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vp56_arith.h
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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
28 #define vp56_rac_get_prob vp56_rac_get_prob
30 {
31  unsigned int code_word = vp56_rac_renorm(c);
32  unsigned int high = c->high;
33  unsigned int low = 1 + (((high - 1) * prob) >> 8);
34  unsigned int low_shift = low << 16;
35  int bit = 0;
36 
37  __asm__(
38  "subl %4, %1 \n\t"
39  "subl %3, %2 \n\t"
40  "leal (%2, %3), %3 \n\t"
41  "setae %b0 \n\t"
42  "cmovb %4, %1 \n\t"
43  "cmovb %3, %2 \n\t"
44  : "+q"(bit), "+r"(high), "+r"(code_word), "+r"(low_shift)
45  : "r"(low)
46  );
47 
48  c->high = high;
49  c->code_word = code_word;
50  return bit;
51 }
52 #endif
53 
54 #endif /* AVCODEC_X86_VP56_ARITH_H */