From bff17fb1d0e39583e44ba93ea214d7434ecef2ce Mon Sep 17 00:00:00 2001 From: Klaus Schmidinger Date: Fri, 3 Aug 2001 14:18:08 +0200 Subject: Added support for replaying DVDs --- ac3dec/bitstream.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 76 insertions(+) create mode 100644 ac3dec/bitstream.c (limited to 'ac3dec/bitstream.c') diff --git a/ac3dec/bitstream.c b/ac3dec/bitstream.c new file mode 100644 index 00000000..296d5ee3 --- /dev/null +++ b/ac3dec/bitstream.c @@ -0,0 +1,76 @@ +/* + * bitstream.c + * + * Copyright (C) Aaron Holtzman - Dec 1999 + * + * This file is part of ac3dec, a free AC-3 audio decoder + * + * ac3dec is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2, or (at your option) + * any later version. + * + * ac3dec is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with GNU Make; see the file COPYING. If not, write to + * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. + * + */ + +#include +#include + +#include "ac3.h" +#include "ac3_internal.h" +#include "bitstream.h" + + +uint_8 *buffer_start = 0; +uint_32 bits_left = 0; +uint_32 current_word; + +static inline void +bitstream_fill_current() +{ + current_word = *((uint_32*)buffer_start)++; + current_word = swab32(current_word); +} + +// +// The fast paths for _get is in the +// bitstream.h header file so it can be inlined. +// +// The "bottom half" of this routine is suffixed _bh +// +// -ah +// + +uint_32 +bitstream_get_bh(uint_32 num_bits) +{ + uint_32 result; + + num_bits -= bits_left; + result = (current_word << (32 - bits_left)) >> (32 - bits_left); + + bitstream_fill_current(); + + if(num_bits != 0) + result = (result << num_bits) | (current_word >> (32 - num_bits)); + + bits_left = 32 - num_bits; + + return result; +} + +void +bitstream_init(uint_8 *start) +{ + //initialize the start of the buffer + buffer_start = start; + bits_left = 0; +} -- cgit v1.2.3