--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/libavutil/buffer.h	Tue Dec 31 14:52:14 2013 +0000
@@ -0,0 +1,274 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * @ingroup lavu_buffer
+ * refcounted data buffer API
+ */
+
+#ifndef AVUTIL_BUFFER_H
+#define AVUTIL_BUFFER_H
+
+#include <stdint.h>
+
+/**
+ * @defgroup lavu_buffer AVBuffer
+ * @ingroup lavu_data
+ *
+ * @{
+ * AVBuffer is an API for reference-counted data buffers.
+ *
+ * There are two core objects in this API -- AVBuffer and AVBufferRef. AVBuffer
+ * represents the data buffer itself; it is opaque and not meant to be accessed
+ * by the caller directly, but only through AVBufferRef. However, the caller may
+ * e.g. compare two AVBuffer pointers to check whether two different references
+ * are describing the same data buffer. AVBufferRef represents a single
+ * reference to an AVBuffer and it is the object that may be manipulated by the
+ * caller directly.
+ *
+ * There are two functions provided for creating a new AVBuffer with a single
+ * reference -- av_buffer_alloc() to just allocate a new buffer, and
+ * av_buffer_create() to wrap an existing array in an AVBuffer. From an existing
+ * reference, additional references may be created with av_buffer_ref().
+ * Use av_buffer_unref() to free a reference (this will automatically free the
+ * data once all the references are freed).
+ *
+ * The convention throughout this API and the rest of FFmpeg is such that the
+ * buffer is considered writable if there exists only one reference to it (and
+ * it has not been marked as read-only). The av_buffer_is_writable() function is
+ * provided to check whether this is true and av_buffer_make_writable() will
+ * automatically create a new writable buffer when necessary.
+ * Of course nothing prevents the calling code from violating this convention,
+ * however that is safe only when all the existing references are under its
+ * control.
+ *
+ * @note Referencing and unreferencing the buffers is thread-safe and thus
+ * may be done from multiple threads simultaneously without any need for
+ * additional locking.
+ *
+ * @note Two different references to the same buffer can point to different
+ * parts of the buffer (i.e. their AVBufferRef.data will not be equal).
+ */
+
+/**
+ * A reference counted buffer type. It is opaque and is meant to be used through
+ * references (AVBufferRef).
+ */
+typedef struct AVBuffer AVBuffer;
+
+/**
+ * A reference to a data buffer.
+ *
+ * The size of this struct is not a part of the public ABI and it is not meant
+ * to be allocated directly.
+ */
+typedef struct AVBufferRef {
+    AVBuffer *buffer;
+
+    /**
+     * The data buffer. It is considered writable if and only if
+     * this is the only reference to the buffer, in which case
+     * av_buffer_is_writable() returns 1.
+     */
+    uint8_t *data;
+    /**
+     * Size of data in bytes.
+     */
+    int      size;
+} AVBufferRef;
+
+/**
+ * Allocate an AVBuffer of the given size using av_malloc().
+ *
+ * @return an AVBufferRef of given size or NULL when out of memory
+ */
+AVBufferRef *av_buffer_alloc(int size);
+
+/**
+ * Same as av_buffer_alloc(), except the returned buffer will be initialized
+ * to zero.
+ */
+AVBufferRef *av_buffer_allocz(int size);
+
+/**
+ * Always treat the buffer as read-only, even when it has only one
+ * reference.
+ */
+#define AV_BUFFER_FLAG_READONLY (1 << 0)
+
+/**
+ * Create an AVBuffer from an existing array.
+ *
+ * If this function is successful, data is owned by the AVBuffer. The caller may
+ * only access data through the returned AVBufferRef and references derived from
+ * it.
+ * If this function fails, data is left untouched.
+ * @param data   data array
+ * @param size   size of data in bytes
+ * @param free   a callback for freeing this buffer's data
+ * @param opaque parameter to be got for processing or passed to free
+ * @param flags  a combination of AV_BUFFER_FLAG_*
+ *
+ * @return an AVBufferRef referring to data on success, NULL on failure.
+ */
+AVBufferRef *av_buffer_create(uint8_t *data, int size,
+                              void (*free)(void *opaque, uint8_t *data),
+                              void *opaque, int flags);
+
+/**
+ * Default free callback, which calls av_free() on the buffer data.
+ * This function is meant to be passed to av_buffer_create(), not called
+ * directly.
+ */
+void av_buffer_default_free(void *opaque, uint8_t *data);
+
+/**
+ * Create a new reference to an AVBuffer.
+ *
+ * @return a new AVBufferRef referring to the same AVBuffer as buf or NULL on
+ * failure.
+ */
+AVBufferRef *av_buffer_ref(AVBufferRef *buf);
+
+/**
+ * Free a given reference and automatically free the buffer if there are no more
+ * references to it.
+ *
+ * @param buf the reference to be freed. The pointer is set to NULL on return.
+ */
+void av_buffer_unref(AVBufferRef **buf);
+
+/**
+ * @return 1 if the caller may write to the data referred to by buf (which is
+ * true if and only if buf is the only reference to the underlying AVBuffer).
+ * Return 0 otherwise.
+ * A positive answer is valid until av_buffer_ref() is called on buf.
+ */
+int av_buffer_is_writable(const AVBufferRef *buf);
+
+/**
+ * @return the opaque parameter set by av_buffer_create.
+ */
+void *av_buffer_get_opaque(const AVBufferRef *buf);
+
+int av_buffer_get_ref_count(const AVBufferRef *buf);
+
+/**
+ * Create a writable reference from a given buffer reference, avoiding data copy
+ * if possible.
+ *
+ * @param buf buffer reference to make writable. On success, buf is either left
+ *            untouched, or it is unreferenced and a new writable AVBufferRef is
+ *            written in its place. On failure, buf is left untouched.
+ * @return 0 on success, a negative AVERROR on failure.
+ */
+int av_buffer_make_writable(AVBufferRef **buf);
+
+/**
+ * Reallocate a given buffer.
+ *
+ * @param buf  a buffer reference to reallocate. On success, buf will be
+ *             unreferenced and a new reference with the required size will be
+ *             written in its place. On failure buf will be left untouched. *buf
+ *             may be NULL, then a new buffer is allocated.
+ * @param size required new buffer size.
+ * @return 0 on success, a negative AVERROR on failure.
+ *
+ * @note the buffer is actually reallocated with av_realloc() only if it was
+ * initially allocated through av_buffer_realloc(NULL) and there is only one
+ * reference to it (i.e. the one passed to this function). In all other cases
+ * a new buffer is allocated and the data is copied.
+ */
+int av_buffer_realloc(AVBufferRef **buf, int size);
+
+/**
+ * @}
+ */
+
+/**
+ * @defgroup lavu_bufferpool AVBufferPool
+ * @ingroup lavu_data
+ *
+ * @{
+ * AVBufferPool is an API for a lock-free thread-safe pool of AVBuffers.
+ *
+ * Frequently allocating and freeing large buffers may be slow. AVBufferPool is
+ * meant to solve this in cases when the caller needs a set of buffers of the
+ * same size (the most obvious use case being buffers for raw video or audio
+ * frames).
+ *
+ * At the beginning, the user must call av_buffer_pool_init() to create the
+ * buffer pool. Then whenever a buffer is needed, call av_buffer_pool_get() to
+ * get a reference to a new buffer, similar to av_buffer_alloc(). This new
+ * reference works in all aspects the same way as the one created by
+ * av_buffer_alloc(). However, when the last reference to this buffer is
+ * unreferenced, it is returned to the pool instead of being freed and will be
+ * reused for subsequent av_buffer_pool_get() calls.
+ *
+ * When the caller is done with the pool and no longer needs to allocate any new
+ * buffers, av_buffer_pool_uninit() must be called to mark the pool as freeable.
+ * Once all the buffers are released, it will automatically be freed.
+ *
+ * Allocating and releasing buffers with this API is thread-safe as long as
+ * either the default alloc callback is used, or the user-supplied one is
+ * thread-safe.
+ */
+
+/**
+ * The buffer pool. This structure is opaque and not meant to be accessed
+ * directly. It is allocated with av_buffer_pool_init() and freed with
+ * av_buffer_pool_uninit().
+ */
+typedef struct AVBufferPool AVBufferPool;
+
+/**
+ * Allocate and initialize a buffer pool.
+ *
+ * @param size size of each buffer in this pool
+ * @param alloc a function that will be used to allocate new buffers when the
+ * pool is empty. May be NULL, then the default allocator will be used
+ * (av_buffer_alloc()).
+ * @return newly created buffer pool on success, NULL on error.
+ */
+AVBufferPool *av_buffer_pool_init(int size, AVBufferRef* (*alloc)(int size));
+
+/**
+ * Mark the pool as being available for freeing. It will actually be freed only
+ * once all the allocated buffers associated with the pool are released. Thus it
+ * is safe to call this function while some of the allocated buffers are still
+ * in use.
+ *
+ * @param pool pointer to the pool to be freed. It will be set to NULL.
+ * @see av_buffer_pool_can_uninit()
+ */
+void av_buffer_pool_uninit(AVBufferPool **pool);
+
+/**
+ * Allocate a new AVBuffer, reusing an old buffer from the pool when available.
+ * This function may be called simultaneously from multiple threads.
+ *
+ * @return a reference to the new buffer on success, NULL on error.
+ */
+AVBufferRef *av_buffer_pool_get(AVBufferPool *pool);
+
+/**
+ * @}
+ */
+
+#endif /* AVUTIL_BUFFER_H */