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strtod.c
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1 /*
2  * C99-compatible strtod() implementation
3  * Copyright (c) 2012 Ronald S. Bultje <rsbultje@gmail.com>
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 #include <ctype.h>
23 #include <limits.h>
24 #include <stdlib.h>
25 
26 #include "libavutil/avstring.h"
27 #include "libavutil/mathematics.h"
28 
29 static char *check_nan_suffix(char *s)
30 {
31  char *start = s;
32 
33  if (*s++ != '(')
34  return start;
35 
36  while ((*s >= 'a' && *s <= 'z') || (*s >= 'A' && *s <= 'Z') ||
37  (*s >= '0' && *s <= '9') || *s == '_')
38  s++;
39 
40  return *s == ')' ? s + 1 : start;
41 }
42 
43 #undef strtod
44 double strtod(const char *, char **);
45 
46 double avpriv_strtod(const char *nptr, char **endptr)
47 {
48  char *end;
49  double res;
50 
51  /* Skip leading spaces */
52  while (isspace(*nptr))
53  nptr++;
54 
55  if (!av_strncasecmp(nptr, "infinity", 8)) {
56  end = nptr + 8;
57  res = INFINITY;
58  } else if (!av_strncasecmp(nptr, "inf", 3)) {
59  end = nptr + 3;
60  res = INFINITY;
61  } else if (!av_strncasecmp(nptr, "+infinity", 9)) {
62  end = nptr + 9;
63  res = INFINITY;
64  } else if (!av_strncasecmp(nptr, "+inf", 4)) {
65  end = nptr + 4;
66  res = INFINITY;
67  } else if (!av_strncasecmp(nptr, "-infinity", 9)) {
68  end = nptr + 9;
69  res = -INFINITY;
70  } else if (!av_strncasecmp(nptr, "-inf", 4)) {
71  end = nptr + 4;
72  res = -INFINITY;
73  } else if (!av_strncasecmp(nptr, "nan", 3)) {
74  end = check_nan_suffix(nptr + 3);
75  res = NAN;
76  } else if (!av_strncasecmp(nptr, "+nan", 4) ||
77  !av_strncasecmp(nptr, "-nan", 4)) {
78  end = check_nan_suffix(nptr + 4);
79  res = NAN;
80  } else if (!av_strncasecmp(nptr, "0x", 2) ||
81  !av_strncasecmp(nptr, "-0x", 3) ||
82  !av_strncasecmp(nptr, "+0x", 3)) {
83  /* FIXME this doesn't handle exponents, non-integers (float/double)
84  * and numbers too large for long long */
85  res = strtoll(nptr, &end, 16);
86  } else {
87  res = strtod(nptr, &end);
88  }
89 
90  if (endptr)
91  *endptr = end;
92 
93  return res;
94 }