upload sdk

git-svn-id: svn://kolibrios.org@4349 a494cfbc-eb01-0410-851d-a64ba20cac60

contrib/sdk/sources/newlib/math/f_pow.c

@@ -0,0 +1,47 @@
+/*
+ * ====================================================
+ * Copyright (C) 1998, 2002 by Red Hat Inc. All rights reserved.
+ *
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+#if !defined(_SOFT_FLOAT)
+
+/*
+Fast version of pow using Intel float instructions.
+
+   double _f_pow (double x, double y);
+
+Function calculates x to power of y.
+The function optimizes the case where x is >0.0 and y is finite.
+In such a case, there is no error checking or setting of errno.
+All other cases defer to normal pow() function which will
+set errno as normal.
+*/
+
+#include <math.h>
+#include <ieeefp.h>
+#include "f_math.h"
+
+double _f_pow (double x, double y)
+{
+  /* following sequence handles the majority of cases for pow() */
+  if (x > 0.0 && check_finite(y))
+    {
+      double result;
+      /* calculate x ** y as 2 ** (y log2(x)).  On Intel, can only
+         raise 2 to an integer or a small fraction, thus, we have
+         to perform two steps 2**integer portion * 2**fraction. */
+      asm ("fyl2x; fld %%st; frndint; fsub %%st,%%st(1);"\
+           "fxch; fchs; f2xm1; fld1; faddp; fxch; fld1; fscale; fstp %%st(1);"\
+           "fmulp" : "=t" (result) : "0" (x), "u" (y) : "st(1)" );
+      return result;
+    }
+  else /* all other strange cases, defer to normal pow() */
+    return pow (x,y);
+}
+
+#endif