Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!henry From: henry@utzoo.UUCP (Henry Spencer) Newsgroups: comp.lang.c Subject: Re: bit-field pointers / arrays Message-ID: <7433@utzoo.UUCP> Date: Fri, 19-Dec-86 13:30:46 EST Article-I.D.: utzoo.7433 Posted: Fri Dec 19 13:30:46 1986 Date-Received: Fri, 19-Dec-86 13:30:46 EST References: <2937@bu-cs.BU.EDU> <321@bms-at.UUCP>, <1170@ucbcad.BERKELEY.EDU> Organization: U of Toronto Zoology Lines: 19 > 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