usr/src/lib/libm/common/R/scalbf.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 __scalbf = scalbf
  30
  31 #include "libm.h"
  32
  33 float
  34 scalbf(float x, float y) {
  35         int     ix, iy, hx, hy, n;
  36
  37         ix = *(int *)&x;
  38         iy = *(int *)&y;
  39         hx = ix & ~0x80000000;
  40         hy = iy & ~0x80000000;
  41
  42         if (hx > 0x7f800000 || hy >= 0x7f800000) {
  43                 /* x is nan or y is inf or nan */
  44                 return ((iy < 0)? x / -y : x * y);
  45         }
  46
  47         /* see if y is an integer without raising inexact */
  48         if (hy >= 0x4b000000) {
  49                 /* |y| >= 2^23, so it must be an integer */
  50                 n = (iy < 0)? -65000 : 65000;
  51         } else if (hy < 0x3f800000) {
  52                 /* |y| < 1, so it must be zero or non-integer */
  53                 return ((hy == 0)? x : (x - x) / (x - x));
  54         } else {
  55                 if (hy & ((1 << (0x96 - (hy >> 23))) - 1))
  56                         return ((y - y) / (y - y));
  57                 n = (int)y;
  58         }
  59         return (scalbnf(x, n));
  60 }