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  1. /**
  2.  * VP5 and VP6 compatible video decoder (arith decoder)
  3.  *
  4.  * Copyright (C) 2006  Aurelien Jacobs <aurel@gnuage.org>
  5.  * Copyright (C) 2010  Eli Friedman
  6.  *
  7.  * This file is part of FFmpeg.
  8.  *
  9.  * FFmpeg is free software; you can redistribute it and/or
  10.  * modify it under the terms of the GNU Lesser General Public
  11.  * License as published by the Free Software Foundation; either
  12.  * version 2.1 of the License, or (at your option) any later version.
  13.  *
  14.  * FFmpeg 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 GNU
  17.  * Lesser General Public License for more details.
  18.  *
  19.  * You should have received a copy of the GNU Lesser General Public
  20.  * License along with FFmpeg; if not, write to the Free Software
  21.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22.  */
  23.  
  24. #ifndef AVCODEC_X86_VP56_ARITH_H
  25. #define AVCODEC_X86_VP56_ARITH_H
  26.  
  27. #if HAVE_INLINE_ASM && HAVE_FAST_CMOV && HAVE_6REGS
  28. #define vp56_rac_get_prob vp56_rac_get_prob
  29. static av_always_inline int vp56_rac_get_prob(VP56RangeCoder *c, uint8_t prob)
  30. {
  31.     unsigned int code_word = vp56_rac_renorm(c);
  32.     unsigned int low = 1 + (((c->high - 1) * prob) >> 8);
  33.     unsigned int low_shift = low << 16;
  34.     int bit = 0;
  35.     c->code_word = code_word;
  36.  
  37.     __asm__(
  38.         "subl  %4, %1      \n\t"
  39.         "subl  %3, %2      \n\t"
  40.         "setae %b0         \n\t"
  41.         "cmovb %4, %1      \n\t"
  42.         "cmovb %5, %2      \n\t"
  43.         : "+q"(bit), "+&r"(c->high), "+&r"(c->code_word)
  44.         : "r"(low_shift), "r"(low), "r"(code_word)
  45.     );
  46.  
  47.     return bit;
  48. }
  49. #endif
  50.  
  51. #endif /* AVCODEC_X86_VP56_ARITH_H */
  52.