[Webkit-unassigned] [Bug 67980] [Chromium/Mac] fast/events/constructors/progress-event-constructor.html is failing

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=67980


Adam Barth <abarth at webkit.org> changed:

           What    |Removed                     |Added
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 Attachment #112459|review?                     |review-
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--- Comment #3 from Adam Barth <abarth at webkit.org>  2011-10-26 09:48:22 PST ---
(From update of attachment 112459)
View in context: https://bugs.webkit.org/attachment.cgi?id=112459&action=review

> Source/WebCore/bindings/v8/OptionsObject.cpp:238
> +        // Calculate d % 2^{64}.
> +        // -2^{64} < fmodValue < 2^{64}.
> +        double fmodValue = fmod(trunc(d), std::numeric_limits<unsigned long long>::max() + 1.0);
> +        if (fmodValue >= 0) {
> +            // 0 <= fmodValue < 2^{64}.
> +            // 0 <= value < 2^{64}. This cast causes no loss.
> +            value = static_cast<unsigned long long>(fmodValue);
> +        } else {
> +            // -2^{64} < fmodValue < 0.
> +            // 0 < fmodValueInUnsignedLongLong < 2^{64}. This cast causes no loss.
> +            unsigned long long fmodValueInUnsignedLongLong = static_cast<unsigned long long>(-fmodValue);
> +            // -1 < (std::numeric_limits<unsigned long long>::max() - fmodValueInUnsignedLongLong) < 2^{64} - 1.
> +            // 0 < value < 2^{64}.
> +            value = std::numeric_limits<unsigned long long>::max() - fmodValueInUnsignedLongLong + 1;
> +        }

This looks cool, but it should be factored into a more general location so that folks can re-use it.  If it's V8-specific logic, it should probably go in V8Utilities.  If it's more general than V8, it should go in WTF somewhere.

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