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From Craig Blake <craigwbl...@mac.com>
Subject Re: half-baked idea? j2me
Date Thu, 03 Nov 2005 17:06:20 GMT
In the course of various jobs I've had to look at lots of chunks of  
the Sun library sources and VM code.  I was under the impression that  
this would be a problem?

Craig

On Nov 3, 2005, at 7:55 AM, Geir Magnusson Jr. wrote:

> Why are you too tainted?
>
> geir
>
> On Nov 2, 2005, at 11:11 PM, Craig Blake wrote:
>
>> Some of us are still hoping for a mostly Java based  
>> implementation.  While I am apparently too "tainted" to contribute  
>> much, it will make it a lot more fun to play around with.
>>
>> Craig
>>
>> On Nov 1, 2005, at 6:05 PM, Robin Garner wrote:
>>
>>
>>> Rodrigo Kumpera wrote:
>>>
>>>
>>>> On 11/1/05, Robin Garner <robin.garner@anu.edu.au> wrote:
>>>>
>>>>
>>>>>> On 11/1/05, Robin Garner <Robin.Garner@anu.edu.au> wrote:
>>>>>>
>>>>>>
>>>>>>> Rodrigo Kumpera wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> AFAIK IKVM, sablevm and jamvm all run on portable devices.
>>>>>>>>
>>>>>>>> Developing a j2me jvm is not as easier as it seens, first,
the
>>>>>>>> footprint and execution performance must be really  
>>>>>>>> optimized, so
>>>>>>>> expect a LOT of assembly coding.
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>> Back to the language wars again :)  This does not necessarily
 
>>>>>>> follow.
>>>>>>> Try googling for the 'squawk' VM - they had a poster at  
>>>>>>> OOPSLA last
>>>>>>> week.  This is a java-in-java virtual machine targetted at  
>>>>>>> embedded
>>>>>>> devices.  The core VM runs in 80KB of memory.  Device drivers
 
>>>>>>> are all
>>>>>>> written in Java.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>> Robin,
>>>>>>
>>>>>> With a java-in-java VM even if you don't write directly in  
>>>>>> assembly
>>>>>> you still need to generate machine code with java anyway, and  
>>>>>> that
>>>>>> will look a lot like asm (JikesRVM baseline JITer for  
>>>>>> example). With
>>>>>> C, for example, you can get away using just an interpreter.
>>>>>>
>>>>>>
>>>>> My mistake, obviously.  When you said "performance must be really
>>>>> optimized, so expect a LOT of assembly coding", I assumed you  
>>>>> were saying
>>>>> that large chunks of the VM would need to be written in  
>>>>> assembler in order
>>>>> to get adequate performance.
>>>>>
>>>>> So what _was_ the point you were making ?
>>>>>
>>>>> cheers
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>> I was just trying to say that a decent j2me VM is not as simple as
>>>> David suggested. Not that C or Java would be more suited to  
>>>> implement
>>>> it. As a matter of fact, I think that java-in-java VMs can be as  
>>>> good
>>>> as C/C++ based JVMs or better.
>>>>
>>>> But one thing is hard to deny, a simple JVM, like bootJVM, is a lot
>>>> easier to write in C than in java (not using an AOT compiler). And
>>>> that was my point, C/C++ sounds to be the easy path to start with.
>>>>
>>>>
>>> Actually my colleagues at ANU and I were remarking last week that  
>>> all the recent discussion on the Harmony list (configure scripts,  
>>> packed structs etc etc) were close to being proof that Java was  
>>> the easier way to go.
>>>
>>> Another data point (FWIW) - joeq, excluding the compiler and the  
>>> class library interface comes in at ~39,000 lines of code.   
>>> bootJVM is already over 50,000.  I know that KLOC is a pretty  
>>> bogus measure of complexity, but it certainly says _something_.   
>>> And Joeq is a fully functioning VM.
>>>
>>> cheers
>>>
>>
>>
>
> -- 
> Geir Magnusson Jr                                  +1-203-665-6437
> geirm@apache.org
>
>


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