bit-field pointers / arrays

Henry Spencer henry at utzoo.UUCP
Sat Dec 20 04:30:46 AEST 1986


> Here is a list of processors which I know to have
> bit-field instructions that I can't get at from 'C':
> 
> ...
> 	PDP-11	(From previous posting)

Uh, really?  Funny how I've never noticed them in all my years of PDP-11
programming.  Please identify them by opcode.  A quick look doesn't find
any relevant previous posting.

The 11 does have instructions that one can't get to from C, mostly fairly
useless or ultra-specialized odds and ends, but bit-fields are absent.
The byte is the smallest unit that the 11 architecture is aware of.  (Even
the BCD arithmetic in the grotesque "commercial instruction set", available
as an add-on for a few of the later 11s, wants numbers to begin and end
on byte boundaries.)
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,decvax,pyramid}!utzoo!henry



More information about the Comp.lang.c mailing list