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55 lines
1.7 KiB
C
55 lines
1.7 KiB
C
/**
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* VP5 and VP6 compatible video decoder (arith decoder)
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*
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* Copyright (C) 2006 Aurelien Jacobs <aurel@gnuage.org>
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* Copyright (C) 2010 Eli Friedman
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef AVCODEC_X86_VP56_ARITH_H
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#define AVCODEC_X86_VP56_ARITH_H
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#if HAVE_INLINE_ASM && HAVE_FAST_CMOV
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#define vp56_rac_get_prob vp56_rac_get_prob
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static av_always_inline int vp56_rac_get_prob(VP56RangeCoder *c, uint8_t prob)
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{
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unsigned int code_word = vp56_rac_renorm(c);
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unsigned int high = c->high;
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unsigned int low = 1 + (((high - 1) * prob) >> 8);
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unsigned int low_shift = low << 16;
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int bit = 0;
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__asm__(
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"subl %4, %1 \n\t"
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"subl %3, %2 \n\t"
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"leal (%2, %3), %3 \n\t"
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"setae %b0 \n\t"
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"cmovb %4, %1 \n\t"
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"cmovb %3, %2 \n\t"
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: "+q"(bit), "+r"(high), "+r"(code_word), "+r"(low_shift)
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: "r"(low)
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);
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c->high = high;
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c->code_word = code_word;
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return bit;
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}
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#endif
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#endif /* AVCODEC_X86_VP56_ARITH_H */
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