avcodec/put_bits: Add rebase_put_bits()

Reviewed-by: Benoit Fouet <benoit.fouet@free.fr>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

1 files changed, 18 insertions, 0 deletions

diff --git a/libavcodec/put_bits.h b/libavcodec/put_bits.h
index 8081fb9ea5..8858caaacc 100644
--- a/libavcodec/put_bits.h
+++ b/libavcodec/put_bits.h
@@ -63,6 +63,24 @@ static inline void init_put_bits(PutBitContext *s, uint8_t *buffer,
 }
 
 /**
+ * Rebase the bit writer onto a reallocated buffer.
+ *
+ * @param buffer the buffer where to put bits
+ * @param buffer_size the size in bytes of buffer,
+ *                    must be larger than the previous size
+ */
+static inline void rebase_put_bits(PutBitContext *s, uint8_t *buffer,
+                                   int buffer_size)
+{
+    av_assert0(8*buffer_size > s->size_in_bits);
+
+    s->buf_end = buffer + buffer_size;
+    s->buf_ptr = buffer + (s->buf_ptr - s->buf);
+    s->buf     = buffer;
+    s->size_in_bits = 8 * buffer_size;
+}
+
+/**
  * @return the total number of bits written to the bitstream.
  */
 static inline int put_bits_count(PutBitContext *s)