[Vm-dev] Simulator Question

[Igor Stasenko]

On 6 January 2011 19:10, Andreas Raab <andreas.raab at gmx.de> wrote:
>
> On 1/6/2011 6:09 PM, Gabriel Hernán Barbuto wrote:
>>
>> I would like to push the selector and the receiver onto the stack and
>> then call something like Interpreter>>#commonSend and then clean the
>> stack.
>
> The 'correct' way to do that would be by:
> a) Creating a process for the message
> b) Setting up the context
> c) Pushing rcvr, selector, args
> d) Run the process until it completes
> e) Return the result
>

(a) can be done once, and then reused for subsequent calls.

(if to move scheduling logic to image side, then its not necessary).

A signal to leave interpreter loop could be that context have nowhere
to return to.

Alas.. the current VM semantics is to signal exception when this happens.

But for, an interpreter simulator one could do the trick by overriding the:

internalCannotReturn: resultObj
	<inline: true>
	self internalPush: activeContext.
	self internalPush: resultObj.
	messageSelector := self splObj: SelectorCannotReturn.
	argumentCount := 1.
	^ self normalSend

and check if its in 'waiting for call to return', and so, do the
proper interpreter state cleanup,
and return value to caller (to one who sent something like:
   simulator send: #foo to: barOop args: { a . b . c . }
)


> Cheers,
>  - Andreas
>
>> Maybe I cannot call Interpreter>>#commonSend because it fetches the
>> next byte code and I don't want to modify the execution state. But at
>> least perform the rest of the calls. I don't know if this makes any
>> sense.
>>
>>> From what I have learned so far. Besides that this approach might not
>>
>> work. The problem seems to be creating the selector. If I can create
>> the selector I will try it anyway.
>>
>> Thanks again.
>>
>> Gabriel
>>
>>
>> On Thu, Jan 6, 2011 at 5:00 PM, Igor Stasenko<siguctua at gmail.com>  wrote:
>>>
>>> On 6 January 2011 16:41, Gabriel Hernán Barbuto<gbarbuto at gmail.com>
>>>  wrote:
>>>>
>>>> Hi
>>>>
>>>> I am working with the InterpreterSimulator and I would like to send a
>>>> message to an object inside the simulated environment. For example, I
>>>> have the oop for true and I want to send it the message printString.
>>>>
>>>> My question is if this is possible. I don't know if there is a way to
>>>> send a message to an object inside the simulation. I have thought
>>>> about tinkering with the stack and calling an interpreter method. But
>>>> I am not sure if this will work.
>>>>
>>>
>>> Hi, Gabriel.
>>> The problem is, that even if you prepare a context and all arguments
>>> for message send,
>>> you should start interpreting the code and then leave the interpret
>>> loop once you received the answer.
>>> But if you look at #interpret method, there is an infinite loop,
>>> and no way how to escape it.
>>>
>>> I don't know if there is a way to tell simulator to leave the loop at
>>> certain point.
>>>
>>>
>>> P.S. In general, it would be cool to have something like:
>>>
>>> sqInt interpreter_call( sqInt receiver , sqInt selector , sqInt *
>>> arguments )
>>>
>>> means: send message to receiver and return the answer.
>>>
>>> Unfortunately, Squeak VM does not provides such things, in contrast to
>>> languages like Lua,
>>> which providing C interoperability layer by default from very
>>> beginning of it existence.
>>>
>>>> Any hint will be much appreciated. Thanks in advance.
>>>>
>>>> Gabriel
>>>>
>>>
>>>
>>> --
>>> Best regards,
>>> Igor Stasenko AKA sig.
>>>
>>
>



-- 
Best regards,
Igor Stasenko AKA sig.