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 __lrint = lrint
  32 
  33 /*
  34  * lrint(x) rounds its argument to the nearest integer according
  35  * to the current rounding direction and converts the result to
  36  * a 32 bit signed integer.
  37  *
  38  * If x is NaN, infinite, or so large that the nearest integer
  39  * would exceed 32 bits, the invalid operation exception is raised.
  40  * If x is not an integer, the inexact exception is raised.
  41  */
  42 
  43 #include <sys/isa_defs.h>         /* _ILP32 */
  44 #include "libm.h"
  45 
  46 #if defined(_ILP32)
  47 long
  48 lrint(double x)
  49 {
  50         /*
  51          * Note: The following code works on x86 (in the default rounding
  52          * precision mode), but one should just use the fistpl instruction
  53          * instead.
  54          */
  55         union {
  56                 unsigned i[2];
  57                 double d;
  58         } xx, yy;
  59 
  60         unsigned hx;
  61 
  62         xx.d = x;
  63         hx = xx.i[HIWORD] & ~0x80000000;
  64 
  65         if (hx < 0x43300000) {               /* |x| < 2^52 */
  66                 /* add and subtract a power of two to round x to an integer */
  67 #if defined(__sparc)
  68                 yy.i[HIWORD] = (xx.i[HIWORD] & 0x80000000) | 0x43300000;
  69 #elif defined(__x86)
  70                 yy.i[HIWORD] = (xx.i[HIWORD] & 0x80000000) | 0x43e00000;
  71 #else
  72 #error Unknown architecture
  73 #endif
  74                 yy.i[LOWORD] = 0;
  75                 x = (x + yy.d) - yy.d;
  76         }
  77 
  78         /* now x is nan, inf, or integral */
  79         return ((long)x);
  80 }
  81 #else
  82 #error Unsupported architecture
  83 #endif /* defined(_ILP32) */