faster bcopy using duffs device (source)
Chris Torek
chris at mimsy.UUCP
Fri Sep 8 14:26:37 AEST 1989
In article <5180 at portia.Stanford.EDU> stergios at Jessica.stanford.edu
(stergios marinopoulos) writes:
>I wanted a faster bcopy, so I used duffs device as a basis for it.
bcopy() should be written in assembly (on most processors), put in
a library, and forgotten about, because---for instance---a dbra loop
beats a Duff loop on a 68010, every time. (And on a 68000, a loop
using movml is best. 68020s have an I-cache, so a hand-coded `Duffish'
loop is a good bet. Some VAXen have a special instruction which does
a good job. [movc3 is done in software on the 610.] `rep movsb' [or
is there a `movsw'?] is best on an 80x86. LDIR is best on a Z80. A
Duff-style loop is probably best on a PDP-11.)
--
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain: chris at mimsy.umd.edu Path: uunet!mimsy!chris
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