usr/src/lib/libm/common/m9x/truncl.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 __truncl = truncl
  31
  32 #include "libm.h"
  33
  34 #if defined(__sparc)
  35 long double
  36 truncl(long double x) {
  37         union {
  38                 unsigned i[4];
  39                 long double q;
  40         } xx;
  41         unsigned hx, sx;
  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                 return (sx ? -0.0L : 0.0L);
  55
  56         j = 0x406f - (hx >> 16);                /* 1 <= j <= 112 */
  57         xx.i[0] = hx;
  58         if (j >= 96) {                          /* 96 <= j <= 112 */
  59                 xx.i[0] &= ~((1 << (j - 96)) - 1);
  60                 xx.i[1] = xx.i[2] = xx.i[3] = 0;
  61         } else if (j >= 64) {                   /* 64 <= j <= 95 */
  62                 xx.i[1] &= ~((1 << (j - 64)) - 1);
  63                 xx.i[2] = xx.i[3] = 0;
  64         } else if (j >= 32) {                   /* 32 <= j <= 63 */
  65                 xx.i[2] &= ~((1 << (j - 32)) - 1);
  66                 xx.i[3] = 0;
  67         } else                                  /* 1 <= j <= 31 */
  68                 xx.i[3] &= ~((1 << j) - 1);
  69
  70         /* negate result if need be */
  71         if (sx)
  72                 xx.i[0] |= 0x80000000;
  73         return (xx.q);
  74 }
  75 #elif defined(__x86)
  76 long double
  77 truncl(long double x) {
  78         union {
  79                 unsigned i[3];
  80                 long double e;
  81         } xx;
  82         int ex, sx, i;
  83
  84         xx.e = x;
  85         ex = xx.i[2] & 0x7fff;
  86         sx = xx.i[2] & 0x8000;
  87         if (ex < 0x403e) {      /* |x| < 2^63 */
  88                 if (ex < 0x3fff)        /* |x| < 1 */
  89                         return (sx ? -0.0L : 0.0L);
  90
  91                 /* chop x at the integer bit */
  92                 if (ex < 0x401e) {
  93                         i = 1 << (0x401d - ex);
  94                         xx.i[1] &= ~(i | (i - 1));
  95                         xx.i[0] = 0;
  96                 } else {
  97                         i = 1 << (0x403d - ex);
  98                         xx.i[0] &= ~(i | (i - 1));
  99                 }
 100                 return (xx.e);
 101         } else if (ex < 0x7fff) /* x is integral */
 102                 return (x);
 103         else                    /* inf or nan */
 104                 return (x + x);
 105 }
 106 #else
 107 #error Unknown architecture
 108 #endif  /* defined(__sparc) || defined(__x86) */