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  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  27  * Use is subject to license terms.
  28  */
  29 
  30 #if defined(ELFOBJ)
  31 #pragma weak nextafterf = __nextafterf
  32 #endif
  33 
  34 #include "libm.h"
  35 
  36 float
  37 nextafterf(float x, float y) {
  38         float w;
  39         int *pw = (int *) &w;
  40         int *px = (int *) &x;
  41         int *py = (int *) &y;
  42         int ix, iy, iz;
  43 
  44         ix = px[0];
  45         iy = py[0];
  46         if ((ix & ~0x80000000) > 0x7f800000)
  47                 return (x * y);         /* + -> * for Cheetah */
  48         if ((iy & ~0x80000000) > 0x7f800000)
  49                 return (y * x);         /* + -> * for Cheetah */
  50         if (ix == iy || (ix | iy) == 0x80000000)
  51                 return (y);             /* C99 requirement */
  52         if ((ix & ~0x80000000) == 0)
  53                 iz = 1 | (iy & 0x80000000);
  54         else if (ix > 0) {
  55                 if (ix > iy)
  56                         iz = ix - 1;
  57                 else
  58                         iz = ix + 1;
  59         } else {
  60                 if (iy < 0 && ix < iy)
  61                         iz = ix + 1;
  62                 else
  63                         iz = ix - 1;
  64         }
  65         pw[0] = iz;
  66         ix = iz & 0x7f800000;
  67         if (ix == 0x7f800000) {
  68                 /* raise overflow */
  69                 volatile float t;
  70 
  71                 *(int *) &t = 0x7f7fffff;
  72                 t *= t;
  73         } else if (ix == 0) {
  74                 /* raise underflow */
  75                 volatile float t;
  76 
  77                 *(int *) &t = 0x00800000;
  78                 t *= t;
  79         }
  80         return (w);
  81 }