usr/src/lib/libm/common/R/atan2pif.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 #include "libm.h"
  30
  31 static const double invpi = 0.3183098861837906715377675;
  32
  33 float
  34 atan2pif(float y, float x) {
  35         int     ix, iy, hx, hy;
  36
  37         ix = *(int *)&x;
  38         iy = *(int *)&y;
  39         hx = ix & ~0x80000000;
  40         hy = iy & ~0x80000000;
  41         if (hx > 0x7f800000 || hy > 0x7f800000) /* x or y is nan */
  42                 return (x * y);
  43         if ((hx | hy) == 0) {
  44                 /* x and y are both zero */
  45                 if (ix == 0)
  46                         return (y);
  47                 return ((iy == 0)? 1.0f : -1.0f);
  48         }
  49         return ((float)(invpi * atan2((double)y, (double)x)));
  50 }