9414bc956c5f3455ca6502e52df10d463124ee3e
[libav.git] / libavcodec / eval.c
1 /*
2 * simple arithmetic expression evaluator
3 *
4 * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
5 *
6 * This library 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 of the License, or (at your option) any later version.
10 *
11 * This library 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 this library; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 *
20 */
21
22 /**
23 * @file eval.c
24 * simple arithmetic expression evaluator.
25 *
26 * see http://joe.hotchkiss.com/programming/eval/eval.html
27 */
28
29 #include "avcodec.h"
30 #include "mpegvideo.h"
31
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #include <math.h>
36
37 #ifndef NAN
38 #define NAN 0.0/0.0
39 #endif
40
41 #ifndef M_PI
42 #define M_PI 3.14159265358979323846
43 #endif
44
45 typedef struct Parser{
46 int stack_index;
47 char *s;
48 double *const_value;
49 const char **const_name; // NULL terminated
50 double (**func1)(void *, double a); // NULL terminated
51 const char **func1_name; // NULL terminated
52 double (**func2)(void *, double a, double b); // NULL terminated
53 char **func2_name; // NULL terminated
54 void *opaque;
55 char **error;
56 } Parser;
57
58 static double evalExpression(Parser *p);
59
60 static int8_t si_prefixes['z' - 'E' + 1]={
61 ['y'-'E']= -24,
62 ['z'-'E']= -21,
63 ['a'-'E']= -18,
64 ['f'-'E']= -15,
65 ['p'-'E']= -12,
66 ['n'-'E']= - 9,
67 ['u'-'E']= - 6,
68 ['m'-'E']= - 3,
69 ['c'-'E']= - 2,
70 ['d'-'E']= - 1,
71 ['h'-'E']= 2,
72 ['k'-'E']= 3,
73 ['K'-'E']= 3,
74 ['M'-'E']= 6,
75 ['G'-'E']= 9,
76 ['T'-'E']= 12,
77 ['P'-'E']= 15,
78 ['E'-'E']= 18,
79 ['Z'-'E']= 21,
80 ['Y'-'E']= 24,
81 };
82
83 /** strtod() function extended with 'k', 'M', 'G', 'ki', 'Mi', 'Gi' and 'B'
84 * postfixes. This allows using f.e. kB, MiB, G and B as a postfix. This
85 * function assumes that the unit of numbers is bits not bytes.
86 */
87 static double av_strtod(const char *name, char **tail) {
88 double d;
89 int p = 0;
90 char *next;
91 d = strtod(name, &next);
92 /* if parsing succeeded, check for and interpret postfixes */
93 if (next!=name) {
94
95 if(*next >= 'E' && *next <= 'z'){
96 int e= si_prefixes[*next - 'E'];
97 if(e){
98 if(next[1] == 'i'){
99 d*= pow( 2, e/0.3);
100 next+=2;
101 }else{
102 d*= pow(10, e);
103 next++;
104 }
105 }
106 }
107
108 if(*next=='B') {
109 d*=8;
110 *next++;
111 }
112 }
113 /* if requested, fill in tail with the position after the last parsed
114 character */
115 if (tail)
116 *tail = next;
117 return d;
118 }
119
120 static int strmatch(const char *s, const char *prefix){
121 int i;
122 for(i=0; prefix[i]; i++){
123 if(prefix[i] != s[i]) return 0;
124 }
125 return 1;
126 }
127
128 static double evalPrimary(Parser *p){
129 double d, d2=NAN;
130 char *next= p->s;
131 int i;
132
133 /* number */
134 d= av_strtod(p->s, &next);
135 if(next != p->s){
136 p->s= next;
137 return d;
138 }
139
140 /* named constants */
141 for(i=0; p->const_name && p->const_name[i]; i++){
142 if(strmatch(p->s, p->const_name[i])){
143 p->s+= strlen(p->const_name[i]);
144 return p->const_value[i];
145 }
146 }
147
148 p->s= strchr(p->s, '(');
149 if(p->s==NULL){
150 *p->error = "missing (";
151 p->s= next;
152 return NAN;
153 }
154 p->s++; // "("
155 d= evalExpression(p);
156 if(p->s[0]== ','){
157 p->s++; // ","
158 d2= evalExpression(p);
159 }
160 if(p->s[0] != ')'){
161 *p->error = "missing )";
162 return NAN;
163 }
164 p->s++; // ")"
165
166 if( strmatch(next, "sinh" ) ) d= sinh(d);
167 else if( strmatch(next, "cosh" ) ) d= cosh(d);
168 else if( strmatch(next, "tanh" ) ) d= tanh(d);
169 else if( strmatch(next, "sin" ) ) d= sin(d);
170 else if( strmatch(next, "cos" ) ) d= cos(d);
171 else if( strmatch(next, "tan" ) ) d= tan(d);
172 else if( strmatch(next, "exp" ) ) d= exp(d);
173 else if( strmatch(next, "log" ) ) d= log(d);
174 else if( strmatch(next, "squish") ) d= 1/(1+exp(4*d));
175 else if( strmatch(next, "gauss" ) ) d= exp(-d*d/2)/sqrt(2*M_PI);
176 else if( strmatch(next, "abs" ) ) d= fabs(d);
177 else if( strmatch(next, "max" ) ) d= d > d2 ? d : d2;
178 else if( strmatch(next, "min" ) ) d= d < d2 ? d : d2;
179 else if( strmatch(next, "gt" ) ) d= d > d2 ? 1.0 : 0.0;
180 else if( strmatch(next, "gte" ) ) d= d >= d2 ? 1.0 : 0.0;
181 else if( strmatch(next, "lt" ) ) d= d > d2 ? 0.0 : 1.0;
182 else if( strmatch(next, "lte" ) ) d= d >= d2 ? 0.0 : 1.0;
183 else if( strmatch(next, "eq" ) ) d= d == d2 ? 1.0 : 0.0;
184 else if( strmatch(next, "(" ) ) d= d;
185 // else if( strmatch(next, "l1" ) ) d= 1 + d2*(d - 1);
186 // else if( strmatch(next, "sq01" ) ) d= (d >= 0.0 && d <=1.0) ? 1.0 : 0.0;
187 else{
188 for(i=0; p->func1_name && p->func1_name[i]; i++){
189 if(strmatch(next, p->func1_name[i])){
190 return p->func1[i](p->opaque, d);
191 }
192 }
193
194 for(i=0; p->func2_name && p->func2_name[i]; i++){
195 if(strmatch(next, p->func2_name[i])){
196 return p->func2[i](p->opaque, d, d2);
197 }
198 }
199
200 *p->error = "unknown function";
201 return NAN;
202 }
203
204 return d;
205 }
206
207 static double evalPow(Parser *p){
208 int sign= (*p->s == '+') - (*p->s == '-');
209 p->s += sign&1;
210 return (sign|1) * evalPrimary(p);
211 }
212
213 static double evalFactor(Parser *p){
214 double ret= evalPow(p);
215 while(p->s[0]=='^'){
216 p->s++;
217 ret= pow(ret, evalPow(p));
218 }
219 return ret;
220 }
221
222 static double evalTerm(Parser *p){
223 double ret= evalFactor(p);
224 while(p->s[0]=='*' || p->s[0]=='/'){
225 if(*p->s++ == '*') ret*= evalFactor(p);
226 else ret/= evalFactor(p);
227 }
228 return ret;
229 }
230
231 static double evalExpression(Parser *p){
232 double ret= 0;
233
234 if(p->stack_index <= 0) //protect against stack overflows
235 return NAN;
236 p->stack_index--;
237
238 do{
239 ret += evalTerm(p);
240 }while(*p->s == '+' || *p->s == '-');
241
242 p->stack_index++;
243
244 return ret;
245 }
246
247 double ff_eval2(char *s, double *const_value, const char **const_name,
248 double (**func1)(void *, double), const char **func1_name,
249 double (**func2)(void *, double, double), char **func2_name,
250 void *opaque, char **error){
251 Parser p;
252
253 p.stack_index=100;
254 p.s= s;
255 p.const_value= const_value;
256 p.const_name = const_name;
257 p.func1 = func1;
258 p.func1_name = func1_name;
259 p.func2 = func2;
260 p.func2_name = func2_name;
261 p.opaque = opaque;
262 p.error= error;
263
264 return evalExpression(&p);
265 }
266
267 #if LIBAVCODEC_VERSION_INT < ((52<<16)+(0<<8)+0)
268 attribute_deprecated double ff_eval(char *s, double *const_value, const char **const_name,
269 double (**func1)(void *, double), const char **func1_name,
270 double (**func2)(void *, double, double), char **func2_name,
271 void *opaque){
272 char *error=NULL;
273 double ret;
274 ret = ff_eval2(s, const_value, const_name, func1, func1_name, func2, func2_name, opaque, &error);
275 if (error)
276 av_log(NULL, AV_LOG_ERROR, "Error evaluating \"%s\": %s\n", s, error);
277 return ret;
278 }
279 #endif
280
281 #ifdef TEST
282 #undef printf
283 static double const_values[]={
284 M_PI,
285 M_E,
286 0
287 };
288 static const char *const_names[]={
289 "PI",
290 "E",
291 0
292 };
293 main(){
294 int i;
295 printf("%f == 12.7\n", ff_eval("1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)", const_values, const_names, NULL, NULL, NULL, NULL, NULL));
296 printf("%f == 0.931322575\n", ff_eval("80G/80Gi", const_values, const_names, NULL, NULL, NULL, NULL, NULL));
297
298 for(i=0; i<1050; i++){
299 START_TIMER
300 ff_eval("1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)", const_values, const_names, NULL, NULL, NULL, NULL, NULL);
301 STOP_TIMER("ff_eval")
302 }
303 }
304 #endif