add fdlibm

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

external/fdlibm/s_modf.c

@@ -0,0 +1,70 @@
+
+/* @(#)s_modf.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.
+ * ====================================================
+ */
+
+/*
+ * modf(double x, double *iptr)
+ * return fraction part of x, and return x's integral part in *iptr.
+ * Method:
+ *	Bit twiddling.
+ *
+ * Exception:
+ *	No exception.
+ */
+
+#include "math.h"
+
+static const double one = 1.0;
+
+double modf(double x, double* iptr) {
+	int	 i0, i1, j0;
+	unsigned i;
+	i0 = __HI(x);			   /* high x */
+	i1 = __LO(x);			   /* low  x */
+	j0 = ((i0 >> 20) & 0x7ff) - 0x3ff; /* exponent of x */
+	if(j0 < 20) {			   /* integer part in high x */
+		if(j0 < 0) {		   /* |x|<1 */
+			__HIp(iptr) = i0 & 0x80000000;
+			__LOp(iptr) = 0; /* *iptr = +-0 */
+			return x;
+		} else {
+			i = (0x000fffff) >> j0;
+			if(((i0 & i) | i1) == 0) { /* x is integral */
+				*iptr = x;
+				__HI(x) &= 0x80000000;
+				__LO(x) = 0; /* return +-0 */
+				return x;
+			} else {
+				__HIp(iptr) = i0 & (~i);
+				__LOp(iptr) = 0;
+				return x - *iptr;
+			}
+		}
+	} else if(j0 > 51) { /* no fraction part */
+		*iptr = x * one;
+		__HI(x) &= 0x80000000;
+		__LO(x) = 0; /* return +-0 */
+		return x;
+	} else { /* fraction part in low x */
+		i = ((unsigned)(0xffffffff)) >> (j0 - 20);
+		if((i1 & i) == 0) { /* x is integral */
+			*iptr = x;
+			__HI(x) &= 0x80000000;
+			__LO(x) = 0; /* return +-0 */
+			return x;
+		} else {
+			__HIp(iptr) = i0;
+			__LOp(iptr) = i1 & (~i);
+			return x - *iptr;
+		}
+	}
+}