/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* vim: set ts=8 sts=2 et sw=2 tw=80: */ /* This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* Implementations of FloatingPoint functions */
#include"mozilla/FloatingPoint.h"
#include <cfloat> // for FLT_MAX
namespace mozilla {
bool IsFloat32Representable(double aValue) { // NaNs and infinities are representable. if (!std::isfinite(aValue)) { returntrue;
}
// If it exceeds finite |float| range, casting to |double| is always undefined // behavior per C++11 [conv.double]p1 last sentence. if (Abs(aValue) > FLT_MAX) { returnfalse;
}
// But if it's within finite range, then either it's 1) an exact value and so // representable, or 2) it's "between two adjacent destination values" and // safe to cast to "an implementation-defined choice of either of those // values". auto valueAsFloat = static_cast<float>(aValue);
// Per [conv.fpprom] this never changes value. auto valueAsFloatAsDouble = static_cast<double>(valueAsFloat);
// Finally, in 1) exact representable value equals exact representable value, // or 2) *changed* value does not equal original value, ergo unrepresentable. return valueAsFloatAsDouble == aValue;
}
} /* namespace mozilla */
¤ Dauer der Verarbeitung: 0.14 Sekunden
(vorverarbeitet)
¤
Die Informationen auf dieser Webseite wurden
nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit,
noch Qualität der bereit gestellten Informationen zugesichert.
Bemerkung:
Die farbliche Syntaxdarstellung ist noch experimentell.
