[Vm-dev] MemoryAccess added as separate package in VMMaker SqueakSource project

Eliot Miranda eliot.miranda at gmail.com
Sat Dec 13 23:07:28 UTC 2008

    can you hum a few bars on how the Smalltalk code looks using this and
not using this?

One of the things I hate most about Slang is the exposed bit twiddlng for
object headers.  i.e. there is nothing that maps to the level of a C struct
with bit fields.  In my Cog Stack interpreter I made a class
InterpreterStackPage map to a struct.  this class is only a container.  I'd
like to do the same for the object header so in Smalltalk one would have a
proper object type that one could send messages like classFormatField and
markBit to and have that map down onto a struct bitfield dereference which
would improve readability in both Smalltalk and C.  Any thoughts on that?

On Sat, Dec 13, 2008 at 2:24 PM, David T. Lewis <lewis at mail.msen.com> wrote:

> I made a separate package for MemoryAccess (Slang implementation of
> sqMemoryAccess.h) and uploaded it to the VMMaker project on SqueakSource.
> In the VMMaker project, VMMaker-dtl.110.mcz contains all prerequisites
> for MemoryAccess-dtl.1.mcz.
> Some support code patches are required to use this for Unix VM generation
> (patches attached). See also http://wiki.squeak.org/squeak/6081 for an
> overview that may be useful if merging into another VMMaker code base.
> MemoryAccess makes no changes to generated VM code until it is enabled
> ("MemoryAccess enable"), so it can be safely loaded into an image and
> used as needed.
> I find that using MemoryAccess helps the C compiler find type casting
> errors, and produces code that is easier to follow in a debugger. On my
> computer, there is no performance difference between the MemoryAccess
> slang versus CPP macros in sqMemoryAccess.h.
> Dave
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