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

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Revision 10 - (hide annotations) (download)
Mon Sep 6 11:40:06 2010 UTC (9 years, 5 months ago) by william
File MIME type: text/plain
File size: 2530 byte(s)
exported r3113 from ./upstream/trunk
1 william 10 /*
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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