Mail Archives: djgpp/1994/04/08/23:35:52
> On a related note, I'm curious about the Intel architecture. Specifically,
> I'd like to know:
> a) Does it have odd-address access restrictions?
No.
> b) Are accesses on longword (4 byte) boundaries faster than word bounds?
Word access on word boundary is fine. Long access needs to be on long
boundary. Violating these rules adds 3 clocks for each operand access
(on a 486, from the manual). Since each movs instruction takes 7 clocks
(on a 486 once again), it seems that the worse case of 7+3+3 would be
potentially 2 times faster than 4*7 changing to movsd from movsb.
I don't have any 386 or Pentium timings handy, or know if there are
other gotchas here.
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