FFmpeg/libavcodec/arm/vp56_arith.h

/*
 * Copyright (C) 2010 Mans Rullgard <mans@mansr.com>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#ifndef AVCODEC_ARM_VP56_ARITH_H
#define AVCODEC_ARM_VP56_ARITH_H

#if CONFIG_THUMB
#   define A(x)
#   define T(x) x
#else
#   define A(x) x
#   define T(x)
#endif

#if HAVE_ARMV6 && HAVE_INLINE_ASM

#define vp56_rac_get_prob vp56_rac_get_prob_armv6
static inline int vp56_rac_get_prob_armv6(VP56RangeCoder *c, int pr)
{
    unsigned shift     = ff_vp56_norm_shift[c->high];
    unsigned code_word = c->code_word << shift;
    unsigned high      = c->high << shift;
    unsigned bit;

    __asm__ ("adds    %3,  %3,  %0           \n"
             "itt     cs                     \n"
             "cmpcs   %7,  %4                \n"
           A("ldrcsh  %2,  [%4], #2          \n")
           T("ldrhcs  %2,  [%4], #2          \n")
             "rsb     %0,  %6,  #256         \n"
             "smlabb  %0,  %5,  %6,  %0      \n"
           T("itttt   cs                     \n")
             "rev16cs %2,  %2                \n"
           T("lslcs   %2,  %2,  %3           \n")
           T("orrcs   %1,  %1,  %2           \n")
           A("orrcs   %1,  %1,  %2,  lsl %3  \n")
             "subcs   %3,  %3,  #16          \n"
             "lsr     %0,  %0,  #8           \n"
             "cmp     %1,  %0,  lsl #16      \n"
             "ittte   ge                     \n"
             "subge   %1,  %1,  %0,  lsl #16 \n"
             "subge   %0,  %5,  %0           \n"
             "movge   %2,  #1                \n"
             "movlt   %2,  #0                \n"
             : "=&r"(c->high), "=&r"(c->code_word), "=&r"(bit),
               "+&r"(c->bits), "+&r"(c->buffer)
             : "r"(high), "r"(pr), "r"(c->end - 1),
               "0"(shift), "1"(code_word)
             : "cc");

    return bit;
}

#define vp56_rac_get_prob_branchy vp56_rac_get_prob_branchy_armv6
static inline int vp56_rac_get_prob_branchy_armv6(VP56RangeCoder *c, int pr)
{
    unsigned shift     = ff_vp56_norm_shift[c->high];
    unsigned code_word = c->code_word << shift;
    unsigned high      = c->high << shift;
    unsigned low;
    unsigned tmp;

    __asm__ ("adds    %3,  %3,  %0           \n"
             "itt     cs                     \n"
             "cmpcs   %7,  %4                \n"
           A("ldrcsh  %2,  [%4], #2          \n")
           T("ldrhcs  %2,  [%4], #2          \n")
             "rsb     %0,  %6,  #256         \n"
             "smlabb  %0,  %5,  %6,  %0      \n"
           T("itttt   cs                     \n")
             "rev16cs %2,  %2                \n"
           T("lslcs   %2,  %2,  %3           \n")
           T("orrcs   %1,  %1,  %2           \n")
           A("orrcs   %1,  %1,  %2,  lsl %3  \n")
             "subcs   %3,  %3,  #16          \n"
             "lsr     %0,  %0,  #8           \n"
             "lsl     %2,  %0,  #16          \n"
             : "=&r"(low), "+&r"(code_word), "=&r"(tmp),
               "+&r"(c->bits), "+&r"(c->buffer)
             : "r"(high), "r"(pr), "r"(c->end - 1), "0"(shift)
             : "cc");

    if (code_word >= tmp) {
        c->high      = high - low;
        c->code_word = code_word - tmp;
        return 1;
    }

    c->high      = low;
    c->code_word = code_word;
    return 0;
}

#endif

#endif /* AVCODEC_ARM_VP56_ARITH_H */