Re: What's the spec for emacs lisp virtual machine ?

[mdj <mdj.mdj@gmail.com>]

On Jul 30, 3:01 pm, Fren Zeee <frenz...@gmail.com> wrote:
> On Jul 29, 8:51 pm, mdj <mdj....@gmail.com> wrote:
>
> > On Jul 23, 4:12 pm, Fren Zeee <frenz...@gmail.com> wrote:
>
> > > Why is a VM needed when there is compiled C code running machine
> > > code ?
>
> > The are two essential reasons. Firstly, the bytecode is more compact
> > in memory than either the machine code or the READ lisp code.
> > Secondly, it loads a good deal faster from disk, allowing emacs to
> > start (relatively) quickly.
>
> an example
>
> preferably from an emacs file from savannah link so one could get an
> idea of the animal.

Any emacs lisp source file will serve as an example.

> theoretical reasons for speed ?

bytecode is simpler to parse, and more compact in its representation
than s-expressions represented as cons cells.

> > Thirdly, it is relatively straightforward to implement a portable
> > bytecode interpreter in C that will then compile on any architecture
> > for which one has a C compiler. This is a great deal less work than
> > developing a 'to-machine-code' compiler for every architecture out
> > there.
>
> Why is it less than porting the C compiler ? How would it be written ?
> assembler ?

Are you suggesting the emacs lisp compiler could target C instead of
bytecode?

> > Keep in mind that the early releases of GNU Emacs were in the mid
> > 1980's when personal computers powerful enough to run Emacs had
> > typically perhaps 1mb of RAM. Keeping the in-memory footprint of Emacs
> > small was more important than raw speed which would need more RAM, and
> > necessitate customizer the code generator for every conceivable
> > architecture.
> > In 1989 there were a LOT of 32bit microprocessor architectures out
> > there, and many still survive to this day.
> > To answer the rest of your questions, I'd recommend enrolling in a
> > good computer science degree.
>
> I am sure someone can point to a tutorial paper or book,
>
> no one need you to give that obvious advice ... so obvious that i
> consider rude

Okay, but your relatively poor command of english is making you appear
very rude as well. Perhaps consider using more words to describe what
you mean. The odd gratuity like 'please' and 'thanks' would do wonders
for your style.