[Vm-dev] Accelerating LargeIntegersPlugin phase 2

David T. Lewis lewis at mail.msen.com
Sun Jan 20 17:39:51 UTC 2013

On Sun, Jan 20, 2013 at 04:52:42PM +0000, Frank Shearar wrote:
> On 20 January 2013 15:37, David T. Lewis <lewis at mail.msen.com> wrote:
> >
> > I'll mention also that, although much work remains to be done in merging
> > oscog and trunk VM code bases, I think that overall we are doing very
> > well with the primitives.  The VM primitives are now almost all in class
> > InterpreterPrimitives, and changes can easily by adopted in both branches.
> > Likewise, the plugins such as LargeIntegersPlugin can easily be kept in
> > sync in the two branches.
> >
> > That means that changes like these can be tested and adopted in either
> > branch at the convenience of the person doing the work. I'm doing my
> > best to pick up changes as they are added to Cog, and Eliot is doing
> > likewise with changes that show up first in the interpreter VM.
> >
> > I don't happen to have a big endian machine, but hopefully someone else
> > has one and can help out with the testing, using either an interpreter
> > VM or Cog VM.
> At the risk of sounding rather ignorant, what kind of machine would
> that be? IIRC the 68k machines were big endian but they've been wiped
> out now haven't they?

Most certainly not, Edgar still has one.

Wikipedia gives a good summary: http://en.wikipedia.org/wiki/Endianness

Older Macs are big endian, and the Squeak VM was originally written on
big endian machines. ARM processors can run in either mode. Most likely
they run as little endian for Linux, and I'm not sure which mode is used
for RISC OS.

In any case, keeping the VM healthy for big and little endian machines is
important to ensure portability of the VM. You never know when somebody
is going to want to do a VM for System 360 ;-)


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