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// BEGIN_COPYRIGHT -*- glean -*-
//
// Copyright (C) 1999 Allen Akin All Rights Reserved.
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the
// Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
// KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
// WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL ALLEN AKIN BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
// AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
// OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
// END_COPYRIGHT
// misc.cpp: implementation of miscellaneous functions
#include <cctype>
#include <cmath>
#ifdef __CYGWIN__
#undef log2
#endif
#include "misc.h"
namespace GLEAN {
///////////////////////////////////////////////////////////////////////////////
// Utility routine to skip whitespace in streams
// This is helpful when interleaving invocations of getline() and
// operator>>. In particular, after operator>> at the end of a line,
// there may be whitespace (especially a newline) remaining; this may
// confuse a subsequent invocation of getline().
///////////////////////////////////////////////////////////////////////////////
void
SkipWhitespace(istream& s) {
char c;
while (s.get(c)) {
if (!isspace(c)) {
s.putback(c);
break;
}
}
} // SkipWhitespace
///////////////////////////////////////////////////////////////////////////////
// Utility routine to compute logarithm, base two
///////////////////////////////////////////////////////////////////////////////
double
log2(double x) {
return 1.4426950408889634 * log(x);
}
///////////////////////////////////////////////////////////////////////////////
// Utility routine to compute error, expressed in bits
// Typically used to convert a floating-point error (in the range [0,1])
// to the number of bits in the representation of a color.
///////////////////////////////////////////////////////////////////////////////
double
ErrorBits(double absError, int repBits) {
if (absError <= 0.0)
return 0.0;
double log2Error = log2(absError) + repBits;
return (log2Error <= 0.0)? 0.0: log2Error;
} // ErrorBits
} // namespace GLEAN
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