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 /*
  27  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  28  * Use is subject to license terms.
  29  */
  30 
  31 #pragma weak __llround = llround
  32 #if defined(__sparcv9) || defined(__amd64)
  33 #pragma weak lround = llround
  34 #pragma weak __lround = llround
  35 #endif
  36 
  37 /*
  38  * llround(x) rounds its argument to the nearest integer, rounding
  39  * ties away from zero, and converts the result to a 64 bit signed
  40  * integer.
  41  *
  42  * If x is NaN, infinite, or so large that the nearest integer
  43  * would exceed 64 bits, the invalid operation exception is raised.
  44  */
  45 
  46 #include "libm.h"
  47 
  48 long long
  49 llround(double x)
  50 {
  51         union {
  52                 unsigned i[2];
  53                 double d;
  54         } xx;
  55 
  56         unsigned hx, sx, i;
  57 
  58         xx.d = x;
  59         hx = xx.i[HIWORD] & ~0x80000000;
  60         sx = xx.i[HIWORD] & 0x80000000;
  61 
  62         if (hx < 0x43300000) {               /* |x| < 2^52 */
  63                 /* handle |x| < 1 */
  64                 if (hx < 0x3ff00000) {
  65                         if (hx >= 0x3fe00000)
  66                                 return (sx ? -1LL : 1LL);
  67 
  68                         return (0LL);
  69                 }
  70 
  71                 /* round x at the integer bit */
  72                 if (hx < 0x41300000) {
  73                         i = 1 << (0x412 - (hx >> 20));
  74                         xx.i[HIWORD] = (xx.i[HIWORD] + i) & ~(i | (i - 1));
  75                         xx.i[LOWORD] = 0;
  76                 } else {
  77                         i = 1 << (0x432 - (hx >> 20));
  78                         xx.i[LOWORD] += i;
  79 
  80                         if (xx.i[LOWORD] < i)
  81                                 xx.i[HIWORD]++;
  82 
  83                         xx.i[LOWORD] &= ~(i | (i - 1));
  84                 }
  85         }
  86 
  87         /* now x is nan, inf, or integral */
  88         return ((long long)xx.d);
  89 }