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ffmpeg / libavutil / eval.c @ d370e3e9

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1
/*
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 * Copyright (c) 2002-2006 Michael Niedermayer <michaelni@gmx.at>
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 * Copyright (c) 2006 Oded Shimon <ods15@ods15.dyndns.org>
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
21

    
22
/**
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 * @file
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 * simple arithmetic expression evaluator.
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 *
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 * see http://joe.hotchkiss.com/programming/eval/eval.html
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 */
28

    
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#include "libavutil/avutil.h"
30
#include "eval.h"
31

    
32
typedef struct Parser {
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    const AVClass *class;
34
    int stack_index;
35
    char *s;
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    const double *const_values;
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    const char * const *const_names;          // NULL terminated
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    double (* const *funcs1)(void *, double a);           // NULL terminated
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    const char * const *func1_names;          // NULL terminated
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    double (* const *funcs2)(void *, double a, double b); // NULL terminated
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    const char * const *func2_names;          // NULL terminated
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    void *opaque;
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    int log_offset;
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    void *log_ctx;
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#define VARS 10
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    double var[VARS];
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} Parser;
48

    
49
static const AVClass class = { "Eval", av_default_item_name, NULL, LIBAVUTIL_VERSION_INT, offsetof(Parser,log_offset), offsetof(Parser,log_ctx) };
50

    
51
static const int8_t si_prefixes['z' - 'E' + 1] = {
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    ['y'-'E']= -24,
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    ['z'-'E']= -21,
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    ['a'-'E']= -18,
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    ['f'-'E']= -15,
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    ['p'-'E']= -12,
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    ['n'-'E']= - 9,
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    ['u'-'E']= - 6,
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    ['m'-'E']= - 3,
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    ['c'-'E']= - 2,
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    ['d'-'E']= - 1,
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    ['h'-'E']=   2,
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    ['k'-'E']=   3,
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    ['K'-'E']=   3,
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    ['M'-'E']=   6,
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    ['G'-'E']=   9,
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    ['T'-'E']=  12,
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    ['P'-'E']=  15,
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    ['E'-'E']=  18,
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    ['Z'-'E']=  21,
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    ['Y'-'E']=  24,
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};
73

    
74
double av_strtod(const char *numstr, char **tail)
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{
76
    double d;
77
    char *next;
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    d = strtod(numstr, &next);
79
    /* if parsing succeeded, check for and interpret postfixes */
80
    if (next!=numstr) {
81
        if (*next >= 'E' && *next <= 'z') {
82
            int e= si_prefixes[*next - 'E'];
83
            if (e) {
84
                if (next[1] == 'i') {
85
                    d*= pow( 2, e/0.3);
86
                    next+=2;
87
                } else {
88
                    d*= pow(10, e);
89
                    next++;
90
                }
91
            }
92
        }
93

    
94
        if (*next=='B') {
95
            d*=8;
96
            next++;
97
        }
98
    }
99
    /* if requested, fill in tail with the position after the last parsed
100
       character */
101
    if (tail)
102
        *tail = next;
103
    return d;
104
}
105

    
106
#define IS_IDENTIFIER_CHAR(c) ((c) - '0' <= 9U || (c) - 'a' <= 25U || (c) - 'A' <= 25U || (c) == '_')
107

    
108
static int strmatch(const char *s, const char *prefix)
109
{
110
    int i;
111
    for (i=0; prefix[i]; i++) {
112
        if (prefix[i] != s[i]) return 0;
113
    }
114
    /* return 1 only if the s identifier is terminated */
115
    return !IS_IDENTIFIER_CHAR(s[i]);
116
}
117

    
118
struct AVExpr {
119
    enum {
120
        e_value, e_const, e_func0, e_func1, e_func2,
121
        e_squish, e_gauss, e_ld,
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        e_mod, e_max, e_min, e_eq, e_gt, e_gte,
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        e_pow, e_mul, e_div, e_add,
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        e_last, e_st, e_while,
125
    } type;
126
    double value; // is sign in other types
127
    union {
128
        int const_index;
129
        double (*func0)(double);
130
        double (*func1)(void *, double);
131
        double (*func2)(void *, double, double);
132
    } a;
133
    struct AVExpr *param[2];
134
};
135

    
136
static double eval_expr(Parser *p, AVExpr *e)
137
{
138
    switch (e->type) {
139
        case e_value:  return e->value;
140
        case e_const:  return e->value * p->const_values[e->a.const_index];
141
        case e_func0:  return e->value * e->a.func0(eval_expr(p, e->param[0]));
142
        case e_func1:  return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));
143
        case e_func2:  return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
144
        case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));
145
        case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }
146
        case e_ld:     return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];
147
        case e_while: {
148
            double d = NAN;
149
            while (eval_expr(p, e->param[0]))
150
                d=eval_expr(p, e->param[1]);
151
            return d;
152
        }
153
        default: {
154
            double d = eval_expr(p, e->param[0]);
155
            double d2 = eval_expr(p, e->param[1]);
156
            switch (e->type) {
157
                case e_mod: return e->value * (d - floor(d/d2)*d2);
158
                case e_max: return e->value * (d >  d2 ?   d : d2);
159
                case e_min: return e->value * (d <  d2 ?   d : d2);
160
                case e_eq:  return e->value * (d == d2 ? 1.0 : 0.0);
161
                case e_gt:  return e->value * (d >  d2 ? 1.0 : 0.0);
162
                case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0);
163
                case e_pow: return e->value * pow(d, d2);
164
                case e_mul: return e->value * (d * d2);
165
                case e_div: return e->value * (d / d2);
166
                case e_add: return e->value * (d + d2);
167
                case e_last:return e->value * d2;
168
                case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);
169
            }
170
        }
171
    }
172
    return NAN;
173
}
174

    
175
static int parse_expr(AVExpr **e, Parser *p);
176

    
177
void av_free_expr(AVExpr *e)
178
{
179
    if (!e) return;
180
    av_free_expr(e->param[0]);
181
    av_free_expr(e->param[1]);
182
    av_freep(&e);
183
}
184

    
185
static int parse_primary(AVExpr **e, Parser *p)
186
{
187
    AVExpr *d = av_mallocz(sizeof(AVExpr));
188
    char *next = p->s, *s0 = p->s;
189
    int ret, i;
190

    
191
    if (!d)
192
        return AVERROR(ENOMEM);
193

    
194
    /* number */
195
    d->value = av_strtod(p->s, &next);
196
    if (next != p->s) {
197
        d->type = e_value;
198
        p->s= next;
199
        *e = d;
200
        return 0;
201
    }
202
    d->value = 1;
203

    
204
    /* named constants */
205
    for (i=0; p->const_names && p->const_names[i]; i++) {
206
        if (strmatch(p->s, p->const_names[i])) {
207
            p->s+= strlen(p->const_names[i]);
208
            d->type = e_const;
209
            d->a.const_index = i;
210
            *e = d;
211
            return 0;
212
        }
213
    }
214

    
215
    p->s= strchr(p->s, '(');
216
    if (p->s==NULL) {
217
        av_log(p, AV_LOG_ERROR, "Undefined constant or missing '(' in '%s'\n", s0);
218
        p->s= next;
219
        av_free_expr(d);
220
        return AVERROR(EINVAL);
221
    }
222
    p->s++; // "("
223
    if (*next == '(') { // special case do-nothing
224
        av_freep(&d);
225
        if ((ret = parse_expr(&d, p)) < 0)
226
            return ret;
227
        if (p->s[0] != ')') {
228
            av_log(p, AV_LOG_ERROR, "Missing ')' in '%s'\n", s0);
229
            av_free_expr(d);
230
            return AVERROR(EINVAL);
231
        }
232
        p->s++; // ")"
233
        *e = d;
234
        return 0;
235
    }
236
    if ((ret = parse_expr(&(d->param[0]), p)) < 0) {
237
        av_free_expr(d);
238
        return ret;
239
    }
240
    if (p->s[0]== ',') {
241
        p->s++; // ","
242
        parse_expr(&d->param[1], p);
243
    }
244
    if (p->s[0] != ')') {
245
        av_log(p, AV_LOG_ERROR, "Missing ')' or too many args in '%s'\n", s0);
246
        av_free_expr(d);
247
        return AVERROR(EINVAL);
248
    }
249
    p->s++; // ")"
250

    
251
    d->type = e_func0;
252
         if (strmatch(next, "sinh"  )) d->a.func0 = sinh;
253
    else if (strmatch(next, "cosh"  )) d->a.func0 = cosh;
254
    else if (strmatch(next, "tanh"  )) d->a.func0 = tanh;
255
    else if (strmatch(next, "sin"   )) d->a.func0 = sin;
256
    else if (strmatch(next, "cos"   )) d->a.func0 = cos;
257
    else if (strmatch(next, "tan"   )) d->a.func0 = tan;
258
    else if (strmatch(next, "atan"  )) d->a.func0 = atan;
259
    else if (strmatch(next, "asin"  )) d->a.func0 = asin;
260
    else if (strmatch(next, "acos"  )) d->a.func0 = acos;
261
    else if (strmatch(next, "exp"   )) d->a.func0 = exp;
262
    else if (strmatch(next, "log"   )) d->a.func0 = log;
263
    else if (strmatch(next, "abs"   )) d->a.func0 = fabs;
264
    else if (strmatch(next, "squish")) d->type = e_squish;
265
    else if (strmatch(next, "gauss" )) d->type = e_gauss;
266
    else if (strmatch(next, "mod"   )) d->type = e_mod;
267
    else if (strmatch(next, "max"   )) d->type = e_max;
268
    else if (strmatch(next, "min"   )) d->type = e_min;
269
    else if (strmatch(next, "eq"    )) d->type = e_eq;
270
    else if (strmatch(next, "gte"   )) d->type = e_gte;
271
    else if (strmatch(next, "gt"    )) d->type = e_gt;
272
    else if (strmatch(next, "lte"   )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gt; }
273
    else if (strmatch(next, "lt"    )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; }
274
    else if (strmatch(next, "ld"    )) d->type = e_ld;
275
    else if (strmatch(next, "st"    )) d->type = e_st;
276
    else if (strmatch(next, "while" )) d->type = e_while;
277
    else {
278
        for (i=0; p->func1_names && p->func1_names[i]; i++) {
279
            if (strmatch(next, p->func1_names[i])) {
280
                d->a.func1 = p->funcs1[i];
281
                d->type = e_func1;
282
                *e = d;
283
                return 0;
284
            }
285
        }
286

    
287
        for (i=0; p->func2_names && p->func2_names[i]; i++) {
288
            if (strmatch(next, p->func2_names[i])) {
289
                d->a.func2 = p->funcs2[i];
290
                d->type = e_func2;
291
                *e = d;
292
                return 0;
293
            }
294
        }
295

    
296
        av_log(p, AV_LOG_ERROR, "Unknown function in '%s'\n", s0);
297
        av_free_expr(d);
298
        return AVERROR(EINVAL);
299
    }
300

    
301
    *e = d;
302
    return 0;
303
}
304

    
305
static AVExpr *new_eval_expr(int type, int value, AVExpr *p0, AVExpr *p1)
306
{
307
    AVExpr *e = av_mallocz(sizeof(AVExpr));
308
    if (!e)
309
        return NULL;
310
    e->type     =type   ;
311
    e->value    =value  ;
312
    e->param[0] =p0     ;
313
    e->param[1] =p1     ;
314
    return e;
315
}
316

    
317
static int parse_pow(AVExpr **e, Parser *p, int *sign)
318
{
319
    *sign= (*p->s == '+') - (*p->s == '-');
320
    p->s += *sign&1;
321
    return parse_primary(e, p);
322
}
323

    
324
static int parse_factor(AVExpr **e, Parser *p)
325
{
326
    int sign, sign2, ret;
327
    AVExpr *e0, *e1, *e2;
328
    if ((ret = parse_pow(&e0, p, &sign)) < 0)
329
        return ret;
330
    while(p->s[0]=='^'){
331
        e1 = e0;
332
        p->s++;
333
        if ((ret = parse_pow(&e2, p, &sign2)) < 0) {
334
            av_free_expr(e1);
335
            return ret;
336
        }
337
        e0 = new_eval_expr(e_pow, 1, e1, e2);
338
        if (!e0) {
339
            av_free_expr(e1);
340
            av_free_expr(e2);
341
            return AVERROR(ENOMEM);
342
        }
343
        if (e0->param[1]) e0->param[1]->value *= (sign2|1);
344
    }
345
    if (e0) e0->value *= (sign|1);
346

    
347
    *e = e0;
348
    return 0;
349
}
350

    
351
static int parse_term(AVExpr **e, Parser *p)
352
{
353
    int ret;
354
    AVExpr *e0, *e1, *e2;
355
    if ((ret = parse_factor(&e0, p)) < 0)
356
        return ret;
357
    while (p->s[0]=='*' || p->s[0]=='/') {
358
        int c= *p->s++;
359
        e1 = e0;
360
        if ((ret = parse_factor(&e2, p)) < 0) {
361
            av_free_expr(e1);
362
            return ret;
363
        }
364
        e0 = new_eval_expr(c == '*' ? e_mul : e_div, 1, e1, e2);
365
        if (!e0) {
366
            av_free_expr(e1);
367
            av_free_expr(e2);
368
            return AVERROR(ENOMEM);
369
        }
370
    }
371
    *e = e0;
372
    return 0;
373
}
374

    
375
static int parse_subexpr(AVExpr **e, Parser *p)
376
{
377
    int ret;
378
    AVExpr *e0, *e1, *e2;
379
    if ((ret = parse_term(&e0, p)) < 0)
380
        return ret;
381
    while (*p->s == '+' || *p->s == '-') {
382
        e1 = e0;
383
        if ((ret = parse_term(&e2, p)) < 0) {
384
            av_free_expr(e1);
385
            return ret;
386
        }
387
        e0 = new_eval_expr(e_add, 1, e1, e2);
388
        if (!e0) {
389
            av_free_expr(e1);
390
            av_free_expr(e2);
391
            return AVERROR(ENOMEM);
392
        }
393
    };
394

    
395
    *e = e0;
396
    return 0;
397
}
398

    
399
static int parse_expr(AVExpr **e, Parser *p)
400
{
401
    int ret;
402
    AVExpr *e0, *e1, *e2;
403
    if (p->stack_index <= 0) //protect against stack overflows
404
        return AVERROR(EINVAL);
405
    p->stack_index--;
406

    
407
    if ((ret = parse_subexpr(&e0, p)) < 0)
408
        return ret;
409
    while (*p->s == ';') {
410
        p->s++;
411
        e1 = e0;
412
        if ((ret = parse_subexpr(&e2, p)) < 0) {
413
            av_free_expr(e1);
414
            return ret;
415
        }
416
        e0 = new_eval_expr(e_last, 1, e1, e2);
417
        if (!e0) {
418
            av_free_expr(e1);
419
            av_free_expr(e2);
420
            return AVERROR(ENOMEM);
421
        }
422
    };
423

    
424
    p->stack_index++;
425
    *e = e0;
426
    return 0;
427
}
428

    
429
static int verify_expr(AVExpr *e)
430
{
431
    if (!e) return 0;
432
    switch (e->type) {
433
        case e_value:
434
        case e_const: return 1;
435
        case e_func0:
436
        case e_func1:
437
        case e_squish:
438
        case e_ld:
439
        case e_gauss: return verify_expr(e->param[0]);
440
        default: return verify_expr(e->param[0]) && verify_expr(e->param[1]);
441
    }
442
}
443

    
444
int av_parse_expr(AVExpr **expr, const char *s,
445
                  const char * const *const_names,
446
                  const char * const *func1_names, double (* const *funcs1)(void *, double),
447
                  const char * const *func2_names, double (* const *funcs2)(void *, double, double),
448
                  int log_offset, void *log_ctx)
449
{
450
    Parser p;
451
    AVExpr *e = NULL;
452
    char *w = av_malloc(strlen(s) + 1);
453
    char *wp = w;
454
    const char *s0 = s;
455
    int ret = 0;
456

    
457
    if (!w)
458
        return AVERROR(ENOMEM);
459

    
460
    while (*s)
461
        if (!isspace(*s++)) *wp++ = s[-1];
462
    *wp++ = 0;
463

    
464
    p.class      = &class;
465
    p.stack_index=100;
466
    p.s= w;
467
    p.const_names = const_names;
468
    p.funcs1      = funcs1;
469
    p.func1_names = func1_names;
470
    p.funcs2      = funcs2;
471
    p.func2_names = func2_names;
472
    p.log_offset = log_offset;
473
    p.log_ctx    = log_ctx;
474

    
475
    if ((ret = parse_expr(&e, &p)) < 0)
476
        goto end;
477
    if (*p.s) {
478
        av_log(&p, AV_LOG_ERROR, "Invalid chars '%s' at the end of expression '%s'\n", p.s, s0);
479
        ret = AVERROR(EINVAL);
480
        goto end;
481
    }
482
    if (!verify_expr(e)) {
483
        av_free_expr(e);
484
        ret = AVERROR(EINVAL);
485
        goto end;
486
    }
487
    *expr = e;
488
end:
489
    av_free(w);
490
    return ret;
491
}
492

    
493
double av_eval_expr(AVExpr *e, const double *const_values, void *opaque)
494
{
495
    Parser p;
496

    
497
    p.const_values = const_values;
498
    p.opaque     = opaque;
499
    return eval_expr(&p, e);
500
}
501

    
502
int av_parse_and_eval_expr(double *d, const char *s,
503
                           const char * const *const_names, const double *const_values,
504
                           const char * const *func1_names, double (* const *funcs1)(void *, double),
505
                           const char * const *func2_names, double (* const *funcs2)(void *, double, double),
506
                           void *opaque, int log_offset, void *log_ctx)
507
{
508
    AVExpr *e = NULL;
509
    int ret = av_parse_expr(&e, s, const_names, func1_names, funcs1, func2_names, funcs2, log_offset, log_ctx);
510

    
511
    if (ret < 0) {
512
        *d = NAN;
513
        return ret;
514
    }
515
    *d = av_eval_expr(e, const_values, opaque);
516
    av_free_expr(e);
517
    return isnan(*d) ? AVERROR(EINVAL) : 0;
518
}
519

    
520
#ifdef TEST
521
#undef printf
522
static double const_values[] = {
523
    M_PI,
524
    M_E,
525
    0
526
};
527

    
528
static const char *const_names[] = {
529
    "PI",
530
    "E",
531
    0
532
};
533

    
534
int main(void)
535
{
536
    int i;
537
    double d;
538
    const char **expr, *exprs[] = {
539
        "",
540
        "1;2",
541
        "-20",
542
        "-PI",
543
        "+PI",
544
        "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
545
        "80G/80Gi"
546
        "1k",
547
        "1Gi",
548
        "1gi",
549
        "1GiFoo",
550
        "1k+1k",
551
        "1Gi*3foo",
552
        "foo",
553
        "foo(",
554
        "foo()",
555
        "foo)",
556
        "sin",
557
        "sin(",
558
        "sin()",
559
        "sin)",
560
        "sin 10",
561
        "sin(1,2,3)",
562
        "sin(1 )",
563
        "1",
564
        "1foo",
565
        "bar + PI + E + 100f*2 + foo",
566
        "13k + 12f - foo(1, 2)",
567
        "1gi",
568
        "1Gi",
569
        "st(0, 123)",
570
        "st(1, 123); ld(1)",
571
        /* compute 1+2+...+N */
572
        "st(0, 1); while(lte(ld(0), 100), st(1, ld(1)+ld(0));st(0, ld(0)+1)); ld(1)",
573
        /* compute Fib(N) */
574
        "st(1, 1); st(2, 2); st(0, 1); while(lte(ld(0),10), st(3, ld(1)+ld(2)); st(1, ld(2)); st(2, ld(3)); st(0, ld(0)+1)); ld(3)",
575
        "while(0, 10)",
576
        "st(0, 1); while(lte(ld(0),100), st(1, ld(1)+ld(0)); st(0, ld(0)+1))",
577
        NULL
578
    };
579

    
580
    for (expr = exprs; *expr; expr++) {
581
        printf("Evaluating '%s'\n", *expr);
582
        av_parse_and_eval_expr(&d, *expr,
583
                               const_names, const_values,
584
                               NULL, NULL, NULL, NULL, NULL, 0, NULL);
585
        printf("'%s' -> %f\n\n", *expr, d);
586
    }
587

    
588
    av_parse_and_eval_expr(&d, "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
589
                           const_names, const_values,
590
                           NULL, NULL, NULL, NULL, NULL, 0, NULL);
591
    printf("%f == 12.7\n", d);
592
    av_parse_and_eval_expr(&d, "80G/80Gi",
593
                           const_names, const_values,
594
                           NULL, NULL, NULL, NULL, NULL, 0, NULL);
595
    printf("%f == 0.931322575\n", d);
596

    
597
    for (i=0; i<1050; i++) {
598
        START_TIMER
599
            av_parse_and_eval_expr(&d, "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
600
                                   const_names, const_values,
601
                                   NULL, NULL, NULL, NULL, NULL, 0, NULL);
602
        STOP_TIMER("av_parse_and_eval_expr")
603
    }
604
    return 0;
605
}
606
#endif