usr/src/lib/libm/common/m9x/lroundf.c

   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 #pragma weak lroundf = __lroundf
  31
  32 #include <sys/isa_defs.h>       /* _ILP32 */
  33 #include "libm.h"
  34
  35 #if defined(_ILP32)
  36 long
  37 lroundf(float x) {
  38         union {
  39                 unsigned i;
  40                 float f;
  41         } xx;
  42         unsigned hx, sx, i;
  43
  44         xx.f = x;
  45         hx = xx.i & ~0x80000000;
  46         sx = xx.i & 0x80000000;
  47         if (hx < 0x4b000000) {          /* |x| < 2^23 */
  48                 if (hx < 0x3f800000) {          /* |x| < 1 */
  49                         if (hx >= 0x3f000000)
  50                                 return (sx ? -1L : 1L);
  51                         return (0L);
  52                 }
  53
  54                 /* round x at the integer bit */
  55                 i = 1 << (0x95 - (hx >> 23));
  56                 xx.i = (xx.i + i) & ~((i << 1) - 1);
  57                 return ((long) xx.f);
  58         }
  59
  60         /* now x is nan, inf, or integral */
  61         return ((long) x);
  62 }
  63 #else
  64 #error Unsupported architecture
  65 #endif  /* defined(_ILP32) */