drivers/filesystems/btrfs/zstd/mem.h

   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 #ifndef __has_builtin
  43 #  define __has_builtin(x) 0  /* compat. with non-clang compilers */
  44 #endif
  45
  46 /* code only tested on 32 and 64 bits systems */
  47 #define MEM_STATIC_ASSERT(c)   { enum { MEM_static_assert = 1/(int)(!!(c)) }; }
  48 MEM_STATIC void MEM_check(void) { MEM_STATIC_ASSERT((sizeof(size_t)==4) || (sizeof(size_t)==8)); }
  49
  50
  51 /*-**************************************************************
  52 *  Basic Types
  53 *****************************************************************/
  54 #if  !defined (__VMS) && (defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */) )
  55 # include <stdint.h>
  56   typedef   uint8_t BYTE;
  57   typedef  uint16_t U16;
  58   typedef   int16_t S16;
  59   typedef  uint32_t U32;
  60   typedef   int32_t S32;
  61   typedef  uint64_t U64;
  62   typedef   int64_t S64;
  63 #else
  64 # include <limits.h>
  65 #if CHAR_BIT != 8
  66 #  error "this implementation requires char to be exactly 8-bit type"
  67 #endif
  68   typedef unsigned char      BYTE;
  69 #if USHRT_MAX != 65535
  70 #  error "this implementation requires short to be exactly 16-bit type"
  71 #endif
  72   typedef unsigned short      U16;
  73   typedef   signed short      S16;
  74 #if UINT_MAX != 4294967295
  75 #  error "this implementation requires int to be exactly 32-bit type"
  76 #endif
  77   typedef unsigned int        U32;
  78   typedef   signed int        S32;
  79 /* note : there are no limits defined for long long type in C90.
  80  * limits exist in C99, however, in such case, <stdint.h> is preferred */
  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 (i.e., 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 depending on alignment.
  98  *            In some circumstances, it's the only known way to get the most performance (i.e. 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) || defined(__GNUC__)
 106 #    define MEM_FORCE_MEMORY_ACCESS 1
 107 #  endif
 108 #endif
 109
 110 MEM_STATIC unsigned MEM_32bits(void) { return sizeof(size_t)==4; }
 111 MEM_STATIC unsigned MEM_64bits(void) { return sizeof(size_t)==8; }
 112
 113 MEM_STATIC unsigned MEM_isLittleEndian(void)
 114 {
 115     const union { U32 u; BYTE c[4]; } one = { 1 };   /* don't use static : performance detrimental  */
 116     return one.c[0];
 117 }
 118
 119 #if defined(MEM_FORCE_MEMORY_ACCESS) && (MEM_FORCE_MEMORY_ACCESS==2)
 120
 121 /* violates C standard, by lying on structure alignment.
 122 Only use if no other choice to achieve best performance on target platform */
 123 MEM_STATIC U16 MEM_read16(const void* memPtr) { return *(const U16*) memPtr; }
 124 MEM_STATIC U32 MEM_read32(const void* memPtr) { return *(const U32*) memPtr; }
 125 MEM_STATIC U64 MEM_read64(const void* memPtr) { return *(const U64*) memPtr; }
 126 MEM_STATIC size_t MEM_readST(const void* memPtr) { return *(const size_t*) 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 #if defined(_MSC_VER) || (defined(__INTEL_COMPILER) && defined(WIN32))
 137     __pragma( pack(push, 1) )
 138     typedef struct { U16 v; } unalign16;
 139     typedef struct { U32 v; } unalign32;
 140     typedef struct { U64 v; } unalign64;
 141     typedef struct { size_t v; } unalignArch;
 142     __pragma( pack(pop) )
 143 #else
 144     typedef struct { U16 v; } __attribute__((packed)) unalign16;
 145     typedef struct { U32 v; } __attribute__((packed)) unalign32;
 146     typedef struct { U64 v; } __attribute__((packed)) unalign64;
 147     typedef struct { size_t v; } __attribute__((packed)) unalignArch;
 148 #endif
 149
 150 MEM_STATIC U16 MEM_read16(const void* ptr) { return ((const unalign16*)ptr)->v; }
 151 MEM_STATIC U32 MEM_read32(const void* ptr) { return ((const unalign32*)ptr)->v; }
 152 MEM_STATIC U64 MEM_read64(const void* ptr) { return ((const unalign64*)ptr)->v; }
 153 MEM_STATIC size_t MEM_readST(const void* ptr) { return ((const unalignArch*)ptr)->v; }
 154
 155 MEM_STATIC void MEM_write16(void* memPtr, U16 value) { ((unalign16*)memPtr)->v = value; }
 156 MEM_STATIC void MEM_write32(void* memPtr, U32 value) { ((unalign32*)memPtr)->v = value; }
 157 MEM_STATIC void MEM_write64(void* memPtr, U64 value) { ((unalign64*)memPtr)->v = value; }
 158
 159 #else
 160
 161 /* default method, safe and standard.
 162    can sometimes prove slower */
 163
 164 MEM_STATIC U16 MEM_read16(const void* memPtr)
 165 {
 166     U16 val; memcpy(&val, memPtr, sizeof(val)); return val;
 167 }
 168
 169 MEM_STATIC U32 MEM_read32(const void* memPtr)
 170 {
 171     U32 val; memcpy(&val, memPtr, sizeof(val)); return val;
 172 }
 173
 174 MEM_STATIC U64 MEM_read64(const void* memPtr)
 175 {
 176     U64 val; memcpy(&val, memPtr, sizeof(val)); return val;
 177 }
 178
 179 MEM_STATIC size_t MEM_readST(const void* memPtr)
 180 {
 181     size_t val; memcpy(&val, memPtr, sizeof(val)); return val;
 182 }
 183
 184 MEM_STATIC void MEM_write16(void* memPtr, U16 value)
 185 {
 186     memcpy(memPtr, &value, sizeof(value));
 187 }
 188
 189 MEM_STATIC void MEM_write32(void* memPtr, U32 value)
 190 {
 191     memcpy(memPtr, &value, sizeof(value));
 192 }
 193
 194 MEM_STATIC void MEM_write64(void* memPtr, U64 value)
 195 {
 196     memcpy(memPtr, &value, sizeof(value));
 197 }
 198
 199 #endif /* MEM_FORCE_MEMORY_ACCESS */
 200
 201 MEM_STATIC U32 MEM_swap32(U32 in)
 202 {
 203 #if (defined (__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 403)) \
 204   || (defined(__clang__) && __has_builtin(__builtin_bswap32))
 205     return __builtin_bswap32(in);
 206 #else
 207     return  ((in << 24) & 0xff000000 ) |
 208             ((in <<  8) & 0x00ff0000 ) |
 209             ((in >>  8) & 0x0000ff00 ) |
 210             ((in >> 24) & 0x000000ff );
 211 #endif
 212 }
 213
 214 MEM_STATIC U64 MEM_swap64(U64 in)
 215 {
 216 #if (defined (__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 403)) \
 217   || (defined(__clang__) && __has_builtin(__builtin_bswap64))
 218     return __builtin_bswap64(in);
 219 #else
 220     return  ((in << 56) & 0xff00000000000000ULL) |
 221             ((in << 40) & 0x00ff000000000000ULL) |
 222             ((in << 24) & 0x0000ff0000000000ULL) |
 223             ((in << 8)  & 0x000000ff00000000ULL) |
 224             ((in >> 8)  & 0x00000000ff000000ULL) |
 225             ((in >> 24) & 0x0000000000ff0000ULL) |
 226             ((in >> 40) & 0x000000000000ff00ULL) |
 227             ((in >> 56) & 0x00000000000000ffULL);
 228 #endif
 229 }
 230
 231 MEM_STATIC size_t MEM_swapST(size_t in)
 232 {
 233     if (MEM_32bits())
 234         return (size_t)MEM_swap32((U32)in);
 235     else
 236         return (size_t)MEM_swap64((U64)in);
 237 }
 238
 239 /*=== Little endian r/w ===*/
 240
 241 MEM_STATIC U16 MEM_readLE16(const void* memPtr)
 242 {
 243     if (MEM_isLittleEndian())
 244         return MEM_read16(memPtr);
 245     else {
 246         const BYTE* p = (const BYTE*)memPtr;
 247         return (U16)(p[0] + (p[1]<<8));
 248     }
 249 }
 250
 251 MEM_STATIC void MEM_writeLE16(void* memPtr, U16 val)
 252 {
 253     if (MEM_isLittleEndian()) {
 254         MEM_write16(memPtr, val);
 255     } else {
 256         BYTE* p = (BYTE*)memPtr;
 257         p[0] = (BYTE)val;
 258         p[1] = (BYTE)(val>>8);
 259     }
 260 }
 261
 262 MEM_STATIC U32 MEM_readLE24(const void* memPtr)
 263 {
 264     return MEM_readLE16(memPtr) + (((const BYTE*)memPtr)[2] << 16);
 265 }
 266
 267 MEM_STATIC void MEM_writeLE24(void* memPtr, U32 val)
 268 {
 269     MEM_writeLE16(memPtr, (U16)val);
 270     ((BYTE*)memPtr)[2] = (BYTE)(val>>16);
 271 }
 272
 273 MEM_STATIC U32 MEM_readLE32(const void* memPtr)
 274 {
 275     if (MEM_isLittleEndian())
 276         return MEM_read32(memPtr);
 277     else
 278         return MEM_swap32(MEM_read32(memPtr));
 279 }
 280
 281 MEM_STATIC void MEM_writeLE32(void* memPtr, U32 val32)
 282 {
 283     if (MEM_isLittleEndian())
 284         MEM_write32(memPtr, val32);
 285     else
 286         MEM_write32(memPtr, MEM_swap32(val32));
 287 }
 288
 289 MEM_STATIC U64 MEM_readLE64(const void* memPtr)
 290 {
 291     if (MEM_isLittleEndian())
 292         return MEM_read64(memPtr);
 293     else
 294         return MEM_swap64(MEM_read64(memPtr));
 295 }
 296
 297 MEM_STATIC void MEM_writeLE64(void* memPtr, U64 val64)
 298 {
 299     if (MEM_isLittleEndian())
 300         MEM_write64(memPtr, val64);
 301     else
 302         MEM_write64(memPtr, MEM_swap64(val64));
 303 }
 304
 305 MEM_STATIC size_t MEM_readLEST(const void* memPtr)
 306 {
 307     if (MEM_32bits())
 308         return (size_t)MEM_readLE32(memPtr);
 309     else
 310         return (size_t)MEM_readLE64(memPtr);
 311 }
 312
 313 MEM_STATIC void MEM_writeLEST(void* memPtr, size_t val)
 314 {
 315     if (MEM_32bits())
 316         MEM_writeLE32(memPtr, (U32)val);
 317     else
 318         MEM_writeLE64(memPtr, (U64)val);
 319 }
 320
 321 /*=== Big endian r/w ===*/
 322
 323 MEM_STATIC U32 MEM_readBE32(const void* memPtr)
 324 {
 325     if (MEM_isLittleEndian())
 326         return MEM_swap32(MEM_read32(memPtr));
 327     else
 328         return MEM_read32(memPtr);
 329 }
 330
 331 MEM_STATIC void MEM_writeBE32(void* memPtr, U32 val32)
 332 {
 333     if (MEM_isLittleEndian())
 334         MEM_write32(memPtr, MEM_swap32(val32));
 335     else
 336         MEM_write32(memPtr, val32);
 337 }
 338
 339 MEM_STATIC U64 MEM_readBE64(const void* memPtr)
 340 {
 341     if (MEM_isLittleEndian())
 342         return MEM_swap64(MEM_read64(memPtr));
 343     else
 344         return MEM_read64(memPtr);
 345 }
 346
 347 MEM_STATIC void MEM_writeBE64(void* memPtr, U64 val64)
 348 {
 349     if (MEM_isLittleEndian())
 350         MEM_write64(memPtr, MEM_swap64(val64));
 351     else
 352         MEM_write64(memPtr, val64);
 353 }
 354
 355 MEM_STATIC size_t MEM_readBEST(const void* memPtr)
 356 {
 357     if (MEM_32bits())
 358         return (size_t)MEM_readBE32(memPtr);
 359     else
 360         return (size_t)MEM_readBE64(memPtr);
 361 }
 362
 363 MEM_STATIC void MEM_writeBEST(void* memPtr, size_t val)
 364 {
 365     if (MEM_32bits())
 366         MEM_writeBE32(memPtr, (U32)val);
 367     else
 368         MEM_writeBE64(memPtr, (U64)val);
 369 }
 370
 371
 372 #if defined (__cplusplus)
 373 }
 374 #endif
 375
 376 #endif /* MEM_H_MODULE */