[Simh] Jump tables for VAV_CPU

[Villy Madsen]

Still waiting for my VMS distribution to show up.  Things must take a lot 
long to reach us up here in the Great White North
(or is it Arabia - North) (Alberta)..

Been wasting time playing with the NetBSD install.  Works fine.

Also playing with VAX_CPU.

At the risk of making it only compilable with GCC (and probably G++ 
although I haven't tried it),  I am gradually replacing the switch 
statments for the addressing mode resolution with jump statements.    That 
way I am doing it, I am able to gradually do it, case statement by case 
statement.

If there is no entry in the jump table, then it goes through the switch - 
case route.  I am currently doing the byte displacement code.

Code the entries for a couple of case statments and recompile.  Make sure 
that it still passes the diagnostics, and then every few iterations boot up 
netbsd...

I havn't done any scientific tests but.....

The current version (last night) installed netbsd from scratch at least 
twice as fast as the distributed version....

When I complete the address modes, I will take a break and try the install 
with

distributed exe
distributed code compiled with GCC (which seems to be ~ half the size of 
the distributed exe)
the jmp code modified version.

If anyone is interested in looking at the code, drop me a note.  Just as a 
warning, the current coding approach was
taken to simplify the conversion process - I really like doing things in 
small bites...

Villy

Villy Madsen
www.members.shaw.ca/villy.madsen