3 * Copyright (C) 2000-2002 Michel Lespinasse <walken@zoy.org>
4 * Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
6 * This file is part of a52dec, a free ATSC A-52 stream decoder.
7 * See http://liba52.sourceforge.net/ for updates.
9 * a52dec is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
14 * a52dec is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
29 #include "a52_internal.h"
30 #include "bitstream.h"
32 #define BUFFER_SIZE 4096
34 static uint32_t * buffer_start;
36 uint32_t a52_bits_left;
37 uint32_t a52_current_word;
39 void a52_bitstream_set_ptr (uint8_t * buf)
43 align = (long)buf & 3;
44 buffer_start = (uint32_t *) (buf - align);
46 bitstream_get (align * 8);
50 bitstream_fill_current()
54 tmp = *(buffer_start++);
55 a52_current_word = swab32 (tmp);
59 * The fast paths for _get is in the
60 * bitstream.h header file so it can be inlined.
62 * The "bottom half" of this routine is suffixed _bh
68 a52_bitstream_get_bh(uint32_t num_bits)
72 num_bits -= a52_bits_left;
73 result = ((a52_current_word << (32u - a52_bits_left)) >>
74 (32u - a52_bits_left));
76 bitstream_fill_current();
79 result = (result << num_bits) | (a52_current_word >> (32u - num_bits));
81 a52_bits_left = 32u - num_bits;
87 a52_bitstream_get_bh_2(uint32_t num_bits)
91 num_bits -= a52_bits_left;
92 result = ((((int32_t)a52_current_word) << (32u - a52_bits_left)) >>
93 (32u - a52_bits_left));
95 bitstream_fill_current();
98 result = (result << num_bits) | (a52_current_word >> (32u - num_bits));
100 a52_bits_left = 32u - num_bits;