BSD 4_3_Tahoe release

[unix-history] / usr / src / usr.lib / libF77 / pow_di.c

diff --git a/usr/src/usr.lib/libF77/pow_di.c b/usr/src/usr.lib/libF77/pow_di.c
index c4a4628..923bb7f 100644 (file)
--- a/usr/src/usr.lib/libF77/pow_di.c
+++ b/usr/src/usr.lib/libF77/pow_di.c
@@ -1,34 +1,33 @@
-double pow_di(ap, bp)
-double *ap;
-long int *bp;
-{
-double pow, x;
-long int n;
+/*
+ * Copyright (c) 1980 Regents of the University of California.
+ * All rights reserved.  The Berkeley software License Agreement
+ * specifies the terms and conditions for redistribution.
+ *
+ *     @(#)pow_di.c    5.3     1/19/88
+ */

 
 

-pow = 1;
-x = *ap;
-n = *bp;
+double
+pow_di(ap, bp)
+       double *ap;
+       long *bp;
+{
+       register long n = *bp;
+       double y, x = *ap;

 
 

-if(n != 0)
-       {
-       if(n < 0)
-               {
-               if(x == 0)
-                       {
-                       return(pow);
-                       }
+       if (!n)
+               return((double)1);
+       if (n < 0) {
+               x = (double)1 / x;

                n = -n;
                n = -n;

-               x = 1/x;
-               }
-       for( ; ; )
-               {
-               if(n & 01)
-                       pow *= x;
-               if(n >>= 1)
+       }
+       while (!(n&1)) {
+               x *= x;
+               n >>= 1;
+       }
+       for (y = x; --n > 0; y *= x)
+               while (!(n&1)) {

                        x *= x;
                        x *= x;

-               else
-                       break;
+                       n >>= 1;

                }
                }

-       }
-return(pow);
+       return(y);

 }
 }