Mercurial > cpython-lru_cache-weakref

annotate Python/strtod.c @ 3323:6098aaa8ae7f legacy-trunk

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
changes for complex numbers
author Guido van Rossum <guido@python.org>
date Fri, 12 Jan 1996 01:09:56 +0000
parents 29ca45eb3ab7
children d6c7e40cbfdf
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
2396
29ca45eb3ab7 for __SC__
Guido van Rossum <guido@python.org>
parents: 749
diff changeset
1 #ifdef HAVE_CONFIG_H
29ca45eb3ab7 for __SC__
Guido van Rossum <guido@python.org>
parents: 749
diff changeset
2 #include "config.h"
29ca45eb3ab7 for __SC__
Guido van Rossum <guido@python.org>
parents: 749
diff changeset
3 #endif
29ca45eb3ab7 for __SC__
Guido van Rossum <guido@python.org>
parents: 749
diff changeset
4
595
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
5 /* comp.sources.misc strtod(), as posted in comp.lang.tcl,
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
6 with bugfix for "123000.0" and acceptance of space after 'e' sign nuked.
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
7
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
8 ************************************************************
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
9 * YOU MUST EDIT THE MACHINE-DEPENDENT DEFINITIONS BELOW!!! *
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
10 ************************************************************
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
11 */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
12
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
13 /* File : stdtod.c (Modified version of str2dbl.c)
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
14 Author : Richard A. O'Keefe @ Quintus Computer Systems, Inc.
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
15 Updated: Tuesday August 2nd, 1988
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
16 Defines: double strtod (char *str, char**ptr)
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
17 */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
18
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
19 /* This is an implementation of the strtod() function described in the
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
20 System V manuals, with a different name to avoid linker problems.
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
21 All that str2dbl() does itself is check that the argument is well-formed
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
22 and is in range. It leaves the work of conversion to atof(), which is
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
23 assumed to exist and deliver correct results (if they can be represented).
208
f352ea4dff70 Initial revision
Guido van Rossum <guido@python.org>
parents:
diff changeset
24
595
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
25 There are two reasons why this should be provided to the net:
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
26 (a) some UNIX systems do not yet have strtod(), or do not have it
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
27 available in the BSD "universe" (but they do have atof()).
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
28 (b) some of the UNIX systems that *do* have it get it wrong.
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
29 (some crash with large arguments, some assign the wrong *ptr value).
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
30 There is a reason why *we* are providing it: we need a correct version
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
31 of strtod(), and if we give this one away maybe someone will look for
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
32 mistakes in it and fix them for us (:-).
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
33 */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
34
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
35 /* The following constants are machine-specific. MD{MIN,MAX}EXPT are
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
36 integers and MD{MIN,MAX}FRAC are strings such that
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
37 0.${MDMAXFRAC}e${MDMAXEXPT} is the largest representable double,
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
38 0.${MDMINFRAC}e${MDMINEXPT} is the smallest representable +ve double
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
39 MD{MIN,MAX}FRAC must not have any trailing zeros.
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
40 The values here are for IEEE-754 64-bit floats.
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
41 It is not perfectly clear to me whether an IEEE infinity should be
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
42 returned for overflow, nor what a portable way of writing one is,
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
43 so HUGE is just 0.MAXFRAC*10**MAXEXPT (this seems still to be the
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
44 UNIX convention).
548
83046664160e Clear errno, just to be sure.
Guido van Rossum <guido@python.org>
parents: 514
diff changeset
45
595
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
46 I do know about <values.h>, but the whole point of this file is that
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
47 we can't always trust that stuff to be there or to be correct.
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
48 */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
49 static int MDMINEXPT = {-323};
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
50 static char MDMINFRAC[] = "494065645841246544";
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
51 static double ZERO = 0.0;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
52
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
53 static int MDMAXEXPT = { 309};
749
32085edd77a7 fix HUGE and MAXVAL (suggested by Tim Peters)
Guido van Rossum <guido@python.org>
parents: 595
diff changeset
54 static char MDMAXFRAC[] = "17976931348623157";
32085edd77a7 fix HUGE and MAXVAL (suggested by Tim Peters)
Guido van Rossum <guido@python.org>
parents: 595
diff changeset
55 static double HUGE = 1.7976931348623157e308;
595
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
56
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
57 extern double atof(); /* Only called when result known to be ok */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
58
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
59 #include <errno.h>
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
60 extern int errno;
208
f352ea4dff70 Initial revision
Guido van Rossum <guido@python.org>
parents:
diff changeset
61
595
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
62 double strtod(str, ptr)
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
63 char *str;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
64 char **ptr;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
65 {
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
66 int sign, scale, dotseen;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
67 int esign, expt;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
68 char *save;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
69 register char *sp, *dp;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
70 register int c;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
71 char *buforg, *buflim;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
72 char buffer[64]; /* 45-digit significand + */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
73 /* 13-digit exponent */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
74 sp = str;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
75 while (*sp == ' ') sp++;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
76 sign = 1;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
77 if (*sp == '-') sign -= 2, sp++;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
78 dotseen = 0, scale = 0;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
79 dp = buffer;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
80 *dp++ = '0'; *dp++ = '.';
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
81 buforg = dp, buflim = buffer+48;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
82 for (save = sp; c = *sp; sp++)
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
83 if (c == '.') {
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
84 if (dotseen) break;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
85 dotseen++;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
86 } else
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
87 if ((unsigned)(c-'0') > (unsigned)('9'-'0')) {
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
88 break;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
89 } else
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
90 if (c == '0') {
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
91 if (dp != buforg) {
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
92 /* This is not the first digit, so we want to keep it */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
93 if (dp < buflim) *dp++ = c;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
94 if (!dotseen) scale++;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
95 } else {
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
96 /* No non-zero digits seen yet */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
97 /* If a . has been seen, scale must be adjusted */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
98 if (dotseen) scale--;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
99 }
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
100 } else {
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
101 /* This is a nonzero digit, so we want to keep it */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
102 if (dp < buflim) *dp++ = c;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
103 /* If it precedes a ., scale must be adjusted */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
104 if (!dotseen) scale++;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
105 }
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
106 if (sp == save) {
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
107 if (ptr) *ptr = str;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
108 errno = EDOM; /* what should this be? */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
109 return ZERO;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
110 }
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
111
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
112 while (dp > buforg && dp[-1] == '0') --dp;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
113 if (dp == buforg) *dp++ = '0';
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
114 *dp = '\0';
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
115 /* Now the contents of buffer are
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
116 +--+--------+-+--------+
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
117 |0.|fraction|\|leftover|
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
118 +--+--------+-+--------+
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
119 ^dp points here
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
120 where fraction begins with 0 iff it is "0", and has at most
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
121 45 digits in it, and leftover is at least 16 characters.
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
122 */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
123 save = sp, expt = 0, esign = 1;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
124 do {
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
125 c = *sp++;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
126 if (c != 'e' && c != 'E') break;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
127 c = *sp++;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
128 if (c == '-') esign -= 2, c = *sp++; else
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
129 if (c == '+' /* || c == ' ' */ ) c = *sp++;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
130 if ((unsigned)(c-'0') > (unsigned)('9'-'0')) break;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
131 while (c == '0') c = *sp++;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
132 for (; (unsigned)(c-'0') <= (unsigned)('9'-'0'); c = *sp++)
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
133 expt = expt*10 + c-'0';
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
134 if (esign < 0) expt = -expt;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
135 save = sp-1;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
136 } while (0);
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
137 if (ptr) *ptr = save;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
138 expt += scale;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
139 /* Now the number is sign*0.fraction*10**expt */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
140 errno = ERANGE;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
141 if (expt > MDMAXEXPT) {
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
142 return HUGE*sign;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
143 } else
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
144 if (expt == MDMAXEXPT) {
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
145 if (strcmp(buforg, MDMAXFRAC) > 0) return HUGE*sign;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
146 } else
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
147 if (expt < MDMINEXPT) {
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
148 return ZERO*sign;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
149 } else
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
150 if (expt == MDMINEXPT) {
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
151 if (strcmp(buforg, MDMINFRAC) < 0) return ZERO*sign;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
152 }
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
153 /* We have now established that the number can be */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
154 /* represented without overflow or underflow */
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
155 (void) sprintf(dp, "E%d", expt);
548
83046664160e Clear errno, just to be sure.
Guido van Rossum <guido@python.org>
parents: 514
diff changeset
156 errno = 0;
595
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
157 return atof(buffer)*sign;
f9cdeebfcb67 New version from the net.
Guido van Rossum <guido@python.org>
parents: 548
diff changeset
158 }