cpython-lru_cache-weakref: Python/strtod.c annotate

annotate Python/strtod.c @ 5758:bfe9ba74c19e legacy-trunk

Fix problem discovered by Greg McFarlane: when an imported module replaces its own entry in sys.module, reference count errors ensue; even if there is no reference count problem, it would be preferable for the import to yield the new thing in sys.modules anyway (if only because that's what later imports will yield). This opens the road to an official hack to implement a __getattr__ like feature for modules: stick an instance in sys.modules[__name__].

author	Guido van Rossum <guido@python.org>
date	Thu, 10 Jul 1997 18:00:45 +0000
parents	d6c7e40cbfdf
children	d834ecdf8c26

rev	line source
2396 29ca45eb3ab7 for __SC__ Guido van Rossum <guido@python.org> parents: 749 diff changeset	1 #include "config.h"
29ca45eb3ab7 for __SC__ Guido van Rossum <guido@python.org> parents: 749 diff changeset	2
595 f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	3 /* 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	4 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	5
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	6 ************************************************************
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	7 * YOU MUST EDIT THE MACHINE-DEPENDENT DEFINITIONS BELOW!!! *
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 */
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 /* File : stdtod.c (Modified version of str2dbl.c)
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	12 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	13 Updated: Tuesday August 2nd, 1988
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	14 Defines: double strtod (char str, char*ptr)
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	15 */
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	16
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	17 /* 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	18 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	19 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	20 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	21 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	22
595 f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	23 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	24 (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	25 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	26 (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	27 (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	28 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	29 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	30 mistakes in it and fix them for us (:-).
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	31 */
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	32
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	33 /* 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	34 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	35 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	36 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	37 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	38 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	39 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	40 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	41 so HUGE is just 0.MAXFRAC10*MAXEXPT (this seems still to be the
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	42 UNIX convention).
548 83046664160e Clear errno, just to be sure. Guido van Rossum <guido@python.org> parents: 514 diff changeset	43
595 f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	44 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	45 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	46 */
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	47 static int MDMINEXPT = {-323};
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	48 static char MDMINFRAC[] = "494065645841246544";
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	49 static double ZERO = 0.0;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	50
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	51 static int MDMAXEXPT = { 309};
749 32085edd77a7 fix HUGE and MAXVAL (suggested by Tim Peters) Guido van Rossum <guido@python.org> parents: 595 diff changeset	52 static char MDMAXFRAC[] = "17976931348623157";
32085edd77a7 fix HUGE and MAXVAL (suggested by Tim Peters) Guido van Rossum <guido@python.org> parents: 595 diff changeset	53 static double HUGE = 1.7976931348623157e308;
595 f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	54
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	55 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	56
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	57 #include <errno.h>
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	58 extern int errno;
208 f352ea4dff70 Initial revision Guido van Rossum <guido@python.org> parents: diff changeset	59
595 f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	60 double strtod(str, ptr)
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	61 char *str;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	62 char **ptr;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	63 {
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	64 int sign, scale, dotseen;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	65 int esign, expt;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	66 char *save;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	67 register char sp, dp;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	68 register int c;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	69 char buforg, buflim;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	70 char buffer[64]; /* 45-digit significand + */
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	71 /* 13-digit exponent */
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	72 sp = str;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	73 while (*sp == ' ') sp++;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	74 sign = 1;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	75 if (*sp == '-') sign -= 2, sp++;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	76 dotseen = 0, scale = 0;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	77 dp = buffer;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	78 dp++ = '0'; dp++ = '.';
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	79 buforg = dp, buflim = buffer+48;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	80 for (save = sp; c = *sp; sp++)
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	81 if (c == '.') {
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	82 if (dotseen) break;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	83 dotseen++;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	84 } else
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	85 if ((unsigned)(c-'0') > (unsigned)('9'-'0')) {
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	86 break;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	87 } else
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	88 if (c == '0') {
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	89 if (dp != buforg) {
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	90 /* 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	91 if (dp < buflim) *dp++ = c;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	92 if (!dotseen) scale++;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	93 } else {
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	94 /* No non-zero digits seen yet */
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	95 /* 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	96 if (dotseen) scale--;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	97 }
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	98 } else {
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	99 /* 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	100 if (dp < buflim) *dp++ = c;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	101 /* If it precedes a ., scale must be adjusted */
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	102 if (!dotseen) scale++;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	103 }
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	104 if (sp == save) {
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	105 if (ptr) *ptr = str;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	106 errno = EDOM; /* what should this be? */
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	107 return ZERO;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	108 }
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	109
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	110 while (dp > buforg && dp[-1] == '0') --dp;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	111 if (dp == buforg) *dp++ = '0';
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	112 *dp = '\0';
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	113 /* Now the contents of buffer are
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	114 +--+--------+-+--------+
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	115 \|0.\|fraction\|\\|leftover\|
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 ^dp points here
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	118 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	119 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	120 */
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	121 save = sp, expt = 0, esign = 1;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	122 do {
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	123 c = *sp++;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	124 if (c != 'e' && c != 'E') break;
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 == '-') esign -= 2, c = *sp++; else
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	127 if (c == '+' /* \|\| c == ' ' / ) c = sp++;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	128 if ((unsigned)(c-'0') > (unsigned)('9'-'0')) break;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	129 while (c == '0') c = *sp++;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	130 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	131 expt = expt*10 + c-'0';
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	132 if (esign < 0) expt = -expt;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	133 save = sp-1;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	134 } while (0);
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	135 if (ptr) *ptr = save;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	136 expt += scale;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	137 /* Now the number is sign0.fraction10*expt /
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	138 errno = ERANGE;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	139 if (expt > MDMAXEXPT) {
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	140 return HUGE*sign;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	141 } else
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	142 if (expt == MDMAXEXPT) {
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	143 if (strcmp(buforg, MDMAXFRAC) > 0) return HUGE*sign;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	144 } else
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	145 if (expt < MDMINEXPT) {
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	146 return ZERO*sign;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	147 } else
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	148 if (expt == MDMINEXPT) {
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	149 if (strcmp(buforg, MDMINFRAC) < 0) return ZERO*sign;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	150 }
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	151 /* 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	152 /* represented without overflow or underflow */
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	153 (void) sprintf(dp, "E%d", expt);
548 83046664160e Clear errno, just to be sure. Guido van Rossum <guido@python.org> parents: 514 diff changeset	154 errno = 0;
595 f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	155 return atof(buffer)*sign;
f9cdeebfcb67 New version from the net. Guido van Rossum <guido@python.org> parents: 548 diff changeset	156 }

Mercurial > cpython-lru_cache-weakref

annotate Python/strtod.c @ 5758:bfe9ba74c19e legacy-trunk