unary.h 1.8 KB

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  1. /*
  2. * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
  3. *
  4. * This file is part of FFmpeg.
  5. *
  6. * FFmpeg is free software; you can redistribute it and/or
  7. * modify it under the terms of the GNU Lesser General Public
  8. * License as published by the Free Software Foundation; either
  9. * version 2.1 of the License, or (at your option) any later version.
  10. *
  11. * FFmpeg is distributed in the hope that it will be useful,
  12. * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13. * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14. * Lesser General Public License for more details.
  15. *
  16. * You should have received a copy of the GNU Lesser General Public
  17. * License along with FFmpeg; if not, write to the Free Software
  18. * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19. */
  20. #ifndef AVCODEC_UNARY_H
  21. #define AVCODEC_UNARY_H
  22. #include "get_bits.h"
  23. /**
  24. * Get unary code of limited length
  25. * @param gb GetBitContext
  26. * @param[in] stop The bitstop value (unary code of 1's or 0's)
  27. * @param[in] len Maximum length
  28. * @return unary 0 based code index. This is also the length in bits of the
  29. * code excluding the stop bit.
  30. * (in case len=1)
  31. * 1 0
  32. * 0 1
  33. * (in case len=2)
  34. * 1 0
  35. * 01 1
  36. * 00 2
  37. * (in case len=3)
  38. * 1 0
  39. * 01 1
  40. * 001 2
  41. * 000 3
  42. */
  43. static inline int get_unary(GetBitContext *gb, int stop, int len)
  44. {
  45. int i;
  46. for(i = 0; i < len && get_bits1(gb) != stop; i++);
  47. return i;
  48. }
  49. /**
  50. * Get unary code terminated by a 0 with a maximum length of 33
  51. * @param gb GetBitContext
  52. * @return Unary length/index
  53. */
  54. static inline int get_unary_0_33(GetBitContext *gb)
  55. {
  56. return get_unary(gb, 0, 33);
  57. }
  58. static inline int get_unary_0_9(GetBitContext *gb)
  59. {
  60. return get_unary(gb, 0, 9);
  61. }
  62. #endif /* AVCODEC_UNARY_H */