19 Mar
2003
19 Mar
'03
6:46 p.m.
Hi -
From: David Evans <dfevans(a)bbcr.uwaterloo.ca>
Ugh.
Am I naive to suggest a rewrite of as? :)
Just a little bit <g>
It's a thought that used to occur to me fairly often a long time
ago. I cured myself of it though after I did the rewrite into
its current form (if you think it's bad now you should have seen it
before ;)).
The biggest problem are the SDI (Span Dependent Instructions). The
PDP-11 has 'jmp' (non conditional but no range limit) and 'br' (many
flavors of conditional branches but with a +/- 128 byte range).
The compiler generates pseudo instructions like 'jeq' and leaves it
up to the assembler to figure out if a branch will reach or if a
branch around a jump is needed. That's a PITA to handle and is
I believe the cause of much ugliness in the assembler.
So I'm fought the urge to rewrite the assembler and 'won' - I no longer
feel the rewrite urges ;)
Cheers,
Steven Schultz