import newlib-2000-02-17 snapshot

1 files changed, 131 insertions, 0 deletions

diff --git a/newlib/libm/common/s_modf.c b/newlib/libm/common/s_modf.c
new file mode 100644
index 000000000..01151397d
--- /dev/null
+++ b/newlib/libm/common/s_modf.c
@@ -0,0 +1,131 @@
+
+/* @(#)s_modf.c 5.1 93/09/24 */
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+
+/*
+FUNCTION
+       <<modf>>, <<modff>>---split fractional and integer parts
+
+INDEX
+	modf
+INDEX
+	modff
+
+ANSI_SYNOPSIS
+	#include <math.h>
+	double modf(double <[val]>, double *<[ipart]>);
+        float modff(float <[val]>, float *<[ipart]>);
+
+TRAD_SYNOPSIS
+	#include <math.h>
+	double modf(<[val]>, <[ipart]>)
+        double <[val]>;
+        double *<[ipart]>;
+
+	float modff(<[val]>, <[ipart]>)
+	float <[val]>;
+        float *<[ipart]>;
+
+DESCRIPTION
+	<<modf>> splits the double <[val]> apart into an integer part
+	and a fractional part, returning the fractional part and
+	storing the integer part in <<*<[ipart]>>>.  No rounding
+	whatsoever is done; the sum of the integer and fractional
+	parts is guaranteed to be exactly  equal to <[val]>.   That
+	is, if . <[realpart]> = modf(<[val]>, &<[intpart]>); then
+	`<<<[realpart]>+<[intpart]>>>' is the same as <[val]>.
+	<<modff>> is identical, save that it takes and returns
+	<<float>> rather than <<double>> values. 
+
+RETURNS
+	The fractional part is returned.  Each result has the same
+	sign as the supplied argument <[val]>.
+
+PORTABILITY
+	<<modf>> is ANSI C. <<modff>> is an extension.
+
+QUICKREF
+	modf  ansi pure 
+	modff - pure
+
+*/
+
+/*
+ * 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"
+
+#ifndef _DOUBLE_IS_32BITS
+
+#ifdef __STDC__
+static const double one = 1.0;
+#else
+static double one = 1.0;
+#endif
+
+#ifdef __STDC__
+	double modf(double x, double *iptr)
+#else
+	double modf(x, iptr)
+	double x,*iptr;
+#endif
+{
+	__int32_t i0,i1,j0;
+	__uint32_t i;
+	EXTRACT_WORDS(i0,i1,x);
+	j0 = ((i0>>20)&0x7ff)-0x3ff;	/* exponent of x */
+	if(j0<20) {			/* integer part in high x */
+	    if(j0<0) {			/* |x|<1 */
+	        INSERT_WORDS(*iptr,i0&0x80000000,0);	/* *iptr = +-0 */
+		return x;
+	    } else {
+		i = (0x000fffff)>>j0;
+		if(((i0&i)|i1)==0) {		/* x is integral */
+		    __uint32_t high;
+		    *iptr = x;
+		    GET_HIGH_WORD(high,x);
+		    INSERT_WORDS(x,high&0x80000000,0);	/* return +-0 */
+		    return x;
+		} else {
+		    INSERT_WORDS(*iptr,i0&(~i),0);
+		    return x - *iptr;
+		}
+	    }
+	} else if (j0>51) {		/* no fraction part */
+	    __uint32_t high;
+	    *iptr = x*one;
+	    GET_HIGH_WORD(high,x);
+	    INSERT_WORDS(x,high&0x80000000,0);	/* return +-0 */
+	    return x;
+	} else {			/* fraction part in low x */
+	    i = ((__uint32_t)(0xffffffff))>>(j0-20);
+	    if((i1&i)==0) { 		/* x is integral */
+	        __uint32_t high;
+		*iptr = x;
+		GET_HIGH_WORD(high,x);
+		INSERT_WORDS(x,high&0x80000000,0);	/* return +-0 */
+		return x;
+	    } else {
+	        INSERT_WORDS(*iptr,i0,i1&(~i));
+		return x - *iptr;
+	    }
+	}
+}
+
+#endif /* _DOUBLE_IS_32BITS */