libavutil/mathematics.c File Reference

miscellaneous math routines and tables More...

#include <assert.h>
#include "avutil.h"
#include "common.h"
#include "mathematics.h"

Go to the source code of this file.

Functions

int64_t av_gcd (int64_t a, int64_t b)
int64_t ff_gcd (int64_t a, int64_t b)
int64_t av_rescale_rnd (int64_t a, int64_t b, int64_t c, enum AVRounding rnd)
 Rescales a 64-bit integer with specified rounding.
int64_t av_rescale (int64_t a, int64_t b, int64_t c)
 Rescales a 64-bit integer with rounding to nearest.
int64_t av_rescale_q (int64_t a, AVRational bq, AVRational cq)
 Rescales a 64-bit integer by 2 rational numbers.

Variables

const uint8_t ff_sqrt_tab [256]
const uint8_t ff_log2_tab [256]


Detailed Description

miscellaneous math routines and tables

Definition in file mathematics.c.


Function Documentation

int64_t av_gcd ( int64_t  a,
int64_t  b 
)

int64_t av_rescale ( int64_t  a,
int64_t  b,
int64_t  c 
) const

int64_t av_rescale_q ( int64_t  a,
AVRational  bq,
AVRational  cq 
)

int64_t av_rescale_rnd ( int64_t  a,
int64_t  b,
int64_t  c,
enum  AVRounding 
) const

Rescales a 64-bit integer with specified rounding.

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

Definition at line 64 of file mathematics.c.

Referenced by av_nearer_q(), av_rescale(), av_rescale_q(), av_rescale_rnd(), dv_write_pack(), ff_nut_reset_ts(), gxf_write_media_preamble(), mov_write_edts_tag(), mov_write_mvhd_tag(), mov_write_tkhd_tag(), rtp_write_header(), and write_packet().

int64_t ff_gcd ( int64_t  a,
int64_t  b 
)

Definition at line 59 of file mathematics.c.


Variable Documentation

const uint8_t ff_log2_tab[256]

Initial value:

{
        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,
        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,
        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,
        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,
        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,
        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,
        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,
        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
}

Definition at line 42 of file mathematics.c.

Referenced by av_log2(), av_log2_16bit(), decode_frame(), rtsp_read_header(), and seq_decode_op1().

const uint8_t ff_sqrt_tab[256]

Initial value:

{
  0, 16, 23, 28, 32, 36, 40, 43, 46, 48, 51, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 77, 79, 80, 82, 84, 85, 87, 88, 90,
 91, 92, 94, 95, 96, 98, 99,100,102,103,104,105,107,108,109,110,111,112,114,115,116,117,118,119,120,121,122,123,124,125,126,127,
128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,144,145,146,147,148,149,150,151,151,152,153,154,155,156,156,
157,158,159,160,160,161,162,163,164,164,165,166,167,168,168,169,170,171,171,172,173,174,174,175,176,176,177,178,179,179,180,181,
182,182,183,184,184,185,186,186,187,188,188,189,190,190,191,192,192,193,194,194,195,196,196,197,198,198,199,200,200,201,202,202,
203,204,204,205,205,206,207,207,208,208,209,210,210,211,212,212,213,213,214,215,215,216,216,217,218,218,219,219,220,220,221,222,
222,223,223,224,224,225,226,226,227,227,228,228,229,230,230,231,231,232,232,233,233,234,235,235,236,236,237,237,238,238,239,239,
240,240,241,242,242,243,243,244,244,245,245,246,246,247,247,248,248,249,249,250,250,251,251,252,252,253,253,254,254,255,255,255
}

Definition at line 31 of file mathematics.c.


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