libavutil/mem.h

   1 /*
   2  * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
   3  *
   4  * This file is part of Libav.
   5  *
   6  * Libav 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  * Libav 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 Libav; 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 "avutil.h"
  34
  35 /**
  36  * @addtogroup lavu_mem
  37  * @{
  38  */
  39
  40
  41 #if defined(__ICC) && __ICC < 1200 || defined(__SUNPRO_C)
  42     #define DECLARE_ALIGNED(n,t,v)      t __attribute__ ((aligned (n))) v
  43     #define DECLARE_ASM_CONST(n,t,v)    const t __attribute__ ((aligned (n))) v
  44 #elif defined(__GNUC__) || defined(__clang__)
  45     #define DECLARE_ALIGNED(n,t,v)      t __attribute__ ((aligned (n))) v
  46     #define DECLARE_ASM_CONST(n,t,v)    static const t av_used __attribute__ ((aligned (n))) v
  47 #elif defined(_MSC_VER)
  48     #define DECLARE_ALIGNED(n,t,v)      __declspec(align(n)) t v
  49     #define DECLARE_ASM_CONST(n,t,v)    __declspec(align(n)) static const t v
  50 #else
  51     #define DECLARE_ALIGNED(n,t,v)      t v
  52     #define DECLARE_ASM_CONST(n,t,v)    static const t v
  53 #endif
  54
  55 #if AV_GCC_VERSION_AT_LEAST(3,1)
  56     #define av_malloc_attrib __attribute__((__malloc__))
  57 #else
  58     #define av_malloc_attrib
  59 #endif
  60
  61 #if AV_GCC_VERSION_AT_LEAST(4,3)
  62     #define av_alloc_size(...) __attribute__((alloc_size(__VA_ARGS__)))
  63 #else
  64     #define av_alloc_size(...)
  65 #endif
  66
  67 /**
  68  * Allocate a block of size bytes with alignment suitable for all
  69  * memory accesses (including vectors if available on the CPU).
  70  * @param size Size in bytes for the memory block to be allocated.
  71  * @return Pointer to the allocated block, NULL if the block cannot
  72  * be allocated.
  73  * @see av_mallocz()
  74  */
  75 void *av_malloc(size_t size) av_malloc_attrib av_alloc_size(1);
  76
  77 /**
  78  * Allocate a block of size * nmemb bytes with av_malloc().
  79  * @param nmemb Number of elements
  80  * @param size Size of the single element
  81  * @return Pointer to the allocated block, NULL if the block cannot
  82  * be allocated.
  83  * @see av_malloc()
  84  */
  85 av_alloc_size(1, 2) void *av_malloc_array(size_t nmemb, size_t size);
  86
  87 /**
  88  * Allocate or reallocate a block of memory.
  89  * If ptr is NULL and size > 0, allocate a new block. If
  90  * size is zero, free the memory block pointed to by ptr.
  91  * @param ptr Pointer to a memory block already allocated with
  92  * av_realloc() or NULL.
  93  * @param size Size in bytes of the memory block to be allocated or
  94  * reallocated.
  95  * @return Pointer to a newly-reallocated block or NULL if the block
  96  * cannot be reallocated or the function is used to free the memory block.
  97  * @warning Pointers originating from the av_malloc() family of functions must
  98  *          not be passed to av_realloc(). The former can be implemented using
  99  *          memalign() (or other functions), and there is no guarantee that
 100  *          pointers from such functions can be passed to realloc() at all.
 101  *          The situation is undefined according to POSIX and may crash with
 102  *          some libc implementations.
 103  * @see av_fast_realloc()
 104  */
 105 void *av_realloc(void *ptr, size_t size) av_alloc_size(2);
 106
 107 /**
 108  * Allocate or reallocate a block of memory.
 109  * If *ptr is NULL and size > 0, allocate a new block. If
 110  * size is zero, free the memory block pointed to by ptr.
 111  * @param   ptr Pointer to a pointer to a memory block already allocated
 112  *          with av_realloc(), or pointer to a pointer to NULL.
 113  *          The pointer is updated on success, or freed on failure.
 114  * @param   size Size in bytes for the memory block to be allocated or
 115  *          reallocated
 116  * @return  Zero on success, an AVERROR error code on failure.
 117  * @warning Pointers originating from the av_malloc() family of functions must
 118  *          not be passed to av_reallocp(). The former can be implemented using
 119  *          memalign() (or other functions), and there is no guarantee that
 120  *          pointers from such functions can be passed to realloc() at all.
 121  *          The situation is undefined according to POSIX and may crash with
 122  *          some libc implementations.
 123  */
 124 int av_reallocp(void *ptr, size_t size);
 125
 126 /**
 127  * Allocate or reallocate an array.
 128  * If ptr is NULL and nmemb > 0, allocate a new block. If
 129  * nmemb is zero, free the memory block pointed to by ptr.
 130  * @param ptr Pointer to a memory block already allocated with
 131  * av_realloc() or NULL.
 132  * @param nmemb Number of elements
 133  * @param size Size of the single element
 134  * @return Pointer to a newly-reallocated block or NULL if the block
 135  * cannot be reallocated or the function is used to free the memory block.
 136  * @warning Pointers originating from the av_malloc() family of functions must
 137  *          not be passed to av_realloc(). The former can be implemented using
 138  *          memalign() (or other functions), and there is no guarantee that
 139  *          pointers from such functions can be passed to realloc() at all.
 140  *          The situation is undefined according to POSIX and may crash with
 141  *          some libc implementations.
 142  */
 143 av_alloc_size(2, 3) void *av_realloc_array(void *ptr, size_t nmemb, size_t size);
 144
 145 /**
 146  * Allocate or reallocate an array through a pointer to a pointer.
 147  * If *ptr is NULL and nmemb > 0, allocate a new block. If
 148  * nmemb is zero, free the memory block pointed to by ptr.
 149  * @param ptr Pointer to a pointer to a memory block already allocated
 150  * with av_realloc(), or pointer to a pointer to NULL.
 151  * The pointer is updated on success, or freed on failure.
 152  * @param nmemb Number of elements
 153  * @param size Size of the single element
 154  * @return Zero on success, an AVERROR error code on failure.
 155  * @warning Pointers originating from the av_malloc() family of functions must
 156  *          not be passed to av_realloc(). The former can be implemented using
 157  *          memalign() (or other functions), and there is no guarantee that
 158  *          pointers from such functions can be passed to realloc() at all.
 159  *          The situation is undefined according to POSIX and may crash with
 160  *          some libc implementations.
 161  */
 162 av_alloc_size(2, 3) int av_reallocp_array(void *ptr, size_t nmemb, size_t size);
 163
 164 /**
 165  * Free a memory block which has been allocated with av_malloc(z)() or
 166  * av_realloc().
 167  * @param ptr Pointer to the memory block which should be freed.
 168  * @note ptr = NULL is explicitly allowed.
 169  * @note It is recommended that you use av_freep() instead.
 170  * @see av_freep()
 171  */
 172 void av_free(void *ptr);
 173
 174 /**
 175  * Allocate a block of size bytes with alignment suitable for all
 176  * memory accesses (including vectors if available on the CPU) and
 177  * zero all the bytes of the block.
 178  * @param size Size in bytes for the memory block to be allocated.
 179  * @return Pointer to the allocated block, NULL if it cannot be allocated.
 180  * @see av_malloc()
 181  */
 182 void *av_mallocz(size_t size) av_malloc_attrib av_alloc_size(1);
 183
 184 /**
 185  * Allocate a block of size * nmemb bytes with 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) void *av_mallocz_array(size_t nmemb, size_t size);
 194
 195 /**
 196  * Duplicate the string s.
 197  * @param s string to be duplicated
 198  * @return Pointer to a newly-allocated string containing a
 199  * copy of s or NULL if the string cannot be allocated.
 200  */
 201 char *av_strdup(const char *s) av_malloc_attrib;
 202
 203 /**
 204  * Duplicate a substring of the string s.
 205  * @param s string to be duplicated
 206  * @param len the maximum length of the resulting string (not counting the
 207  *            terminating byte).
 208  * @return Pointer to a newly-allocated string containing a
 209  * copy of s or NULL if the string cannot be allocated.
 210  */
 211 char *av_strndup(const char *s, size_t len) av_malloc_attrib;
 212
 213 /**
 214  * Free a memory block which has been allocated with av_malloc(z)() or
 215  * av_realloc() and set the pointer pointing to it to NULL.
 216  * @param ptr Pointer to the pointer to the memory block which should
 217  * be freed.
 218  * @see av_free()
 219  */
 220 void av_freep(void *ptr);
 221
 222 /**
 223  * deliberately overlapping memcpy implementation
 224  * @param dst destination buffer
 225  * @param back how many bytes back we start (the initial size of the overlapping window)
 226  * @param cnt number of bytes to copy, must be >= 0
 227  *
 228  * cnt > back is valid, this will copy the bytes we just copied,
 229  * thus creating a repeating pattern with a period length of back.
 230  */
 231 void av_memcpy_backptr(uint8_t *dst, int back, int cnt);
 232
 233 /**
 234  * Reallocate the given block if it is not large enough, otherwise do nothing.
 235  *
 236  * @see av_realloc
 237  */
 238 void *av_fast_realloc(void *ptr, unsigned int *size, size_t min_size);
 239
 240 /**
 241  * Allocate a buffer, reusing the given one if large enough.
 242  *
 243  * Contrary to av_fast_realloc the current buffer contents might not be
 244  * preserved and on error the old buffer is freed, thus no special
 245  * handling to avoid memleaks is necessary.
 246  *
 247  * @param ptr pointer to pointer to already allocated buffer, overwritten with pointer to new buffer
 248  * @param size size of the buffer *ptr points to
 249  * @param min_size minimum size of *ptr buffer after returning, *ptr will be NULL and
 250  *                 *size 0 if an error occurred.
 251  */
 252 void av_fast_malloc(void *ptr, unsigned int *size, size_t min_size);
 253
 254 /**
 255  * @}
 256  */
 257
 258 #endif /* AVUTIL_MEM_H */