## ffmpeg / libavcodec / liba52 / bitstream.h @ 976f969b

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1 | 976f969b | Zdenek Kabelac | ```
/*
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2 | ```
* bitstream.h
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3 | ```
* Copyright (C) 2000-2002 Michel Lespinasse <walken@zoy.org>
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4 | ```
* Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
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5 | ```
*
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6 | ```
* This file is part of a52dec, a free ATSC A-52 stream decoder.
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7 | ```
* See http://liba52.sourceforge.net/ for updates.
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8 | ```
*
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9 | ```
* a52dec is free software; you can redistribute it and/or modify
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10 | ```
* it under the terms of the GNU General Public License as published by
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11 | ```
* the Free Software Foundation; either version 2 of the License, or
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12 | ```
* (at your option) any later version.
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13 | ```
*
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14 | ```
* a52dec is distributed in the hope that it will be useful,
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15 | ```
* but WITHOUT ANY WARRANTY; without even the implied warranty of
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16 | ```
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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17 | ```
* GNU General Public License for more details.
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18 | ```
*
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19 | ```
* You should have received a copy of the GNU General Public License
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20 | ```
* along with this program; if not, write to the Free Software
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21 | ```
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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22 | ```
*/
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23 | |||

24 | ```
/* (stolen from the kernel) */
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25 | ```
#ifdef WORDS_BIGENDIAN
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26 | |||

27 | ```
# define swab32(x) (x)
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28 | |||

29 | ```
#else
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30 | |||

31 | ```
# if 0 && defined (__i386__)
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32 | |||

33 | ```
# define swab32(x) __i386_swab32(x)
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34 | ```
static inline const uint32_t __i386_swab32(uint32_t x)
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35 | ```
{
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36 | ```
__asm__("bswap %0" : "=r" (x) : "0" (x));
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37 | ```
return x;
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38 | ```
}
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39 | |||

40 | ```
# else
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41 | |||

42 | ```
# define swab32(x)\
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43 | ```
((((uint8_t*)&x)[0] << 24) | (((uint8_t*)&x)[1] << 16) | \
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44 | ```
(((uint8_t*)&x)[2] << 8) | (((uint8_t*)&x)[3]))
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45 | |||

46 | ```
# endif
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47 | ```
#endif
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48 | |||

49 | ```
extern uint32_t a52_bits_left;
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50 | ```
extern uint32_t a52_current_word;
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51 | |||

52 | ```
void a52_bitstream_set_ptr (uint8_t * buf);
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53 | uint32_t a52_bitstream_get_bh(uint32_t num_bits); |
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54 | int32_t a52_bitstream_get_bh_2(uint32_t num_bits); |
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55 | |||

56 | static inline uint32_t |
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57 | bitstream_get(uint32_t num_bits) |
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58 | { |
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59 | uint32_t result; |
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60 | |||

61 | ```
if(num_bits < a52_bits_left) {
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62 | result = (a52_current_word << (32 - a52_bits_left)) >> (32 - num_bits); |
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63 | a52_bits_left -= num_bits; |
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64 | ```
return result;
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65 | } |
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66 | |||

67 | ```
return a52_bitstream_get_bh(num_bits);
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68 | } |
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69 | |||

70 | static inline int32_t |
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71 | bitstream_get_2(uint32_t num_bits) |
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72 | { |
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73 | int32_t result; |
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74 | |||

75 | ```
if(num_bits < a52_bits_left) {
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76 | result = (((int32_t)a52_current_word) << (32 - a52_bits_left)) >> (32 - num_bits); |
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77 | a52_bits_left -= num_bits; |
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78 | ```
return result;
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79 | } |
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80 | |||

81 | ```
return a52_bitstream_get_bh_2(num_bits);
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82 | } |