[Vm-dev] Microsecond clock primitives in Cog and SqueakVM

[Eliot Miranda]

Hi David,

    first, thatks very much.  These will enable us to simplify the time
implementation significantly, and that's important.

On Wed, Aug 15, 2012 at 8:07 PM, David T. Lewis <lewis at mail.msen.com> wrote:

>
> We currently have incompatible implementations of microsecond clock
> primitives
> in SqueakVM and Cog. Opinions may vary as the the preferred approach, but
> the
> inconsistencies need to be reconciled.
>
> I have implemented the Cog primitives on SqueakVM, and the SqueakVM
> primitive
> on Cog. The platform source support for these is different on Cog and
> trunk, but it
> turned out to be straightforward to do equivalent implementations in the
> two VMMaker
> branches. I would like to suggest that we adopt a common set of three
> primitives in
> both Cog and SqueakVM trunk. We can worry about reconciling the platform
> sources
> in the future, meanwhile there is value in providing a common api for the
> primitives.
>
> The three primitives of interest are these:
>
> primitiveUtcWithOffset
>         "Answer an array with UTC microseconds since the Posix epoch and
>         the current seconds offset from GMT in the local time zone.
>         This is a named (not numbered) primitive in the null module (ie
> the VM)"
>
> primitiveUTCMicrosecondClock
>         "Answer the UTC microseconds since the Smalltalk epoch. The value
> is
>         derived from the Posix epoch with a constant offset corresponding
> to
>         elapsed microseconds between the two epochs according to RFC 868."
>
> primitiveLocalMicrosecondClock
>         "Answer the local microseconds since the Smalltalk epoch. The
> value is
>         derived from the Posix epoch with a constant offset corresponding
> to
>         elapsed microseconds between the two epochs according to RFC 868,
> and
>         with an offset duration corresponding to the current offset of
> local
>         time from UTC."
>
> I am attaching two change sets for consideration.
> Cog-primitiveUtcWithOffset-dtl.cs
> is for inclusion in oscog to provide an implementation of the SqueakVM
> primitiveUtcWithOffset.
> SqueakVM-cogMicrosecondPrimitives-dtl.cs is for inclusion in the
> interpreter VM to
> provide implementions of primitiveUTCMicrosecondClock and
> primitiveLocalMicrosecondClock
> and add them to the numbered primitives table.
>
> Does this sound like a reasonable solution? If so, I will commit
> primitiveUTCMicrosecondClock
> and primitiveLocalMicrosecondClock to VMMaker trunk, and request that the
> primitiveUtcWithOffset change be added to Cog.
>

It does, but I need some time to integrate first.  I'll report back soon.


>
> Thanks,
> Dave
>
>
>


-- 
best,
Eliot
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