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      1 /**************************************************************************
      2  *
      3  * Copyright 2008 Tungsten Graphics, Inc., Cedar Park, Texas.
      4  * All Rights Reserved.
      5  *
      6  * Permission is hereby granted, free of charge, to any person obtaining a
      7  * copy of this software and associated documentation files (the
      8  * "Software"), to deal in the Software without restriction, including
      9  * without limitation the rights to use, copy, modify, merge, publish,
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     11  * permit persons to whom the Software is furnished to do so, subject to
     12  * the following conditions:
     13  *
     14  * The above copyright notice and this permission notice (including the
     15  * next paragraph) shall be included in all copies or substantial portions
     16  * of the Software.
     17  *
     18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
     19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
     20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
     21  * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
     22  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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     24  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
     25  *
     26  **************************************************************************/
     27 
     28 
     29 
     30 #include "util/u_math.h"
     31 
     32 
     33 /** 2^x, for x in [-1.0, 1.0) */
     34 float pow2_table[POW2_TABLE_SIZE];
     35 
     36 
     37 static void
     38 init_pow2_table(void)
     39 {
     40    int i;
     41    for (i = 0; i < POW2_TABLE_SIZE; i++)
     42       pow2_table[i] = (float) pow(2.0, (i - POW2_TABLE_OFFSET) / POW2_TABLE_SCALE);
     43 }
     44 
     45 
     46 /** log2(x), for x in [1.0, 2.0) */
     47 float log2_table[LOG2_TABLE_SIZE];
     48 
     49 
     50 static void
     51 init_log2_table(void)
     52 {
     53    unsigned i;
     54    for (i = 0; i < LOG2_TABLE_SIZE; i++)
     55       log2_table[i] = (float) log2(1.0 + i * (1.0 / LOG2_TABLE_SCALE));
     56 }
     57 
     58 
     59 /**
     60  * One time init for math utilities.
     61  */
     62 void
     63 util_init_math(void)
     64 {
     65    static boolean initialized = FALSE;
     66    if (!initialized) {
     67       init_pow2_table();
     68       init_log2_table();
     69       initialized = TRUE;
     70    }
     71 }
     72 
     73 
     74