SquirrelJME/SquirrelJME

# 2016/02/05

***DISCLAIMER***: _These notes are from the defunct k8 project which_
_precedes SquirrelJME. The notes for SquirrelJME start on 2016/02/26!_
_The k8 project was effectively a Java SE 8 operating system and as such_
_all of the notes are in the context of that scope. That project is no_
_longer my goal as SquirrelJME is the spiritual successor to it._

## 09:35

Using a separate `FieldValue` with indices should make it easier and cleaner to
implement as `FieldValue` will just get things by their index.

## 11:23

Well my breakfast was rather nice.

## 12:18

I have this idea of creating a JavaME 8 virtual machine (the VM part in C)
and then having a basic library implementation. I could target Palm OS, DOS,
and a few other ancient no longer used systems.

## 12:20

Actually the VM environment for JavaME has been brought closer to JavaSE and
it can be thought up of being a very stripped down version of JavaSE. I can
actually run a diff to see which classes are new and which classes are not
new.

## 12:32

Looks like the ME base classes in the CLDC profile has a bunch of classes
missing. So I desired to do this I would have to split "-core" into one for
"-cldc" and "-core" for the remaining stuff and then solve any potential
dependencies that they might rely on. So really my library is just Java SE
8 Embedded. Well supporting that will be the first goal.

## 12:40

I could probably go ME, but that would not be as useful for me since I do not
have many extremely low memory devices. One I do have is Arduinos and a Zilog
development board. The arduinos have extremely tiny amounts of flash and RAM so
a virtual machine would probably be too hefty to run on it. The Zilog I have
is a bit better but not by much. However my own compact1 support would have the
possibility of running on hardware such as the Nintendo 64 and Dreamcast which
are very memory limited. The Playstation is even more limited with 2MiB of RAM,
very ouch.

## 12:59

It could however help me to understand the byte code better and how it
executes though.

## 13:06

The question is though, do I make it compatible with existing virtual machines
so it can become a JVM library (jvm.dll/libjvm.so)?

## 15:16

Well I have been doing that right now, but it appears it would be more work in
the end. The one thing I dislike about C is the lack of namespaces, everything
is essentially just a global symbol.

## 16:26

Actually, forget that, not going to write a C virtual machine interface.
However what I will do is move the jvm.h and jni.h to system-command-cc since
users might want to compile pre-existing JNI code to run in Squirrnix which is
pure Java (and if their native code is C instead of Java then they would have
to rewrite everything in Java using Squirrnix specific interfaces).

## 20:07

My XServe G5 is quite loud but also quite fast. Hotspot does have PowerPC
64-bit support so I wonder if OpenJDK 8 on Debian's PPC64 sid port has it
enabled. If it does then it will be super fast.

## 20:15

Well this method that is essentially just

    [FINE] @0 aload_0
    [FINE] @1 invokespecial
    [FINE] @4 return

Disassembles correctly. This is the method
`net.multiphasicapps.k8.kernel.platform.ieee1275.powerpc.Main`.

## 20:19

On that PowerPC 64-bit machine, JamVM at least goes by speedily.

## 20:58

So far the stuff seems much simpler and more concise compared to the previously
mixed assembler and disassembler. Also without MutableOpCode the values can be
directly read from the program without having a buffer in the middle.

## 21:36

Upgrading the Linux kernel on it makes it not sound like a jet anymore, I
suppose power management was figured out. Nice however since I no longer need
hearing protection from the sound because it is quite low currently rather than
just blasting all fans to maximum. I hear a beat though so some fans are
resonating differently most likely. This is good though for Squirrnix however
as this means the fans or the temperature related stuff is software controlled
rather than having it pure hardware. Sometimes the fans speed up (their pitch
increases) but then eventually it gets lower.