inferno-os tree was separated from the inferno-os-android (separated from the Android driver)

1 files changed, 72 insertions, 0 deletions

diff --git a/libmath/fdlibm/s_modf.c b/libmath/fdlibm/s_modf.c
new file mode 100644
index 0000000..4549b87
--- /dev/null
+++ b/libmath/fdlibm/s_modf.c
@@ -0,0 +1,72 @@
+/* derived from /netlib/fdlibm */
+
+/* @(#)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 "fdlibm.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;
+	    }
+	}
+}