Reply by Everett M. Greene●October 4, 20052005-10-04
Wim Lewis <wiml@hhhh.org> writes:
[snip]
> I find it interesting that the use of ARMs in embedded devices seems
> to be putting pressure on the architecture to adopt more traditionally
> CISC-like features --- the ThumbEE instructions include an array-bounds-
> check instruction, for example.
Classic tradeoff? You can do it once in hardware or
a gazillion times in software...
Reply by coolblue●October 4, 20052005-10-04
thank you lewis. it was really helpful.
thank you one and all
kaushik
Reply by Wim Lewis●October 4, 20052005-10-04
In article <1128344026.758735.40320@o13g2000cwo.googlegroups.com>,
Hans Odeberg <hans_odeberg@yahoo.com> wrote:
>coolblue wrote:
>> i couldnt get what exactly "jazelle java hardware acceleration" mean?
>
>Like the phrase says, the CPU contains some HW that accelerates Java.
>For more details, go to www.arm.com and search for "Jazelle".
Hm. I was idly curious, so I did the obvious google query and ended up
at <http://www.arm.com/products/solutions/Jazelle.html>. Jazelle appears
to be two things:
"Jazelle DBX" is an extension to allow the processor to directly
execute the JVM bytecode ("In addition to the 32-bit ARM and 16-bit
Thumb instruction sets, an 8-bit Java instruction set has been
introduced. [...] There is a single new ARM instruction: 'Branch-to-Java'
for entering Java state.")
"Jazelle RCT" is the addition of a few new Thumb instructions that are
useful for code generators emitting code for compiled Java or other
similar languages. (It "adds 12 new instructions to Thumb2 and modifies
the behavior of some existing Thumb2 instructions and is accessible
through entering a new state 'ThumbEE'.")
ARM claims a huge reduction in generated code size by using the ThumbEE
(a.k.a. Jazelle RCT) instructions.
I find it interesting that the use of ARMs in embedded devices seems
to be putting pressure on the architecture to adopt more traditionally
CISC-like features --- the ThumbEE instructions include an array-bounds-
check instruction, for example.
--
Wim Lewis <wiml@hhhh.org>, Seattle, WA, USA. PGP keyID 27F772C1
Reply by Hans Odeberg●October 3, 20052005-10-03
coolblue wrote:
> Hi all,
> i couldnt get what exactly "jazelle java hardware acceleration" mean?
> i found this in ARM processor manual. i couldnt find clearcut
> definition or explanation about this. can anyone put some light on
> this?
> thank you
> kaushik
Like the phrase says, the CPU contains some HW that accelerates Java.
For more details, go to www.arm.com and search for "Jazelle".
Reply by larwe●October 3, 20052005-10-03
> i couldnt get what exactly "jazelle java hardware acceleration" mean?
It's designed to get computer science majors excited. If you're in
engineering, don't worry about it. If you're a computer science major,
then don't worry about it either.
Reply by coolblue●October 3, 20052005-10-03
Hi all,
i couldnt get what exactly "jazelle java hardware acceleration" mean?
i found this in ARM processor manual. i couldnt find clearcut
definition or explanation about this. can anyone put some light on
this?
thank you
kaushik