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/*
* Copyright (c) 2010 Mans Rullgard <mans@mansr.com>
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVUTIL_INTMATH_H
#define AVUTIL_INTMATH_H
#include <stdint.h>
#include "config.h"
#include "attributes.h"
/**
* @addtogroup lavu_internal
* @{
*/
extern const uint32_t ff_inverse[257];
#if ARCH_ARM
# include "arm/intmath.h"
#elif ARCH_X86
# include "x86/intmath.h"
#endif
#if HAVE_FAST_CLZ && AV_GCC_VERSION_AT_LEAST(3,4)
#ifndef av_log2
# define av_log2(x) (31 - __builtin_clz((x)|1))
# ifndef av_log2_16bit
# define av_log2_16bit av_log2
# endif
#endif /* av_log2 */
#endif /* AV_GCC_VERSION_AT_LEAST(3,4) */
#ifndef FASTDIV
# if CONFIG_FASTDIV
# define FASTDIV(a,b) ((uint32_t)((((uint64_t)a) * ff_inverse[b]) >> 32))
# else
# define FASTDIV(a,b) ((a) / (b))
# endif
#endif /* FASTDIV */
#include "common.h"
extern const uint8_t ff_sqrt_tab[256];
static inline av_const unsigned int ff_sqrt(unsigned int a)
{
unsigned int b;
if (a < 255) return (ff_sqrt_tab[a + 1] - 1) >> 4;
else if (a < (1 << 12)) b = ff_sqrt_tab[a >> 4] >> 2;
#if !CONFIG_SMALL
else if (a < (1 << 14)) b = ff_sqrt_tab[a >> 6] >> 1;
else if (a < (1 << 16)) b = ff_sqrt_tab[a >> 8] ;
#endif
else {
int s = av_log2_16bit(a >> 16) >> 1;
unsigned int c = a >> (s + 2);
b = ff_sqrt_tab[c >> (s + 8)];
b = FASTDIV(c,b) + (b << s);
}
return b - (a < b * b);
}
/**
* @}
*/
#endif /* AVUTIL_INTMATH_H */
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