Rodrigo Kumpera wrote:
On 11/1/05, Robin Garner <[EMAIL PROTECTED]> wrote:
On 11/1/05, Robin Garner <[EMAIL PROTECTED]> 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
