2 * simple arithmetic expression evaluator
4 * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
6 * This file is part of FFmpeg.
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
26 * simple arithmetic expression evaluator.
28 * see http://joe.hotchkiss.com/programming/eval/eval.html
32 #include "mpegvideo.h"
44 #define M_PI 3.14159265358979323846
47 typedef struct Parser{
51 const char **const_name; // NULL terminated
52 double (**func1)(void *, double a); // NULL terminated
53 const char **func1_name; // NULL terminated
54 double (**func2)(void *, double a, double b); // NULL terminated
55 char **func2_name; // NULL terminated
60 static double evalExpression(Parser *p);
62 static int8_t si_prefixes['z' - 'E' + 1]={
85 /** strtod() function extended with 'k', 'M', 'G', 'ki', 'Mi', 'Gi' and 'B'
86 * postfixes. This allows using f.e. kB, MiB, G and B as a postfix. This
87 * function assumes that the unit of numbers is bits not bytes.
89 static double av_strtod(const char *name, char **tail) {
92 d = strtod(name, &next);
93 /* if parsing succeeded, check for and interpret postfixes */
96 if(*next >= 'E' && *next <= 'z'){
97 int e= si_prefixes[*next - 'E'];
114 /* if requested, fill in tail with the position after the last parsed
121 static int strmatch(const char *s, const char *prefix){
123 for(i=0; prefix[i]; i++){
124 if(prefix[i] != s[i]) return 0;
129 static double evalPrimary(Parser *p){
135 d= av_strtod(p->s, &next);
141 /* named constants */
142 for(i=0; p->const_name && p->const_name[i]; i++){
143 if(strmatch(p->s, p->const_name[i])){
144 p->s+= strlen(p->const_name[i]);
145 return p->const_value[i];
149 p->s= strchr(p->s, '(');
151 *p->error = "missing (";
156 d= evalExpression(p);
159 d2= evalExpression(p);
162 *p->error = "missing )";
167 if( strmatch(next, "sinh" ) ) d= sinh(d);
168 else if( strmatch(next, "cosh" ) ) d= cosh(d);
169 else if( strmatch(next, "tanh" ) ) d= tanh(d);
170 else if( strmatch(next, "sin" ) ) d= sin(d);
171 else if( strmatch(next, "cos" ) ) d= cos(d);
172 else if( strmatch(next, "tan" ) ) d= tan(d);
173 else if( strmatch(next, "exp" ) ) d= exp(d);
174 else if( strmatch(next, "log" ) ) d= log(d);
175 else if( strmatch(next, "squish") ) d= 1/(1+exp(4*d));
176 else if( strmatch(next, "gauss" ) ) d= exp(-d*d/2)/sqrt(2*M_PI);
177 else if( strmatch(next, "abs" ) ) d= fabs(d);
178 else if( strmatch(next, "max" ) ) d= d > d2 ? d : d2;
179 else if( strmatch(next, "min" ) ) d= d < d2 ? d : d2;
180 else if( strmatch(next, "gt" ) ) d= d > d2 ? 1.0 : 0.0;
181 else if( strmatch(next, "gte" ) ) d= d >= d2 ? 1.0 : 0.0;
182 else if( strmatch(next, "lt" ) ) d= d > d2 ? 0.0 : 1.0;
183 else if( strmatch(next, "lte" ) ) d= d >= d2 ? 0.0 : 1.0;
184 else if( strmatch(next, "eq" ) ) d= d == d2 ? 1.0 : 0.0;
185 else if( strmatch(next, "(" ) ) d= d;
186 // else if( strmatch(next, "l1" ) ) d= 1 + d2*(d - 1);
187 // else if( strmatch(next, "sq01" ) ) d= (d >= 0.0 && d <=1.0) ? 1.0 : 0.0;
189 for(i=0; p->func1_name && p->func1_name[i]; i++){
190 if(strmatch(next, p->func1_name[i])){
191 return p->func1[i](p->opaque, d);
195 for(i=0; p->func2_name && p->func2_name[i]; i++){
196 if(strmatch(next, p->func2_name[i])){
197 return p->func2[i](p->opaque, d, d2);
201 *p->error = "unknown function";
208 static double evalPow(Parser *p){
209 int sign= (*p->s == '+') - (*p->s == '-');
211 return (sign|1) * evalPrimary(p);
214 static double evalFactor(Parser *p){
215 double ret= evalPow(p);
218 ret= pow(ret, evalPow(p));
223 static double evalTerm(Parser *p){
224 double ret= evalFactor(p);
225 while(p->s[0]=='*' || p->s[0]=='/'){
226 if(*p->s++ == '*') ret*= evalFactor(p);
227 else ret/= evalFactor(p);
232 static double evalExpression(Parser *p){
235 if(p->stack_index <= 0) //protect against stack overflows
241 }while(*p->s == '+' || *p->s == '-');
248 double ff_eval2(char *s, double *const_value, const char **const_name,
249 double (**func1)(void *, double), const char **func1_name,
250 double (**func2)(void *, double, double), char **func2_name,
251 void *opaque, char **error){
256 p.const_value= const_value;
257 p.const_name = const_name;
259 p.func1_name = func1_name;
261 p.func2_name = func2_name;
265 return evalExpression(&p);
268 #if LIBAVCODEC_VERSION_INT < ((52<<16)+(0<<8)+0)
269 attribute_deprecated double ff_eval(char *s, double *const_value, const char **const_name,
270 double (**func1)(void *, double), const char **func1_name,
271 double (**func2)(void *, double, double), char **func2_name,
275 ret = ff_eval2(s, const_value, const_name, func1, func1_name, func2, func2_name, opaque, &error);
277 av_log(NULL, AV_LOG_ERROR, "Error evaluating \"%s\": %s\n", s, error);
284 static double const_values[]={
289 static const char *const_names[]={
296 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));
297 printf("%f == 0.931322575\n", ff_eval("80G/80Gi", const_values, const_names, NULL, NULL, NULL, NULL, NULL));
299 for(i=0; i<1050; i++){
301 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);
302 STOP_TIMER("ff_eval")