ffmpeg / libavutil / mathematics.h @ 65db0587
History  View  Annotate  Download (3.41 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 021101301 USA

19 
*/

20  
21 
#ifndef AVUTIL_MATHEMATICS_H

22 
#define AVUTIL_MATHEMATICS_H

23  
24 
#include <stdint.h> 
25 
#include <math.h> 
26 
#include "attributes.h" 
27 
#include "rational.h" 
28  
29 
#ifndef M_E

30 
#define M_E 2.7182818284590452354 /* e */ 
31 
#endif

32 
#ifndef M_LN2

33 
#define M_LN2 0.69314718055994530942 /* log_e 2 */ 
34 
#endif

35 
#ifndef M_LN10

36 
#define M_LN10 2.30258509299404568402 /* log_e 10 */ 
37 
#endif

38 
#ifndef M_LOG2_10

39 
#define M_LOG2_10 3.32192809488736234787 /* log_2 10 */ 
40 
#endif

41 
#ifndef M_PI

42 
#define M_PI 3.14159265358979323846 /* pi */ 
43 
#endif

44 
#ifndef M_SQRT1_2

45 
#define M_SQRT1_2 0.70710678118654752440 /* 1/sqrt(2) */ 
46 
#endif

47 
#ifndef M_SQRT2

48 
#define M_SQRT2 1.41421356237309504880 /* sqrt(2) */ 
49 
#endif

50 
#ifndef NAN

51 
#define NAN (0.0/0.0) 
52 
#endif

53 
#ifndef INFINITY

54 
#define INFINITY (1.0/0.0) 
55 
#endif

56  
57 
enum AVRounding {

58 
AV_ROUND_ZERO = 0, ///< Round toward zero. 
59 
AV_ROUND_INF = 1, ///< Round away from zero. 
60 
AV_ROUND_DOWN = 2, ///< Round toward infinity. 
61 
AV_ROUND_UP = 3, ///< Round toward +infinity. 
62 
AV_ROUND_NEAR_INF = 5, ///< Round to nearest and halfway cases away from zero. 
63 
}; 
64  
65 
/**

66 
* Returns the greatest common divisor of a and b.

67 
* If both a and b are 0 or either or both are <0 then behavior is

68 
* undefined.

69 
*/

70 
int64_t av_const av_gcd(int64_t a, int64_t b); 
71  
72 
/**

73 
* Rescales a 64bit integer with rounding to nearest.

74 
* A simple a*b/c isn't possible as it can overflow.

75 
*/

76 
int64_t av_rescale(int64_t a, int64_t b, int64_t c) av_const; 
77  
78 
/**

79 
* Rescales a 64bit integer with specified rounding.

80 
* A simple a*b/c isn't possible as it can overflow.

81 
*/

82 
int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding) av_const;

83  
84 
/**

85 
* Rescales a 64bit integer by 2 rational numbers.

86 
*/

87 
int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const; 
88  
89 
/**

90 
* Compares 2 timestamps each in its own timebases.

91 
* The result of the function is undefined if one of the timestamps

92 
* is outside the int64_t range when represented in the others timebase.

93 
* @return 1 if ts_a is before ts_b, 1 if ts_a is after ts_b or 0 if they represent the same position

94 
*/

95 
int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b);

96  
97 
/**

98 
* Compare 2 integers modulo mod.

99 
* That is we compare integers a and b for which only the least significant log2(mod) bits are known

100 
* @param mod must be a power of 2

101 
* @returns a negative value if a is smaller than b

102 
* a positiv value if a is greater than b

103 
* 0 if a equals b

104 
*/

105 
int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod); 
106  
107 
#endif /* AVUTIL_MATHEMATICS_H */ 