Subj : Re: spidermonkey: byte arrays - again
To   : netscape.public.mozilla.jseng
From : Shanti Rao
Date : Thu Sep 16 2004 02:04 pm

Jens,

What are you using it for? Arbitrary indexing and manipulation, or sequential 
scanning of text?

Do you need to do

myarray[5]

or

myarray.seek(5)
myarray.read(2)

How much data do you want to store?

Do you need the array to be resizable?

Is it write-once-read-many or random-access?

Do you need bulk mathematical operations?

Do you want to read the values as numbers or as characters?

I'vd found that a JS Array of 10k floating-point numbers works just fine for 
light computation.

Shanti

> Hi,
> 
> I am at the byte arrays again ;-)
> 
> Intro:
> Unfortunately Javascript does not have a native/primtive c-style byte
> array for raw data. Especially when wrapping native code you need it.
> (For example networking, image processing, compression/decompression,
> ...)
> 
> Possible "solutions":
> 1. use javascript string:
>   a) only use 8bit of 16bit chars
>      + simple
>      - bloat
>      - confusing / error prone
>   b) use all 16 bit
>      - what about odd number of bytes? needs some ugly hack
> 
> 2. use javascript array:
>   I only did a quick look at how the arrays are done and guess
>   this would be real bloat
> 
> 3. write some native/host object:
>   + efficient (memory and cpu)
>   - no literal notation => solution 1 or 2 needed to get
>     something close to a literal notation:
>     new ByteArray("thisisraw8bitdatastoredin16bit")
>     new ByteArray([10,20,30,...])
>     new ByteArray("\u3744\u....",odd|even) or similar hack
> 
> probably best thread for implementing 3:
> http://groups.google.de/groups?th=35ba422a08cd0319
> 
> 
> Now the real question:
> Did someone write a ByteArray object/class and wants to share the code?
> 
> Thanks
> Jens

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