[breaking out a new thread since this is orthogonal to the NaN issue]
While the Khronos spec never specified an endianness, TC39 agreed in May 2012
to make the byte order explicitly little-endian in ES6:
https://mail.mozilla.org/pipermail/es-discuss/2012-May/022834.html
The de facto reality is that there are essentially no big-endian browsers for
developers to test on. Web content is being invited to introduce byte-order
dependencies. DataView is usually held up as the counter-argument, as if the
*existence* of a safe alternative API means no one will ever misuse the unsafe
one. Even if we don't take into account human nature, Murphy's Law, and the
fact that the web is the world's largest fuzz tester, a wholly rational
developer may often prefer not to use DataView because it's still easier to
read out bytes using [ ] notation instead of DataView methods.
I myself -- possibly the one person in the world who cares most about this
issue! -- accidentally created a buggy app that wouldn't work on a big-endian
system, because I had no way of testing it:
https://github.com/dherman/float.js/commit/deb5bf2f5696ce29d9a6c1a6bf7c479a3784fd7b
In summary: we already agreed on TC39 to close this loophole, it's the right
thing to do, and concern about potential performance issues on non-existent
browsers of non-existent systems should not trump portability and correctly
executing existing web content.
Dave
This was not the plan of record on TC39. The plan was to fix the semantics as
little-endian.
On Mar 25, 2013, at 6:00 PM, Brendan Eich <[email protected]> wrote:
> Right, thanks for the reminder. It all comes back now, including the "how to
> write correct ending-independent typed array code" bit.
>
> /be
>
> On Mar 25, 2013, at 4:33 PM, Kenneth Russell <[email protected]> wrote:
>
>> On Mon, Mar 25, 2013 at 4:23 PM, Brendan Eich <[email protected]> wrote:
>>> Allen Wirfs-Brock wrote:
>>>>
>>>> On Mar 25, 2013, at 4:05 PM, Brendan Eich wrote:
>>>>
>>>>> Allen Wirfs-Brock wrote:
>>>>>>
>>>>>> BTW, isn't cannonicalization of endian-ness for both integers and floats
>>>>>> a bigger interop issue than NaN cannonicalization? I know this was
>>>>>> discussed in the past, but it doesn't seem to be covered in the latest
>>>>>> Khronos spec. Was there ever a resolution as to whether or not
>>>>>> TypedArray
>>>>>> [[Set]] operations need to use a cannonical endian-ness?
>>>>>
>>>>> Search for "byte order" at
>>>>> https://www.khronos.org/registry/typedarray/specs/latest/.
>>>>
>>>>
>>>> I had already search for "endian" with similar results. It says that the
>>>> default for DataViews gets/sets that do not specify a byte order is
>>>> big-endean. It doesn't say anything (that I can find) about such accesses
>>>> on
>>>> TypedArray gets/sets.
>>>
>>>
>>> Oh, odd -- I recall that it used to say little-endian. Typed arrays are LE
>>> to match dominant architectures, while DataViews are BE to match packed
>>> serialization use-cases.
>>>
>>> Ken, did something get edited out?
>>
>> No. The typed array views (everything except DataView) have used the
>> host machine's endianness from day one by design -- although the typed
>> array spec does not state this explicitly. If desired, text can be
>> added to the specification to this effect. Any change in this behavior
>> will destroy the performance of APIs like WebGL and Web Audio on
>> big-endian architectures.
>>
>> Correctly written code works identically on big-endian and
>> little-endian architectures. See
>> http://www.html5rocks.com/en/tutorials/webgl/typed_arrays/ for a
>> detailed description of the usage of the APIs.
>>
>> DataView, which is designed for input/output, operates on data with a
>> specified endianness.
>>
>> -Ken
>> _______________________________________________
>> es-discuss mailing list
>> [email protected]
>> https://mail.mozilla.org/listinfo/es-discuss
> _______________________________________________
> es-discuss mailing list
> [email protected]
> https://mail.mozilla.org/listinfo/es-discuss
_______________________________________________
es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
