usr/src/lib/libm/common/R/log1pf.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  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  23  */
  24 /*
  25  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
  26  * Use is subject to license terms.
  27  */
  28
  29 #pragma weak __log1pf = log1pf
  30
  31 #include "libm.h"
  32
  33 static const float zero = 0.0f;
  34
  35 float
  36 log1pf(float x) {
  37         int     ix;
  38
  39         ix = *(int *)&x;
  40         if (ix >= 0x7f800000) {
  41                 /* x is +inf or nan */
  42                 return (x * x);
  43         }
  44         if (ix < 0) {
  45                 ix &= ~0x80000000;
  46                 if (ix == 0x3f800000) /* x is -1 */
  47                         return (x / zero);
  48                 if (ix > 0x3f800000) /* x is < -1 or nan */
  49                         return ((x * zero) / zero);
  50         }
  51         return ((float)log1p((double)x));
  52 }