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1/*
2 * arbitrary precision integers
3 * Copyright (c) 2004 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/**
23 * @file
24 * arbitrary precision integers
25 * @author Michael Niedermayer <michaelni@gmx.at>
26 */
27
28#include "common.h"
29#include "integer.h"
30#include "avassert.h"
31
32static const AVInteger zero_i;
33
34AVInteger av_add_i(AVInteger a, AVInteger b){
35 int i, carry=0;
36
37 for(i=0; i<AV_INTEGER_SIZE; i++){
38 carry= (carry>>16) + a.v[i] + b.v[i];
39 a.v[i]= carry;
40 }
41 return a;
42}
43
44AVInteger av_sub_i(AVInteger a, AVInteger b){
45 int i, carry=0;
46
47 for(i=0; i<AV_INTEGER_SIZE; i++){
48 carry= (carry>>16) + a.v[i] - b.v[i];
49 a.v[i]= carry;
50 }
51 return a;
52}
53
54int av_log2_i(AVInteger a){
55 int i;
56
57 for(i=AV_INTEGER_SIZE-1; i>=0; i--){
58 if(a.v[i])
59 return av_log2_16bit(a.v[i]) + 16*i;
60 }
61 return -1;
62}
63
64AVInteger av_mul_i(AVInteger a, AVInteger b){
65 AVInteger out;
66 int i, j;
67 int na= (av_log2_i(a)+16) >> 4;
68 int nb= (av_log2_i(b)+16) >> 4;
69
70 memset(&out, 0, sizeof(out));
71
72 for(i=0; i<na; i++){
73 unsigned int carry=0;
74
75 if(a.v[i])
76 for(j=i; j<AV_INTEGER_SIZE && j-i<=nb; j++){
77 carry= (carry>>16) + out.v[j] + a.v[i]*b.v[j-i];
78 out.v[j]= carry;
79 }
80 }
81
82 return out;
83}
84
85int av_cmp_i(AVInteger a, AVInteger b){
86 int i;
87 int v= (int16_t)a.v[AV_INTEGER_SIZE-1] - (int16_t)b.v[AV_INTEGER_SIZE-1];
88 if(v) return (v>>16)|1;
89
90 for(i=AV_INTEGER_SIZE-2; i>=0; i--){
91 int v= a.v[i] - b.v[i];
92 if(v) return (v>>16)|1;
93 }
94 return 0;
95}
96
97AVInteger av_shr_i(AVInteger a, int s){
98 AVInteger out;
99 int i;
100
101 for(i=0; i<AV_INTEGER_SIZE; i++){
102 unsigned int index= i + (s>>4);
103 unsigned int v=0;
104 if(index+1<AV_INTEGER_SIZE) v = a.v[index+1]<<16;
105 if(index <AV_INTEGER_SIZE) v+= a.v[index ];
106 out.v[i]= v >> (s&15);
107 }
108 return out;
109}
110
111AVInteger av_mod_i(AVInteger *quot, AVInteger a, AVInteger b){
112 int i= av_log2_i(a) - av_log2_i(b);
113 AVInteger quot_temp;
114 if(!quot) quot = &quot_temp;
115
116 if ((int16_t)a.v[AV_INTEGER_SIZE-1] < 0) {
117 a = av_mod_i(quot, av_sub_i(zero_i, a), b);
118 *quot = av_sub_i(zero_i, *quot);
119 return av_sub_i(zero_i, a);
120 }
121
122 av_assert2((int16_t)a.v[AV_INTEGER_SIZE-1] >= 0 && (int16_t)b.v[AV_INTEGER_SIZE-1] >= 0);
123 av_assert2(av_log2_i(b)>=0);
124
125 if(i > 0)
126 b= av_shr_i(b, -i);
127
128 memset(quot, 0, sizeof(AVInteger));
129
130 while(i-- >= 0){
131 *quot= av_shr_i(*quot, -1);
132 if(av_cmp_i(a, b) >= 0){
133 a= av_sub_i(a, b);
134 quot->v[0] += 1;
135 }
136 b= av_shr_i(b, 1);
137 }
138 return a;
139}
140
141AVInteger av_div_i(AVInteger a, AVInteger b){
142 AVInteger quot;
143 av_mod_i(&quot, a, b);
144 return quot;
145}
146
147AVInteger av_int2i(int64_t a){
148 AVInteger out;
149 int i;
150
151 for(i=0; i<AV_INTEGER_SIZE; i++){
152 out.v[i]= a;
153 a>>=16;
154 }
155 return out;
156}
157
158int64_t av_i2int(AVInteger a){
159 int i;
160 int64_t out=(int8_t)a.v[AV_INTEGER_SIZE-1];
161
162 for(i= AV_INTEGER_SIZE-2; i>=0; i--){
163 out = (out<<16) + a.v[i];
164 }
165 return out;
166}
167
168#ifdef TEST
169
170const uint8_t ff_log2_tab[256]={
171 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,
172 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,
173 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,
174 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,
175 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,
176 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,
177 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,
178 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
179};
180
181int main(void){
182 int64_t a,b;
183
184 for(a=7; a<256*256*256; a+=13215){
185 for(b=3; b<256*256*256; b+=27118){
186 AVInteger ai= av_int2i(a);
187 AVInteger bi= av_int2i(b);
188
189 av_assert0(av_i2int(ai) == a);
190 av_assert0(av_i2int(bi) == b);
191 av_assert0(av_i2int(av_add_i(ai,bi)) == a+b);
192 av_assert0(av_i2int(av_sub_i(ai,bi)) == a-b);
193 av_assert0(av_i2int(av_mul_i(ai,bi)) == a*b);
194 av_assert0(av_i2int(av_shr_i(ai, 9)) == a>>9);
195 av_assert0(av_i2int(av_shr_i(ai,-9)) == a<<9);
196 av_assert0(av_i2int(av_shr_i(ai, 17)) == a>>17);
197 av_assert0(av_i2int(av_shr_i(ai,-17)) == a<<17);
198 av_assert0(av_log2_i(ai) == av_log2(a));
199 av_assert0(av_i2int(av_div_i(ai,bi)) == a/b);
200 }
201 }
202 return 0;
203}
204#endif
205
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