1 files changed, 60 insertions, 0 deletions
diff --git a/StdLib/LibC/Math/s_scalbn.c b/StdLib/LibC/Math/s_scalbn.c
new file mode 100644
index 0000000000..072f1c7c89
--- /dev/null
+++ b/StdLib/LibC/Math/s_scalbn.c
@@ -0,0 +1,60 @@
+/* @(#)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.
+ * ====================================================
+ */
+#include  <LibConfig.h>
+#include  <sys/EfiCdefs.h>
+#if defined(LIBM_SCCS) && !defined(lint)
+__RCSID("$NetBSD: s_scalbn.c,v 1.12 2002/05/26 22:01:58 wiz Exp $");
+#endif
+
+/*
+ * 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"
+
+static const double
+two54   =  1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
+twom54  =  5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
+huge   = 1.0e+300,
+tiny   = 1.0e-300;
+
+double
+scalbn(double x, int n)
+{
+  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 (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;
+}