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mem: Extend and edit Doxygen

tags/n3.2
Timothy Gu 9 years ago
parent
cc5e5548df
commit
1ae4b1e09d
1 changed files with 451 additions and 137 deletions
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  1. +451
    -137
      libavutil/mem.h

+ 451
- 137
libavutil/mem.h View File

@@ -20,7 +20,8 @@

/**
* @file
* memory handling functions
* @ingroup lavu_mem
* Memory handling functions
*/

#ifndef AVUTIL_MEM_H
@@ -35,9 +36,56 @@

/**
* @addtogroup lavu_mem
* Utilities for manipulating memory.
*
* FFmpeg has several applications of memory that are not required of a typical
* program. For example, the computing-heavy components like video decoding and
* encoding can be sped up significantly through the use of aligned memory.
*
* However, for each of FFmpeg's applications of memory, there might not be a
* recognized or standardized API for that specific use. Memory alignment, for
* instance, varies wildly depending on operating systems, architectures, and
* compilers. Hence, this component of @ref libavutil is created to make
* dealing with memory consistently possible on all platforms.
*
* @{
*
* @defgroup lavu_mem_macros Alignment Macros
* Helper macros for declaring aligned variables.
* @{
*/

/**
* @def DECLARE_ALIGNED(n,t,v)
* Declare a variable that is aligned in memory.
*
* @code{.c}
* DECLARE_ALIGNED(16, uint16_t, aligned_int) = 42;
* DECLARE_ALIGNED(32, uint8_t, aligned_array)[128];
*
* // The default-alignment equivalent would be
* uint16_t aligned_int = 42;
* uint8_t aligned_array[128];
* @endcode
*
* @param n Minimum alignment in bytes
* @param t Type of the variable (or array element)
* @param v Name of the variable
*/

/**
* @def DECLARE_ASM_CONST(n,t,v)
* Declare a static constant aligned variable appropriate for use in inline
* assembly code.
*
* @code{.c}
* DECLARE_ASM_CONST(16, uint64_t, pw_08) = UINT64_C(0x0008000800080008);
* @endcode
*
* @param n Minimum alignment in bytes
* @param t Type of the variable (or array element)
* @param v Name of the variable
*/

#if defined(__INTEL_COMPILER) && __INTEL_COMPILER < 1110 || defined(__SUNPRO_C)
#define DECLARE_ALIGNED(n,t,v) t __attribute__ ((aligned (n))) v
@@ -60,12 +108,47 @@
#define DECLARE_ASM_CONST(n,t,v) static const t v
#endif

/**
* @}
*/

/**
* @defgroup lavu_mem_attrs Function Attributes
* Function attributes applicable to memory handling functions.
*
* These function attributes can help compilers emit more useful warnings, or
* generate better code.
* @{
*/

/**
* @def av_malloc_attrib
* Function attribute denoting a malloc-like function.
*
* @see <a href="https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-g_t_0040code_007bmalloc_007d-function-attribute-3251">Function attribute `malloc` in GCC's documentation</a>
*/

#if AV_GCC_VERSION_AT_LEAST(3,1)
#define av_malloc_attrib __attribute__((__malloc__))
#else
#define av_malloc_attrib
#endif

/**
* @def av_alloc_size(...)
* Function attribute used on a function that allocates memory, whose size is
* given by the specified parameter(s).
*
* @code{.c}
* void *av_malloc(size_t size) av_alloc_size(1);
* void *av_calloc(size_t nmemb, size_t size) av_alloc_size(1, 2);
* @endcode
*
* @param ... One or two parameter indexes, separated by a comma
*
* @see <a href="https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-g_t_0040code_007balloc_005fsize_007d-function-attribute-3220">Function attribute `alloc_size` in GCC's documentation</a>
*/

#if AV_GCC_VERSION_AT_LEAST(4,3)
#define av_alloc_size(...) __attribute__((alloc_size(__VA_ARGS__)))
#else
@@ -73,31 +156,51 @@
#endif

/**
* Allocate a block of size bytes with alignment suitable for all
* memory accesses (including vectors if available on the CPU).
* @param size Size in bytes for the memory block to be allocated.
* @return Pointer to the allocated block, NULL if the block cannot
* be allocated.
* @}
*/

/**
* @defgroup lavu_mem_funcs Heap Management
* Functions responsible for allocating, freeing, and copying memory.
*
* All memory allocation functions have a built-in upper limit of `INT_MAX`
* bytes. This may be changed with av_max_alloc(), although exercise extreme
* caution when doing so.
*
* @{
*/

/**
* Allocate a memory block with alignment suitable for all memory accesses
* (including vectors if available on the CPU).
*
* @param size Size in bytes for the memory block to be allocated
* @return Pointer to the allocated block, or `NULL` if the block cannot
* be allocated
* @see av_mallocz()
*/
void *av_malloc(size_t size) av_malloc_attrib av_alloc_size(1);

/**
* Allocate a block of size bytes with alignment suitable for all
* memory accesses (including vectors if available on the CPU) and
* zero all the bytes of the block.
* @param size Size in bytes for the memory block to be allocated.
* @return Pointer to the allocated block, NULL if it cannot be allocated.
* Allocate a memory block with alignment suitable for all memory accesses
* (including vectors if available on the CPU) and zero all the bytes of the
* block.
*
* @param size Size in bytes for the memory block to be allocated
* @return Pointer to the allocated block, or `NULL` if it cannot be allocated
* @see av_malloc()
*/
void *av_mallocz(size_t size) av_malloc_attrib av_alloc_size(1);

/**
* Allocate a block of size * nmemb bytes with av_malloc().
* @param nmemb Number of elements
* @param size Size of the single element
* @return Pointer to the allocated block, NULL if the block cannot
* be allocated.
* Allocate a memory block for an array with av_malloc().
*
* The allocated memory will have size `size * nmemb` bytes.
*
* @param nmemb Number of element
* @param size Size of a single element
* @return Pointer to the allocated block, or `NULL` if the block cannot
* be allocated
* @see av_malloc()
*/
av_alloc_size(1, 2) static inline void *av_malloc_array(size_t nmemb, size_t size)
@@ -108,11 +211,15 @@ av_alloc_size(1, 2) static inline void *av_malloc_array(size_t nmemb, size_t siz
}

/**
* Allocate a block of size * nmemb bytes with av_mallocz().
* Allocate a memory block for an array with av_mallocz().
*
* The allocated memory will have size `size * nmemb` bytes.
*
* @param nmemb Number of elements
* @param size Size of the single element
* @return Pointer to the allocated block, NULL if the block cannot
* be allocated.
* @param size Size of the single element
* @return Pointer to the allocated block, or `NULL` if the block cannot
* be allocated
*
* @see av_mallocz()
* @see av_malloc_array()
*/
@@ -124,200 +231,382 @@ av_alloc_size(1, 2) static inline void *av_mallocz_array(size_t nmemb, size_t si
}

/**
* Allocate a block of nmemb * size bytes with alignment suitable for all
* memory accesses (including vectors if available on the CPU) and
* zero all the bytes of the block.
* The allocation will fail if nmemb * size is greater than or equal
* to INT_MAX.
* @param nmemb
* @param size
* @return Pointer to the allocated block, NULL if it cannot be allocated.
* Non-inlined equivalent of av_mallocz_array().
*
* Created for symmetry with the calloc() C function.
*/
void *av_calloc(size_t nmemb, size_t size) av_malloc_attrib;

/**
* Allocate or reallocate a block of memory.
* If ptr is NULL and size > 0, allocate a new block. If
* size is zero, free the memory block pointed to by ptr.
* @param ptr Pointer to a memory block already allocated with
* av_realloc() or NULL.
* Allocate, reallocate, or free a block of memory.
*
* If `ptr` is `NULL` and `size` > 0, allocate a new block. If `size` is
* zero, free the memory block pointed to by `ptr`. Otherwise, expand or
* shrink that block of memory according to `size`.
*
* @param ptr Pointer to a memory block already allocated with
* av_realloc() or `NULL`
* @param size Size in bytes of the memory block to be allocated or
* reallocated.
* @return Pointer to a newly-reallocated block or NULL if the block
* cannot be reallocated or the function is used to free the memory block.
* reallocated
*
* @return Pointer to a newly-reallocated block or `NULL` if the block
* cannot be reallocated or the function is used to free the memory block
*
* @warning Pointers originating from the av_malloc() family of functions must
* not be passed to av_realloc(). The former can be implemented using
* memalign() (or other functions), and there is no guarantee that
* pointers from such functions can be passed to realloc() at all.
* The situation is undefined according to POSIX and may crash with
* some libc implementations.
* @warning Unlike av_malloc(), the returned pointer is not guaranteed to be
* correctly aligned.
* @see av_fast_realloc()
* @see av_reallocp()
*/
void *av_realloc(void *ptr, size_t size) av_alloc_size(2);

/**
* Allocate or reallocate a block of memory.
* If *ptr is NULL and size > 0, allocate a new block. If
* size is zero, free the memory block pointed to by ptr.
* @param ptr Pointer to a pointer to a memory block already allocated
* with av_realloc(), or pointer to a pointer to NULL.
* The pointer is updated on success, or freed on failure.
* @param size Size in bytes for the memory block to be allocated or
* reallocated
* @return Zero on success, an AVERROR error code on failure.
* Allocate, reallocate, or free a block of memory through a pointer to a
* pointer.
*
* If `*ptr` is `NULL` and `size` > 0, allocate a new block. If `size` is
* zero, free the memory block pointed to by `*ptr`. Otherwise, expand or
* shrink that block of memory according to `size`.
*
* @param[in,out] ptr Pointer to a pointer to a memory block already allocated
* with av_realloc(), or a pointer to `NULL`. The pointer
* is updated on success, or freed on failure.
* @param[in] size Size in bytes for the memory block to be allocated or
* reallocated
*
* @return Zero on success, an AVERROR error code on failure
*
* @warning Pointers originating from the av_malloc() family of functions must
* not be passed to av_reallocp(). The former can be implemented using
* memalign() (or other functions), and there is no guarantee that
* pointers from such functions can be passed to realloc() at all.
* The situation is undefined according to POSIX and may crash with
* some libc implementations.
* @warning Unlike av_malloc(), the allocated memory is not guaranteed to be
* correctly aligned.
*/
av_warn_unused_result
int av_reallocp(void *ptr, size_t size);

/**
* Allocate or reallocate a block of memory.
* This function does the same thing as av_realloc, except:
* - It takes two arguments and checks the result of the multiplication for
* integer overflow.
* Allocate, reallocate, or free a block of memory.
*
* This function does the same thing as av_realloc(), except:
* - It takes two size arguments and allocates `nelem * elsize` bytes,
* after checking the result of the multiplication for integer overflow.
* - It frees the input block in case of failure, thus avoiding the memory
* leak with the classic "buf = realloc(buf); if (!buf) return -1;".
* leak with the classic
* @code{.c}
* buf = realloc(buf);
* if (!buf)
* return -1;
* @endcode
* pattern.
*/
void *av_realloc_f(void *ptr, size_t nelem, size_t elsize);

/**
* Allocate or reallocate an array.
* If ptr is NULL and nmemb > 0, allocate a new block. If
* nmemb is zero, free the memory block pointed to by ptr.
* @param ptr Pointer to a memory block already allocated with
* av_realloc() or NULL.
* @param nmemb Number of elements
* @param size Size of the single element
* Allocate, reallocate, or free an array.
*
* If `ptr` is `NULL` and `nmemb` > 0, allocate a new block. If
* `nmemb` is zero, free the memory block pointed to by `ptr`.
*
* @param ptr Pointer to a memory block already allocated with
* av_realloc() or `NULL`
* @param nmemb Number of elements in the array
* @param size Size of the single element of the array
*
* @return Pointer to a newly-reallocated block or NULL if the block
* cannot be reallocated or the function is used to free the memory block.
* cannot be reallocated or the function is used to free the memory block
*
* @warning Pointers originating from the av_malloc() family of functions must
* not be passed to av_realloc(). The former can be implemented using
* memalign() (or other functions), and there is no guarantee that
* pointers from such functions can be passed to realloc() at all.
* The situation is undefined according to POSIX and may crash with
* some libc implementations.
* @warning Unlike av_malloc(), the allocated memory is not guaranteed to be
* correctly aligned.
* @see av_reallocp_array()
*/
av_alloc_size(2, 3) void *av_realloc_array(void *ptr, size_t nmemb, size_t size);

/**
* Allocate or reallocate an array through a pointer to a pointer.
* If *ptr is NULL and nmemb > 0, allocate a new block. If
* nmemb is zero, free the memory block pointed to by ptr.
* @param ptr Pointer to a pointer to a memory block already allocated
* with av_realloc(), or pointer to a pointer to NULL.
* The pointer is updated on success, or freed on failure.
* @param nmemb Number of elements
* @param size Size of the single element
* @return Zero on success, an AVERROR error code on failure.
* Allocate, reallocate, or free an array through a pointer to a pointer.
*
* If `*ptr` is `NULL` and `nmemb` > 0, allocate a new block. If `nmemb` is
* zero, free the memory block pointed to by `*ptr`.
*
* @param[in,out] ptr Pointer to a pointer to a memory block already
* allocated with av_realloc(), or a pointer to `NULL`.
* The pointer is updated on success, or freed on failure.
* @param[in] nmemb Number of elements
* @param[in] size Size of the single element
*
* @return Zero on success, an AVERROR error code on failure
*
* @warning Pointers originating from the av_malloc() family of functions must
* not be passed to av_realloc(). The former can be implemented using
* memalign() (or other functions), and there is no guarantee that
* pointers from such functions can be passed to realloc() at all.
* The situation is undefined according to POSIX and may crash with
* some libc implementations.
* @warning Unlike av_malloc(), the allocated memory is not guaranteed to be
* correctly aligned.
*/
av_alloc_size(2, 3) int av_reallocp_array(void *ptr, size_t nmemb, size_t size);

/**
* Reallocate the given block if it is not large enough, otherwise do nothing.
* Reallocate the given buffer if it is not large enough, otherwise do nothing.
*
* If the given buffer is `NULL`, then a new uninitialized buffer is allocated.
*
* If the given buffer is not large enough, and reallocation fails, `NULL` is
* returned and `*size` is set to 0, but the original buffer is not changed or
* freed.
*
* A typical use pattern follows:
*
* @code{.c}
* uint8_t *buf = ...;
* uint8_t *new_buf = av_fast_realloc(buf, &current_size, size_needed);
* if (!new_buf) {
* // Allocation failed; clean up original buffer
* av_freep(&buf);
* return AVERROR(ENOMEM);
* }
* @endcode
*
* @see av_realloc
* @param[in,out] ptr Already allocated buffer, or `NULL`
* @param[in,out] size Pointer to current size of buffer `ptr`. `*size` is
* changed to `min_size` in case of success or 0 in
* case of failure
* @param[in] min_size New size of buffer `ptr`
* @return `ptr` if the buffer is large enough, a pointer to newly reallocated
* buffer if the buffer was not large enough, or `NULL` in case of
* error
* @see av_realloc()
* @see av_fast_malloc()
*/
void *av_fast_realloc(void *ptr, unsigned int *size, size_t min_size);

/**
* Allocate a buffer, reusing the given one if large enough.
*
* Contrary to av_fast_realloc the current buffer contents might not be
* preserved and on error the old buffer is freed, thus no special
* handling to avoid memleaks is necessary.
* Contrary to av_fast_realloc(), the current buffer contents might not be
* preserved and on error the old buffer is freed, thus no special handling to
* avoid memleaks is necessary.
*
* @param ptr pointer to pointer to already allocated buffer, overwritten with pointer to new buffer
* @param size size of the buffer *ptr points to
* @param min_size minimum size of *ptr buffer after returning, *ptr will be NULL and
* *size 0 if an error occurred.
* `*ptr` is allowed to be `NULL`, in which case allocation always happens if
* `size_needed` is greater than 0.
*
* @code{.c}
* uint8_t *buf = ...;
* av_fast_malloc(&buf, &current_size, size_needed);
* if (!buf) {
* // Allocation failed; buf already freed
* return AVERROR(ENOMEM);
* }
* @endcode
*
* @param[in,out] ptr Pointer to pointer to an already allocated buffer.
* `*ptr` will be overwritten with pointer to new
* buffer on success or `NULL` on failure
* @param[in,out] size Pointer to current size of buffer `*ptr`. `*size` is
* changed to `min_size` in case of success or 0 in
* case of failure
* @param[in] min_size New size of buffer `*ptr`
* @see av_realloc()
* @see av_fast_mallocz()
*/
void av_fast_malloc(void *ptr, unsigned int *size, size_t min_size);

/**
* Allocate a buffer, reusing the given one if large enough.
* Allocate and clear a buffer, reusing the given one if large enough.
*
* Like av_fast_malloc(), but all newly allocated space is initially cleared.
* Reused buffer is not cleared.
*
* All newly allocated space is initially cleared
* Contrary to av_fast_realloc the current buffer contents might not be
* preserved and on error the old buffer is freed, thus no special
* handling to avoid memleaks is necessary.
* `*ptr` is allowed to be `NULL`, in which case allocation always happens if
* `size_needed` is greater than 0.
*
* @param ptr pointer to pointer to already allocated buffer, overwritten with pointer to new buffer
* @param size size of the buffer *ptr points to
* @param min_size minimum size of *ptr buffer after returning, *ptr will be NULL and
* *size 0 if an error occurred.
* @param[in,out] ptr Pointer to pointer to an already allocated buffer.
* `*ptr` will be overwritten with pointer to new
* buffer on success or `NULL` on failure
* @param[in,out] size Pointer to current size of buffer `*ptr`. `*size` is
* changed to `min_size` in case of success or 0 in
* case of failure
* @param[in] min_size New size of buffer `*ptr`
* @see av_fast_malloc()
*/
void av_fast_mallocz(void *ptr, unsigned int *size, size_t min_size);

/**
* Free a memory block which has been allocated with av_malloc(z)() or
* av_realloc().
* Free a memory block which has been allocated with a function of av_malloc()
* or av_realloc() family.
*
* @param ptr Pointer to the memory block which should be freed.
* @note ptr = NULL is explicitly allowed.
* @note It is recommended that you use av_freep() instead.
*
* @note `ptr = NULL` is explicitly allowed.
* @note It is recommended that you use av_freep() instead, to prevent leaving
* behind dangling pointers.
* @see av_freep()
*/
void av_free(void *ptr);

/**
* Free a memory block which has been allocated with av_malloc(z)() or
* av_realloc() and set the pointer pointing to it to NULL.
* @param ptr Pointer to the pointer to the memory block which should
* be freed.
* @note passing a pointer to a NULL pointer is safe and leads to no action.
* Free a memory block which has been allocated with a function of av_malloc()
* or av_realloc() family, and set the pointer pointing to it to `NULL`.
*
* @code{.c}
* uint8_t *buf = av_malloc(16);
* av_free(buf);
* // buf now contains a dangling pointer to freed memory, and accidental
* // dereference of buf will result in a use-after-free, which may be a
* // security risk.
*
* uint8_t *buf = av_malloc(16);
* av_freep(&buf);
* // buf is now NULL, and accidental dereference will only result in a
* // NULL-pointer dereference.
* @endcode
*
* @param ptr Pointer to the pointer to the memory block which should be freed
* @note `*ptr = NULL` is safe and leads to no action.
* @see av_free()
*/
void av_freep(void *ptr);

/**
* Duplicate the string s.
* @param s string to be duplicated
* Duplicate a string.
*
* @param s String to be duplicated
* @return Pointer to a newly-allocated string containing a
* copy of s or NULL if the string cannot be allocated.
* copy of `s` or `NULL` if the string cannot be allocated
* @see av_strndup()
*/
char *av_strdup(const char *s) av_malloc_attrib;

/**
* Duplicate a substring of the string s.
* @param s string to be duplicated
* @param len the maximum length of the resulting string (not counting the
* terminating byte).
* Duplicate a substring of a string.
*
* @param s String to be duplicated
* @param len Maximum length of the resulting string (not counting the
* terminating byte)
* @return Pointer to a newly-allocated string containing a
* copy of s or NULL if the string cannot be allocated.
* substring of `s` or `NULL` if the string cannot be allocated
*/
char *av_strndup(const char *s, size_t len) av_malloc_attrib;

/**
* Duplicate the buffer p.
* @param p buffer to be duplicated
* Duplicate a buffer with av_malloc().
*
* @param p Buffer to be duplicated
* @param size Size in bytes of the buffer copied
* @return Pointer to a newly allocated buffer containing a
* copy of p or NULL if the buffer cannot be allocated.
* copy of `p` or `NULL` if the buffer cannot be allocated
*/
void *av_memdup(const void *p, size_t size);

/**
* deliberately overlapping memcpy implementation
* @param dst destination buffer
* @param back how many bytes back we start (the initial size of the overlapping window), must be > 0
* @param cnt number of bytes to copy, must be >= 0
* Overlapping memcpy() implementation.
*
* @param dst Destination buffer
* @param back Number of bytes back to start copying (i.e. the initial size of
* the overlapping window); must be > 0
* @param cnt Number of bytes to copy; must be >= 0
*
* cnt > back is valid, this will copy the bytes we just copied,
* thus creating a repeating pattern with a period length of back.
* @note `cnt > back` is valid, this will copy the bytes we just copied,
* thus creating a repeating pattern with a period length of `back`.
*/
void av_memcpy_backptr(uint8_t *dst, int back, int cnt);

/**
* Add an element to a dynamic array.
* @}
*/

/**
* @defgroup lavu_mem_dynarray Dynamic Array
*
* Utilities to make an array grow when needed.
*
* Sometimes, the programmer would want to have an array that can grow when
* needed. The libavutil dynamic array utilities fill that need.
*
* libavutil supports two systems of appending elements onto a dynamically
* allocated array, the first one storing the pointer to the value in the
* array, and the second storing the value directly. In both systems, the
* caller is responsible for maintaining a variable containing the length of
* the array, as well as freeing of the array after use.
*
* The first system stores pointers to values in a block of dynamically
* allocated memory. Since only pointers are stored, the function does not need
* to know the size of the type. Both av_dynarray_add() and
* av_dynarray_add_nofree() implement this system.
*
* @code
* type **array = NULL; //< an array of pointers to values
* int nb = 0; //< a variable to keep track of the length of the array
*
* type to_be_added = ...;
* type to_be_added2 = ...;
*
* av_dynarray_add(&array, &nb, &to_be_added);
* if (nb == 0)
* return AVERROR(ENOMEM);
*
* av_dynarray_add(&array, &nb, &to_be_added2);
* if (nb == 0)
* return AVERROR(ENOMEM);
*
* // Now:
* // nb == 2
* // &to_be_added == array[0]
* // &to_be_added2 == array[1]
*
* av_freep(&array);
* @endcode
*
* The second system stores the value directly in a block of memory. As a
* result, the function has to know the size of the type. av_dynarray2_add()
* implements this mechanism.
*
* @code
* type *array = NULL; //< an array of values
* int nb = 0; //< a variable to keep track of the length of the array
*
* type to_be_added = ...;
* type to_be_added2 = ...;
*
* type *addr = av_dynarray2_add((void **)&array, &nb, sizeof(*array), NULL);
* if (!addr)
* return AVERROR(ENOMEM);
* memcpy(addr, &to_be_added, sizeof(to_be_added));
*
* // Shortcut of the above.
* type *addr = av_dynarray2_add((void **)&array, &nb, sizeof(*array),
* (const void *)&to_be_added2);
* if (!addr)
* return AVERROR(ENOMEM);
*
* // Now:
* // nb == 2
* // to_be_added == array[0]
* // to_be_added2 == array[1]
*
* av_freep(&array);
* @endcode
*
* @{
*/

/**
* Add the pointer to an element to a dynamic array.
*
* The array to grow is supposed to be an array of pointers to
* structures, and the element to add must be a pointer to an already
@@ -327,14 +616,14 @@ void av_memcpy_backptr(uint8_t *dst, int back, int cnt);
* Therefore, the amortized cost of adding an element is constant.
*
* In case of success, the pointer to the array is updated in order to
* point to the new grown array, and the number pointed to by nb_ptr
* point to the new grown array, and the number pointed to by `nb_ptr`
* is incremented.
* In case of failure, the array is freed, *tab_ptr is set to NULL and
* *nb_ptr is set to 0.
* In case of failure, the array is freed, `*tab_ptr` is set to `NULL` and
* `*nb_ptr` is set to 0.
*
* @param tab_ptr pointer to the array to grow
* @param nb_ptr pointer to the number of elements in the array
* @param elem element to add
* @param[in,out] tab_ptr Pointer to the array to grow
* @param[in,out] nb_ptr Pointer to the number of elements in the array
* @param[in] elem Element to add
* @see av_dynarray_add_nofree(), av_dynarray2_add()
*/
void av_dynarray_add(void *tab_ptr, int *nb_ptr, void *elem);
@@ -346,42 +635,56 @@ void av_dynarray_add(void *tab_ptr, int *nb_ptr, void *elem);
* but it doesn't free memory on fails. It returns error code
* instead and leave current buffer untouched.
*
* @param tab_ptr pointer to the array to grow
* @param nb_ptr pointer to the number of elements in the array
* @param elem element to add
* @return >=0 on success, negative otherwise.
* @return >=0 on success, negative otherwise
* @see av_dynarray_add(), av_dynarray2_add()
*/
av_warn_unused_result
int av_dynarray_add_nofree(void *tab_ptr, int *nb_ptr, void *elem);

/**
* Add an element of size elem_size to a dynamic array.
* Add an element of size `elem_size` to a dynamic array.
*
* The array is reallocated when its number of elements reaches powers of 2.
* Therefore, the amortized cost of adding an element is constant.
*
* In case of success, the pointer to the array is updated in order to
* point to the new grown array, and the number pointed to by nb_ptr
* point to the new grown array, and the number pointed to by `nb_ptr`
* is incremented.
* In case of failure, the array is freed, *tab_ptr is set to NULL and
* *nb_ptr is set to 0.
*
* @param tab_ptr pointer to the array to grow
* @param nb_ptr pointer to the number of elements in the array
* @param elem_size size in bytes of the elements in the array
* @param elem_data pointer to the data of the element to add. If NULL, the space of
* the new added element is not filled.
* @return pointer to the data of the element to copy in the new allocated space.
* If NULL, the new allocated space is left uninitialized."
* In case of failure, the array is freed, `*tab_ptr` is set to `NULL` and
* `*nb_ptr` is set to 0.
*
* @param[in,out] tab_ptr Pointer to the array to grow
* @param[in,out] nb_ptr Pointer to the number of elements in the array
* @param[in] elem_size Size in bytes of an element in the array
* @param[in] elem_data Pointer to the data of the element to add. If
* `NULL`, the space of the newly added element is
* allocated but left uninitialized.
*
* @return Pointer to the data of the element to copy in the newly allocated
* space
* @see av_dynarray_add(), av_dynarray_add_nofree()
*/
void *av_dynarray2_add(void **tab_ptr, int *nb_ptr, size_t elem_size,
const uint8_t *elem_data);

/**
* Multiply two size_t values checking for overflow.
* @return 0 if success, AVERROR(EINVAL) if overflow.
* @}
*/

/**
* @defgroup lavu_mem_misc Miscellaneous Functions
*
* Other functions related to memory allocation.
*
* @{
*/

/**
* Multiply two `size_t` values checking for overflow.
*
* @param[in] a,b Operands of multiplication
* @param[out] r Pointer to the result of the operation
* @return 0 on success, AVERROR(EINVAL) on overflow
*/
static inline int av_size_mult(size_t a, size_t b, size_t *r)
{
@@ -395,11 +698,22 @@ static inline int av_size_mult(size_t a, size_t b, size_t *r)
}

/**
* Set the maximum size that may me allocated in one block.
* Set the maximum size that may be allocated in one block.
*
* The value specified with this function is effective for all libavutil's @ref
* lavu_mem_funcs "heap management functions."
*
* By default, the max value is defined as `INT_MAX`.
*
* @param max Value to be set as the new maximum size
*
* @warning Exercise extreme caution when using this function. Don't touch
* this if you do not understand the full consequence of doing so.
*/
void av_max_alloc(size_t max);

/**
* @}
* @}
*/



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