1 /*
   2  * Copyright (c) 2000, 2003, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 
  27 #include "mlib_image.h"
  28 
  29 /***************************************************************/
  30 typedef union {
  31   mlib_d64 db;
  32   struct {
  33 #ifdef _LITTLE_ENDIAN
  34     mlib_s32 int1, int0;
  35 #else
  36     mlib_s32 int0, int1;
  37 #endif
  38   } two_int;
  39 } type_union_mlib_d64;
  40 
  41 #define DVAIN52 4.503599627370496e15
  42 
  43 /***************************************************************/
  44 mlib_s32 mlib_ilogb(mlib_d64 X)
  45 {
  46   type_union_mlib_d64 arg;
  47   mlib_s32 n;
  48 
  49   if (X == 0.0)
  50     return -MLIB_S32_MAX;
  51   arg.db = X;
  52   n = arg.two_int.int0 & 0x7ff00000;
  53   if (n)
  54     n = (n < 0x7ff00000) ? (n >> 20) - 1023 : MLIB_S32_MAX;
  55   else {
  56     arg.db = X * DVAIN52;
  57     n = ((arg.two_int.int0 & 0x7ff00000) >> 20) - 1075;
  58   }
  59   return n;
  60 }
  61 
  62 /***************************************************************/