-/* This is not a proper strtod() implementation, but sufficient for Python.
- Python won't detect floating point constant overflow, though. */
+/* comp.sources.misc strtod(), as posted in comp.lang.tcl,
+ with bugfix for "123000.0" and acceptance of space after 'e' sign nuked.
-extern int errno;
+ ************************************************************
+ * YOU MUST EDIT THE MACHINE-DEPENDENT DEFINITIONS BELOW!!! *
+ ************************************************************
+*/
-extern int strlen();
-extern double atof();
+/* File : stdtod.c (Modified version of str2dbl.c)
+ Author : Richard A. O'Keefe @ Quintus Computer Systems, Inc.
+ Updated: Tuesday August 2nd, 1988
+ Defines: double strtod (char *str, char**ptr)
+*/
-double
-strtod(p, pp)
- char *p;
- char **pp;
-{
- double res;
+/* This is an implementation of the strtod() function described in the
+ System V manuals, with a different name to avoid linker problems.
+ All that str2dbl() does itself is check that the argument is well-formed
+ and is in range. It leaves the work of conversion to atof(), which is
+ assumed to exist and deliver correct results (if they can be represented).
- if (pp)
- *pp = p + strlen(p);
- res = atof(p);
- errno = 0;
- return res;
+ There are two reasons why this should be provided to the net:
+ (a) some UNIX systems do not yet have strtod(), or do not have it
+ available in the BSD "universe" (but they do have atof()).
+ (b) some of the UNIX systems that *do* have it get it wrong.
+ (some crash with large arguments, some assign the wrong *ptr value).
+ There is a reason why *we* are providing it: we need a correct version
+ of strtod(), and if we give this one away maybe someone will look for
+ mistakes in it and fix them for us (:-).
+*/
+
+/* The following constants are machine-specific. MD{MIN,MAX}EXPT are
+ integers and MD{MIN,MAX}FRAC are strings such that
+ 0.${MDMAXFRAC}e${MDMAXEXPT} is the largest representable double,
+ 0.${MDMINFRAC}e${MDMINEXPT} is the smallest representable +ve double
+ MD{MIN,MAX}FRAC must not have any trailing zeros.
+ The values here are for IEEE-754 64-bit floats.
+ It is not perfectly clear to me whether an IEEE infinity should be
+ returned for overflow, nor what a portable way of writing one is,
+ so HUGE is just 0.MAXFRAC*10**MAXEXPT (this seems still to be the
+ UNIX convention).
+
+ I do know about <values.h>, but the whole point of this file is that
+ we can't always trust that stuff to be there or to be correct.
+*/
+static int MDMINEXPT = {-323};
+static char MDMINFRAC[] = "494065645841246544";
+static double ZERO = 0.0;
+
+static int MDMAXEXPT = { 309};
+static char MDMAXFRAC[] = "17976931348623147";
+static double HUGE = 1.7976931348623147e308;
+
+extern double atof(); /* Only called when result known to be ok */
+
+#include <errno.h>
+extern int errno;
+
+double strtod(str, ptr)
+ char *str;
+ char **ptr;
+ {
+ int sign, scale, dotseen;
+ int esign, expt;
+ char *save;
+ register char *sp, *dp;
+ register int c;
+ char *buforg, *buflim;
+ char buffer[64]; /* 45-digit significand + */
+ /* 13-digit exponent */
+ sp = str;
+ while (*sp == ' ') sp++;
+ sign = 1;
+ if (*sp == '-') sign -= 2, sp++;
+ dotseen = 0, scale = 0;
+ dp = buffer;
+ *dp++ = '0'; *dp++ = '.';
+ buforg = dp, buflim = buffer+48;
+ for (save = sp; c = *sp; sp++)
+ if (c == '.') {
+ if (dotseen) break;
+ dotseen++;
+ } else
+ if ((unsigned)(c-'0') > (unsigned)('9'-'0')) {
+ break;
+ } else
+ if (c == '0') {
+ if (dp != buforg) {
+ /* This is not the first digit, so we want to keep it */
+ if (dp < buflim) *dp++ = c;
+ if (!dotseen) scale++;
+ } else {
+ /* No non-zero digits seen yet */
+ /* If a . has been seen, scale must be adjusted */
+ if (dotseen) scale--;
+ }
+ } else {
+ /* This is a nonzero digit, so we want to keep it */
+ if (dp < buflim) *dp++ = c;
+ /* If it precedes a ., scale must be adjusted */
+ if (!dotseen) scale++;
+ }
+ if (sp == save) {
+ if (ptr) *ptr = str;
+ errno = EDOM; /* what should this be? */
+ return ZERO;
+ }
-}
+ while (dp > buforg && dp[-1] == '0') --dp;
+ if (dp == buforg) *dp++ = '0';
+ *dp = '\0';
+ /* Now the contents of buffer are
+ +--+--------+-+--------+
+ |0.|fraction|\|leftover|
+ +--+--------+-+--------+
+ ^dp points here
+ where fraction begins with 0 iff it is "0", and has at most
+ 45 digits in it, and leftover is at least 16 characters.
+ */
+ save = sp, expt = 0, esign = 1;
+ do {
+ c = *sp++;
+ if (c != 'e' && c != 'E') break;
+ c = *sp++;
+ if (c == '-') esign -= 2, c = *sp++; else
+ if (c == '+' /* || c == ' ' */ ) c = *sp++;
+ if ((unsigned)(c-'0') > (unsigned)('9'-'0')) break;
+ while (c == '0') c = *sp++;
+ for (; (unsigned)(c-'0') <= (unsigned)('9'-'0'); c = *sp++)
+ expt = expt*10 + c-'0';
+ if (esign < 0) expt = -expt;
+ save = sp-1;
+ } while (0);
+ if (ptr) *ptr = save;
+ expt += scale;
+ /* Now the number is sign*0.fraction*10**expt */
+ errno = ERANGE;
+ if (expt > MDMAXEXPT) {
+ return HUGE*sign;
+ } else
+ if (expt == MDMAXEXPT) {
+ if (strcmp(buforg, MDMAXFRAC) > 0) return HUGE*sign;
+ } else
+ if (expt < MDMINEXPT) {
+ return ZERO*sign;
+ } else
+ if (expt == MDMINEXPT) {
+ if (strcmp(buforg, MDMINFRAC) < 0) return ZERO*sign;
+ }
+ /* We have now established that the number can be */
+ /* represented without overflow or underflow */
+ (void) sprintf(dp, "E%d", expt);
+ errno = 0;
+ return atof(buffer)*sign;
+ }
projects / thirdparty / Python / cpython.git / commitdiff
