Statistics
| Branch: | Revision:

ffmpeg / libavutil / eval.c @ 8bb12e71

History | View | Annotate | Download (16.6 KB)

1
/*
2
 * Copyright (c) 2002-2006 Michael Niedermayer <michaelni@gmx.at>
3
 * Copyright (c) 2006 Oded Shimon <ods15@ods15.dyndns.org>
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
 * simple arithmetic expression evaluator.
25
 *
26
 * see http://joe.hotchkiss.com/programming/eval/eval.html
27
 */
28

    
29
#include "libavutil/avutil.h"
30
#include "eval.h"
31

    
32
typedef struct Parser {
33
    const AVClass *class;
34
    int stack_index;
35
    char *s;
36
    const double *const_values;
37
    const char * const *const_names;          // NULL terminated
38
    double (* const *funcs1)(void *, double a);           // NULL terminated
39
    const char * const *func1_names;          // NULL terminated
40
    double (* const *funcs2)(void *, double a, double b); // NULL terminated
41
    const char * const *func2_names;          // NULL terminated
42
    void *opaque;
43
    int log_offset;
44
    void *log_ctx;
45
#define VARS 10
46
    double var[VARS];
47
} 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] = {
52
    ['y'-'E']= -24,
53
    ['z'-'E']= -21,
54
    ['a'-'E']= -18,
55
    ['f'-'E']= -15,
56
    ['p'-'E']= -12,
57
    ['n'-'E']= - 9,
58
    ['u'-'E']= - 6,
59
    ['m'-'E']= - 3,
60
    ['c'-'E']= - 2,
61
    ['d'-'E']= - 1,
62
    ['h'-'E']=   2,
63
    ['k'-'E']=   3,
64
    ['K'-'E']=   3,
65
    ['M'-'E']=   6,
66
    ['G'-'E']=   9,
67
    ['T'-'E']=  12,
68
    ['P'-'E']=  15,
69
    ['E'-'E']=  18,
70
    ['Z'-'E']=  21,
71
    ['Y'-'E']=  24,
72
};
73

    
74
double av_strtod(const char *numstr, char **tail)
75
{
76
    double d;
77
    char *next;
78
    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
static int strmatch(const char *s, const char *prefix)
107
{
108
    int i;
109
    for (i=0; prefix[i]; i++) {
110
        if (prefix[i] != s[i]) return 0;
111
    }
112
    return 1;
113
}
114

    
115
struct AVExpr {
116
    enum {
117
        e_value, e_const, e_func0, e_func1, e_func2,
118
        e_squish, e_gauss, e_ld,
119
        e_mod, e_max, e_min, e_eq, e_gt, e_gte,
120
        e_pow, e_mul, e_div, e_add,
121
        e_last, e_st, e_while,
122
    } type;
123
    double value; // is sign in other types
124
    union {
125
        int const_index;
126
        double (*func0)(double);
127
        double (*func1)(void *, double);
128
        double (*func2)(void *, double, double);
129
    } a;
130
    struct AVExpr *param[2];
131
};
132

    
133
static double eval_expr(Parser *p, AVExpr *e)
134
{
135
    switch (e->type) {
136
        case e_value:  return e->value;
137
        case e_const:  return e->value * p->const_values[e->a.const_index];
138
        case e_func0:  return e->value * e->a.func0(eval_expr(p, e->param[0]));
139
        case e_func1:  return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));
140
        case e_func2:  return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
141
        case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));
142
        case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }
143
        case e_ld:     return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];
144
        case e_while: {
145
            double d = NAN;
146
            while (eval_expr(p, e->param[0]))
147
                d=eval_expr(p, e->param[1]);
148
            return d;
149
        }
150
        default: {
151
            double d = eval_expr(p, e->param[0]);
152
            double d2 = eval_expr(p, e->param[1]);
153
            switch (e->type) {
154
                case e_mod: return e->value * (d - floor(d/d2)*d2);
155
                case e_max: return e->value * (d >  d2 ?   d : d2);
156
                case e_min: return e->value * (d <  d2 ?   d : d2);
157
                case e_eq:  return e->value * (d == d2 ? 1.0 : 0.0);
158
                case e_gt:  return e->value * (d >  d2 ? 1.0 : 0.0);
159
                case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0);
160
                case e_pow: return e->value * pow(d, d2);
161
                case e_mul: return e->value * (d * d2);
162
                case e_div: return e->value * (d / d2);
163
                case e_add: return e->value * (d + d2);
164
                case e_last:return e->value * d2;
165
                case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);
166
            }
167
        }
168
    }
169
    return NAN;
170
}
171

    
172
static int parse_expr(AVExpr **e, Parser *p);
173

    
174
void av_free_expr(AVExpr *e)
175
{
176
    if (!e) return;
177
    av_free_expr(e->param[0]);
178
    av_free_expr(e->param[1]);
179
    av_freep(&e);
180
}
181

    
182
static int parse_primary(AVExpr **e, Parser *p)
183
{
184
    AVExpr *d = av_mallocz(sizeof(AVExpr));
185
    char *next = p->s, *s0 = p->s;
186
    int ret, i;
187

    
188
    if (!d)
189
        return AVERROR(ENOMEM);
190

    
191
    /* number */
192
    d->value = av_strtod(p->s, &next);
193
    if (next != p->s) {
194
        d->type = e_value;
195
        p->s= next;
196
        *e = d;
197
        return 0;
198
    }
199
    d->value = 1;
200

    
201
    /* named constants */
202
    for (i=0; p->const_names && p->const_names[i]; i++) {
203
        if (strmatch(p->s, p->const_names[i])) {
204
            p->s+= strlen(p->const_names[i]);
205
            d->type = e_const;
206
            d->a.const_index = i;
207
            *e = d;
208
            return 0;
209
        }
210
    }
211

    
212
    p->s= strchr(p->s, '(');
213
    if (p->s==NULL) {
214
        av_log(p, AV_LOG_ERROR, "Undefined constant or missing '(' in '%s'\n", s0);
215
        p->s= next;
216
        av_free_expr(d);
217
        return AVERROR(EINVAL);
218
    }
219
    p->s++; // "("
220
    if (*next == '(') { // special case do-nothing
221
        av_freep(&d);
222
        if ((ret = parse_expr(&d, p)) < 0)
223
            return ret;
224
        if (p->s[0] != ')') {
225
            av_log(p, AV_LOG_ERROR, "Missing ')' in '%s'\n", s0);
226
            av_free_expr(d);
227
            return AVERROR(EINVAL);
228
        }
229
        p->s++; // ")"
230
        *e = d;
231
        return 0;
232
    }
233
    if ((ret = parse_expr(&(d->param[0]), p)) < 0) {
234
        av_free_expr(d);
235
        return ret;
236
    }
237
    if (p->s[0]== ',') {
238
        p->s++; // ","
239
        parse_expr(&d->param[1], p);
240
    }
241
    if (p->s[0] != ')') {
242
        av_log(p, AV_LOG_ERROR, "Missing ')' or too many args in '%s'\n", s0);
243
        av_free_expr(d);
244
        return AVERROR(EINVAL);
245
    }
246
    p->s++; // ")"
247

    
248
    d->type = e_func0;
249
         if (strmatch(next, "sinh"  )) d->a.func0 = sinh;
250
    else if (strmatch(next, "cosh"  )) d->a.func0 = cosh;
251
    else if (strmatch(next, "tanh"  )) d->a.func0 = tanh;
252
    else if (strmatch(next, "sin"   )) d->a.func0 = sin;
253
    else if (strmatch(next, "cos"   )) d->a.func0 = cos;
254
    else if (strmatch(next, "tan"   )) d->a.func0 = tan;
255
    else if (strmatch(next, "atan"  )) d->a.func0 = atan;
256
    else if (strmatch(next, "asin"  )) d->a.func0 = asin;
257
    else if (strmatch(next, "acos"  )) d->a.func0 = acos;
258
    else if (strmatch(next, "exp"   )) d->a.func0 = exp;
259
    else if (strmatch(next, "log"   )) d->a.func0 = log;
260
    else if (strmatch(next, "abs"   )) d->a.func0 = fabs;
261
    else if (strmatch(next, "squish")) d->type = e_squish;
262
    else if (strmatch(next, "gauss" )) d->type = e_gauss;
263
    else if (strmatch(next, "mod"   )) d->type = e_mod;
264
    else if (strmatch(next, "max"   )) d->type = e_max;
265
    else if (strmatch(next, "min"   )) d->type = e_min;
266
    else if (strmatch(next, "eq"    )) d->type = e_eq;
267
    else if (strmatch(next, "gte"   )) d->type = e_gte;
268
    else if (strmatch(next, "gt"    )) d->type = e_gt;
269
    else if (strmatch(next, "lte"   )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gt; }
270
    else if (strmatch(next, "lt"    )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; }
271
    else if (strmatch(next, "ld"    )) d->type = e_ld;
272
    else if (strmatch(next, "st"    )) d->type = e_st;
273
    else if (strmatch(next, "while" )) d->type = e_while;
274
    else {
275
        for (i=0; p->func1_names && p->func1_names[i]; i++) {
276
            if (strmatch(next, p->func1_names[i])) {
277
                d->a.func1 = p->funcs1[i];
278
                d->type = e_func1;
279
                *e = d;
280
                return 0;
281
            }
282
        }
283

    
284
        for (i=0; p->func2_names && p->func2_names[i]; i++) {
285
            if (strmatch(next, p->func2_names[i])) {
286
                d->a.func2 = p->funcs2[i];
287
                d->type = e_func2;
288
                *e = d;
289
                return 0;
290
            }
291
        }
292

    
293
        av_log(p, AV_LOG_ERROR, "Unknown function in '%s'\n", s0);
294
        av_free_expr(d);
295
        return AVERROR(EINVAL);
296
    }
297

    
298
    *e = d;
299
    return 0;
300
}
301

    
302
static AVExpr *new_eval_expr(int type, int value, AVExpr *p0, AVExpr *p1)
303
{
304
    AVExpr *e = av_mallocz(sizeof(AVExpr));
305
    if (!e)
306
        return NULL;
307
    e->type     =type   ;
308
    e->value    =value  ;
309
    e->param[0] =p0     ;
310
    e->param[1] =p1     ;
311
    return e;
312
}
313

    
314
static int parse_pow(AVExpr **e, Parser *p, int *sign)
315
{
316
    *sign= (*p->s == '+') - (*p->s == '-');
317
    p->s += *sign&1;
318
    return parse_primary(e, p);
319
}
320

    
321
static int parse_factor(AVExpr **e, Parser *p)
322
{
323
    int sign, sign2, ret;
324
    AVExpr *e0, *e1, *e2;
325
    if ((ret = parse_pow(&e0, p, &sign)) < 0)
326
        return ret;
327
    while(p->s[0]=='^'){
328
        e1 = e0;
329
        p->s++;
330
        if ((ret = parse_pow(&e2, p, &sign2)) < 0) {
331
            av_free_expr(e1);
332
            return ret;
333
        }
334
        e0 = new_eval_expr(e_pow, 1, e1, e2);
335
        if (!e0) {
336
            av_free_expr(e1);
337
            av_free_expr(e2);
338
            return AVERROR(ENOMEM);
339
        }
340
        if (e0->param[1]) e0->param[1]->value *= (sign2|1);
341
    }
342
    if (e0) e0->value *= (sign|1);
343

    
344
    *e = e0;
345
    return 0;
346
}
347

    
348
static int parse_term(AVExpr **e, Parser *p)
349
{
350
    int ret;
351
    AVExpr *e0, *e1, *e2;
352
    if ((ret = parse_factor(&e0, p)) < 0)
353
        return ret;
354
    while (p->s[0]=='*' || p->s[0]=='/') {
355
        int c= *p->s++;
356
        e1 = e0;
357
        if ((ret = parse_factor(&e2, p)) < 0) {
358
            av_free_expr(e1);
359
            return ret;
360
        }
361
        e0 = new_eval_expr(c == '*' ? e_mul : e_div, 1, e1, e2);
362
        if (!e0) {
363
            av_free_expr(e1);
364
            av_free_expr(e2);
365
            return AVERROR(ENOMEM);
366
        }
367
    }
368
    *e = e0;
369
    return 0;
370
}
371

    
372
static int parse_subexpr(AVExpr **e, Parser *p)
373
{
374
    int ret;
375
    AVExpr *e0, *e1, *e2;
376
    if ((ret = parse_term(&e0, p)) < 0)
377
        return ret;
378
    while (*p->s == '+' || *p->s == '-') {
379
        e1 = e0;
380
        if ((ret = parse_term(&e2, p)) < 0) {
381
            av_free_expr(e1);
382
            return ret;
383
        }
384
        e0 = new_eval_expr(e_add, 1, e1, e2);
385
        if (!e0) {
386
            av_free_expr(e1);
387
            av_free_expr(e2);
388
            return AVERROR(ENOMEM);
389
        }
390
    };
391

    
392
    *e = e0;
393
    return 0;
394
}
395

    
396
static int parse_expr(AVExpr **e, Parser *p)
397
{
398
    int ret;
399
    AVExpr *e0, *e1, *e2;
400
    if (p->stack_index <= 0) //protect against stack overflows
401
        return AVERROR(EINVAL);
402
    p->stack_index--;
403

    
404
    if ((ret = parse_subexpr(&e0, p)) < 0)
405
        return ret;
406
    while (*p->s == ';') {
407
        p->s++;
408
        e1 = e0;
409
        if ((ret = parse_subexpr(&e2, p)) < 0) {
410
            av_free_expr(e1);
411
            return ret;
412
        }
413
        e0 = new_eval_expr(e_last, 1, e1, e2);
414
        if (!e0) {
415
            av_free_expr(e1);
416
            av_free_expr(e2);
417
            return AVERROR(ENOMEM);
418
        }
419
    };
420

    
421
    p->stack_index++;
422
    *e = e0;
423
    return 0;
424
}
425

    
426
static int verify_expr(AVExpr *e)
427
{
428
    if (!e) return 0;
429
    switch (e->type) {
430
        case e_value:
431
        case e_const: return 1;
432
        case e_func0:
433
        case e_func1:
434
        case e_squish:
435
        case e_ld:
436
        case e_gauss: return verify_expr(e->param[0]);
437
        default: return verify_expr(e->param[0]) && verify_expr(e->param[1]);
438
    }
439
}
440

    
441
int av_parse_expr(AVExpr **expr, const char *s,
442
                  const char * const *const_names,
443
                  const char * const *func1_names, double (* const *funcs1)(void *, double),
444
                  const char * const *func2_names, double (* const *funcs2)(void *, double, double),
445
                  int log_offset, void *log_ctx)
446
{
447
    Parser p;
448
    AVExpr *e = NULL;
449
    char *w = av_malloc(strlen(s) + 1);
450
    char *wp = w;
451
    const char *s0 = s;
452
    int ret = 0;
453

    
454
    if (!w)
455
        return AVERROR(ENOMEM);
456

    
457
    while (*s)
458
        if (!isspace(*s++)) *wp++ = s[-1];
459
    *wp++ = 0;
460

    
461
    p.class      = &class;
462
    p.stack_index=100;
463
    p.s= w;
464
    p.const_names = const_names;
465
    p.funcs1      = funcs1;
466
    p.func1_names = func1_names;
467
    p.funcs2      = funcs2;
468
    p.func2_names = func2_names;
469
    p.log_offset = log_offset;
470
    p.log_ctx    = log_ctx;
471

    
472
    if ((ret = parse_expr(&e, &p)) < 0)
473
        goto end;
474
    if (*p.s) {
475
        av_log(&p, AV_LOG_ERROR, "Invalid chars '%s' at the end of expression '%s'\n", p.s, s0);
476
        ret = AVERROR(EINVAL);
477
        goto end;
478
    }
479
    if (!verify_expr(e)) {
480
        av_free_expr(e);
481
        ret = AVERROR(EINVAL);
482
        goto end;
483
    }
484
    *expr = e;
485
end:
486
    av_free(w);
487
    return ret;
488
}
489

    
490
double av_eval_expr(AVExpr *e, const double *const_values, void *opaque)
491
{
492
    Parser p;
493

    
494
    p.const_values = const_values;
495
    p.opaque     = opaque;
496
    return eval_expr(&p, e);
497
}
498

    
499
int av_parse_and_eval_expr(double *d, const char *s,
500
                           const char * const *const_names, const double *const_values,
501
                           const char * const *func1_names, double (* const *funcs1)(void *, double),
502
                           const char * const *func2_names, double (* const *funcs2)(void *, double, double),
503
                           void *opaque, int log_offset, void *log_ctx)
504
{
505
    AVExpr *e = NULL;
506
    int ret = av_parse_expr(&e, s, const_names, func1_names, funcs1, func2_names, funcs2, log_offset, log_ctx);
507

    
508
    if (ret < 0) {
509
        *d = NAN;
510
        return ret;
511
    }
512
    *d = av_eval_expr(e, const_values, opaque);
513
    av_free_expr(e);
514
    return isnan(*d) ? AVERROR(EINVAL) : 0;
515
}
516

    
517
#ifdef TEST
518
#undef printf
519
static double const_values[] = {
520
    M_PI,
521
    M_E,
522
    0
523
};
524

    
525
static const char *const_names[] = {
526
    "PI",
527
    "E",
528
    0
529
};
530

    
531
int main(void)
532
{
533
    int i;
534
    double d;
535
    const char **expr, *exprs[] = {
536
        "",
537
        "1;2",
538
        "-20",
539
        "-PI",
540
        "+PI",
541
        "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
542
        "80G/80Gi"
543
        "1k",
544
        "1Gi",
545
        "1gi",
546
        "1GiFoo",
547
        "1k+1k",
548
        "1Gi*3foo",
549
        "foo",
550
        "foo(",
551
        "foo()",
552
        "foo)",
553
        "sin",
554
        "sin(",
555
        "sin()",
556
        "sin)",
557
        "sin 10",
558
        "sin(1,2,3)",
559
        "sin(1 )",
560
        "1",
561
        "1foo",
562
        "bar + PI + E + 100f*2 + foo",
563
        "13k + 12f - foo(1, 2)",
564
        "1gi",
565
        "1Gi",
566
        NULL
567
    };
568

    
569
    for (expr = exprs; *expr; expr++) {
570
        printf("Evaluating '%s'\n", *expr);
571
        av_parse_and_eval_expr(&d, *expr,
572
                               const_names, const_values,
573
                               NULL, NULL, NULL, NULL, NULL, 0, NULL);
574
        printf("'%s' -> %f\n\n", *expr, d);
575
    }
576

    
577
    av_parse_and_eval_expr(&d, "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
578
                           const_names, const_values,
579
                           NULL, NULL, NULL, NULL, NULL, 0, NULL);
580
    printf("%f == 12.7\n", d);
581
    av_parse_and_eval_expr(&d, "80G/80Gi",
582
                           const_names, const_values,
583
                           NULL, NULL, NULL, NULL, NULL, 0, NULL);
584
    printf("%f == 0.931322575\n", d);
585

    
586
    for (i=0; i<1050; i++) {
587
        START_TIMER
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
        STOP_TIMER("av_parse_and_eval_expr")
592
    }
593
    return 0;
594
}
595
#endif