JPEGReadWriter, Differences between Squeak and VisualWorks
Andres Valloud
sqrmax at cvtci.com.ar
Sun May 2 04:42:29 UTC 1999
Hi.
> > These selectors, #>> and #<<, should be deleted from Squeak...
> I put these methods into Squeak
Ouch!!!... :) oops, sorry!
> to assist code generation for the VM and associated primitives. The C
> translator has to compile a run-time test for the sign of the shift count in
> the case of bitShift:, so we use >> and << for speed where this is known
> (nearly everywhere).
Ahhhhhhh! Yes... now the picture is clear.
> Clearly, this information should be documented in those methods, along with
> the fact that the primitive bitShift: is faster in Squeak.
Hmmmmm... is the JPEG reader converted to C too? Besides >> and <<, today I
found a method in the JPEG reader with something like
(aNumber to: someOther by: yetAnother) do: aBlock
.... errr... now I don't know what to say! :)))... another little thing. Would it
be ok if Float>>#rounded was rendered into a bytecode? Most FPUs should have a
round-to-integer instruction.
Andres.
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