ppc/gen/isinf.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /* Copyright (c) 1992, 1997 NeXT Software, Inc.  All rights reserved.
  23  *
  24  *      File:   libc/gen/ppc/isinf.c
  25  *      Author: Derek B Clegg, NeXT Software, Inc.
  26  *
  27  * HISTORY
  28 *  24-Jan-1997 Umesh Vaishampayan (umeshv@NeXT.com)
  29 *       Ported to PPC.
  30  *  11-Nov-92  Derek B Clegg (dclegg@next.com)
  31  *      Created.
  32  *
  33  * int isinf(double value);
  34  *
  35  * Returns 1 if `value' is equal to positive IEEE infinity, -1 if `value'
  36  * is equal to negative IEEE infinity, 0 otherwise.
  37  *
  38  * An IEEE infinity is a double value with the maximum biased exponent value
  39  * (2047) and a zero fraction value.
  40  */
  41 #import "fp.h"
  42
  43 int
  44 isinf(double value)
  45 {
  46     union dbl d;
  47
  48     d.value = value;
  49     if (d.u[0] == 0x7FF00000 && d.u[1] == 0)
  50         return 1;
  51     if (d.u[0] == 0xFFF00000 && d.u[1] == 0)
  52         return -1;
  53     return 0;
  54 }