165 lines
4.1 KiB
C++
165 lines
4.1 KiB
C++
///////////////////////////////////////////////////////////////////////////
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//
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// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
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// Digital Ltd. LLC
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Industrial Light & Magic nor the names of
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// its contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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///////////////////////////////////////////////////////////////////////////
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//---------------------------------------------------------------------------
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//
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// toFloat
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//
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// A program to generate the lookup table for half-to-float
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// conversion needed by class half.
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// The program loops over all 65536 possible half numbers,
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// converts each of them to a float, and prints the result.
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//
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//---------------------------------------------------------------------------
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#include <iostream>
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#include <iomanip>
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using namespace std;
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//---------------------------------------------------
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// Interpret an unsigned short bit pattern as a half,
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// and convert that half to the corresponding float's
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// bit pattern.
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//---------------------------------------------------
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unsigned int
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halfToFloat (unsigned short y)
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{
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int s = (y >> 15) & 0x00000001;
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int e = (y >> 10) & 0x0000001f;
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int m = y & 0x000003ff;
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if (e == 0)
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{
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if (m == 0)
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{
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//
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// Plus or minus zero
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//
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return s << 31;
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}
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else
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{
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//
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// Denormalized number -- renormalize it
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//
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while (!(m & 0x00000400))
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{
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m <<= 1;
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e -= 1;
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}
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e += 1;
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m &= ~0x00000400;
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}
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}
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else if (e == 31)
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{
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if (m == 0)
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{
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//
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// Positive or negative infinity
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//
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return (s << 31) | 0x7f800000;
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}
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else
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{
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//
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// Nan -- preserve sign and significand bits
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//
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return (s << 31) | 0x7f800000 | (m << 13);
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}
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}
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//
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// Normalized number
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//
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e = e + (127 - 15);
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m = m << 13;
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//
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// Assemble s, e and m.
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//
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return (s << 31) | (e << 23) | m;
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}
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//---------------------------------------------
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// Main - prints the half-to-float lookup table
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//---------------------------------------------
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int
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main ()
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{
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cout.precision (9);
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cout.setf (ios_base::hex, ios_base::basefield);
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cout << "//\n"
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"// This is an automatically generated file.\n"
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"// Do not edit.\n"
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"//\n\n";
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cout << "{\n ";
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const int iMax = (1 << 16);
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for (int i = 0; i < iMax; i++)
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{
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cout << "{0x" << setfill ('0') << setw (8) << halfToFloat (i) << "}, ";
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if (i % 4 == 3)
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{
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cout << "\n";
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if (i < iMax - 1)
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cout << " ";
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}
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}
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cout << "};\n";
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return 0;
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}
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