2 * simple arithmetic expression evaluator
4 * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
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.
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.
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
24 * simple arithmetic expression evaluator.
26 * see http://joe.hotchkiss.com/programming/eval/eval.html
30 #include "mpegvideo.h"
42 #define M_PI 3.14159265358979323846
45 typedef struct Parser{
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
57 static double evalExpression(Parser *p);
59 static int strmatch(const char *s, const char *prefix){
61 for(i=0; prefix[i]; i++){
62 if(prefix[i] != s[i]) return 0;
67 static int8_t si_prefixes['z' - 'E' + 1]={
90 static double evalPrimary(Parser *p){
96 d= strtod(p->s, &next);
98 if(*next >= 'E' && *next <= 'z'){
99 int e= si_prefixes[*next - 'E'];
114 /* named constants */
115 for(i=0; p->const_name && p->const_name[i]; i++){
116 if(strmatch(p->s, p->const_name[i])){
117 p->s+= strlen(p->const_name[i]);
118 return p->const_value[i];
122 p->s= strchr(p->s, '(');
124 av_log(NULL, AV_LOG_ERROR, "Parser: missing ( in \"%s\"\n", next);
128 d= evalExpression(p);
131 d2= evalExpression(p);
134 av_log(NULL, AV_LOG_ERROR, "Parser: missing ) in \"%s\"\n", next);
139 if( strmatch(next, "sinh" ) ) d= sinh(d);
140 else if( strmatch(next, "cosh" ) ) d= cosh(d);
141 else if( strmatch(next, "tanh" ) ) d= tanh(d);
142 else if( strmatch(next, "sin" ) ) d= sin(d);
143 else if( strmatch(next, "cos" ) ) d= cos(d);
144 else if( strmatch(next, "tan" ) ) d= tan(d);
145 else if( strmatch(next, "exp" ) ) d= exp(d);
146 else if( strmatch(next, "log" ) ) d= log(d);
147 else if( strmatch(next, "squish") ) d= 1/(1+exp(4*d));
148 else if( strmatch(next, "gauss" ) ) d= exp(-d*d/2)/sqrt(2*M_PI);
149 else if( strmatch(next, "abs" ) ) d= fabs(d);
150 else if( strmatch(next, "max" ) ) d= d > d2 ? d : d2;
151 else if( strmatch(next, "min" ) ) d= d < d2 ? d : d2;
152 else if( strmatch(next, "gt" ) ) d= d > d2 ? 1.0 : 0.0;
153 else if( strmatch(next, "gte" ) ) d= d >= d2 ? 1.0 : 0.0;
154 else if( strmatch(next, "lt" ) ) d= d > d2 ? 0.0 : 1.0;
155 else if( strmatch(next, "lte" ) ) d= d >= d2 ? 0.0 : 1.0;
156 else if( strmatch(next, "eq" ) ) d= d == d2 ? 1.0 : 0.0;
157 else if( strmatch(next, "(" ) ) d= d;
158 // else if( strmatch(next, "l1" ) ) d= 1 + d2*(d - 1);
159 // else if( strmatch(next, "sq01" ) ) d= (d >= 0.0 && d <=1.0) ? 1.0 : 0.0;
161 for(i=0; p->func1_name && p->func1_name[i]; i++){
162 if(strmatch(next, p->func1_name[i])){
163 return p->func1[i](p->opaque, d);
167 for(i=0; p->func2_name && p->func2_name[i]; i++){
168 if(strmatch(next, p->func2_name[i])){
169 return p->func2[i](p->opaque, d, d2);
173 av_log(NULL, AV_LOG_ERROR, "Parser: unknown function in \"%s\"\n", next);
180 static double evalPow(Parser *p){
181 int sign= (*p->s == '+') - (*p->s == '-');
183 return (sign|1) * evalPrimary(p);
186 static double evalFactor(Parser *p){
187 double ret= evalPow(p);
190 ret= pow(ret, evalPow(p));
195 static double evalTerm(Parser *p){
196 double ret= evalFactor(p);
197 while(p->s[0]=='*' || p->s[0]=='/'){
198 if(*p->s++ == '*') ret*= evalFactor(p);
199 else ret/= evalFactor(p);
204 static double evalExpression(Parser *p){
207 if(p->stack_index <= 0) //protect against stack overflows
213 }while(*p->s == '+' || *p->s == '-');
220 double ff_eval(char *s, double *const_value, const char **const_name,
221 double (**func1)(void *, double), const char **func1_name,
222 double (**func2)(void *, double, double), char **func2_name,
228 p.const_value= const_value;
229 p.const_name = const_name;
231 p.func1_name = func1_name;
233 p.func2_name = func2_name;
236 return evalExpression(&p);
241 static double const_values[]={
246 static const char *const_names[]={
253 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));
254 printf("%f == 0.931322575\n", ff_eval("80G/80Gi", const_values, const_names, NULL, NULL, NULL, NULL, NULL));
256 for(i=0; i<1050; i++){
258 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);
259 STOP_TIMER("ff_eval")