Function simplicity_closeBitstream

src/simplicity/bitstream.c:13–24

Closes a bitstream by consuming all remaining bits. * Returns 'SIMPLICITY_ERR_BITSTREAM_TRAILING_BYTES' if CHAR_BIT or more bits remain in the stream. * Otherwise, returns 'SIMPLICITY_ERR_BITSTREAM_ILLEGAL_PADDING' if any remaining bits are non-zero. * Otherwise returns 'SIMPLICITY_NO_ERROR'. * * Precondition: NULL != stream */

 * Precondition: NULL != stream
 */
simplicity_err simplicity_closeBitstream(bitstream* stream) {
  if (1 < stream->len) return SIMPLICITY_ERR_BITSTREAM_TRAILING_BYTES;        /* If there is more than one byte remaining. */
  if (1 == stream->len) {
    if (0 == stream->offset) return SIMPLICITY_ERR_BITSTREAM_TRAILING_BYTES;  /* If there is one byte remaining */
    if (0 != (*stream->arr & (UCHAR_MAX >> stream->offset))) {                /* If any of the unconsumed bits are non-zero */
      return SIMPLICITY_ERR_BITSTREAM_ILLEGAL_PADDING;
    }
  }
  /* Otherwise there are either 0 bits remaining or there are between 1 and CHAR_BITS-1 bits remaining and they are all zero. */
  *stream = (bitstream){0};
  return SIMPLICITY_NO_ERROR;
}

/* Fetches up to 31 bits from 'stream' as the 'n' least significant bits of return value.
 * The 'n' bits are set from the MSB to the LSB.