[Info-vax] Whither VMS?

[Bob Eager]

On Fri, 09 Oct 2009 08:23:54 +0000, glen herrmannsfeldt wrote:

> Bob Eager <rde42 at spamcop.net> wrote:
> < On Fri, 09 Oct 2009 01:35:48 +0000, glen herrmannsfeldt wrote:
>  
> <> IA32 has special instructions for counting (in CX, ECX) and for <>
> incremented address load/store.  It is probably easier and maybe faster
> <> to do the counted loop.  Some loops can be done with one instruction
> <> with a LOOP prefix.
>  
> < (a) LOOP isn't a prefix
> < (b) on modern CPUs, it's avoided because it's a very slow
> instruction..
> 
> Oops, it is the REP (and similar) prefixes that I meant to say, which is
> a prefix.  No idea how fast it is.

Sorry, if I'd read slower (!) I'd have realised that was what you meant. 
I think REP is pretty fast...




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