On Sun, Feb 21, 2016 at 10:06:24AM -0800, Eliot Miranda wrote:
> Hi David,
> 
>     since WordArray is defined as a sequence of 32-bit integer slots, a one element WordArray has its first element in the first four bytes on both big and little endianness 64-bit and 32-bit platforms and so two elements are not necessary.  I could add this to the comment.  And yes, this is possible because there are no compact classes to prevent a more general adoptInstance:.
> 

Thanks Eliot,

Yes that makes sense and I suppose it would be a bug if the resulting ByteArray
was anything /other/ than 4 bytes in size, so my suggestion does not make sense.

r.e. the comment, I only meant that it should not refer to "String" any more.
Maybe you (or anyone) can make that minor update the next time something gets
committed to System.

Thanks,
Dave


> _,,,^..^,,,_ (phone)
> 
> > On Feb 21, 2016, at 8:50 AM, David T. Lewis <lewis at mail.msen.com> wrote:
> > 
> >> On Sun, Feb 21, 2016 at 07:40:22AM +0000, commits at source.squeak.org wrote:
> >> Eliot Miranda uploaded a new version of System to project The Trunk:
> >> http://source.squeak.org/trunk/System-eem.801.mcz
> >> 
> >> ==================== Summary ====================
> >> 
> >> Name: System-eem.801
> >> Author: eem
> >> Time: 20 February 2016, 11:40:02.089874 pm
> >> UUID: cb00963a-1c90-40c0-9539-04c88c0afa5f
> >> Ancestors: System-mt.800
> >> 
> >> In Spur calcEndianness can be a lot simpler.
> > 
> > This works in Spur because ByteArray can now adopt an instance of WordArray,
> > is that right?
> > 
> > Does the test work on big endian 64-bit? I think that it will, but if there
> > is any doubt it might be safer to use a two element WordArray:
> > 
> >    WordArray with: 16r01020304 with: 16r01020304
> > 
> > The method comment describes the old String implementation, so it would be
> > good to update that.
> > 
> > Dave
> > 
> > 
> > 
> >> =============== Diff against System-mt.800 ===============
> >> 
> >> Item was changed:
> >>  ----- Method: SmalltalkImage>>calcEndianness (in category 'system attributes') -----
> >>  calcEndianness
> >> -    | bytes word blt |
> >>      "What endian-ness is the current hardware?  The String '1234' will be stored into a machine word.  On BigEndian machines (the Mac), $1 will be the high byte if the word.  On LittleEndian machines (the PC), $4 will be the high byte."
> >>      "Smalltalk endianness"
> >> +    | wordThenBytes |
> >> +    wordThenBytes := WordArray with: 16r01020304.
> >> +    ByteArray adoptInstance: wordThenBytes.
> >> +    wordThenBytes first = 1 ifTrue: [^#big].
> >> +    wordThenBytes first = 4 ifTrue: [^#little].
> >> +    self error: 'The author is confused'!
> >> - 
> >> -    bytes := ByteArray withAll: #(0 0 0 0).  "(1 2 3 4) or (4 3 2 1)"
> >> -    word := WordArray with: 16r01020304.
> >> -    blt := (BitBlt toForm: (Form new hackBits: bytes)) 
> >> -                sourceForm: (Form new hackBits: word).
> >> -    blt combinationRule: Form over.  "store"
> >> -    blt sourceY: 0; destY: 0; height: 1; width: 4.
> >> -    blt sourceX: 0; destX: 0.
> >> -    blt copyBits.  "paste the word into the bytes"
> >> -    bytes first = 1 ifTrue: [^ #big].
> >> -    bytes first = 4 ifTrue: [^ #little].
> >> -    self error: 'Ted is confused'.!
> >