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 roundl = __roundl
  31 
  32 #include "libm.h"
  33 
  34 #if defined(__sparc)
  35 long double
  36 roundl(long double x) {
  37         union {
  38                 unsigned i[4];
  39                 long double q;
  40         } xx;
  41         unsigned hx, sx, v;
  42         int j;
  43 
  44         xx.q = x;
  45         sx = xx.i[0] & 0x80000000;
  46         hx = xx.i[0] & ~0x80000000;
  47 
  48         /* handle trivial cases */
  49         if (hx >= 0x406f0000) /* |x| >= 2^112 + ... or x is nan */
  50                 return (hx >= 0x7fff0000 ? x + x : x);
  51 
  52         /* handle |x| < 1 */
  53         if (hx < 0x3fff0000) {
  54                 if (hx >= 0x3ffe0000)
  55                         return (sx ? -1.0L : 1.0L);
  56                 return (sx ? -0.0L : 0.0L);
  57         }
  58 
  59         xx.i[0] = hx;
  60         j = 0x406f - (hx >> 16);          /* 1 <= j <= 112 */
  61         if (j >= 96) {                               /* 96 <= j <= 112 */
  62                 v = (1U << (j - 96)) >> 1;
  63                 if (v) {
  64                         if (xx.i[0] & v)
  65                                 xx.i[0] += v;
  66                         xx.i[0] &= ~(v - 1);
  67                 } else if (xx.i[1] & 0x80000000)
  68                                 ++xx.i[0];
  69                 xx.i[1] = xx.i[2] = xx.i[3] = 0;
  70         } else if (j >= 64) {                        /* 64 <= j <= 95 */
  71                 v = (1U << (j - 64)) >> 1;
  72                 if (v) {
  73                         if (xx.i[1] & v) {
  74                                 xx.i[1] += v;
  75                                 if (xx.i[1] < v)
  76                                         ++xx.i[0];
  77                         }
  78                         xx.i[1] &= ~(v - 1);
  79                 } else if (xx.i[2] & 0x80000000) {
  80                                 if (++xx.i[1] == 0)
  81                                         ++xx.i[0];
  82                 }
  83                 xx.i[2] = xx.i[3] = 0;
  84         } else if (j >= 32) {                        /* 32 <= j <= 63 */
  85                 v = (1U << (j - 32)) >> 1;
  86                 if (v) {
  87                         if (xx.i[2] & v) {
  88                                 xx.i[2] += v;
  89                                 if (xx.i[2] < v) {
  90                                         if (++xx.i[1] == 0)
  91                                                 ++xx.i[0];
  92                                 }
  93                         }
  94                         xx.i[2] &= ~(v - 1);
  95                 } else if (xx.i[3] & 0x80000000) {
  96                                 if (++xx.i[2] == 0) {
  97                                         if (++xx.i[1] == 0)
  98                                                 ++xx.i[0];
  99                                 }
 100                 }
 101                 xx.i[3] = 0;
 102         } else {                                /* 1 <= j <= 31 */
 103                 v = 1U << (j - 1);
 104                 if (xx.i[3] & v) {
 105                         xx.i[3] += v;
 106                         if (xx.i[3] < v) {
 107                                 if (++xx.i[2] == 0) {
 108                                         if (++xx.i[1] == 0)
 109                                                 ++xx.i[0];
 110                                 }
 111                         }
 112                 }
 113                 xx.i[3] &= ~(v - 1);
 114         }
 115 
 116         /* negate result if need be */
 117         if (sx)
 118                 xx.i[0] |= 0x80000000;
 119         return (xx.q);
 120 }
 121 #elif defined(__x86)
 122 long double
 123 roundl(long double x) {
 124         union {
 125                 unsigned i[3];
 126                 long double e;
 127         } xx;
 128         int ex, sx, i;
 129 
 130         xx.e = x;
 131         ex = xx.i[2] & 0x7fff;
 132         sx = xx.i[2] & 0x8000;
 133         if (ex < 0x403e) {   /* |x| < 2^63 */
 134                 if (ex < 0x3fff) {   /* |x| < 1 */
 135                         if (ex >= 0x3ffe)
 136                                 return (sx ? -1.0L : 1.0L);
 137                         return (sx ? -0.0L : 0.0L);
 138                 }
 139 
 140                 /* round x at the integer bit */
 141                 if (ex < 0x401e) {
 142                         i = 1 << (0x401d - ex);
 143                         xx.i[1] = (xx.i[1] + i) & ~(i | (i - 1));
 144                         xx.i[0] = 0;
 145                 } else {
 146                         i = 1 << (0x403d - ex);
 147                         xx.i[0] += i;
 148                         if (xx.i[0] < i)
 149                                 xx.i[1]++;
 150                         xx.i[0] &= ~(i | (i - 1));
 151                 }
 152                 if (xx.i[1] == 0) {
 153                         xx.i[2] = sx | ++ex;
 154                         xx.i[1] = 0x80000000U;
 155                 }
 156                 return (xx.e);
 157         } else if (ex < 0x7fff)      /* x is integral */
 158                 return (x);
 159         else                    /* inf or nan */
 160                 return (x + x);
 161 }
 162 #else
 163 #error Unknown architecture
 164 #endif  /* defined(__sparc) || defined(__x86) */