1 files changed, 93 insertions, 0 deletions
diff --git a/src/stdlib/strtold.c b/src/stdlib/strtold.c
new file mode 100644
index 00000000..54f80469
--- /dev/null
+++ b/src/stdlib/strtold.c
@@ -0,0 +1,93 @@
+#include <stdlib.h>
+#include <errno.h>
+#include <ctype.h>
+
+long double strtold(const char *s1, char **p)
+{
+	const unsigned char *s = s1;
+	long double x = 0;
+	long double frac;
+	int sign = 0;
+	int nonzero = 0;
+	int radix = '.';
+	long e;
+
+	if (!p) p = (char **)&s1;
+
+	/* Initial whitespace */
+	for (; isspace(*s); s++);
+
+	/* Optional sign */
+	if (*s == '-') sign = *s++;
+	else if (*s == '+') s++;
+
+	/* Handle infinities and NaNs. */
+	if ((s[0]|32)=='i' && (s[1]|32)=='n' && (s[2]|32)=='f') {
+		*p = (char *)s + 3;
+		return sign ? -1.0/0.0 : 1.0/0.0;
+	} else if ((s[0]|32)=='n' && (s[1]|32)=='a' && (s[2]|32)=='n') {
+		*p = (char *)s + 3;
+		return 0.0/0.0;
+	}
+
+	/* Possible hex float */
+	if (s[0]=='0' && (s[1]|32)=='x') {
+		/* Mantissa must be non-degenerate */
+		if (!isxdigit(s[2]) && (s[2]!=radix || !isxdigit(s[3]))) {
+			/* Decimal float 0, 'x' extraneous */
+			*p = (char *)++s;
+			return 0;
+		}
+		/* We have a real hex float */
+		s += 2;
+		for (; isxdigit(*s); s++) {
+			x = 16*x + (isdigit(*s)?*s-'0':(*s|32)-'a');
+			if (*s!='0') nonzero=1;
+		}
+		if (*s == radix) {
+			frac = 1.0/16.0;
+			for (s++; isxdigit(*s); s++) {
+				x += frac * (isdigit(*s)?*s-'0':(*s|32)-'a');
+				frac *= 1.0/16.0;
+				if (*s!='0') nonzero=1;
+			}
+		}
+		if ((*s|32) == 'p') {
+			e = strtol(s+1, (void *)&s, 10);
+			for (; e>0; e--) x *= 2.0;
+			for (; e<0; e++) x *= 0.5;
+		}
+		if ((nonzero && !x) || !(1.0/x))
+			errno = ERANGE;
+		*p = (char *)s;
+		return sign ? -x : x;
+	}
+
+	/* Mantissa must be non-degenerate */
+	if (!isdigit(s[0]) && (s[0]!=radix || !isdigit(s[1]))) {
+		*p = (char *)s1;
+		return 0;
+	}
+
+	for (; isdigit(*s); s++) {
+		x = 10*x + *s-'0';
+		if (*s!='0') nonzero=1;
+	}
+	if (*s == radix) {
+		frac = 10.0;
+		for (s++; isdigit(*s); s++) {
+			x += (*s-'0') / frac;
+			frac *= 10.0;
+			if (*s!='0') nonzero=1;
+		}
+	}
+	if ((*s|32)=='e') {
+		e = strtol(++s, (void *)&s, 10);
+		for (; e>0; e--) x *= 10.0;
+		for (; e<0; e++) x /= 10.0;
+	}
+	if ((nonzero && !x) || !(1.0/x))
+		errno = ERANGE;
+	*p = (char*)s;
+	return sign ? -x : x;
+}