/src/FreeImage/Source/OpenEXR/Half/toFloat.cpp
https://bitbucket.org/cabalistic/ogredeps/ · C++ · 164 lines · 65 code · 30 blank · 69 comment · 14 complexity · 24afbf33ae9ba2c95b762924da158a41 MD5 · raw file
- ///////////////////////////////////////////////////////////////////////////
- //
- // Copyright (c) 2002, 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
- // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- //
- ///////////////////////////////////////////////////////////////////////////
- //---------------------------------------------------------------------------
- //
- // toFloat
- //
- // A program to generate the lookup table for half-to-float
- // conversion needed by class half.
- // The program loops over all 65536 possible half numbers,
- // converts each of them to a float, and prints the result.
- //
- //---------------------------------------------------------------------------
- #include <iostream>
- #include <iomanip>
- using namespace std;
- //---------------------------------------------------
- // Interpret an unsigned short bit pattern as a half,
- // and convert that half to the corresponding float's
- // bit pattern.
- //---------------------------------------------------
- unsigned int
- halfToFloat (unsigned short y)
- {
- int s = (y >> 15) & 0x00000001;
- int e = (y >> 10) & 0x0000001f;
- int m = y & 0x000003ff;
- if (e == 0)
- {
- if (m == 0)
- {
- //
- // Plus or minus zero
- //
- return s << 31;
- }
- else
- {
- //
- // Denormalized number -- renormalize it
- //
- while (!(m & 0x00000400))
- {
- m <<= 1;
- e -= 1;
- }
- e += 1;
- m &= ~0x00000400;
- }
- }
- else if (e == 31)
- {
- if (m == 0)
- {
- //
- // Positive or negative infinity
- //
- return (s << 31) | 0x7f800000;
- }
- else
- {
- //
- // Nan -- preserve sign and significand bits
- //
- return (s << 31) | 0x7f800000 | (m << 13);
- }
- }
- //
- // Normalized number
- //
- e = e + (127 - 15);
- m = m << 13;
- //
- // Assemble s, e and m.
- //
- return (s << 31) | (e << 23) | m;
- }
- //---------------------------------------------
- // Main - prints the half-to-float lookup table
- //---------------------------------------------
- int
- main ()
- {
- cout.precision (9);
- cout.setf (ios_base::hex, ios_base::basefield);
- cout << "//\n"
- "// This is an automatically generated file.\n"
- "// Do not edit.\n"
- "//\n\n";
- cout << "{\n ";
- const int iMax = (1 << 16);
- for (int i = 0; i < iMax; i++)
- {
- cout << "{0x" << setfill ('0') << setw (8) << halfToFloat (i) << "}, ";
- if (i % 4 == 3)
- {
- cout << "\n";
- if (i < iMax - 1)
- cout << " ";
- }
- }
- cout << "};\n";
- return 0;
- }