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 #pragma weak nexttowardf = __nexttowardf
  31 
  32 #include "libm.h"
  33 
  34 static union {
  35         unsigned i;
  36         float f;
  37 } C[] = {
  38         0x00800000,
  39         0x7f000000,
  40         0x7fffffff
  41 };
  42 
  43 #define tiny    C[0].f
  44 #define huge    C[1].f
  45 #define qnan    C[2].f
  46 
  47 #if defined(__sparc)
  48 
  49 enum fcc_type {
  50         fcc_equal = 0,
  51         fcc_less = 1,
  52         fcc_greater = 2,
  53         fcc_unordered = 3
  54 };
  55 
  56 #ifdef __sparcv9
  57 #define _Q_cmp  _Qp_cmp
  58 #endif
  59 
  60 extern enum fcc_type _Q_cmp(const long double *, const long double *);
  61 
  62 float
  63 __nexttowardf(float x, long double y) {
  64         union {
  65                 unsigned i;
  66                 float f;
  67         } xx;
  68         union {
  69                 unsigned i[4];
  70                 long double q;
  71         } yy;
  72         long double lx;
  73         unsigned hx;
  74         volatile float dummy;
  75         enum fcc_type rel;
  76 
  77         /*
  78          * It would be somewhat more efficient to check for NaN and
  79          * zero operands before converting x to long double and then
  80          * to code the comparison in line rather than calling _Q_cmp.
  81          * However, since this code probably won't get used much,
  82          * I'm opting in favor of simplicity instead.
  83          */
  84         lx = xx.f = x;
  85         hx = xx.i & ~0x80000000;
  86 
  87         /* check for each of four possible orderings */
  88         rel = _Q_cmp(&lx, &y);
  89         if (rel == fcc_unordered)
  90                 return (qnan);
  91 
  92         if (rel == fcc_equal) {
  93                 if (hx == 0) {  /* x is zero; return zero with y's sign */
  94                         yy.q = y;
  95                         xx.i = yy.i[0];
  96                         return (xx.f);
  97                 }
  98                 return (x);
  99         }
 100 
 101         if (rel == fcc_less) {
 102                 if (hx == 0)    /* x is zero */
 103                         xx.i = 0x00000001;
 104                 else if ((int) xx.i >= 0)    /* x is positive */
 105                         xx.i++;
 106                 else
 107                         xx.i--;
 108         } else {
 109                 if (hx == 0)    /* x is zero */
 110                         xx.i = 0x80000001;
 111                 else if ((int) xx.i >= 0)    /* x is positive */
 112                         xx.i--;
 113                 else
 114                         xx.i++;
 115         }
 116 
 117         /* raise exceptions as needed */
 118         hx = xx.i & ~0x80000000;
 119         if (hx == 0x7f800000) {
 120                 dummy = huge;
 121                 dummy *= huge;
 122         } else if (hx < 0x00800000) {
 123                 dummy = tiny;
 124                 dummy *= tiny;
 125         }
 126 
 127         return (xx.f);
 128 }
 129 
 130 #elif defined(__x86)
 131 
 132 float
 133 __nexttowardf(float x, long double y) {
 134         union {
 135                 unsigned i;
 136                 float f;
 137         } xx;
 138         unsigned hx;
 139         long double lx;
 140         volatile float dummy;
 141 
 142         lx = xx.f = x;
 143         hx = xx.i & ~0x80000000;
 144 
 145         /* check for each of four possible orderings */
 146         if (isunordered(lx, y))
 147                 return ((float) (lx + y));
 148 
 149         if (lx == y)
 150                 return ((float) y);
 151 
 152         if (lx < y) {
 153                 if (hx == 0)    /* x is zero */
 154                         xx.i = 0x00000001;
 155                 else if ((int) xx.i >= 0)    /* x is positive */
 156                         xx.i++;
 157                 else
 158                         xx.i--;
 159         } else {
 160                 if (hx == 0)    /* x is zero */
 161                         xx.i = 0x80000001;
 162                 else if ((int) xx.i >= 0)    /* x is positive */
 163                         xx.i--;
 164                 else
 165                         xx.i++;
 166         }
 167 
 168         /* raise exceptions as needed */
 169         hx = xx.i & ~0x80000000;
 170         if (hx == 0x7f800000) {
 171                 dummy = huge;
 172                 dummy *= huge;
 173         } else if (hx < 0x00800000) {
 174                 dummy = tiny;
 175                 dummy *= tiny;
 176         }
 177 
 178         return (xx.f);
 179 }
 180 
 181 #else
 182 #error Unknown architecture
 183 #endif