*****************************************************************************/
void NextDataPacket( bit_stream_t * p_bit_stream )
{
- WORD_TYPE buffer_left;
- ptrdiff_t i_bytes_left;
decoder_fifo_t * p_fifo = p_bit_stream->p_decoder_fifo;
boolean_t b_new_pes;
- /* Put the remaining bytes (not aligned on a word boundary) in a
- * temporary buffer. */
- i_bytes_left = p_bit_stream->p_end - p_bit_stream->p_byte;
- buffer_left = *((WORD_TYPE *)p_bit_stream->p_end - 1);
-
/* We are looking for the next data packet that contains real data,
* and not just a PES header */
do
{
p_bit_stream->pf_bitstream_callback( p_bit_stream, b_new_pes );
}
+}
- /* Copy remaining bits of the previous packet */
- *((WORD_TYPE *)p_bit_stream->p_byte - 1) = buffer_left;
- p_bit_stream->p_byte -= i_bytes_left;
+/*****************************************************************************
+ * UnalignedShowBits : return i_bits bits from the bit stream, even when
+ * not aligned on a word boundary
+ *****************************************************************************/
+u32 UnalignedShowBits( bit_stream_t * p_bit_stream, unsigned int i_bits )
+{
+ /* We just fill in the bit buffer. */
+ while( p_bit_stream->fifo.i_available < i_bits )
+ {
+ if( p_bit_stream->p_byte < p_bit_stream->p_end )
+ {
+ p_bit_stream->fifo.buffer |= *(p_bit_stream->p_byte++)
+ << (8 * sizeof(WORD_TYPE) - 8
+ - p_bit_stream->fifo.i_available);
+ p_bit_stream->fifo.i_available += 8;
+ }
+ else
+ {
+ p_bit_stream->pf_next_data_packet( p_bit_stream );
+ p_bit_stream->fifo.buffer |= *(p_bit_stream->p_byte++)
+ << (8 * sizeof(WORD_TYPE) - 8
+ - p_bit_stream->fifo.i_available);
+ p_bit_stream->fifo.i_available += 8;
+ }
+ }
+ return( p_bit_stream->fifo.buffer >> (8 * sizeof(WORD_TYPE) - i_bits) );
}
+
+/*****************************************************************************
+ * UnalignedGetBits : returns i_bits bits from the bit stream and removes
+ * them from the buffer, even when the bit stream is not aligned on a word
+ * boundary
+ *****************************************************************************/
+u32 UnalignedGetBits( bit_stream_t * p_bit_stream, unsigned int i_bits )
+{
+ u32 i_result;
+
+ i_result = p_bit_stream->fifo.buffer
+ >> (8 * sizeof(WORD_TYPE) - i_bits);
+ i_bits = -p_bit_stream->fifo.i_available;
+
+ /* Gather missing bytes. */
+ while( i_bits >= 8 )
+ {
+ if( p_bit_stream->p_byte < p_bit_stream->p_end )
+ {
+ i_result |= *(p_bit_stream->p_byte++) << (i_bits - 8);
+ i_bits -= 8;
+ }
+ else
+ {
+ p_bit_stream->pf_next_data_packet( p_bit_stream );
+ i_result |= *(p_bit_stream->p_byte++) << (i_bits - 8);
+ i_bits -= 8;
+ }
+ }
+
+ /* Gather missing bits. */
+ if( i_bits > 0 )
+ {
+ unsigned int i_tmp = 8 - i_bits;
+
+ if( p_bit_stream->p_byte < p_bit_stream->p_end )
+ {
+ i_result |= *p_bit_stream->p_byte >> i_tmp;
+ p_bit_stream->fifo.buffer = *(p_bit_stream->p_byte++)
+ << ( sizeof(WORD_TYPE) * 8 - i_tmp );
+ p_bit_stream->fifo.i_available = i_tmp;
+ }
+ else
+ {
+ p_bit_stream->pf_next_data_packet( p_bit_stream );
+ i_result |= *p_bit_stream->p_byte >> i_tmp;
+ p_bit_stream->fifo.buffer = *(p_bit_stream->p_byte++)
+ << ( sizeof(WORD_TYPE) * 8 - i_tmp );
+ p_bit_stream->fifo.i_available = i_tmp;
+ }
+ }
+ else
+ {
+ p_bit_stream->fifo.i_available = 0;
+ p_bit_stream->fifo.buffer = 0;
+ }
+
+ if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
+ {
+ /* Get aligned on a word boundary. Otherwise it is safer
+ * to do it the next time.
+ * NB : we _will_ get aligned, because we have at most
+ * sizeof(WORD_TYPE) - 1 bytes to store, and at least
+ * sizeof(WORD_TYPE) - 1 empty bytes in the bit buffer. */
+ AlignWord( p_bit_stream );
+ }
+
+ return( i_result );
+}
+
+/*****************************************************************************
+ * UnalignedRemoveBits : removes i_bits (== -i_available) from the bit
+ * buffer, even when the bit stream is not aligned on a word boundary
+ *****************************************************************************/
+void UnalignedRemoveBits( bit_stream_t * p_bit_stream )
+{
+ /* First remove all unnecessary bytes. */
+ while( p_bit_stream->fifo.i_available <= -8 )
+ {
+ if( p_bit_stream->p_byte < p_bit_stream->p_end )
+ {
+ p_bit_stream->p_byte++;
+ p_bit_stream->fifo.i_available += 8;
+ }
+ else
+ {
+ p_bit_stream->pf_next_data_packet( p_bit_stream );
+ p_bit_stream->p_byte++;
+ p_bit_stream->fifo.i_available += 8;
+ }
+ }
+
+ /* Remove unnecessary bits. */
+ if( p_bit_stream->fifo.i_available < 0 )
+ {
+ if( p_bit_stream->p_byte < p_bit_stream->p_end )
+ {
+ p_bit_stream->fifo.buffer = *(p_bit_stream->p_byte++)
+ << ( sizeof(WORD_TYPE) * 8 - 8
+ - p_bit_stream->fifo.i_available );
+ p_bit_stream->fifo.i_available += 8;
+ }
+ else
+ {
+ p_bit_stream->pf_next_data_packet( p_bit_stream );
+ p_bit_stream->fifo.buffer = *(p_bit_stream->p_byte++)
+ << ( sizeof(WORD_TYPE) * 8 - 8
+ - p_bit_stream->fifo.i_available );
+ p_bit_stream->fifo.i_available += 8;
+ }
+ }
+ else
+ {
+ p_bit_stream->fifo.buffer = 0;
+ }
+
+ if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
+ {
+ /* Get aligned on a word boundary. Otherwise it is safer
+ * to do it the next time.
+ * NB : we _will_ get aligned, because we have at most
+ * sizeof(WORD_TYPE) - 1 bytes to store, and at least
+ * sizeof(WORD_TYPE) - 1 empty bytes in the bit buffer. */
+ AlignWord( p_bit_stream );
+ }
+}
+
projects / vlc / blobdiff