2 * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
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.
14 #if defined (__cplusplus)
18 /*-****************************************
20 ******************************************/
21 #include <stddef.h> /* size_t, ptrdiff_t */
22 #include <string.h> /* memcpy */
25 /*-****************************************
27 ******************************************/
28 #if defined(_MSC_VER) /* Visual Studio */
29 # include <stdlib.h> /* _byteswap_ulong */
30 # include <intrin.h> /* _byteswap_* */
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
39 # define MEM_STATIC static /* this version may generate warnings for unused static functions; disable the relevant warning */
43 # define __has_builtin(x) 0 /* compat. with non-clang compilers */
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)); }
51 /*-**************************************************************
53 *****************************************************************/
54 #if !defined (__VMS) && (defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */) )
66 # error "this implementation requires char to be exactly 8-bit type"
68 typedef unsigned char BYTE;
69 #if USHRT_MAX != 65535
70 # error "this implementation requires short to be exactly 16-bit type"
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"
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;
86 /*-**************************************************************
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)
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
110 MEM_STATIC unsigned MEM_32bits(void) { return sizeof(size_t)==4; }
111 MEM_STATIC unsigned MEM_64bits(void) { return sizeof(size_t)==8; }
113 MEM_STATIC unsigned MEM_isLittleEndian(void)
115 const union { U32 u; BYTE c[4]; } one = { 1 }; /* don't use static : performance detrimental */
119 #if defined(MEM_FORCE_MEMORY_ACCESS) && (MEM_FORCE_MEMORY_ACCESS==2)
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; }
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; }
132 #elif defined(MEM_FORCE_MEMORY_ACCESS) && (MEM_FORCE_MEMORY_ACCESS==1)
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) )
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;
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; }
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; }
161 /* default method, safe and standard.
162 can sometimes prove slower */
164 MEM_STATIC U16 MEM_read16(const void* memPtr)
166 U16 val; memcpy(&val, memPtr, sizeof(val)); return val;
169 MEM_STATIC U32 MEM_read32(const void* memPtr)
171 U32 val; memcpy(&val, memPtr, sizeof(val)); return val;
174 MEM_STATIC U64 MEM_read64(const void* memPtr)
176 U64 val; memcpy(&val, memPtr, sizeof(val)); return val;
179 MEM_STATIC size_t MEM_readST(const void* memPtr)
181 size_t val; memcpy(&val, memPtr, sizeof(val)); return val;
184 MEM_STATIC void MEM_write16(void* memPtr, U16 value)
186 memcpy(memPtr, &value, sizeof(value));
189 MEM_STATIC void MEM_write32(void* memPtr, U32 value)
191 memcpy(memPtr, &value, sizeof(value));
194 MEM_STATIC void MEM_write64(void* memPtr, U64 value)
196 memcpy(memPtr, &value, sizeof(value));
199 #endif /* MEM_FORCE_MEMORY_ACCESS */
201 MEM_STATIC U32 MEM_swap32(U32 in)
203 #if defined(_MSC_VER) /* Visual Studio */
204 return _byteswap_ulong(in);
205 #elif (defined (__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 403)) \
206 || (defined(__clang__) && __has_builtin(__builtin_bswap32))
207 return __builtin_bswap32(in);
209 return ((in << 24) & 0xff000000 ) |
210 ((in << 8) & 0x00ff0000 ) |
211 ((in >> 8) & 0x0000ff00 ) |
212 ((in >> 24) & 0x000000ff );
216 MEM_STATIC U64 MEM_swap64(U64 in)
218 #if defined(_MSC_VER) /* Visual Studio */
219 return _byteswap_uint64(in);
220 #elif (defined (__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 403)) \
221 || (defined(__clang__) && __has_builtin(__builtin_bswap64))
222 return __builtin_bswap64(in);
224 return ((in << 56) & 0xff00000000000000ULL) |
225 ((in << 40) & 0x00ff000000000000ULL) |
226 ((in << 24) & 0x0000ff0000000000ULL) |
227 ((in << 8) & 0x000000ff00000000ULL) |
228 ((in >> 8) & 0x00000000ff000000ULL) |
229 ((in >> 24) & 0x0000000000ff0000ULL) |
230 ((in >> 40) & 0x000000000000ff00ULL) |
231 ((in >> 56) & 0x00000000000000ffULL);
235 MEM_STATIC size_t MEM_swapST(size_t in)
238 return (size_t)MEM_swap32((U32)in);
240 return (size_t)MEM_swap64((U64)in);
243 /*=== Little endian r/w ===*/
245 MEM_STATIC U16 MEM_readLE16(const void* memPtr)
247 if (MEM_isLittleEndian())
248 return MEM_read16(memPtr);
250 const BYTE* p = (const BYTE*)memPtr;
251 return (U16)(p[0] + (p[1]<<8));
255 MEM_STATIC void MEM_writeLE16(void* memPtr, U16 val)
257 if (MEM_isLittleEndian()) {
258 MEM_write16(memPtr, val);
260 BYTE* p = (BYTE*)memPtr;
262 p[1] = (BYTE)(val>>8);
266 MEM_STATIC U32 MEM_readLE24(const void* memPtr)
268 return MEM_readLE16(memPtr) + (((const BYTE*)memPtr)[2] << 16);
271 MEM_STATIC void MEM_writeLE24(void* memPtr, U32 val)
273 MEM_writeLE16(memPtr, (U16)val);
274 ((BYTE*)memPtr)[2] = (BYTE)(val>>16);
277 MEM_STATIC U32 MEM_readLE32(const void* memPtr)
279 if (MEM_isLittleEndian())
280 return MEM_read32(memPtr);
282 return MEM_swap32(MEM_read32(memPtr));
285 MEM_STATIC void MEM_writeLE32(void* memPtr, U32 val32)
287 if (MEM_isLittleEndian())
288 MEM_write32(memPtr, val32);
290 MEM_write32(memPtr, MEM_swap32(val32));
293 MEM_STATIC U64 MEM_readLE64(const void* memPtr)
295 if (MEM_isLittleEndian())
296 return MEM_read64(memPtr);
298 return MEM_swap64(MEM_read64(memPtr));
301 MEM_STATIC void MEM_writeLE64(void* memPtr, U64 val64)
303 if (MEM_isLittleEndian())
304 MEM_write64(memPtr, val64);
306 MEM_write64(memPtr, MEM_swap64(val64));
309 MEM_STATIC size_t MEM_readLEST(const void* memPtr)
312 return (size_t)MEM_readLE32(memPtr);
314 return (size_t)MEM_readLE64(memPtr);
317 MEM_STATIC void MEM_writeLEST(void* memPtr, size_t val)
320 MEM_writeLE32(memPtr, (U32)val);
322 MEM_writeLE64(memPtr, (U64)val);
325 /*=== Big endian r/w ===*/
327 MEM_STATIC U32 MEM_readBE32(const void* memPtr)
329 if (MEM_isLittleEndian())
330 return MEM_swap32(MEM_read32(memPtr));
332 return MEM_read32(memPtr);
335 MEM_STATIC void MEM_writeBE32(void* memPtr, U32 val32)
337 if (MEM_isLittleEndian())
338 MEM_write32(memPtr, MEM_swap32(val32));
340 MEM_write32(memPtr, val32);
343 MEM_STATIC U64 MEM_readBE64(const void* memPtr)
345 if (MEM_isLittleEndian())
346 return MEM_swap64(MEM_read64(memPtr));
348 return MEM_read64(memPtr);
351 MEM_STATIC void MEM_writeBE64(void* memPtr, U64 val64)
353 if (MEM_isLittleEndian())
354 MEM_write64(memPtr, MEM_swap64(val64));
356 MEM_write64(memPtr, val64);
359 MEM_STATIC size_t MEM_readBEST(const void* memPtr)
362 return (size_t)MEM_readBE32(memPtr);
364 return (size_t)MEM_readBE64(memPtr);
367 MEM_STATIC void MEM_writeBEST(void* memPtr, size_t val)
370 MEM_writeBE32(memPtr, (U32)val);
372 MEM_writeBE64(memPtr, (U64)val);
376 #if defined (__cplusplus)
380 #endif /* MEM_H_MODULE */