A new function, avpriv_buffer_fast_alloc, is added. Its distinguishing
feature is that the content of the buffer is considered expendable
for the given reference, so that no data copying is performed.
Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@googlemail.com>
---
libavutil/buffer.c | 37 +++++++++++++++++++++++++++++++++++++
libavutil/buffer.h | 19 +++++++++++++++++++
2 files changed, 56 insertions(+)
diff --git a/libavutil/buffer.c b/libavutil/buffer.c
index 8d1aa5fa84..8303f2fc80 100644
--- a/libavutil/buffer.c
+++ b/libavutil/buffer.c
@@ -215,6 +215,43 @@ int av_buffer_realloc(AVBufferRef **pbuf, int size)
return 0;
}
+int avpriv_buffer_fast_alloc(AVBufferRef **pbuf, int min_size)
+{
+ AVBufferRef *buf = *pbuf;
+
+ if (!buf || !av_buffer_is_writable(buf)) {
+ av_buffer_unref(pbuf);
+
+ buf = av_buffer_alloc(FFMAX(min_size + (min_size >> 4) + 32,
+ min_size));
+ if (!buf)
+ return AVERROR(ENOMEM);
+
+ *pbuf = buf;
+ return 0;
+ }
+
+ if (min_size <= buf->buffer->size) {
+ buf->data = buf->buffer->data;
+ buf->size = buf->buffer->size;
+ return 0;
+ }
+
+ min_size = FFMAX(min_size + (min_size >> 4) + 32, min_size);
+ av_free(buf->buffer->data);
+ buf->buffer->data = av_malloc(min_size);
+ if (!buf->buffer->data) {
+ av_free(buf->buffer);
+ av_freep(pbuf);
+ return AVERROR(ENOMEM);
+ }
+
+ buf->data = buf->buffer->data;
+ buf->size = buf->buffer->size = min_size;
+
+ return 0;
+}
+
AVBufferPool *av_buffer_pool_init2(int size, void *opaque,
AVBufferRef* (*alloc)(void *opaque, int
size),
void (*pool_free)(void *opaque))
diff --git a/libavutil/buffer.h b/libavutil/buffer.h
index 73b6bd0b14..26715275c4 100644
--- a/libavutil/buffer.h
+++ b/libavutil/buffer.h
@@ -197,6 +197,25 @@ int av_buffer_make_writable(AVBufferRef **buf);
*/
int av_buffer_realloc(AVBufferRef **buf, int size);
+/**
+ * Create a writable buffer with given minimum size, reusing the given buffer
+ * if possible. The content of the buffer is considered expendable for the
+ * given reference and might not be preserved at all if the buffer is writable.
+ * The underlying buffer must be compatible with av_free; furthermore, only the
+ * default free callback may be used.
+ *
+ * @param buf Pointer to NULL or a pointer to a pointer to a buffer
reference.
+ * On success, **buf will be an AVBufferRef whose size is the
+ * allocated size. On failure the reference is unreferenced.
+ * If *buf is NULL, a new buffer is allocated.
+ * @param min_size Desired minimal buffer size in bytes.
+ * @return 0 on success, a negative AVERROR on failure.
+ *
+ * @note The function intentionally overallocates in order to reduce the need
+ * for future allocations.
+ */
+int avpriv_buffer_fast_alloc(AVBufferRef **buf, int min_size);
+
/**
* @}
*/
--
2.19.1
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