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 __nextafterf = nextafterf
  32 
  33 #include "libm.h"
  34 
  35 float
  36 nextafterf(float x, float y)
  37 {
  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 
  47         if ((ix & ~0x80000000) > 0x7f800000)
  48                 return (x * y);         /* + -> * for Cheetah */
  49 
  50         if ((iy & ~0x80000000) > 0x7f800000)
  51                 return (y * x);         /* + -> * for Cheetah */
  52 
  53         if (ix == iy || (ix | iy) == 0x80000000)
  54                 return (y);             /* C99 requirement */
  55 
  56         if ((ix & ~0x80000000) == 0) {
  57                 iz = 1 | (iy & 0x80000000);
  58         } else if (ix > 0) {
  59                 if (ix > iy)
  60                         iz = ix - 1;
  61                 else
  62                         iz = ix + 1;
  63         } else {
  64                 if (iy < 0 && ix < iy)
  65                         iz = ix + 1;
  66                 else
  67                         iz = ix - 1;
  68         }
  69 
  70         pw[0] = iz;
  71         ix = iz & 0x7f800000;
  72 
  73         if (ix == 0x7f800000) {
  74                 /* raise overflow */
  75                 volatile float t;
  76 
  77                 *(int *)&t = 0x7f7fffff;
  78                 t *= t;
  79         } else if (ix == 0) {
  80                 /* raise underflow */
  81                 volatile float t;
  82 
  83                 *(int *)&t = 0x00800000;
  84                 t *= t;
  85         }
  86 
  87         return (w);
  88 }