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 (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 
  22 /*
  23  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  24  */
  25 
  26 /*
  27  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  28  * Use is subject to license terms.
  29  */
  30 
  31 #pragma weak modff = __modff
  32 #pragma weak _modff = __modff
  33 
  34 #include "libm.h"
  35 
  36 float
  37 __modff(float x, float *iptr)
  38 {
  39         union {
  40                 unsigned i;
  41                 float f;
  42         } xx, yy;
  43 
  44         unsigned hx, s;
  45 
  46         xx.f = x;
  47         hx = xx.i & ~0x80000000;
  48 
  49         if (hx >= 0x4b000000) {              /* x is NaN, infinite, or integral */
  50                 *iptr = x;
  51 
  52                 if (hx <= 0x7f800000)
  53                         xx.i &= 0x80000000;
  54 
  55                 return (xx.f);
  56         }
  57 
  58         if (hx < 0x3f800000) {               /* |x| < 1 */
  59                 xx.i &= 0x80000000;
  60                 *iptr = xx.f;
  61                 return (x);
  62         }
  63 
  64         /* split x at the binary point */
  65         s = xx.i & 0x80000000;
  66         yy.i = xx.i & ~((1 << (0x96 - (hx >> 23))) - 1);
  67         *iptr = yy.f;
  68         xx.f -= yy.f;
  69         xx.i = (xx.i & ~0x80000000) | s;
  70         /* restore sign in case difference is 0 */
  71         return (xx.f);
  72 }