usr/src/lib/libm/common/m9x/lroundl.c

   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 __lroundl = lroundl
  31
  32 #include <sys/isa_defs.h>       /* _ILP32 */
  33 #include "libm.h"
  34
  35 #if defined(_ILP32)
  36 #if defined(__sparc)
  37 long
  38 lroundl(long double x) {
  39         union {
  40                 unsigned i[4];
  41                 long double q;
  42         } xx;
  43         union {
  44                 unsigned i;
  45                 float f;
  46         } tt;
  47         unsigned hx, sx, frac, l;
  48         int j;
  49
  50         xx.q = x;
  51         sx = xx.i[0] & 0x80000000;
  52         hx = xx.i[0] & ~0x80000000;
  53
  54         /* handle trivial cases */
  55         if (hx > 0x401e0000) { /* |x| > 2^31 + ... or x is nan */
  56                 /* convert an out-of-range float */
  57                 tt.i = sx | 0x7f000000;
  58                 return ((long) tt.f);
  59         }
  60
  61         /* handle |x| < 1 */
  62         if (hx < 0x3fff0000) {
  63                 if (hx >= 0x3ffe0000)
  64                         return (sx ? -1L : 1L);
  65                 return (0L);
  66         }
  67
  68         /* extract the integer and fractional parts of x */
  69         j = 0x406f - (hx >> 16);                /* 91 <= j <= 112 */
  70         xx.i[0] = 0x10000 | (xx.i[0] & 0xffff);
  71         if (j >= 96) {                          /* 96 <= j <= 112 */
  72                 l = xx.i[0] >> (j - 96);
  73                 frac = ((xx.i[0] << 1) << (127 - j)) | (xx.i[1] >> (j - 96));
  74                 if (((xx.i[1] << 1) << (127 - j)) | xx.i[2] | xx.i[3])
  75                         frac |= 1;
  76         } else {                                /* 91 <= j <= 95 */
  77                 l = (xx.i[0] << (96 - j)) | (xx.i[1] >> (j - 64));
  78                 frac = (xx.i[1] << (96 - j)) | (xx.i[2] >> (j - 64));
  79                 if ((xx.i[2] << (96 - j)) | xx.i[3])
  80                         frac |= 1;
  81         }
  82
  83         /* round */
  84         if (frac >= 0x80000000U)
  85                 l++;
  86
  87         /* check for result out of range (note that z is |x| at this point) */
  88         if (l > 0x80000000U || (l == 0x80000000U && !sx)) {
  89                 tt.i = sx | 0x7f000000;
  90                 return ((long) tt.f);
  91         }
  92
  93         /* negate result if need be */
  94         if (sx)
  95                 l = -l;
  96         return ((long) l);
  97 }
  98 #elif defined(__x86)
  99 long
 100 lroundl(long double x) {
 101         union {
 102                 unsigned i[3];
 103                 long double e;
 104         } xx;
 105         int ex, sx, i;
 106
 107         xx.e = x;
 108         ex = xx.i[2] & 0x7fff;
 109         sx = xx.i[2] & 0x8000;
 110         if (ex < 0x403e) {      /* |x| < 2^63 */
 111                 if (ex < 0x3fff) {      /* |x| < 1 */
 112                         if (ex >= 0x3ffe)
 113                                 return (sx ? -1L : 1L);
 114                         return (0L);
 115                 }
 116
 117                 /* round x at the integer bit */
 118                 if (ex < 0x401e) {
 119                         i = 1 << (0x401d - ex);
 120                         xx.i[1] = (xx.i[1] + i) & ~(i | (i - 1));
 121                         xx.i[0] = 0;
 122                 } else {
 123                         i = 1 << (0x403d - ex);
 124                         xx.i[0] += i;
 125                         if (xx.i[0] < i)
 126                                 xx.i[1]++;
 127                         xx.i[0] &= ~(i | (i - 1));
 128                 }
 129                 if (xx.i[1] == 0) {
 130                         xx.i[2] = sx | ++ex;
 131                         xx.i[1] = 0x80000000U;
 132                 }
 133         }
 134
 135         /* now x is nan, inf, or integral */
 136         return ((long) xx.e);
 137 }
 138 #else
 139 #error Unknown architecture
 140 #endif  /* defined(__sparc) || defined(__x86) */
 141 #else
 142 #error Unsupported architecture
 143 #endif  /* defined(_ILP32) */