Re: [Gm2] two versions of DeviceTablePtrValue

[Fischlin Andreas]

Indeed, I wanted to suggest the same. Ask Rick Sutcliffe.

Regards,
Andreas
 

On 05/Jun/2010, at 16:04 , Breeden, Thomas (tmb) wrote:

> 
> Yes, the "CAST(IOLink.DeviceTablePtr, cid)" does not look so good.
> 
> Using "IOLink.DeviceTablePtrValue (cid, MyDid)" to get the pointer should not 
> be
> a problem in your custom stream implementation, since your module is the
> one that does the "IOLink.AllocateDeviceId (MyDid)" on initialization, and 
> knows
> what the value of MyDid is.
> 
> However, I don't see how one could implement IOChan procedures without
> using the CAST(), since something like IOChan's 
> PROCEDURE RawWrite(cid:ChanId; from:ADDRESS; locsToWrite:CARDINAL);
> does not have the DeviceId associated with the passed ChanId.
> 
> If seems like it must assume that the ChanId is the DeviceTablePtr in order 
> to find the
> correct device callback routine:
>    did := CAST(IOLink.DeviceTablePtr, cid);
>    did^.doRawWrite(did, from, locsToWrite);
> 
> I suspect that Rick Sutcliffe would be the best person to explain the 
> architecture
> here.
> 
> regards,
> 
> Tom
> address@hidden
> 
>> From: gm2-bounces On Behalf Of Martin Kalbfuß address@hidden
>> Sent: Saturday, June 05, 2010 7:30 AM
>> To: GNU Modula-2
>> Subject: Re: [Gm2] two versions of DeviceTablePtrValue
>> 
>> I still wonder how to implement your own channel the right way. There's
>> no ISO conform way. to obtain the did out of the cid, because
>> DeviceTablePtrValue needs the did as parameter.
>> 
>> To implement an open/close pair for your custom stream like
>> 
>> OpenMyChannel(VAR cid : IOChan.ChanId);
>> CloseMyCannel(VAR cid : IOChan.ChanId);
>> 
>> you have to store the did externally in an array or something similar.
>> Do you think that's the right way to do it?
> 
>> From: gm2-bounces On Behalf Of Martin Kalbfuß address@hidden
>> Sent: Friday, June 04, 2010 6:32 PM
>> To: GNU Modula-2
>> Subject: RE: [Gm2] iso streams
>> 
>> Many thanks,
>> 
>> I wonder, that there's no default implementation of
>> such a stream.
>> 
>> I had a look at your code. I've seen, that you did a cast
>> 
>> p := SYSTEM.CAST(IOLink.DeviceTablePtr, cid);
>> 
>> Is this standard conform? There is a function to get the table.
> 
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