src/gallium/auxiliary/util/u_math.c

   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,
  10  * distribute, sub license, and/or sell copies of the Software, and to
  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,
  23  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  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_SIZE));
  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