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/src/FreeImage/Source/OpenEXR/Half/eLut.cpp

https://bitbucket.org/cabalistic/ogredeps/
C++ | 114 lines | 45 code | 18 blank | 51 comment | 7 complexity | 982a90d0eba60fd6ab9d771c559b296a MD5 | raw file
  1///////////////////////////////////////////////////////////////////////////
  2//
  3// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
  4// Digital Ltd. LLC
  5// 
  6// All rights reserved.
  7// 
  8// Redistribution and use in source and binary forms, with or without
  9// modification, are permitted provided that the following conditions are
 10// met:
 11// *       Redistributions of source code must retain the above copyright
 12// notice, this list of conditions and the following disclaimer.
 13// *       Redistributions in binary form must reproduce the above
 14// copyright notice, this list of conditions and the following disclaimer
 15// in the documentation and/or other materials provided with the
 16// distribution.
 17// *       Neither the name of Industrial Light & Magic nor the names of
 18// its contributors may be used to endorse or promote products derived
 19// from this software without specific prior written permission. 
 20// 
 21// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 22// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 23// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 24// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 25// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 26// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 27// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 28// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 29// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 30// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 31// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 32//
 33///////////////////////////////////////////////////////////////////////////
 34
 35
 36
 37#include <iostream>
 38#include <iomanip>
 39
 40using namespace std;
 41
 42//-----------------------------------------------------
 43// Compute a lookup table for float-to-half conversion.
 44//
 45// When indexed with the combined sign and exponent of
 46// a float, the table either returns the combined sign
 47// and exponent of the corresponding half, or zero if
 48// the corresponding half may not be normalized (zero,
 49// denormalized, overflow).
 50//-----------------------------------------------------
 51
 52void
 53initELut (unsigned short eLut[])
 54{
 55    for (int i = 0; i < 0x100; i++)
 56    {
 57	int e = (i & 0x0ff) - (127 - 15);
 58
 59	if (e <= 0 || e >= 30)
 60	{
 61	    //
 62	    // Special case
 63	    //
 64
 65	    eLut[i]         = 0;
 66	    eLut[i | 0x100] = 0;
 67	}
 68	else
 69	{
 70	    //
 71	    // Common case - normalized half, no exponent overflow possible
 72	    //
 73
 74	    eLut[i]         =  (e << 10);
 75	    eLut[i | 0x100] = ((e << 10) | 0x8000);
 76	}
 77    }
 78}
 79
 80
 81//------------------------------------------------------------
 82// Main - prints the sign-and-exponent conversion lookup table
 83//------------------------------------------------------------
 84
 85int
 86main ()
 87{
 88    const int tableSize = 1 << 9;
 89    unsigned short eLut[tableSize];
 90    initELut (eLut);
 91
 92    cout << "//\n"
 93	    "// This is an automatically generated file.\n"
 94	    "// Do not edit.\n"
 95	    "//\n\n";
 96
 97    cout << "{\n    ";
 98
 99    for (int i = 0; i < tableSize; i++)
100    {
101	cout << setw (5) << eLut[i] << ", ";
102
103	if (i % 8 == 7)
104	{
105	    cout << "\n";
106
107	    if (i < tableSize - 1)
108		cout << "    ";
109	}
110    }
111
112    cout << "};\n";
113    return 0;
114}