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 #if defined(ELFOBJ)
  31 #pragma weak lrintf = __lrintf
  32 #endif
  33 
  34 #include <sys/isa_defs.h> /* _ILP32 */
  35 #include "libm.h"
  36 
  37 #if defined(_ILP32)
  38 long
  39 lrintf(float x) {
  40         /*
  41          * Note: The following code works on x86 (in the default rounding
  42          * precision mode), but one should just use the fistpl instruction
  43          * instead.
  44          */
  45         union {
  46                 unsigned i;
  47                 float f;
  48         } xx, yy;
  49         unsigned hx;
  50 
  51         xx.f = x;
  52         hx = xx.i & ~0x80000000;
  53         if (hx < 0x4b000000) {       /* |x| < 2^23 */
  54                 /* add and subtract a power of two to round x to an integer */
  55 #if defined(__sparc)
  56                 yy.i = (xx.i & 0x80000000) | 0x4b000000;
  57 #elif defined(__x86)
  58                 /* assume 64-bit precision */
  59                 yy.i = (xx.i & 0x80000000) | 0x5f000000;
  60 #else
  61 #error Unknown architecture
  62 #endif
  63                 x = (x + yy.f) - yy.f;
  64                 return ((long) x);
  65         }
  66 
  67         /* now x is nan, inf, or integral */
  68         return ((long) x);
  69 }
  70 #else
  71 #error Unsupported architecture
  72 #endif  /* defined(_ILP32) */