add fdlibm

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

external/fdlibm/s_floor.c

@@ -0,0 +1,74 @@
+
+/* @(#)s_floor.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.
+ * ====================================================
+ */
+
+/*
+ * floor(x)
+ * Return x rounded toward -inf to integral value
+ * Method:
+ *	Bit twiddling.
+ * Exception:
+ *	Inexact flag raised if x not equal to floor(x).
+ */
+
+#include "math.h"
+
+static const double hugev = 1.0e300;
+
+double floor(double x) {
+	int	 i0, i1, j0;
+	unsigned i, j;
+	i0 = __HI(x);
+	i1 = __LO(x);
+	j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
+	if(j0 < 20) {
+		if(j0 < 0) {		      /* raise inexact if x != 0 */
+			if(hugev + x > 0.0) { /* return 0*sign(x) if |x|<1 */
+				if(i0 >= 0) {
+					i0 = i1 = 0;
+				} else if(((i0 & 0x7fffffff) | i1) != 0) {
+					i0 = 0xbff00000;
+					i1 = 0;
+				}
+			}
+		} else {
+			i = (0x000fffff) >> j0;
+			if(((i0 & i) | i1) == 0) return x; /* x is integral */
+			if(hugev + x > 0.0) {		   /* raise inexact flag */
+				if(i0 < 0) i0 += (0x00100000) >> j0;
+				i0 &= (~i);
+				i1 = 0;
+			}
+		}
+	} 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 */
+		if(hugev + x > 0.0) {	    /* raise inexact flag */
+			if(i0 < 0) {
+				if(j0 == 20) i0 += 1;
+				else {
+					j = i1 + (1 << (52 - j0));
+					if(j < i1) i0 += 1; /* got a carry */
+					i1 = j;
+				}
+			}
+			i1 &= (~i);
+		}
+	}
+	__HI(x) = i0;
+	__LO(x) = i1;
+	return x;
+}