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From: pec@necntc.UUCP (Paul Cohen)
Newsgroups: comp.arch,comp.lang.c
Subject: Re: sizeof(char)
Message-ID: <510@necntc.UUCP>
Date: Tue, 11-Nov-86 08:46:44 EST
Article-I.D.: necntc.510
Posted: Tue Nov 11 08:46:44 1986
Date-Received: Tue, 11-Nov-86 21:08:19 EST
References: <4617@brl-smoke.ARPA> <657@dg_rtp.UUCP>
Reply-To: pec@necntc.UUCP (Paul Cohen)
Organization: NEC Electronics Inc.  Natick, MA 01760
Lines: 18
Xref: mnetor comp.arch:8 comp.lang.c:12


On the subject of bit addressing, NEC's new V60 and V70 microprocessors
come very close to full bit addressing.  In particular, bit-string 
operations can move, search or perform primitive logic operations on 
strings of bits starting at any bit in the virtual address space and 
ending up to 4 giga-bits later.  Additional bit-field and bit operations 
are available, but for these instructions the bit address must be formed 
using a bit offset of no more than 32 from a designated byte.  The 
bitstring operations have no limitation on the size of the offset.

On a related subject, are there any strong feelings out there about
whether a high level language like C should support bit addressing?
For example, what about arrays of bits?  This would seem to be very
useful at least for graphics applications.

K & R, not to mention the proposed ANSI C standard have nothing to say
about the permitted size of bitfields.  Does anyone know of a C compiler
that supports bitfields in excess of 32 bits?