- add some more math functions (patch from gentoo/solar)

1 files changed, 63 insertions, 0 deletions

diff --git a/libm/s_scalbln.c b/libm/s_scalbln.c
new file mode 100644
index 000000000..a780f3710
--- /dev/null
+++ b/libm/s_scalbln.c
@@ -0,0 +1,63 @@
+/* @(#)s_scalbn.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.
+ * ====================================================
+ */
+
+/*
+ * scalbn (double x, int n)
+ * scalbn(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"
+
+libm_hidden_proto(scalbln)
+#ifdef __STDC__
+static const double
+#else
+static double
+#endif
+two54   =  1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
+twom54  =  5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
+huge   = 1.0e+300,
+tiny   = 1.0e-300;
+
+#ifdef __STDC__
+	double scalbln (double x, long int n)
+#else
+	double scalbln (x,n)
+	double x; long int n;
+#endif
+{
+	int32_t k,hx,lx;
+	EXTRACT_WORDS(hx,lx,x);
+        k = (hx&0x7ff00000)>>20;		/* 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 (k==0x7ff) return x+x;		/* NaN or Inf */
+        k = k+n;
+        if (n> 50000 || k >  0x7fe)
+	  return huge*copysign(huge,x); /* overflow  */
+	if (n< -50000) return tiny*copysign(tiny,x); /*underflow*/
+        if (k > 0)				/* normal result */
+	    {SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20)); return x;}
+        if (k <= -54)
+	  return tiny*copysign(tiny,x);	/*underflow*/
+        k += 54;				/* subnormal result */
+	SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20));
+        return x*twom54;
+}
+libm_hidden_def(scalbln)