Same concept as av_fast_malloc(). If the buffer passed to it is writable
and big enough it will be reused, otherwise a new one will be allocated
instead.
Signed-off-by: James Almer <jamr...@gmail.com>
---
TODO: Changelog and APIChanges entries, version bump.
libavutil/buffer.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
libavutil/buffer.h | 42 ++++++++++++++++++++++++++++++++++++
2 files changed, 105 insertions(+)
diff --git a/libavutil/buffer.c b/libavutil/buffer.c
index 8d1aa5fa84..16ce1b82e2 100644
--- a/libavutil/buffer.c
+++ b/libavutil/buffer.c
@@ -215,6 +215,69 @@ int av_buffer_realloc(AVBufferRef **pbuf, int size)
return 0;
}
+static av_always_inline int buffer_fast_alloc(AVBufferRef **pbuf, int size,
int zero_alloc)
+{
+ AVBufferRef *buf = *pbuf;
+ AVBuffer *b;
+ uint8_t *data;
+
+ if (!buf || !av_buffer_is_writable(buf) || buf->data != buf->buffer->data)
{
+ /* Buffer can't be reused, and neither can the entire AVBufferRef.
+ * Unref the latter and alloc a new one. */
+ av_buffer_unref(pbuf);
+
+ buf = av_buffer_alloc(size);
+ if (!buf)
+ return AVERROR(ENOMEM);
+
+ if (zero_alloc)
+ memset(buf->data, 0, size);
+
+ *pbuf = buf;
+ return 0;
+ }
+ b = buf->buffer;
+
+ if (size <= b->size) {
+ /* Buffer can be reused. Update the size of AVBufferRef but leave the
+ * AVBuffer untouched. */
+ buf->size = FFMAX(0, size);
+ return 0;
+ }
+
+ /* Buffer can't be reused, but there's no need to alloc new AVBuffer and
+ * AVBufferRef structs. Free the existing buffer, allocate a new one, and
+ * reset AVBuffer and AVBufferRef to default values. */
+ b->free(b->opaque, b->data);
+ b->free = av_buffer_default_free;
+ b->opaque = NULL;
+ b->flags = 0;
+
+ data = av_malloc(size);
+ if (!data) {
+ av_buffer_unref(pbuf);
+ return AVERROR(ENOMEM);
+ }
+
+ if (zero_alloc)
+ memset(data, 0, size);
+
+ b->data = buf->data = data;
+ b->size = buf->size = size;
+
+ return 0;
+}
+
+int av_buffer_fast_alloc(AVBufferRef **pbuf, int size)
+{
+ return buffer_fast_alloc(pbuf, size, 0);
+}
+
+int av_buffer_fast_allocz(AVBufferRef **pbuf, int size)
+{
+ return buffer_fast_alloc(pbuf, size, 1);
+}
+
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..1166017d22 100644
--- a/libavutil/buffer.h
+++ b/libavutil/buffer.h
@@ -197,6 +197,48 @@ int av_buffer_make_writable(AVBufferRef **buf);
*/
int av_buffer_realloc(AVBufferRef **buf, int size);
+/**
+ * Allocate a buffer, reusing the given one if writable and large enough.
+ *
+ * @code{.c}
+ * AVBufferRef *buf = ...;
+ * int ret = av_buffer_fast_alloc(&buf, size);
+ * if (ret < 0) {
+ * // Allocation failed; buf already freed
+ * return ret;
+ * }
+ * @endcode
+ *
+ * @param buf A buffer reference. *buf may be NULL. On success, a new buffer
+ * reference will be written in its place. On failure, it will be
+ * unreferenced and set to NULL.
+ * @param size Required buffer size.
+ *
+ * @return 0 on success, a negative AVERROR on failure.
+ *
+ * @see av_buffer_realloc()
+ * @see av_buffer_fast_allocz()
+ */
+int av_buffer_fast_alloc(AVBufferRef **buf, int size);
+
+/**
+ * Allocate and clear a buffer, reusing the given one if writable and large
+ * enough.
+ *
+ * Like av_buffer_fast_alloc(), but all newly allocated space is initially
+ * cleared. Reused buffer is not cleared.
+ *
+ * @param buf A buffer reference. *buf may be NULL. On success, a new buffer
+ * reference will be written in its place. On failure, it will be
+ * unreferenced and set to NULL.
+ * @param size Required buffer size.
+ *
+ * @return 0 on success, a negative AVERROR on failure.
+ *
+ * @see av_buffer_fast_alloc()
+ */
+int av_buffer_fast_allocz(AVBufferRef **buf, int size);
+
/**
* @}
*/
--
2.16.2
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