FFmpeg  4.0
rational.c
Go to the documentation of this file.
1 /*
2  * rational numbers
3  * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "libavutil/rational.c"
23 #include "libavutil/integer.h"
24 
25 int main(void)
26 {
27  AVRational a,b,r;
28  int i,j,k;
29  static const int64_t numlist[] = {
30  INT64_MIN, INT64_MIN+1, INT64_MAX, INT32_MIN, INT32_MAX, 1,0,-1,
31  123456789, INT32_MAX-1, INT32_MAX+1LL, UINT32_MAX-1, UINT32_MAX, UINT32_MAX+1LL
32  };
33 
34  for (a.num = -2; a.num <= 2; a.num++) {
35  for (a.den = -2; a.den <= 2; a.den++) {
36  for (b.num = -2; b.num <= 2; b.num++) {
37  for (b.den = -2; b.den <= 2; b.den++) {
38  int c = av_cmp_q(a,b);
39  double d = av_q2d(a) == av_q2d(b) ?
40  0 : (av_q2d(a) - av_q2d(b));
41  if (d > 0) d = 1;
42  else if (d < 0) d = -1;
43  else if (d != d) d = INT_MIN;
44  if (c != d)
45  av_log(NULL, AV_LOG_ERROR, "%d/%d %d/%d, %d %f\n", a.num,
46  a.den, b.num, b.den, c,d);
47  r = av_sub_q(av_add_q(b,a), b);
48  if(b.den && (r.num*a.den != a.num*r.den || !r.num != !a.num || !r.den != !a.den))
49  av_log(NULL, AV_LOG_ERROR, "%d/%d ", r.num, r.den);
50  }
51  }
52  }
53  }
54 
55  for (i = 0; i < FF_ARRAY_ELEMS(numlist); i++) {
56  int64_t a = numlist[i];
57 
58  for (j = 0; j < FF_ARRAY_ELEMS(numlist); j++) {
59  int64_t b = numlist[j];
60  if (b<=0)
61  continue;
62  for (k = 0; k < FF_ARRAY_ELEMS(numlist); k++) {
63  int64_t c = numlist[k];
64  int64_t res;
65  AVInteger ai;
66 
67  if (c<=0)
68  continue;
69  res = av_rescale_rnd(a,b,c, AV_ROUND_ZERO);
70 
71  ai = av_mul_i(av_int2i(a), av_int2i(b));
72  ai = av_div_i(ai, av_int2i(c));
73 
74  if (av_cmp_i(ai, av_int2i(INT64_MAX)) > 0 && res == INT64_MIN)
75  continue;
76  if (av_cmp_i(ai, av_int2i(INT64_MIN)) < 0 && res == INT64_MIN)
77  continue;
78  if (av_cmp_i(ai, av_int2i(res)) == 0)
79  continue;
80 
81  // Special exception for INT64_MIN, remove this in case INT64_MIN is handled without off by 1 error
82  if (av_cmp_i(ai, av_int2i(res-1)) == 0 && a == INT64_MIN)
83  continue;
84 
85  av_log(NULL, AV_LOG_ERROR, "%"PRId64" * %"PRId64" / %"PRId64" = %"PRId64" or %"PRId64"\n", a,b,c, res, av_i2int(ai));
86  }
87  }
88  }
89 
90  for (a.num = 1; a.num <= 10; a.num++) {
91  for (a.den = 1; a.den <= 10; a.den++) {
92  if (av_gcd(a.num, a.den) > 1)
93  continue;
94  for (b.num = 1; b.num <= 10; b.num++) {
95  for (b.den = 1; b.den <= 10; b.den++) {
96  int start;
97  if (av_gcd(b.num, b.den) > 1)
98  continue;
99  if (av_cmp_q(b, a) < 0)
100  continue;
101  for (start = 0; start < 10 ; start++) {
102  int acc= start;
103  int i;
104 
105  for (i = 0; i<100; i++) {
106  int exact = start + av_rescale_q(i+1, b, a);
107  acc = av_add_stable(a, acc, b, 1);
108  if (FFABS(acc - exact) > 2) {
109  av_log(NULL, AV_LOG_ERROR, "%d/%d %d/%d, %d %d\n", a.num,
110  a.den, b.num, b.den, acc, exact);
111  return 1;
112  }
113  }
114  }
115  }
116  }
117  }
118  }
119 
120  for (a.den = 1; a.den < 0x100000000U/3; a.den*=3) {
121  for (a.num = -1; a.num < (1<<27); a.num += 1 + a.num/100) {
122  float f = av_int2float(av_q2intfloat(a));
123  float f2 = av_q2d(a);
124  if (fabs(f - f2) > fabs(f)/5000000) {
125  av_log(NULL, AV_LOG_ERROR, "%d/%d %f %f\n", a.num,
126  a.den, f, f2);
127  return 1;
128  }
129 
130  }
131  }
132 
133  return 0;
134 }
#define NULL
Definition: coverity.c:32
int acc
Definition: yuv2rgb.c:554
static av_always_inline float av_int2float(uint32_t i)
Reinterpret a 32-bit integer as a float.
Definition: intfloat.h:40
int num
Numerator.
Definition: rational.h:59
const char * b
Definition: vf_curves.c:113
rational numbers
uint32_t av_q2intfloat(AVRational q)
Convert an AVRational to a IEEE 32-bit float expressed in fixed-point format.
Definition: rational.c:152
AVRational av_sub_q(AVRational b, AVRational c)
Subtract one rational from another.
Definition: rational.c:101
static double av_q2d(AVRational a)
Convert an AVRational to a double.
Definition: rational.h:104
#define av_log(a,...)
int64_t av_i2int(AVInteger a)
Convert the given AVInteger to an int64_t.
Definition: integer.c:158
int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq)
Rescale a 64-bit integer by 2 rational numbers.
Definition: mathematics.c:142
AVInteger av_int2i(int64_t a)
Convert the given int64_t to an AVInteger.
Definition: integer.c:147
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
const char * r
Definition: vf_curves.c:111
AVInteger av_mul_i(AVInteger a, AVInteger b)
Definition: integer.c:64
int64_t av_gcd(int64_t a, int64_t b)
Compute the greatest common divisor of two integer operands.
Definition: mathematics.c:37
int av_cmp_i(AVInteger a, AVInteger b)
Return 0 if a==b, 1 if a>b and -1 if a<b.
Definition: integer.c:85
Round toward zero.
Definition: mathematics.h:80
#define FFABS(a)
Absolute value, Note, INT_MIN / INT64_MIN result in undefined behavior as they are not representable ...
Definition: common.h:72
int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding rnd)
Rescale a 64-bit integer with specified rounding.
Definition: mathematics.c:58
#define FF_ARRAY_ELEMS(a)
Rational number (pair of numerator and denominator).
Definition: rational.h:58
static int av_cmp_q(AVRational a, AVRational b)
Compare two rationals.
Definition: rational.h:89
arbitrary precision integers
int64_t av_add_stable(AVRational ts_tb, int64_t ts, AVRational inc_tb, int64_t inc)
Add a value to a timestamp.
Definition: mathematics.c:191
static double c[64]
AVRational av_add_q(AVRational b, AVRational c)
Add two rationals.
Definition: rational.c:93
AVInteger av_div_i(AVInteger a, AVInteger b)
Return a/b.
Definition: integer.c:141
int den
Denominator.
Definition: rational.h:60
void INT64 start
Definition: avisynth_c.h:690
int main(void)
Definition: rational.c:25