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mem.h
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1 /*
2  * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 /**
22  * @file
23  * memory handling functions
24  */
25 
26 #ifndef AVUTIL_MEM_H
27 #define AVUTIL_MEM_H
28 
29 #include <limits.h>
30 #include <stdint.h>
31 
32 #include "attributes.h"
33 #include "error.h"
34 #include "avutil.h"
35 
36 /**
37  * @addtogroup lavu_mem
38  * @{
39  */
40 
41 
42 #if defined(__INTEL_COMPILER) && __INTEL_COMPILER < 1110 || defined(__SUNPRO_C)
43  #define DECLARE_ALIGNED(n,t,v) t __attribute__ ((aligned (n))) v
44  #define DECLARE_ASM_CONST(n,t,v) const t __attribute__ ((aligned (n))) v
45 #elif defined(__TI_COMPILER_VERSION__)
46  #define DECLARE_ALIGNED(n,t,v) \
47  AV_PRAGMA(DATA_ALIGN(v,n)) \
48  t __attribute__((aligned(n))) v
49  #define DECLARE_ASM_CONST(n,t,v) \
50  AV_PRAGMA(DATA_ALIGN(v,n)) \
51  static const t __attribute__((aligned(n))) v
52 #elif defined(__GNUC__)
53  #define DECLARE_ALIGNED(n,t,v) t __attribute__ ((aligned (n))) v
54  #define DECLARE_ASM_CONST(n,t,v) static const t av_used __attribute__ ((aligned (n))) v
55 #elif defined(_MSC_VER)
56  #define DECLARE_ALIGNED(n,t,v) __declspec(align(n)) t v
57  #define DECLARE_ASM_CONST(n,t,v) __declspec(align(n)) static const t v
58 #else
59  #define DECLARE_ALIGNED(n,t,v) t v
60  #define DECLARE_ASM_CONST(n,t,v) static const t v
61 #endif
62 
63 #if AV_GCC_VERSION_AT_LEAST(3,1)
64  #define av_malloc_attrib __attribute__((__malloc__))
65 #else
66  #define av_malloc_attrib
67 #endif
68 
69 #if AV_GCC_VERSION_AT_LEAST(4,3)
70  #define av_alloc_size(...) __attribute__((alloc_size(__VA_ARGS__)))
71 #else
72  #define av_alloc_size(...)
73 #endif
74 
75 /**
76  * Allocate a block of size bytes with alignment suitable for all
77  * memory accesses (including vectors if available on the CPU).
78  * @param size Size in bytes for the memory block to be allocated.
79  * @return Pointer to the allocated block, NULL if the block cannot
80  * be allocated.
81  * @see av_mallocz()
82  */
84 
85 /**
86  * Helper function to allocate a block of size * nmemb bytes with
87  * using av_malloc()
88  * @param nmemb Number of elements
89  * @param size Size of the single element
90  * @return Pointer to the allocated block, NULL if the block cannot
91  * be allocated.
92  * @see av_malloc()
93  */
94 av_alloc_size(1, 2) static inline void *av_malloc_array(size_t nmemb, size_t size)
95 {
96  if (size <= 0 || nmemb >= INT_MAX / size)
97  return NULL;
98  return av_malloc(nmemb * size);
99 }
100 
101 /**
102  * Allocate or reallocate a block of memory.
103  * If ptr is NULL and size > 0, allocate a new block. If
104  * size is zero, free the memory block pointed to by ptr.
105  * @param ptr Pointer to a memory block already allocated with
106  * av_malloc(z)() or av_realloc() or NULL.
107  * @param size Size in bytes for the memory block to be allocated or
108  * reallocated.
109  * @return Pointer to a newly reallocated block or NULL if the block
110  * cannot be reallocated or the function is used to free the memory block.
111  * @see av_fast_realloc()
112  */
113 void *av_realloc(void *ptr, size_t size) av_alloc_size(2);
114 
115 /**
116  * Allocate or reallocate a block of memory.
117  * This function does the same thing as av_realloc, except:
118  * - It takes two arguments and checks the result of the multiplication for
119  * integer overflow.
120  * - It frees the input block in case of failure, thus avoiding the memory
121  * leak with the classic "buf = realloc(buf); if (!buf) return -1;".
122  */
123 void *av_realloc_f(void *ptr, size_t nelem, size_t elsize);
124 
125 /**
126  * Allocate or reallocate an array.
127  * If ptr is NULL and nmemb > 0, allocate a new block. If
128  * nmemb is zero, free the memory block pointed to by ptr.
129  * @param ptr Pointer to a memory block already allocated with
130  * av_malloc(z)() or av_realloc() or NULL.
131  * @param nmemb Number of elements
132  * @param size Size of the single element
133  * @return Pointer to a newly reallocated block or NULL if the block
134  * cannot be reallocated or the function is used to free the memory block.
135  */
136 av_alloc_size(2, 3) void *av_realloc_array(void *ptr, size_t nmemb, size_t size);
137 
138 /**
139  * Allocate or reallocate an array.
140  * If *ptr is NULL and nmemb > 0, allocate a new block. If
141  * nmemb is zero, free the memory block pointed to by ptr.
142  * @param ptr Pointer to a pointer to a memory block already allocated
143  * with av_malloc(z)() or av_realloc(), or pointer to a pointer to NULL.
144  * The pointer is updated on success, or freed on failure.
145  * @param nmemb Number of elements
146  * @param size Size of the single element
147  * @return Zero on success, an AVERROR error code on failure.
148  */
149 av_alloc_size(2, 3) int av_reallocp_array(void *ptr, size_t nmemb, size_t size);
150 
151 /**
152  * Free a memory block which has been allocated with av_malloc(z)() or
153  * av_realloc().
154  * @param ptr Pointer to the memory block which should be freed.
155  * @note ptr = NULL is explicitly allowed.
156  * @note It is recommended that you use av_freep() instead.
157  * @see av_freep()
158  */
159 void av_free(void *ptr);
160 
161 /**
162  * Allocate a block of size bytes with alignment suitable for all
163  * memory accesses (including vectors if available on the CPU) and
164  * zero all the bytes of the block.
165  * @param size Size in bytes for the memory block to be allocated.
166  * @return Pointer to the allocated block, NULL if it cannot be allocated.
167  * @see av_malloc()
168  */
169 void *av_mallocz(size_t size) av_malloc_attrib av_alloc_size(1);
170 
171 /**
172  * Allocate a block of nmemb * size bytes with alignment suitable for all
173  * memory accesses (including vectors if available on the CPU) and
174  * zero all the bytes of the block.
175  * The allocation will fail if nmemb * size is greater than or equal
176  * to INT_MAX.
177  * @param nmemb
178  * @param size
179  * @return Pointer to the allocated block, NULL if it cannot be allocated.
180  */
181 void *av_calloc(size_t nmemb, size_t size) av_malloc_attrib;
182 
183 /**
184  * Helper function to allocate a block of size * nmemb bytes with
185  * using av_mallocz()
186  * @param nmemb Number of elements
187  * @param size Size of the single element
188  * @return Pointer to the allocated block, NULL if the block cannot
189  * be allocated.
190  * @see av_mallocz()
191  * @see av_malloc_array()
192  */
193 av_alloc_size(1, 2) static inline void *av_mallocz_array(size_t nmemb, size_t size)
194 {
195  if (size <= 0 || nmemb >= INT_MAX / size)
196  return NULL;
197  return av_mallocz(nmemb * size);
198 }
199 
200 /**
201  * Duplicate the string s.
202  * @param s string to be duplicated
203  * @return Pointer to a newly allocated string containing a
204  * copy of s or NULL if the string cannot be allocated.
205  */
206 char *av_strdup(const char *s) av_malloc_attrib;
207 
208 /**
209  * Duplicate the buffer p.
210  * @param p buffer to be duplicated
211  * @return Pointer to a newly allocated buffer containing a
212  * copy of p or NULL if the buffer cannot be allocated.
213  */
214 void *av_memdup(const void *p, size_t size);
215 
216 /**
217  * Free a memory block which has been allocated with av_malloc(z)() or
218  * av_realloc() and set the pointer pointing to it to NULL.
219  * @param ptr Pointer to the pointer to the memory block which should
220  * be freed.
221  * @see av_free()
222  */
223 void av_freep(void *ptr);
224 
225 /**
226  * Add an element to a dynamic array.
227  *
228  * The array to grow is supposed to be an array of pointers to
229  * structures, and the element to add must be a pointer to an already
230  * allocated structure.
231  *
232  * The array is reallocated when its size reaches powers of 2.
233  * Therefore, the amortized cost of adding an element is constant.
234  *
235  * In case of success, the pointer to the array is updated in order to
236  * point to the new grown array, and the number pointed to by nb_ptr
237  * is incremented.
238  * In case of failure, the array is freed, *tab_ptr is set to NULL and
239  * *nb_ptr is set to 0.
240  *
241  * @param tab_ptr pointer to the array to grow
242  * @param nb_ptr pointer to the number of elements in the array
243  * @param elem element to add
244  * @see av_dynarray2_add()
245  */
246 void av_dynarray_add(void *tab_ptr, int *nb_ptr, void *elem);
247 
248 /**
249  * Add an element of size elem_size to a dynamic array.
250  *
251  * The array is reallocated when its number of elements reaches powers of 2.
252  * Therefore, the amortized cost of adding an element is constant.
253  *
254  * In case of success, the pointer to the array is updated in order to
255  * point to the new grown array, and the number pointed to by nb_ptr
256  * is incremented.
257  * In case of failure, the array is freed, *tab_ptr is set to NULL and
258  * *nb_ptr is set to 0.
259  *
260  * @param tab_ptr pointer to the array to grow
261  * @param nb_ptr pointer to the number of elements in the array
262  * @param elem_size size in bytes of the elements in the array
263  * @param elem_data pointer to the data of the element to add. If NULL, the space of
264  * the new added element is not filled.
265  * @return pointer to the data of the element to copy in the new allocated space.
266  * If NULL, the new allocated space is left uninitialized."
267  * @see av_dynarray_add()
268  */
269 void *av_dynarray2_add(void **tab_ptr, int *nb_ptr, size_t elem_size,
270  const uint8_t *elem_data);
271 
272 /**
273  * Multiply two size_t values checking for overflow.
274  * @return 0 if success, AVERROR(EINVAL) if overflow.
275  */
276 static inline int av_size_mult(size_t a, size_t b, size_t *r)
277 {
278  size_t t = a * b;
279  /* Hack inspired from glibc: only try the division if nelem and elsize
280  * are both greater than sqrt(SIZE_MAX). */
281  if ((a | b) >= ((size_t)1 << (sizeof(size_t) * 4)) && a && t / a != b)
282  return AVERROR(EINVAL);
283  *r = t;
284  return 0;
285 }
286 
287 /**
288  * Set the maximum size that may me allocated in one block.
289  */
290 void av_max_alloc(size_t max);
291 
292 /**
293  * @brief deliberately overlapping memcpy implementation
294  * @param dst destination buffer
295  * @param back how many bytes back we start (the initial size of the overlapping window), must be > 0
296  * @param cnt number of bytes to copy, must be >= 0
297  *
298  * cnt > back is valid, this will copy the bytes we just copied,
299  * thus creating a repeating pattern with a period length of back.
300  */
301 void av_memcpy_backptr(uint8_t *dst, int back, int cnt);
302 
303 /**
304  * @}
305  */
306 
307 #endif /* AVUTIL_MEM_H */