endianness

Kevin Gadd kevin.gadd at gmail.com
Tue Apr 2 15:36:48 PDT 2013


Is there a reason why DataView wasn't specified as static methods that take
an ArrayBuffer in the first place? That would solve the problem of figuring
out when/how often to create DataView instances, and eliminate the garbage
created by using DataViews.


On Tue, Apr 2, 2013 at 3:23 PM, Kenneth Russell <kbr at google.com> wrote:

> On Tue, Apr 2, 2013 at 3:03 PM, Aymeric Vitte <vitteaymeric at gmail.com>
> wrote:
> >
> > Le 02/04/2013 04:24, Kenneth Russell a écrit :
> >>
> >> Agreed. DataView's methods are all simple and should be easy to
> >> optimize. Because they include a conditional byte swap, they can't run
> >> quite as fast as the typed arrays' accessors -- but they shouldn't
> >> need to. DataView was designed to support file and network I/O, where
> >> throughput is limited by the disk or network connection. The typed
> >> array views were designed for in-memory assembly of data to be
> >> submitted to the graphics card, sound card, etc., and must run as fast
> >> as possible.
> >
> > When you are streaming things, what's the correct use of DataViews?
> >
> > ie : you are supposed to create each time you want to read some bytes a
> > DataView (which can be optimized or whatever, but still with some costs)?
> >
> > Maybe it's outside of the scope of this discussion, I have already
> provided
> > examples, I still suspect that I am using it wrongly or that ArrayBuffers
> > are more adapted to webgl (ie static buffer manipulation) than network
> > streaming (ie dynamic buffer manipulation).
> >
> > Probably I am wrong but really would like to know then what's the correct
> > use.
>
> If I understand your question, then the correct use of DataView is:
> upon receiving an ArrayBuffer, create a DataView referring to it. When
> iterating down the contents of the ArrayBuffer, continue to use the
> same DataView instance, just incrementing the offset. In
> abstract-tls/lib/abstract-tls.js there are some operations which
> create a new DataView just to read or write a single element; this
> isn't the correct usage.
> http://www.html5rocks.com/en/tutorials/webgl/typed_arrays/ may be a
> useful reference.
>
> If you're handling streaming data then presumably you're receiving
> multiple ArrayBuffers, one after the other. You should create one
> DataView per buffer. The only challenge is properly handling the
> boundary from one buffer to the next, if the boundary is within an
> element like a uint16 or uint32.
>
> -Ken
>



-- 
-kg
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