[RC5] Porting to Atari?

Joe Zbiciak j-zbiciak1 at ti.com
Sat Mar 21 23:43:36 EST 1998

'Alexander Li Cohen' said previously:
| While everyone has been talking of porting to an Atari, I had an
| idea. What's wrong with the 286.  I've got one that I haven't turned on
| in almost a year, and I'm sure others are in the same situation.  Would
| it be even slightly feasible to make a port to these dinosaurs we all
| used to have(or still have, as door stops!)?

The biggest problem with 16-bit and 8-bit machines is that their
fundamental machine word-size is too narrow for the flavor of RC5 we're
cracking.  For instance, on a 286, I'd need a handful of instructions
(including a branch or two, probably) to properly perform a rotate,
whereas on a 386 and later it is one instruction.

I can't even remember if there is a "rotate by n based on register"
instruction in 286 asm...  If there were, it's probably microcoded
to take 1 cycle per bit, since I don't think the 286 (or even the 386)
used a barrel rotator/shifter.



 +----------- Joseph Zbiciak ----------+
 | - - - -  j-zbiciak1 at ti.com  - - - - |       Ignorance is the
 |- http://www.primenet.com/~im14u2c/ -|       Mother of Devotion.
 | - - -Texas Instruments, Dallas- - - |          -- Robert Burton
 +-----#include "std_disclaimer.h"-----+
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