Statistics
| Branch: | Revision:

ffmpeg / libavutil / mathematics.c @ 10e26bc7

History | View | Annotate | Download (4.29 KB)

1
/*
2
 * Copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
3
 *
4
 * This file is part of FFmpeg.
5
 *
6
 * FFmpeg 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
 * FFmpeg 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 FFmpeg; if not, write to the Free Software
18
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19
 */
20

    
21
/**
22
 * @file mathematics.c
23
 * Miscellaneous math routines and tables.
24
 */
25

    
26
#include "common.h"
27
#include "mathematics.h"
28

    
29
const uint8_t ff_sqrt_tab[128]={
30
        0, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5,
31
        5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
32
        8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
33
        9, 9, 9, 9,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,11,11,11,11,11,11,11
34
};
35

    
36
const uint8_t ff_log2_tab[256]={
37
        0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
38
        5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
39
        6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
40
        6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
41
        7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
42
        7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
43
        7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
44
        7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
45
};
46

    
47
int64_t ff_gcd(int64_t a, int64_t b){
48
    if(b) return ff_gcd(b, a%b);
49
    else  return a;
50
}
51

    
52
int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding rnd){
53
    int64_t r=0;
54
    assert(c > 0);
55
    assert(b >=0);
56
    assert(rnd >=0 && rnd<=5 && rnd!=4);
57

    
58
    if(a<0 && a != INT64_MIN) return -av_rescale_rnd(-a, b, c, rnd ^ ((rnd>>1)&1));
59

    
60
    if(rnd==AV_ROUND_NEAR_INF) r= c/2;
61
    else if(rnd&1)             r= c-1;
62

    
63
    if(b<=INT_MAX && c<=INT_MAX){
64
        if(a<=INT_MAX)
65
            return (a * b + r)/c;
66
        else
67
            return a/c*b + (a%c*b + r)/c;
68
    }else{
69
#if 1
70
        uint64_t a0= a&0xFFFFFFFF;
71
        uint64_t a1= a>>32;
72
        uint64_t b0= b&0xFFFFFFFF;
73
        uint64_t b1= b>>32;
74
        uint64_t t1= a0*b1 + a1*b0;
75
        uint64_t t1a= t1<<32;
76
        int i;
77

    
78
        a0 = a0*b0 + t1a;
79
        a1 = a1*b1 + (t1>>32) + (a0<t1a);
80
        a0 += r;
81
        a1 += a0<r;
82

    
83
        for(i=63; i>=0; i--){
84
//            int o= a1 & 0x8000000000000000ULL;
85
            a1+= a1 + ((a0>>i)&1);
86
            t1+=t1;
87
            if(/*o || */c <= a1){
88
                a1 -= c;
89
                t1++;
90
            }
91
        }
92
        return t1;
93
    }
94
#else
95
        AVInteger ai;
96
        ai= av_mul_i(av_int2i(a), av_int2i(b));
97
        ai= av_add_i(ai, av_int2i(r));
98

    
99
        return av_i2int(av_div_i(ai, av_int2i(c)));
100
    }
101
#endif
102
}
103

    
104
int64_t av_rescale(int64_t a, int64_t b, int64_t c){
105
    return av_rescale_rnd(a, b, c, AV_ROUND_NEAR_INF);
106
}
107

    
108
int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq){
109
    int64_t b= bq.num * (int64_t)cq.den;
110
    int64_t c= cq.num * (int64_t)bq.den;
111
    return av_rescale_rnd(a, b, c, AV_ROUND_NEAR_INF);
112
}
113
#if 0
114
#include "integer.h"
115
#undef printf
116
main(){
117
    int64_t a,b,c,d,e;
118

119
    for(a=7; a<(1LL<<62); a+=a/3+1){
120
        for(b=3; b<(1LL<<62); b+=b/4+1){
121
            for(c=9; c<(1LL<<62); c+=(c*2)/5+3){
122
                int64_t r= c/2;
123
                AVInteger ai;
124
                ai= av_mul_i(av_int2i(a), av_int2i(b));
125
                ai= av_add_i(ai, av_int2i(r));
126

127
                d= av_i2int(av_div_i(ai, av_int2i(c)));
128

129
                e= av_rescale(a,b,c);
130

131
                if((double)a * (double)b / (double)c > (1LL<<63))
132
                    continue;
133

134
                if(d!=e) printf("%"PRId64"*%"PRId64"/%"PRId64"= %"PRId64"=%"PRId64"\n", a, b, c, d, e);
135
            }
136
        }
137
    }
138
}
139
#endif