1 files changed, 117 insertions, 0 deletions
diff --git a/missing.d/strtod.c b/missing.d/strtod.c
new file mode 100644
index 00000000..79350a1e
--- /dev/null
+++ b/missing.d/strtod.c
@@ -0,0 +1,117 @@
+/*
+ * strtod.c
+ *
+ * Stupid version of System V strtod(3) library routine.
+ * Does no overflow/underflow checking.
+ *
+ * A real number is defined to be
+ *	optional leading white space
+ *	optional sign
+ *	string of digits with optional decimal point
+ *	optional 'e' or 'E'
+ *		followed by optional sign or space
+ *		followed by an integer
+ *
+ * if ptr is not NULL a pointer to the character terminating the
+ * scan is returned in *ptr.  If no number formed, *ptr is set to str
+ * and 0 is returned.
+ *
+ * For speed, we don't do the conversion ourselves.  Instead, we find
+ * the end of the number and then call atof() to do the dirty work.
+ * This bought us a 10% speedup on a sample program at uunet.uu.net.
+ */
+
+#include <ctype.h>
+
+extern double atof();
+
+double
+strtod (s, ptr)
+register char *s, **ptr;
+{
+	double ret = 0.0;
+	char *start = s;
+	char *begin = NULL;
+	int success = 0;
+
+	/* optional white space */
+	while (isspace(*s))
+		s++;
+
+	/* optional sign */
+	if (*s == '+' || *s == '-') {
+		s++;
+		if (*(s-1) == '-')
+			begin = s - 1;
+		else
+			begin = s;
+	}
+
+	/* string of digits with optional decimal point */
+	if (isdigit(*s) && ! begin)
+		begin = s;
+
+	while (isdigit(*s)) {
+		s++;
+		success++;
+	}
+
+	if (*s == '.') {
+		if (! begin)
+			begin = s;
+		s++;
+		while (isdigit(*s))
+			s++;
+		success++;
+	}
+
+	if (s == start || success == 0)		/* nothing there */
+		goto out;
+
+	/*
+ 	 *	optional 'e' or 'E'
+	 *		followed by optional sign or space
+	 *		followed by an integer
+	 */
+
+	if (*s == 'e' || *s == 'E') {
+		s++;
+
+		/* XXX - atof probably doesn't allow spaces here */
+		while (isspace(*s))
+			s++;
+
+		if (*s == '+' || *s == '-')
+			s++;
+
+		while (isdigit(*s))
+			s++;
+	}
+
+	/* go for it */
+	ret = atof(begin);
+
+out:
+	if (! success)
+		s = start;	/* in case all we did was skip whitespace */
+
+	if (ptr)
+		*ptr = s;
+
+	return ret;
+}
+
+#ifdef TEST
+main (argc, argv)
+int argc;
+char **argv;
+{
+	double d;
+	char *p;
+
+	for (argc--, argv++; argc; argc--, argv++) {
+		d = strtod (*argv, & p);
+		printf ("%lf [%s]\n", d, p);
+	}
+}
+#endif