opencv/3rdparty/openexr/IlmImf/b44ExpLogTable.cpp

///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2006, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
// *       Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// *       Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// *       Neither the name of Industrial Light & Magic nor the names of
// its contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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///////////////////////////////////////////////////////////////////////////

//---------------------------------------------------------------------------
//
//	b44ExpLogTable
//
//	A program to generate lookup tables for
//
//		y = exp (x / 8)
//
//	and
//		x = 8 * log (x);
//
//	where x and y are 16-bit floating-point numbers
//
//	The tables are used by class B44Compressor.
//
//---------------------------------------------------------------------------

#include <half.h>
#include <math.h>
#include <iostream>
#include <iomanip>

using namespace std;

//---------------------------------------------
// Main - prints the half-to-float lookup table
//---------------------------------------------

int
main ()
{
#ifndef HAVE_IOS_BASE
    cout.setf (ios::hex, ios::basefield);
#else
    cout.setf (ios_base::hex, ios_base::basefield);
#endif

    cout << "//\n"
        "// This is an automatically generated file.\n"
        "// Do not edit.\n"
        "//\n\n";

    const int iMax = (1 << 16);

    cout << "const unsigned short expTable[] =\n"
        "{\n"
        "    ";

    for (int i = 0; i < iMax; i++)
    {
    half h;
    h.setBits (i);

    if (!h.isFinite())
        h = 0;
    else if (h >= 8 * log (HALF_MAX))
        h = HALF_MAX;
    else
        h = exp (h / 8);

    cout << "0x" << setfill ('0') << setw (4) << h.bits() << ", ";

    if (i % 8 == 7)
    {
        cout << "\n";

        if (i < iMax - 1)
        cout << "    ";
    }
    }

    cout << "};\n\n";

    cout << "const unsigned short logTable[] =\n"
        "{\n"
        "    ";

    for (int i = 0; i < iMax; i++)
    {
    half h;
    h.setBits (i);

    if (!h.isFinite() || h < 0)
        h = 0;
    else
        h = 8 * log (h);

    cout << "0x" << setfill ('0') << setw (4) << h.bits() << ", ";

    if (i % 8 == 7)
    {
        cout << "\n";

        if (i < iMax - 1)
        cout << "    ";
    }
    }

    cout << "};\n";

    return 0;
}