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 __lrintf = lrintf
  32 
  33 #include <sys/isa_defs.h>         /* _ILP32 */
  34 #include "libm.h"
  35 
  36 #if defined(_ILP32)
  37 long
  38 lrintf(float x)
  39 {
  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 
  50         unsigned hx;
  51 
  52         xx.f = x;
  53         hx = xx.i & ~0x80000000;
  54 
  55         if (hx < 0x4b000000) {               /* |x| < 2^23 */
  56                 /* add and subtract a power of two to round x to an integer */
  57 #if defined(__sparc)
  58                 yy.i = (xx.i & 0x80000000) | 0x4b000000;
  59 #elif defined(__x86)
  60                 /* assume 64-bit precision */
  61                 yy.i = (xx.i & 0x80000000) | 0x5f000000;
  62 #else
  63 #error Unknown architecture
  64 #endif
  65                 x = (x + yy.f) - yy.f;
  66                 return ((long)x);
  67         }
  68 
  69         /* now x is nan, inf, or integral */
  70         return ((long)x);
  71 }
  72 #else
  73 #error Unsupported architecture
  74 #endif /* defined(_ILP32) */