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From Craig Blake <craigwbl...@mac.com>
Subject Re: half-baked idea? j2me
Date Thu, 03 Nov 2005 04:11:41 GMT
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


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