lavu/mem: add av_dynarray2_add()

Based on a patch by Clément Bœsch.

See thread:
From: Clément Bœsch <ubitux@gmail.com>
Subject: [FFmpeg-devel] [PATCH 1/5] lavu: add av_dynarray_alloc_elem().
Date: Sun, 14 Apr 2013 03:07:54 +0200

1 files changed, 25 insertions, 0 deletions

diff --git a/libavutil/mem.h b/libavutil/mem.h
index 8433ada1e8..a3294690cf 100644
--- a/libavutil/mem.h
+++ b/libavutil/mem.h
@@ -215,10 +215,35 @@ void av_freep(void *ptr);
  * @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
+ * @see av_dynarray2_add()
  */
 void av_dynarray_add(void *tab_ptr, int *nb_ptr, void *elem);
 
 /**
+ * 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
+ * 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."
+ * @see av_dynarray_add()
+ */
+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.
  */