[libav-devel] [PATCH] bitstream: Add bitstream_apply_sign() helper function

[Diego Biurrun]

This reads a sign bit from the bitstream and flips the sign of the
provided value accordingly.
---

.. as suggested by Anton ..

 libavcodec/bitstream.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/libavcodec/bitstream.h b/libavcodec/bitstream.h
index 539b721..180bf66 100644
--- a/libavcodec/bitstream.h
+++ b/libavcodec/bitstream.h
@@ -377,4 +377,11 @@ static inline int bitstream_decode210(BitstreamContext *bc)
         return 2 - bitstream_read_bit(bc);
 }
 
+/* Read sign bit and flip the sign of the provided value accordingly. */
+static inline int bitstream_apply_sign(BitstreamContext *bc, int val)
+{
+    int sign = bitstream_read_signed(bc, 1);
+    return (val ^ sign) - sign;
+}
+
 #endif /* AVCODEC_BITSTREAM_H */
-- 
2.7.3