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mathematics.c
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1 /*
2  * Copyright (c) 2005-2012 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
23  * miscellaneous math routines and tables
24  */
25 
26 #include <stdint.h>
27 #include <limits.h>
28 
29 #include "mathematics.h"
30 #include "libavutil/common.h"
31 #include "avassert.h"
32 #include "version.h"
33 
34 #if FF_API_AV_REVERSE
35 const uint8_t av_reverse[256] = {
36 0x00,0x80,0x40,0xC0,0x20,0xA0,0x60,0xE0,0x10,0x90,0x50,0xD0,0x30,0xB0,0x70,0xF0,
37 0x08,0x88,0x48,0xC8,0x28,0xA8,0x68,0xE8,0x18,0x98,0x58,0xD8,0x38,0xB8,0x78,0xF8,
38 0x04,0x84,0x44,0xC4,0x24,0xA4,0x64,0xE4,0x14,0x94,0x54,0xD4,0x34,0xB4,0x74,0xF4,
39 0x0C,0x8C,0x4C,0xCC,0x2C,0xAC,0x6C,0xEC,0x1C,0x9C,0x5C,0xDC,0x3C,0xBC,0x7C,0xFC,
40 0x02,0x82,0x42,0xC2,0x22,0xA2,0x62,0xE2,0x12,0x92,0x52,0xD2,0x32,0xB2,0x72,0xF2,
41 0x0A,0x8A,0x4A,0xCA,0x2A,0xAA,0x6A,0xEA,0x1A,0x9A,0x5A,0xDA,0x3A,0xBA,0x7A,0xFA,
42 0x06,0x86,0x46,0xC6,0x26,0xA6,0x66,0xE6,0x16,0x96,0x56,0xD6,0x36,0xB6,0x76,0xF6,
43 0x0E,0x8E,0x4E,0xCE,0x2E,0xAE,0x6E,0xEE,0x1E,0x9E,0x5E,0xDE,0x3E,0xBE,0x7E,0xFE,
44 0x01,0x81,0x41,0xC1,0x21,0xA1,0x61,0xE1,0x11,0x91,0x51,0xD1,0x31,0xB1,0x71,0xF1,
45 0x09,0x89,0x49,0xC9,0x29,0xA9,0x69,0xE9,0x19,0x99,0x59,0xD9,0x39,0xB9,0x79,0xF9,
46 0x05,0x85,0x45,0xC5,0x25,0xA5,0x65,0xE5,0x15,0x95,0x55,0xD5,0x35,0xB5,0x75,0xF5,
47 0x0D,0x8D,0x4D,0xCD,0x2D,0xAD,0x6D,0xED,0x1D,0x9D,0x5D,0xDD,0x3D,0xBD,0x7D,0xFD,
48 0x03,0x83,0x43,0xC3,0x23,0xA3,0x63,0xE3,0x13,0x93,0x53,0xD3,0x33,0xB3,0x73,0xF3,
49 0x0B,0x8B,0x4B,0xCB,0x2B,0xAB,0x6B,0xEB,0x1B,0x9B,0x5B,0xDB,0x3B,0xBB,0x7B,0xFB,
50 0x07,0x87,0x47,0xC7,0x27,0xA7,0x67,0xE7,0x17,0x97,0x57,0xD7,0x37,0xB7,0x77,0xF7,
51 0x0F,0x8F,0x4F,0xCF,0x2F,0xAF,0x6F,0xEF,0x1F,0x9F,0x5F,0xDF,0x3F,0xBF,0x7F,0xFF,
52 };
53 #endif
54 
55 int64_t av_gcd(int64_t a, int64_t b)
56 {
57  if (b)
58  return av_gcd(b, a % b);
59  else
60  return a;
61 }
62 
63 int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding rnd)
64 {
65  int64_t r = 0;
66  av_assert2(c > 0);
67  av_assert2(b >=0);
68  av_assert2((unsigned)(rnd&~AV_ROUND_PASS_MINMAX)<=5 && (rnd&~AV_ROUND_PASS_MINMAX)!=4);
69 
70  if (c <= 0 || b < 0 || !((unsigned)(rnd&~AV_ROUND_PASS_MINMAX)<=5 && (rnd&~AV_ROUND_PASS_MINMAX)!=4))
71  return INT64_MIN;
72 
73  if (rnd & AV_ROUND_PASS_MINMAX) {
74  if (a == INT64_MIN || a == INT64_MAX)
75  return a;
76  rnd -= AV_ROUND_PASS_MINMAX;
77  }
78 
79  if (a < 0 && a != INT64_MIN)
80  return -av_rescale_rnd(-a, b, c, rnd ^ ((rnd >> 1) & 1));
81 
82  if (rnd == AV_ROUND_NEAR_INF)
83  r = c / 2;
84  else if (rnd & 1)
85  r = c - 1;
86 
87  if (b <= INT_MAX && c <= INT_MAX) {
88  if (a <= INT_MAX)
89  return (a * b + r) / c;
90  else
91  return a / c * b + (a % c * b + r) / c;
92  } else {
93 #if 1
94  uint64_t a0 = a & 0xFFFFFFFF;
95  uint64_t a1 = a >> 32;
96  uint64_t b0 = b & 0xFFFFFFFF;
97  uint64_t b1 = b >> 32;
98  uint64_t t1 = a0 * b1 + a1 * b0;
99  uint64_t t1a = t1 << 32;
100  int i;
101 
102  a0 = a0 * b0 + t1a;
103  a1 = a1 * b1 + (t1 >> 32) + (a0 < t1a);
104  a0 += r;
105  a1 += a0 < r;
106 
107  for (i = 63; i >= 0; i--) {
108  a1 += a1 + ((a0 >> i) & 1);
109  t1 += t1;
110  if (c <= a1) {
111  a1 -= c;
112  t1++;
113  }
114  }
115  return t1;
116  }
117 #else
118  AVInteger ai;
119  ai = av_mul_i(av_int2i(a), av_int2i(b));
120  ai = av_add_i(ai, av_int2i(r));
121 
122  return av_i2int(av_div_i(ai, av_int2i(c)));
123  }
124 #endif
125 }
126 
127 int64_t av_rescale(int64_t a, int64_t b, int64_t c)
128 {
129  return av_rescale_rnd(a, b, c, AV_ROUND_NEAR_INF);
130 }
131 
132 int64_t av_rescale_q_rnd(int64_t a, AVRational bq, AVRational cq,
133  enum AVRounding rnd)
134 {
135  int64_t b = bq.num * (int64_t)cq.den;
136  int64_t c = cq.num * (int64_t)bq.den;
137  return av_rescale_rnd(a, b, c, rnd);
138 }
139 
140 int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq)
141 {
142  return av_rescale_q_rnd(a, bq, cq, AV_ROUND_NEAR_INF);
143 }
144 
145 int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b)
146 {
147  int64_t a = tb_a.num * (int64_t)tb_b.den;
148  int64_t b = tb_b.num * (int64_t)tb_a.den;
149  if ((FFABS(ts_a)|a|FFABS(ts_b)|b) <= INT_MAX)
150  return (ts_a*a > ts_b*b) - (ts_a*a < ts_b*b);
151  if (av_rescale_rnd(ts_a, a, b, AV_ROUND_DOWN) < ts_b)
152  return -1;
153  if (av_rescale_rnd(ts_b, b, a, AV_ROUND_DOWN) < ts_a)
154  return 1;
155  return 0;
156 }
157 
158 int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod)
159 {
160  int64_t c = (a - b) & (mod - 1);
161  if (c > (mod >> 1))
162  c -= mod;
163  return c;
164 }
165 
166 int64_t av_rescale_delta(AVRational in_tb, int64_t in_ts, AVRational fs_tb, int duration, int64_t *last, AVRational out_tb){
167  int64_t a, b, this;
168 
169  av_assert0(in_ts != AV_NOPTS_VALUE);
170  av_assert0(duration >= 0);
171 
172  if (*last == AV_NOPTS_VALUE || !duration || in_tb.num*(int64_t)out_tb.den <= out_tb.num*(int64_t)in_tb.den) {
173 simple_round:
174  *last = av_rescale_q(in_ts, in_tb, fs_tb) + duration;
175  return av_rescale_q(in_ts, in_tb, out_tb);
176  }
177 
178  a = av_rescale_q_rnd(2*in_ts-1, in_tb, fs_tb, AV_ROUND_DOWN) >>1;
179  b = (av_rescale_q_rnd(2*in_ts+1, in_tb, fs_tb, AV_ROUND_UP )+1)>>1;
180  if (*last < 2*a - b || *last > 2*b - a)
181  goto simple_round;
182 
183  this = av_clip64(*last, a, b);
184  *last = this + duration;
185 
186  return av_rescale_q(this, fs_tb, out_tb);
187 }
188 
189 int64_t av_add_stable(AVRational ts_tb, int64_t ts, AVRational inc_tb, int64_t inc)
190 {
191  int64_t m, d;
192 
193  if (inc != 1)
194  inc_tb = av_mul_q(inc_tb, (AVRational) {inc, 1});
195 
196  m = inc_tb.num * (int64_t)ts_tb.den;
197  d = inc_tb.den * (int64_t)ts_tb.num;
198 
199  if (m % d == 0)
200  return ts + m / d;
201  if (m < d)
202  return ts;
203 
204  {
205  int64_t old = av_rescale_q(ts, ts_tb, inc_tb);
206  int64_t old_ts = av_rescale_q(old, inc_tb, ts_tb);
207  return av_rescale_q(old + 1, inc_tb, ts_tb) + (ts - old_ts);
208  }
209 }