short fixed point <-> double conversion routines; ok henning@

src/usr.sbin/ntpd/ntpd.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntpd.h,v 1.21 2004/07/10 18:42:51 henning Exp $ */
+/*	$OpenBSD: ntpd.h,v 1.22 2004/07/10 22:24:20 alexander Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -212,3 +212,5 @@ double	gettime(void);
 void	d_to_tv(double, struct timeval *);
 double	lfp_to_d(struct l_fixedpt);
 struct	l_fixedpt d_to_lfp(double);
+double	sfp_to_d(struct s_fixedpt);
+struct	s_fixedpt d_to_sfp(double);

src/usr.sbin/ntpd/util.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: util.c,v 1.7 2004/07/07 07:38:21 henning Exp $ */
+/*	$OpenBSD: util.c,v 1.8 2004/07/10 22:24:20 alexander Exp $ */
 
 /*
  * Copyright (c) 2004 Alexander Guy <alexander.guy@andern.org>
@@ -62,3 +62,27 @@ d_to_lfp(double d)
 
 	return (lfp);
 }
+
+double
+sfp_to_d(struct s_fixedpt sfp)
+{
+	double	ret;
+
+	sfp.int_part = ntohs(sfp.int_part);
+	sfp.fraction = ntohs(sfp.fraction);
+
+	ret = (double)(sfp.int_part) + ((double)sfp.fraction / USHRT_MAX);
+
+	return (ret);
+}
+
+struct s_fixedpt
+d_to_sfp(double d)
+{
+	struct s_fixedpt	sfp;
+
+	sfp.int_part = htons((u_int16_t)d);
+	sfp.fraction = htons((u_int16_t)((d - (u_int16_t)d) * USHRT_MAX));
+
+	return (sfp);
+}