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 */
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)); }
47 /*-**************************************************************
49 *****************************************************************/
50 #if !defined (__VMS) && (defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */) )
59 typedef intptr_t iPtrDiff;
60 typedef uintptr_t uPtrDiff;
62 typedef unsigned char BYTE;
63 typedef unsigned short U16;
64 typedef signed short S16;
65 typedef unsigned int U32;
66 typedef signed int S32;
67 typedef unsigned long long U64;
68 typedef signed long long S64;
69 typedef ptrdiff_t iPtrDiff;
70 typedef size_t uPtrDiff;
74 /*-**************************************************************
76 *****************************************************************/
77 /* MEM_FORCE_MEMORY_ACCESS :
78 * By default, access to unaligned memory is controlled by `memcpy()`, which is safe and portable.
79 * Unfortunately, on some target/compiler combinations, the generated assembly is sub-optimal.
80 * The below switch allow to select different access method for improved performance.
81 * Method 0 (default) : use `memcpy()`. Safe and portable.
82 * Method 1 : `__packed` statement. It depends on compiler extension (i.e., not portable).
83 * This method is safe if your compiler supports it, and *generally* as fast or faster than `memcpy`.
84 * Method 2 : direct access. This method is portable but violate C standard.
85 * It can generate buggy code on targets depending on alignment.
86 * In some circumstances, it's the only known way to get the most performance (i.e. GCC + ARMv6)
87 * See http://fastcompression.blogspot.fr/2015/08/accessing-unaligned-memory.html for details.
88 * Prefer these methods in priority order (0 > 1 > 2)
90 #ifndef MEM_FORCE_MEMORY_ACCESS /* can be defined externally, on command line for example */
91 # 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__) )
92 # define MEM_FORCE_MEMORY_ACCESS 2
93 # elif defined(__INTEL_COMPILER) || defined(__GNUC__)
94 # define MEM_FORCE_MEMORY_ACCESS 1
98 MEM_STATIC unsigned MEM_32bits(void) { return sizeof(size_t)==4; }
99 MEM_STATIC unsigned MEM_64bits(void) { return sizeof(size_t)==8; }
101 MEM_STATIC unsigned MEM_isLittleEndian(void)
103 const union { U32 u; BYTE c[4]; } one = { 1 }; /* don't use static : performance detrimental */
107 #if defined(MEM_FORCE_MEMORY_ACCESS) && (MEM_FORCE_MEMORY_ACCESS==2)
109 /* violates C standard, by lying on structure alignment.
110 Only use if no other choice to achieve best performance on target platform */
111 MEM_STATIC U16 MEM_read16(const void* memPtr) { return *(const U16*) memPtr; }
112 MEM_STATIC U32 MEM_read32(const void* memPtr) { return *(const U32*) memPtr; }
113 MEM_STATIC U64 MEM_read64(const void* memPtr) { return *(const U64*) memPtr; }
114 MEM_STATIC size_t MEM_readST(const void* memPtr) { return *(const size_t*) memPtr; }
116 MEM_STATIC void MEM_write16(void* memPtr, U16 value) { *(U16*)memPtr = value; }
117 MEM_STATIC void MEM_write32(void* memPtr, U32 value) { *(U32*)memPtr = value; }
118 MEM_STATIC void MEM_write64(void* memPtr, U64 value) { *(U64*)memPtr = value; }
120 #elif defined(MEM_FORCE_MEMORY_ACCESS) && (MEM_FORCE_MEMORY_ACCESS==1)
122 /* __pack instructions are safer, but compiler specific, hence potentially problematic for some compilers */
123 /* currently only defined for gcc and icc */
124 #if defined(_MSC_VER) || (defined(__INTEL_COMPILER) && defined(WIN32))
125 __pragma( pack(push, 1) )
126 typedef union { U16 u16; U32 u32; U64 u64; size_t st; } unalign;
127 __pragma( pack(pop) )
129 typedef union { U16 u16; U32 u32; U64 u64; size_t st; } __attribute__((packed)) unalign;
132 MEM_STATIC U16 MEM_read16(const void* ptr) { return ((const unalign*)ptr)->u16; }
133 MEM_STATIC U32 MEM_read32(const void* ptr) { return ((const unalign*)ptr)->u32; }
134 MEM_STATIC U64 MEM_read64(const void* ptr) { return ((const unalign*)ptr)->u64; }
135 MEM_STATIC size_t MEM_readST(const void* ptr) { return ((const unalign*)ptr)->st; }
137 MEM_STATIC void MEM_write16(void* memPtr, U16 value) { ((unalign*)memPtr)->u16 = value; }
138 MEM_STATIC void MEM_write32(void* memPtr, U32 value) { ((unalign*)memPtr)->u32 = value; }
139 MEM_STATIC void MEM_write64(void* memPtr, U64 value) { ((unalign*)memPtr)->u64 = value; }
143 /* default method, safe and standard.
144 can sometimes prove slower */
146 MEM_STATIC U16 MEM_read16(const void* memPtr)
148 U16 val; memcpy(&val, memPtr, sizeof(val)); return val;
151 MEM_STATIC U32 MEM_read32(const void* memPtr)
153 U32 val; memcpy(&val, memPtr, sizeof(val)); return val;
156 MEM_STATIC U64 MEM_read64(const void* memPtr)
158 U64 val; memcpy(&val, memPtr, sizeof(val)); return val;
161 MEM_STATIC size_t MEM_readST(const void* memPtr)
163 size_t val; memcpy(&val, memPtr, sizeof(val)); return val;
166 MEM_STATIC void MEM_write16(void* memPtr, U16 value)
168 memcpy(memPtr, &value, sizeof(value));
171 MEM_STATIC void MEM_write32(void* memPtr, U32 value)
173 memcpy(memPtr, &value, sizeof(value));
176 MEM_STATIC void MEM_write64(void* memPtr, U64 value)
178 memcpy(memPtr, &value, sizeof(value));
181 #endif /* MEM_FORCE_MEMORY_ACCESS */
183 MEM_STATIC U32 MEM_swap32(U32 in)
185 #if defined(_MSC_VER) /* Visual Studio */
186 return _byteswap_ulong(in);
187 #elif defined (__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 403)
188 return __builtin_bswap32(in);
190 return ((in << 24) & 0xff000000 ) |
191 ((in << 8) & 0x00ff0000 ) |
192 ((in >> 8) & 0x0000ff00 ) |
193 ((in >> 24) & 0x000000ff );
197 MEM_STATIC U64 MEM_swap64(U64 in)
199 #if defined(_MSC_VER) /* Visual Studio */
200 return _byteswap_uint64(in);
201 #elif defined (__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 403)
202 return __builtin_bswap64(in);
204 return ((in << 56) & 0xff00000000000000ULL) |
205 ((in << 40) & 0x00ff000000000000ULL) |
206 ((in << 24) & 0x0000ff0000000000ULL) |
207 ((in << 8) & 0x000000ff00000000ULL) |
208 ((in >> 8) & 0x00000000ff000000ULL) |
209 ((in >> 24) & 0x0000000000ff0000ULL) |
210 ((in >> 40) & 0x000000000000ff00ULL) |
211 ((in >> 56) & 0x00000000000000ffULL);
215 MEM_STATIC size_t MEM_swapST(size_t in)
218 return (size_t)MEM_swap32((U32)in);
220 return (size_t)MEM_swap64((U64)in);
223 /*=== Little endian r/w ===*/
225 MEM_STATIC U16 MEM_readLE16(const void* memPtr)
227 if (MEM_isLittleEndian())
228 return MEM_read16(memPtr);
230 const BYTE* p = (const BYTE*)memPtr;
231 return (U16)(p[0] + (p[1]<<8));
235 MEM_STATIC void MEM_writeLE16(void* memPtr, U16 val)
237 if (MEM_isLittleEndian()) {
238 MEM_write16(memPtr, val);
240 BYTE* p = (BYTE*)memPtr;
242 p[1] = (BYTE)(val>>8);
246 MEM_STATIC U32 MEM_readLE24(const void* memPtr)
248 return MEM_readLE16(memPtr) + (((const BYTE*)memPtr)[2] << 16);
251 MEM_STATIC void MEM_writeLE24(void* memPtr, U32 val)
253 MEM_writeLE16(memPtr, (U16)val);
254 ((BYTE*)memPtr)[2] = (BYTE)(val>>16);
257 MEM_STATIC U32 MEM_readLE32(const void* memPtr)
259 if (MEM_isLittleEndian())
260 return MEM_read32(memPtr);
262 return MEM_swap32(MEM_read32(memPtr));
265 MEM_STATIC void MEM_writeLE32(void* memPtr, U32 val32)
267 if (MEM_isLittleEndian())
268 MEM_write32(memPtr, val32);
270 MEM_write32(memPtr, MEM_swap32(val32));
273 MEM_STATIC U64 MEM_readLE64(const void* memPtr)
275 if (MEM_isLittleEndian())
276 return MEM_read64(memPtr);
278 return MEM_swap64(MEM_read64(memPtr));
281 MEM_STATIC void MEM_writeLE64(void* memPtr, U64 val64)
283 if (MEM_isLittleEndian())
284 MEM_write64(memPtr, val64);
286 MEM_write64(memPtr, MEM_swap64(val64));
289 MEM_STATIC size_t MEM_readLEST(const void* memPtr)
292 return (size_t)MEM_readLE32(memPtr);
294 return (size_t)MEM_readLE64(memPtr);
297 MEM_STATIC void MEM_writeLEST(void* memPtr, size_t val)
300 MEM_writeLE32(memPtr, (U32)val);
302 MEM_writeLE64(memPtr, (U64)val);
305 /*=== Big endian r/w ===*/
307 MEM_STATIC U32 MEM_readBE32(const void* memPtr)
309 if (MEM_isLittleEndian())
310 return MEM_swap32(MEM_read32(memPtr));
312 return MEM_read32(memPtr);
315 MEM_STATIC void MEM_writeBE32(void* memPtr, U32 val32)
317 if (MEM_isLittleEndian())
318 MEM_write32(memPtr, MEM_swap32(val32));
320 MEM_write32(memPtr, val32);
323 MEM_STATIC U64 MEM_readBE64(const void* memPtr)
325 if (MEM_isLittleEndian())
326 return MEM_swap64(MEM_read64(memPtr));
328 return MEM_read64(memPtr);
331 MEM_STATIC void MEM_writeBE64(void* memPtr, U64 val64)
333 if (MEM_isLittleEndian())
334 MEM_write64(memPtr, MEM_swap64(val64));
336 MEM_write64(memPtr, val64);
339 MEM_STATIC size_t MEM_readBEST(const void* memPtr)
342 return (size_t)MEM_readBE32(memPtr);
344 return (size_t)MEM_readBE64(memPtr);
347 MEM_STATIC void MEM_writeBEST(void* memPtr, size_t val)
350 MEM_writeBE32(memPtr, (U32)val);
352 MEM_writeBE64(memPtr, (U64)val);
356 #if defined (__cplusplus)
360 #endif /* MEM_H_MODULE */