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