1/*
2 * Copyright (c) 2010 Mans Rullgard <mans@mansr.com>
3 *
4 * This file is part of Libav.
5 *
6 * Libav is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * Libav is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with Libav; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21#ifndef AVUTIL_INTMATH_H
22#define AVUTIL_INTMATH_H
23
24#include <stdint.h>
25#include "config.h"
26#include "attributes.h"
27
28/**
29 * @addtogroup lavu_internal
30 * @{
31 */
32
33extern const uint32_t ff_inverse[257];
34
35#if   ARCH_ARM
36#   include "arm/intmath.h"
37#elif ARCH_X86
38#   include "x86/intmath.h"
39#endif
40
41#if HAVE_FAST_CLZ && AV_GCC_VERSION_AT_LEAST(3,4)
42
43#ifndef av_log2
44#   define av_log2(x) (31 - __builtin_clz((x)|1))
45#   ifndef av_log2_16bit
46#      define av_log2_16bit av_log2
47#   endif
48#endif /* av_log2 */
49
50#endif /* AV_GCC_VERSION_AT_LEAST(3,4) */
51
52#ifndef FASTDIV
53#   if CONFIG_FASTDIV
54#       define FASTDIV(a,b) ((uint32_t)((((uint64_t)a) * ff_inverse[b]) >> 32))
55#   else
56#       define FASTDIV(a,b) ((a) / (b))
57#   endif
58#endif /* FASTDIV */
59
60#include "common.h"
61
62extern const uint8_t ff_sqrt_tab[256];
63
64static inline av_const unsigned int ff_sqrt(unsigned int a)
65{
66    unsigned int b;
67
68    if (a < 255) return (ff_sqrt_tab[a + 1] - 1) >> 4;
69    else if (a < (1 << 12)) b = ff_sqrt_tab[a >> 4] >> 2;
70#if !CONFIG_SMALL
71    else if (a < (1 << 14)) b = ff_sqrt_tab[a >> 6] >> 1;
72    else if (a < (1 << 16)) b = ff_sqrt_tab[a >> 8]   ;
73#endif
74    else {
75        int s = av_log2_16bit(a >> 16) >> 1;
76        unsigned int c = a >> (s + 2);
77        b = ff_sqrt_tab[c >> (s + 8)];
78        b = FASTDIV(c,b) + (b << s);
79    }
80
81    return b - (a < b * b);
82}
83
84/**
85 * @}
86 */
87#endif /* AVUTIL_INTMATH_H */
88