From daf1e0d3de03bd424016e2a7520e4e94ece5c0ac Mon Sep 17 00:00:00 2001
From: Ben Avison <bavison@riscosopen.org>
Date: Wed, 31 Jul 2013 23:46:08 +0100
Subject: [PATCH] avio: Add an internal function for reading without copying
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As long as there is enough contiguous data in the avio buffer,
just return a pointer to it instead of copying it to the caller
provided buffer.
Signed-off-by: Martin Storsjö <martin@martin.st>
---
libavformat/avio_internal.h | 17 +++++++++++++++++
libavformat/aviobuf.c | 12 ++++++++++++
2 files changed, 29 insertions(+)
diff --git a/libavformat/avio_internal.h b/libavformat/avio_internal.h
index 3da2fc84224..4fa3adb2706 100644
--- a/libavformat/avio_internal.h
+++ b/libavformat/avio_internal.h
@@ -37,6 +37,23 @@ int ffio_init_context(AVIOContext *s,
int64_t (*seek)(void *opaque, int64_t offset, int whence));
+/**
+ * Read size bytes from AVIOContext, returning a pointer.
+ * Note that the data pointed at by the returned pointer is only
+ * valid until the next call that references the same IO context.
+ * @param s IO context
+ * @param buf pointer to buffer into which to assemble the requested
+ * data if it is not available in contiguous addresses in the
+ * underlying buffer
+ * @param size number of bytes requested
+ * @param data address at which to store pointer: this will be a
+ * a direct pointer into the underlying buffer if the requested
+ * number of bytes are available at contiguous addresses, otherwise
+ * will be a copy of buf
+ * @return number of bytes read or AVERROR
+ */
+int ffio_read_indirect(AVIOContext *s, unsigned char *buf, int size, unsigned char **data);
+
/**
* Read size bytes from AVIOContext into buf.
* This reads at most 1 packet. If that is not enough fewer bytes will be
diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
index bc89768ef60..07aa88068f1 100644
--- a/libavformat/aviobuf.c
+++ b/libavformat/aviobuf.c
@@ -490,6 +490,18 @@ int avio_read(AVIOContext *s, unsigned char *buf, int size)
return size1 - size;
}
+int ffio_read_indirect(AVIOContext *s, unsigned char *buf, int size, unsigned char **data)
+{
+ if (s->buf_end - s->buf_ptr >= size && !s->write_flag) {
+ *data = s->buf_ptr;
+ s->buf_ptr += size;
+ return size;
+ } else {
+ *data = buf;
+ return avio_read(s, buf, size);
+ }
+}
+
int ffio_read_partial(AVIOContext *s, unsigned char *buf, int size)
{
int len;
--
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