compilers/pcc/pcc-libs-1.0.0/libF77/pow_ri.c

   1 /*      $Id: pow_ri.c,v 1.3 2008/02/28 16:48:50 ragge Exp $     */
   2 /*
   3  * Copyright(C) Caldera International Inc. 2001-2002. All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * Redistributions of source code and documentation must retain the above
  10  * copyright notice, this list of conditions and the following disclaimer.
  11  * Redistributions in binary form must reproduce the above copyright
  12  * notice, this list of conditionsand the following disclaimer in the
  13  * documentation and/or other materials provided with the distribution.
  14  * All advertising materials mentioning features or use of this software
  15  * must display the following acknowledgement:
  16  *      This product includes software developed or owned by Caldera
  17  *      International, Inc.
  18  * Neither the name of Caldera International, Inc. nor the names of other
  19  * contributors may be used to endorse or promote products derived from
  20  * this software without specific prior written permission.
  21  *
  22  * USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA
  23  * INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR
  24  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  25  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  26  * DISCLAIMED.  IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OFLIABILITY, WHETHER IN CONTRACT,
  31  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  32  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  33  * POSSIBILITY OF SUCH DAMAGE.
  34  */
  35 #include "f77lib.h"
  36
  37 float
  38 pow_ri(float *ap, long int *bp)
  39 {
  40         double pow, x;
  41         long int n;
  42
  43         pow = 1;
  44         x = *ap;
  45         n = *bp;
  46
  47         if(n != 0) {
  48                 if(n < 0) {
  49                         if(x == 0) {
  50                                 return(pow);
  51                         }
  52                         n = -n;
  53                         x = 1/x;
  54                 }
  55                 for( ; ; ) {
  56                         if(n & 01)
  57                                 pow *= x;
  58                         if(n >>= 1)
  59                                 x *= x;
  60                         else
  61                                 break;
  62                 }
  63         }
  64         return(pow);
  65 }