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Diffstat (limited to 'Source/OpenEXR/Half/toFloat.cpp')
| -rw-r--r-- | Source/OpenEXR/Half/toFloat.cpp | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/Source/OpenEXR/Half/toFloat.cpp b/Source/OpenEXR/Half/toFloat.cpp new file mode 100644 index 0000000..001bc51 --- /dev/null +++ b/Source/OpenEXR/Half/toFloat.cpp @@ -0,0 +1,164 @@ +/////////////////////////////////////////////////////////////////////////// +// +// 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; +} |