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 __llrint = llrint
  32 #if defined(__sparcv9) || defined(__amd64)
  33 #pragma weak lrint = llrint
  34 #pragma weak __lrint = llrint
  35 #endif
  36 
  37 /*
  38  * llrint(x) rounds its argument to the nearest integer according
  39  * to the current rounding direction and converts the result to a
  40  * 64 bit signed integer.
  41  *
  42  * If x is NaN, infinite, or so large that the nearest integer would
  43  * exceed 64 bits, the invalid operation exception is raised.  If x
  44  * is not an integer, the inexact exception is raised.
  45  */
  46 
  47 #include "libm.h"
  48 
  49 long long
  50 llrint(double x)
  51 {
  52         /*
  53          * Note: The following code works on x86 (in the default rounding
  54          * precision mode), but one should just use the fistpll instruction
  55          * instead.
  56          */
  57         union {
  58                 unsigned i[2];
  59                 double d;
  60         } xx, yy;
  61 
  62         unsigned hx;
  63 
  64         xx.d = x;
  65         hx = xx.i[HIWORD] & ~0x80000000;
  66 
  67         if (hx < 0x43300000) {               /* |x| < 2^52 */
  68                 /* add and subtract a power of two to round x to an integer */
  69 #if defined(__sparc) || defined(__amd64)
  70                 yy.i[HIWORD] = (xx.i[HIWORD] & 0x80000000) | 0x43300000;
  71 #elif defined(__i386)                   /* !defined(__amd64) */
  72                 yy.i[HIWORD] = (xx.i[HIWORD] & 0x80000000) | 0x43e00000;
  73 #else
  74 #error Unknown architecture
  75 #endif
  76                 yy.i[LOWORD] = 0;
  77                 x = (x + yy.d) - yy.d;
  78         }
  79 
  80         /* now x is nan, inf, or integral */
  81         return ((long long)x);
  82 }