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