FFmpeg
rational.c
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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
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
Definition: undefined.txt:36
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
#define f(width, name)
Definition: cbs_vp9.c:255
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
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 i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
const char * r
Definition: vf_curves.c:114
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
#define b
Definition: input.c:41
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
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:766
int main(void)
Definition: rational.c:25