U64 val; memcpy(&val, memPtr, sizeof(val)); return val; |
| 164 | } |
| 165 | |
| 166 | MEM_STATIC void MEM_write16(void* memPtr, U16 value) |
| 167 | { |
| 168 | memcpy(memPtr, &value, sizeof(value)); |
| 169 | } |
| 170 | |
| 171 | MEM_STATIC void MEM_write32(void* memPtr, U32 value) |
| 172 | { |
| 173 | memcpy(memPtr, &value, sizeof(value)); |
| 174 | } |
| 175 | |
| 176 | MEM_STATIC void MEM_write64(void* memPtr, U64 value) |
| 177 | { |
| 178 | memcpy(memPtr, &value, sizeof(value)); |
| 179 | } |
| 180 | |
| 181 | #endif // MEM_FORCE_MEMORY_ACCESS |
| 182 | |
| 183 | |
| 184 | MEM_STATIC U16 MEM_readLE16(const void* memPtr) |
| 185 | { |
| 186 | if (MEM_isLittleEndian()) |
| 187 | return MEM_read16(memPtr); |
| 188 | else |
| 189 | { |
| 190 | const BYTE* p = (const BYTE*)memPtr; |
| 191 | return (U16)(p[0] + (p[1]<<8)); |
| 192 | } |
| 193 | } |
| 194 | |
| 195 | MEM_STATIC void MEM_writeLE16(void* memPtr, U16 val) |
| 196 | { |
| 197 | if (MEM_isLittleEndian()) |
| 198 | { |
| 199 | MEM_write16(memPtr, val); |
| 200 | } |
| 201 | else |
| 202 | { |
| 203 | BYTE* p = (BYTE*)memPtr; |
| 204 | p[0] = (BYTE)val; |
| 205 | p[1] = (BYTE)(val>>8); |
| 206 | } |
| 207 | } |
| 208 | |
| 209 | MEM_STATIC U32 MEM_readLE32(const void* memPtr) |
| 210 | { |
| 211 | if (MEM_isLittleEndian()) |
| 212 | return MEM_read32(memPtr); |
| 213 | else |
| 214 | { |
| 215 | const BYTE* p = (const BYTE*)memPtr; |
| 216 | return (U32)((U32)p[0] + ((U32)p[1]<<8) + ((U32)p[2]<<16) + ((U32)p[3]<<24)); |
| 217 | } |
| 218 | } |
| 219 | |
| 220 | MEM_STATIC void MEM_writeLE32(void* memPtr, U32 val32) |
| 221 | { |
| 222 | if (MEM_isLittleEndian()) |
| 223 | { |
| 224 | MEM_write32(memPtr, val32); |
| 225 | } |
| 226 | else |
| 227 | { |
| 228 | BYTE* p = (BYTE*)memPtr; |
| 229 | p[0] = (BYTE)val32; |
| 230 | p[1] = (BYTE)(val32>>8); |
| 231 | p[2] = (BYTE)(val32>>16); |
| 232 | p[3] = (BYTE)(val32>>24); |
| 233 | } |
| 234 | } |
| 235 | |
| 236 | MEM_STATIC U64 MEM_readLE64(const void* memPtr) |
| 237 | { |
| 238 | if (MEM_isLittleEndian()) |
| 239 | return MEM_read64(memPtr); |
| 240 | else |
| 241 | { |
| 242 | const BYTE* p = (const BYTE*)memPtr; |
| 243 | return (U64)((U64)p[0] + ((U64)p[1]<<8) + ((U64)p[2]<<16) + ((U64)p[3]<<24) |
| 244 | + ((U64)p[4]<<32) + ((U64)p[5]<<40) + ((U64)p[6]<<48) + ((U64)p[7]<<56)); |
| 245 | } |
| 246 | } |
| 247 | |
| 248 | MEM_STATIC void MEM_writeLE64(void* memPtr, U64 val64) |
| 249 | { |
| 250 | if (MEM_isLittleEndian()) |
| 251 | { |
| 252 | MEM_write64(memPtr, val64); |
| 253 | } |
| 254 | else |
| 255 | { |
| 256 | BYTE* p = (BYTE*)memPtr; |
| 257 | p[0] = (BYTE)val64; |
| 258 | p[1] = (BYTE)(val64>>8); |
| 259 | p[2] = (BYTE)(val64>>16); |
| 260 | p[3] = (BYTE)(val64>>24); |
| 261 | p[4] = (BYTE)(val64>>32); |
| 262 | p[5] = (BYTE)(val64>>40); |
| 263 | p[6] = (BYTE)(val64>>48); |
| 264 | p[7] = (BYTE)(val64>>56); |
| 265 | } |
| 266 | } |
| 267 | |
| 268 | MEM_STATIC size_t MEM_readLEST(const void* memPtr) |
| 269 | { |
| 270 | if (MEM_32bits()) |
| 271 | return (size_t)MEM_readLE32(memPtr); |
| 272 | else |
| 273 | return (size_t)MEM_readLE64(memPtr); |
| 274 | } |
| 275 | |
| 276 | MEM_STATIC void MEM_writeLEST(void* memPtr, size_t val) |
| 277 | { |
| 278 | if (MEM_32bits()) |
| 279 | MEM_writeLE32(memPtr, (U32)val); |
| 280 | else |
| 281 | MEM_writeLE64(memPtr, (U64)val); |
| 282 | } |
| 283 | |
| 284 | #if defined (__cplusplus) |
| 285 | } |
| 286 | #endif |
| 287 | |
| 288 | #endif /* MEM_H_MODULE */ |
| 289 | |