--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/libavutil/fifo.h	Tue Dec 31 14:52:14 2013 +0000
@@ -0,0 +1,144 @@
+/*
+ * 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
+ * a very simple circular buffer FIFO implementation
+ */
+
+#ifndef AVUTIL_FIFO_H
+#define AVUTIL_FIFO_H
+
+#include <stdint.h>
+#include "avutil.h"
+#include "attributes.h"
+
+typedef struct AVFifoBuffer {
+    uint8_t *buffer;
+    uint8_t *rptr, *wptr, *end;
+    uint32_t rndx, wndx;
+} AVFifoBuffer;
+
+/**
+ * Initialize an AVFifoBuffer.
+ * @param size of FIFO
+ * @return AVFifoBuffer or NULL in case of memory allocation failure
+ */
+AVFifoBuffer *av_fifo_alloc(unsigned int size);
+
+/**
+ * Free an AVFifoBuffer.
+ * @param f AVFifoBuffer to free
+ */
+void av_fifo_free(AVFifoBuffer *f);
+
+/**
+ * Reset the AVFifoBuffer to the state right after av_fifo_alloc, in particular it is emptied.
+ * @param f AVFifoBuffer to reset
+ */
+void av_fifo_reset(AVFifoBuffer *f);
+
+/**
+ * Return the amount of data in bytes in the AVFifoBuffer, that is the
+ * amount of data you can read from it.
+ * @param f AVFifoBuffer to read from
+ * @return size
+ */
+int av_fifo_size(AVFifoBuffer *f);
+
+/**
+ * Return the amount of space in bytes in the AVFifoBuffer, that is the
+ * amount of data you can write into it.
+ * @param f AVFifoBuffer to write into
+ * @return size
+ */
+int av_fifo_space(AVFifoBuffer *f);
+
+/**
+ * Feed data from an AVFifoBuffer to a user-supplied callback.
+ * @param f AVFifoBuffer to read from
+ * @param buf_size number of bytes to read
+ * @param func generic read function
+ * @param dest data destination
+ */
+int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int));
+
+/**
+ * Feed data from a user-supplied callback to an AVFifoBuffer.
+ * @param f AVFifoBuffer to write to
+ * @param src data source; non-const since it may be used as a
+ * modifiable context by the function defined in func
+ * @param size number of bytes to write
+ * @param func generic write function; the first parameter is src,
+ * the second is dest_buf, the third is dest_buf_size.
+ * func must return the number of bytes written to dest_buf, or <= 0 to
+ * indicate no more data available to write.
+ * If func is NULL, src is interpreted as a simple byte array for source data.
+ * @return the number of bytes written to the FIFO
+ */
+int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void*, void*, int));
+
+/**
+ * Resize an AVFifoBuffer.
+ * In case of reallocation failure, the old FIFO is kept unchanged.
+ *
+ * @param f AVFifoBuffer to resize
+ * @param size new AVFifoBuffer size in bytes
+ * @return <0 for failure, >=0 otherwise
+ */
+int av_fifo_realloc2(AVFifoBuffer *f, unsigned int size);
+
+/**
+ * Enlarge an AVFifoBuffer.
+ * In case of reallocation failure, the old FIFO is kept unchanged.
+ * The new fifo size may be larger than the requested size.
+ *
+ * @param f AVFifoBuffer to resize
+ * @param additional_space the amount of space in bytes to allocate in addition to av_fifo_size()
+ * @return <0 for failure, >=0 otherwise
+ */
+int av_fifo_grow(AVFifoBuffer *f, unsigned int additional_space);
+
+/**
+ * Read and discard the specified amount of data from an AVFifoBuffer.
+ * @param f AVFifoBuffer to read from
+ * @param size amount of data to read in bytes
+ */
+void av_fifo_drain(AVFifoBuffer *f, int size);
+
+/**
+ * Return a pointer to the data stored in a FIFO buffer at a certain offset.
+ * The FIFO buffer is not modified.
+ *
+ * @param f    AVFifoBuffer to peek at, f must be non-NULL
+ * @param offs an offset in bytes, its absolute value must be less
+ *             than the used buffer size or the returned pointer will
+ *             point outside to the buffer data.
+ *             The used buffer size can be checked with av_fifo_size().
+ */
+static inline uint8_t *av_fifo_peek2(const AVFifoBuffer *f, int offs)
+{
+    uint8_t *ptr = f->rptr + offs;
+    if (ptr >= f->end)
+        ptr = f->buffer + (ptr - f->end);
+    else if (ptr < f->buffer)
+        ptr = f->end - (f->buffer - ptr);
+    return ptr;
+}
+
+#endif /* AVUTIL_FIFO_H */