126 lines
3.1 KiB
C++
126 lines
3.1 KiB
C++
///////////////////////////////////////////////////////////////////////////
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//
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// Copyright (c) 2006, 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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// Rational numbers
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//
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// The double-to-Rational conversion code below
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// was contributed to OpenEXR by Greg Ward.
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//
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//-----------------------------------------------------------------------------
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#include <ImfRational.h>
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#include <cmath>
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using namespace std;
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namespace Imf {
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namespace {
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double
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frac (double x, double e)
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{
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return x - floor (x + e);
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}
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double
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square (double x)
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{
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return x * x;
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}
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double
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denom (double x, double e)
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{
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if (e > frac (x, e))
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{
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return 1;
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}
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else
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{
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double r = frac (1 / x, e);
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if (e > r)
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{
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return floor (1 / x + e);
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}
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else
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{
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return denom (frac (1 / r, e), e / square (x * r)) +
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floor (1 / x + e) * denom (frac (1 / x, e), e / square (x));
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}
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}
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}
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} // namespace
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Rational::Rational (double x)
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{
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int sign;
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if (x >= 0)
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{
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sign = 1; // positive
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}
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else if (x < 0)
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{
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sign = -1; // negative
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x = -x;
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}
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else
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{
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n = 0; // NaN
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d = 0;
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return;
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}
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if (x >= (1U << 31) - 0.5)
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{
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n = sign; // infinity
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d = 0;
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return;
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}
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double e = (x < 1? 1: x) / (1U << 30);
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d = (unsigned int) denom (x, e);
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n = sign * (int) floor (x * d + 0.5);
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}
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} // namespace Imf
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