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-rw-r--r--sysdeps/libm-ieee754/s_scalbnl.c71
1 files changed, 71 insertions, 0 deletions
diff --git a/sysdeps/libm-ieee754/s_scalbnl.c b/sysdeps/libm-ieee754/s_scalbnl.c
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+++ b/sysdeps/libm-ieee754/s_scalbnl.c
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+/* s_scalbnl.c -- long double version of s_scalbn.c.
+ * Conversion to long double by Ulrich Drepper,
+ * Cygnus Support, drepper@cygnus.com.
+ */
+
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+
+#if defined(LIBM_SCCS) && !defined(lint)
+static char rcsid[] = "$NetBSD: $";
+#endif
+
+/*
+ * scalbnl (long double x, int n)
+ * scalbnl(x,n) returns x* 2**n  computed by  exponent
+ * manipulation rather than by actually performing an
+ * exponentiation or a multiplication.
+ */
+
+#include "math.h"
+#include "math_private.h"
+
+#ifdef __STDC__
+static const long double
+#else
+static long double
+#endif
+two54   =  1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
+twom54  =  5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
+huge   = 1.0e+300,
+tiny   = 1.0e-300;
+
+#ifdef __STDC__
+	long double __scalbnl (long double x, int n)
+#else
+	long double __scalbnl (x,n)
+	long double x; int n;
+#endif
+{
+	int32_t k,es,hx,lx;
+	GET_LDOUBLE_WORDS(es,hx,lx,x);
+        k = es&0x7fff;				/* extract exponent */
+        if (k==0) {				/* 0 or subnormal x */
+            if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
+	    x *= two54;
+	    GET_HIGH_WORD(hx,x);
+	    k = ((hx&0x7ff00000)>>20) - 54;
+            if (n< -50000) return tiny*x; 	/*underflow*/
+	    }
+        if (k==0x7ff) return x+x;		/* NaN or Inf */
+        k = k+n;
+        if (k >  0x7fe) return huge*__copysign(huge,x); /* overflow  */
+        if (k > 0) 				/* normal result */
+	    {SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20)); return x;}
+        if (k <= -54)
+            if (n > 50000) 	/* in case integer overflow in n+k */
+		return huge*__copysign(huge,x);	/*overflow*/
+	    else return tiny*__copysign(tiny,x); 	/*underflow*/
+        k += 54;				/* subnormal result */
+	SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20));
+        return x*twom54;
+}
+weak_alias (__scalbnl, scalbnl)