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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /sysdeps/generic/floor.c
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Diffstat (limited to 'sysdeps/generic/floor.c')
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1 files changed, 74 insertions, 0 deletions
diff --git a/sysdeps/generic/floor.c b/sysdeps/generic/floor.c
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+/* snarfed from BSD common_source/floor.c:
+ * Copyright (c) 1985 Regents of the University of California.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef lint
+static char sccsid[] = "@(#)floor.c	5.7 (Berkeley) 10/9/90";
+#endif /* not lint */
+
+#include "mathimpl.h"
+
+vc(L, 4503599627370496.0E0 ,0000,5c00,0000,0000, 55, 1.0) /* 2**55 */
+
+ic(L, 4503599627370496.0E0, 52, 1.0)			  /* 2**52 */
+
+#ifdef vccast
+#define	L	vccast(L)
+#endif
+
+/*
+ * floor(x) := the largest integer no larger than x;
+ * ceil(x) := -floor(-x), for all real x.
+ *
+ * Note: Inexact will be signaled if x is not an integer, as is
+ *	customary for IEEE 754.  No other signal can be emitted.
+ */
+double
+floor(x)
+double x;
+{
+	double y;
+
+	if (
+#if !defined(vax)&&!defined(tahoe)
+		x != x ||	/* NaN */
+#endif	/* !defined(vax)&&!defined(tahoe) */
+		x >= L)		/* already an even integer */
+		return x;
+	else if (x < (double)0)
+		return -ceil(-x);
+	else {			/* now 0 <= x < L */
+		y = L+x;		/* destructive store must be forced */
+		y -= L;			/* an integer, and |x-y| < 1 */
+		return x < y ? y-(double)1 : y;
+	}
+}