--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/libsys/sprintf/float.c	Fri Jul 20 20:36:19 2018 +0000
@@ -0,0 +1,122 @@
+/*
+ * Embedded [v]sprintf() implementation by Mychaela Falconia,
+ * loosely based on the 4.3BSD-Tahoe version.
+ *
+ * This module contains the floating point conversion functions.
+ */
+
+#include <sys/types.h>
+#include <ctype.h>
+#include "defs.h"
+
+extern double modf();
+
+extern u_char * _sprintf_field(u_char *op, int width, int flags, int sign,
+			u_char *body, int size, int dprec, int fpprec);
+
+#define	MAX_INT_DIGITS	10	/* 2^32-1 in decimal */
+#define	MAXFRACT	16	/* max sensible for 64-bit double */
+#define	DEFPREC		6
+
+static char *
+emit_integer_portion(unsigned number, char *endp)
+{
+	char *t = endp;
+
+	do {
+		*--t = tochar(number % 10);
+		number /= 10;
+	} while (number);
+	return (t);
+}
+
+static int
+f_round(double fract, char *start, char *end, int sign)
+{
+	double tmp;
+
+	(void)modf(fract * 10, &tmp);
+	if (tmp > 4)
+		for (;; --end) {
+			if (*end == '.')
+				--end;
+			if (++*end <= '9')
+				break;
+			*end = '0';
+			if (end == start) {
+				*--end = '1';
+				return(1);
+			}
+		}
+	/* ``"%.3f", (double)-0.0004'' gives you a negative 0. */
+	else if (sign == '-')
+		for (;; --end) {
+			if (*end == '.')
+				--end;
+			if (*end != '0')
+				break;
+			if (end == start)
+				return(-1);	/* clear the -ve */
+		}
+	return(0);
+}
+
+u_char *
+_sprintf_percent_f(u_char *op, int width, int flags, int sign,
+		double number, int prec)
+{
+	char buf[MAX_INT_DIGITS + 1 + MAXFRACT];
+	int extra_prec = 0;
+	int origsign = sign;
+	int round_stat;
+	double fract, tmp;
+	char *start, *t;
+
+	/* first order of business: weed out infinities and NaNs */
+	if (isinf(number)) {
+		if (number < 0)
+			sign = '-';
+		return _sprintf_field(op, width, flags, sign, "Inf", 3, 0, 0);
+	}
+	if (isnan(number))
+		return _sprintf_field(op, width, flags, sign, "NaN", 3, 0, 0);
+	/* OK, we know it's a valid real like in the good old VAX days */
+	if (number < 0) {
+		sign = '-';
+		number = -number;
+	}
+	fract = modf(number, &tmp);
+	if (tmp > (double) 0xFFFFFFFF)
+		return _sprintf_field(op, width, flags, sign, "Toobig", 6,
+					0, 0);
+	start = emit_integer_portion((unsigned) tmp, buf + MAX_INT_DIGITS);
+	if (prec > MAXFRACT) {
+		extra_prec = prec - MAXFRACT;
+		prec = MAXFRACT;
+	} else if (prec == -1)
+		prec = DEFPREC;
+	t = buf + MAX_INT_DIGITS;
+	/*
+	 * if precision required or alternate flag set, add in a
+	 * decimal point.
+	 */
+	if (prec || flags&ALT)
+		*t++ = '.';
+	/* if requires more precision and some fraction left */
+	if (fract) {
+		if (prec)
+			do {
+				fract = modf(fract * 10, &tmp);
+				*t++ = tochar((int)tmp);
+			} while (--prec && fract);
+		if (fract) {
+			round_stat = f_round(fract, start, t - 1, sign);
+			if (round_stat == 1)
+				start--;
+			else if (round_stat == -1)
+				sign = origsign;
+		}
+	}
+	return _sprintf_field(op, width, flags, sign, start, t - start,
+				0, prec + extra_prec);
+}