3 files changed, 162 insertions, 1 deletions

diff --git a/libavutil/Makefile b/libavutil/Makefile
index 5b78adc53b..045041465f 100644
--- a/libavutil/Makefile
+++ b/libavutil/Makefile
@@ -16,9 +16,10 @@ OBJS= mathematics.o \
       adler32.o \
       log.o \
       mem.o \
+      fifo.o \
 
 HEADERS = avutil.h common.h mathematics.h integer.h rational.h \
-          intfloat_readwrite.h md5.h adler32.h log.h
+          intfloat_readwrite.h md5.h adler32.h log.h fifo.h
 
 NAME=avutil
 ifeq ($(BUILD_SHARED),yes)
diff --git a/libavutil/fifo.c b/libavutil/fifo.c
new file mode 100644
index 0000000000..77461829d2
--- /dev/null
+++ b/libavutil/fifo.c
@@ -0,0 +1,135 @@
+/*
+ * A very simple circular buffer FIFO implementation
+ * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
+ * Copyright (c) 2006 Roman Shaposhnik
+ *
+ * This library 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 of the License, or (at your option) any later version.
+ *
+ * This library 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 this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+#include "common.h"
+#include "fifo.h"
+
+int av_fifo_init(AVFifoBuffer *f, int size)
+{
+    f->buffer = av_malloc(size);
+    if (!f->buffer)
+        return -1;
+    f->end = f->buffer + size;
+    f->wptr = f->rptr = f->buffer;
+    return 0;
+}
+
+void av_fifo_free(AVFifoBuffer *f)
+{
+    av_free(f->buffer);
+}
+
+int av_fifo_size(AVFifoBuffer *f)
+{
+    int size = f->wptr - f->rptr;
+    if (size < 0)
+        size += f->end - f->buffer;
+    return size;
+}
+
+/**
+ * Get data from the fifo (returns -1 if not enough data).
+ */
+int av_fifo_read(AVFifoBuffer *f, uint8_t *buf, int buf_size)
+{
+    int len;
+    int size = f->wptr - f->rptr;
+    if (size < 0)
+        size += f->end - f->buffer;
+
+    if (size < buf_size)
+        return -1;
+    while (buf_size > 0) {
+        len = FFMIN(f->end - f->rptr, buf_size);
+        memcpy(buf, f->rptr, len);
+        buf += len;
+        f->rptr += len;
+        if (f->rptr >= f->end)
+            f->rptr = f->buffer;
+        buf_size -= len;
+    }
+    return 0;
+}
+
+/**
+ * Resizes a FIFO.
+ */
+void av_fifo_realloc(AVFifoBuffer *f, unsigned int new_size) {
+    unsigned int old_size= f->end - f->buffer;
+
+    if(old_size < new_size){
+        uint8_t *old= f->buffer;
+
+        f->buffer= av_realloc(f->buffer, new_size);
+
+        f->rptr += f->buffer - old;
+        f->wptr += f->buffer - old;
+
+        if(f->wptr < f->rptr){
+            memmove(f->rptr + new_size - old_size, f->rptr, f->buffer + old_size - f->rptr);
+            f->rptr += new_size - old_size;
+        }
+        f->end= f->buffer + new_size;
+    }
+}
+
+void av_fifo_write(AVFifoBuffer *f, const uint8_t *buf, int size)
+{
+    int len;
+
+    while (size > 0) {
+        len = FFMIN(f->end - f->wptr, size);
+        memcpy(f->wptr, buf, len);
+        f->wptr += len;
+        if (f->wptr >= f->end)
+            f->wptr = f->buffer;
+        buf += len;
+        size -= len;
+    }
+}
+
+
+/* get data from the fifo (return -1 if not enough data) */
+int av_fifo_generic_read(AVFifoBuffer *f, int buf_size, void (*func)(void*, void*, int), void* dest)
+{
+    int len;
+    int size = f->wptr - f->rptr;
+    if (size < 0)
+        size += f->end - f->buffer;
+
+    if (size < buf_size)
+        return -1;
+    while (buf_size > 0) {
+        len = FFMIN(f->end - f->rptr, buf_size);
+        func(dest, f->rptr, len);
+        f->rptr += len;
+        if (f->rptr >= f->end)
+            f->rptr = f->buffer;
+        buf_size -= len;
+    }
+    return 0;
+}
+
+/* discard data from the fifo */
+void av_fifo_drain(AVFifoBuffer *f, int size)
+{
+    f->rptr += size;
+    if (f->rptr >= f->end)
+        f->rptr -= f->end - f->buffer;
+}
diff --git a/libavutil/fifo.h b/libavutil/fifo.h
new file mode 100644
index 0000000000..9dec0e62d9
--- /dev/null
+++ b/libavutil/fifo.h
@@ -0,0 +1,25 @@
+#ifndef FIFO_H
+#define FIFO_H
+
+typedef struct AVFifoBuffer {
+    uint8_t *buffer;
+    uint8_t *rptr, *wptr, *end;
+} AVFifoBuffer;
+
+int av_fifo_init(AVFifoBuffer *f, int size);
+void av_fifo_free(AVFifoBuffer *f);
+int av_fifo_size(AVFifoBuffer *f);
+int av_fifo_read(AVFifoBuffer *f, uint8_t *buf, int buf_size);
+int av_fifo_generic_read(AVFifoBuffer *f, int buf_size, void (*func)(void*, void*, int), void* dest);
+void av_fifo_write(AVFifoBuffer *f, const uint8_t *buf, int size);
+void av_fifo_realloc(AVFifoBuffer *f, unsigned int size);
+void av_fifo_drain(AVFifoBuffer *f, int size);
+
+static inline uint8_t av_fifo_peek(AVFifoBuffer *f, int offs)
+{
+    uint8_t *ptr = f->rptr + offs;
+    if (ptr >= f->end)
+        ptr -= f->end - f->buffer;
+    return *ptr;
+}
+#endif /* FIFO_H */