/[pcsx2_0.9.7]/trunk/3rdparty/liba52/bitstream.c
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Contents of /trunk/3rdparty/liba52/bitstream.c

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Revision 10 - (show annotations) (download)
Mon Sep 6 11:40:06 2010 UTC (9 years, 4 months ago) by william
File MIME type: text/plain
File size: 2530 byte(s)
exported r3113 from ./upstream/trunk
1 /*
2 * bitstream.c
3 * Copyright (C) 2000-2002 Michel Lespinasse <walken@zoy.org>
4 * Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
5 *
6 * This file is part of a52dec, a free ATSC A-52 stream decoder.
7 * See http://liba52.sourceforge.net/ for updates.
8 *
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.
13 *
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.
18 *
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
22 */
23
24 #include "config.h"
25
26 #include "inttypes.h"
27
28 #include "a52.h"
29 #include "a52_internal.h"
30 #include "bitstream.h"
31
32 #define BUFFER_SIZE 4096
33
34 void a52_bitstream_set_ptr (a52_state_t * state, uint8_t * buf)
35 {
36 int align;
37
38 align = (long)buf & 3;
39 state->buffer_start = (uint32_t *) (buf - align);
40 state->bits_left = 0;
41 bitstream_get (state, align * 8);
42 }
43
44 static inline void bitstream_fill_current (a52_state_t * state)
45 {
46 uint32_t tmp;
47
48 tmp = *(state->buffer_start++);
49 state->current_word = swab32 (tmp);
50 }
51
52 /*
53 * The fast paths for _get is in the
54 * bitstream.h header file so it can be inlined.
55 *
56 * The "bottom half" of this routine is suffixed _bh
57 *
58 * -ah
59 */
60
61 uint32_t a52_bitstream_get_bh (a52_state_t * state, uint32_t num_bits)
62 {
63 uint32_t result;
64
65 num_bits -= state->bits_left;
66 result = ((state->current_word << (32 - state->bits_left)) >>
67 (32 - state->bits_left));
68
69 bitstream_fill_current (state);
70
71 if (num_bits != 0)
72 result = (result << num_bits) | (state->current_word >> (32 - num_bits));
73
74 state->bits_left = 32 - num_bits;
75
76 return result;
77 }
78
79 int32_t a52_bitstream_get_bh_2 (a52_state_t * state, uint32_t num_bits)
80 {
81 int32_t result;
82
83 num_bits -= state->bits_left;
84 result = ((((int32_t)state->current_word) << (32 - state->bits_left)) >>
85 (32 - state->bits_left));
86
87 bitstream_fill_current(state);
88
89 if (num_bits != 0)
90 result = (result << num_bits) | (state->current_word >> (32 - num_bits));
91
92 state->bits_left = 32 - num_bits;
93
94 return result;
95 }

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