usr/src/lib/libbc/libc/gen/common/frexp.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 #pragma ident   "%Z%%M% %I%     %E% SMI"  /* from UCB 5.2 3/9/86 */
  23
  24 /*
  25  * the call
  26  *      x = frexp(arg,&exp);
  27  * must return a double fp quantity x which is <1.0
  28  * and the corresponding binary exponent "exp".
  29  * such that
  30  *      arg = x*2^exp
  31  */
  32 double
  33 frexp(x, i)
  34         double x;
  35         int *i;
  36 {
  37         int neg, j;
  38
  39         j = 0;
  40         neg = 0;
  41         if (x<0) {
  42                 x = -x;
  43                 neg = 1;
  44         }
  45         if (x>=1.0)
  46                 while (x>=1.0) {
  47                         j = j+1;
  48                         x = x/2;
  49                 }
  50         else if (x < 0.5 && x != 0.0)
  51                 while(x<0.5) {
  52                         j = j-1;
  53                         x = 2*x;
  54                 }
  55         *i = j;
  56         if(neg)
  57                 x = -x;
  58         return (x);
  59 }