add fdlibm

git-svn-id: http://svn2.nishi.boats/svn/milsko/trunk@557 b9cfdab3-6d41-4d17-bbe4-086880011989

external/fdlibm/s_rint.c

@@ -0,0 +1,76 @@
+
+/* @(#)s_rint.c 1.3 95/01/18 */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunSoft, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+/*
+ * rint(x)
+ * Return x rounded to integral value according to the prevailing
+ * rounding mode.
+ * Method:
+ *	Using floating addition.
+ * Exception:
+ *	Inexact flag raised if x not equal to rint(x).
+ */
+
+#include "math.h"
+
+static const double
+    TWO52[2] = {
+	4.50359962737049600000e+15,  /* 0x43300000, 0x00000000 */
+	-4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
+};
+
+double rint(double x) {
+	int	 i0, j0, sx;
+	unsigned i, i1;
+	double	 w, t;
+	i0 = __HI(x);
+	sx = (i0 >> 31) & 1;
+	i1 = __LO(x);
+	j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
+	if(j0 < 20) {
+		if(j0 < 0) {
+			if(((i0 & 0x7fffffff) | i1) == 0) return x;
+			i1 |= (i0 & 0x0fffff);
+			i0 &= 0xfffe0000;
+			i0 |= ((i1 | -i1) >> 12) & 0x80000;
+			__HI(x) = i0;
+			w	= TWO52[sx] + x;
+			t	= w - TWO52[sx];
+			i0	= __HI(t);
+			__HI(t) = (i0 & 0x7fffffff) | (sx << 31);
+			return t;
+		} else {
+			i = (0x000fffff) >> j0;
+			if(((i0 & i) | i1) == 0) return x; /* x is integral */
+			i >>= 1;
+			if(((i0 & i) | i1) != 0) {
+				if(j0 == 19) i1 = 0x40000000;
+				else
+					i0 = (i0 & (~i)) | ((0x20000) >> j0);
+			}
+		}
+	} else if(j0 > 51) {
+		if(j0 == 0x400) return x + x; /* inf or NaN */
+		else
+			return x; /* x is integral */
+	} else {
+		i = ((unsigned)(0xffffffff)) >> (j0 - 20);
+		if((i1 & i) == 0) return x; /* x is integral */
+		i >>= 1;
+		if((i1 & i) != 0) i1 = (i1 & (~i)) | ((0x40000000) >> (j0 - 20));
+	}
+	__HI(x) = i0;
+	__LO(x) = i1;
+	w	= TWO52[sx] + x;
+	return w - TWO52[sx];
+}