Optimized floor for 64-bit architectures

1 files changed, 79 insertions, 0 deletions

diff --git a/sysdeps/ieee754/dbl-64/wordsize-64/s_floor.c b/sysdeps/ieee754/dbl-64/wordsize-64/s_floor.c
new file mode 100644
index 0000000000..d52e4dbeb7
--- /dev/null
+++ b/sysdeps/ieee754/dbl-64/wordsize-64/s_floor.c
@@ -0,0 +1,79 @@
+/* Round double to integer away from zero.
+   Copyright (C) 2011 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 2011.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+/* Based on a version which carries the following copyright:  */
+
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+#include "math.h"
+#include "math_private.h"
+
+/*
+ * floor(x)
+ * Return x rounded toward -inf to integral value
+ * Method:
+ *	Bit twiddling.
+ * Exception:
+ *	Inexact flag raised if x not equal to floor(x).
+ */
+
+static const double huge = 1.0e300;
+
+
+double
+__floor (double x)
+{
+	int64_t i0;
+	EXTRACT_WORDS64(i0,x);
+	int32_t j0 = ((i0>>52)&0x7ff)-0x3ff;
+	if(__builtin_expect(j0<52, 1)) {
+	    if(j0<0) {	/* raise inexact if x != 0 */
+		if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
+		    if(i0>=0) {i0=0;}
+		    else if((i0&0x7fffffffffffffffl)!=0)
+			{ i0=0xbff0000000000000l;}
+		}
+	    } else {
+		uint64_t i = (0x000fffffffffffffl)>>j0;
+		if((i0&i)==0) return x; /* x is integral */
+		if(huge+x>0.0) {	/* raise inexact flag */
+		    if(i0<0) i0 += (0x0010000000000000l)>>j0;
+		    i0 &= (~i);
+		}
+	    }
+	    INSERT_WORDS64(x,i0);
+	} else if (j0==0x400)
+	    return x+x;	/* inf or NaN */
+	return x;
+}
+weak_alias (__floor, floor)
+#ifdef NO_LONG_DOUBLE
+strong_alias (__floor, __floorl)
+weak_alias (__floor, floorl)
+#endif