Article View: net.lang.c
Article #9669Re: Generic pointers
From: Chris Torek
Date: Tue, 28 Oct 1986 22:44
Date: Tue, 28 Oct 1986 22:44
27 lines
1394 bytes
1394 bytes
In article <7800017@datacube> stephen@datacube.UUCP writes: >I generally use or define caddr_t as the type of a generic pointer, and then >use macros to perform the indicated operations, i.e.: > >caddr_t generic_pointer; > >#define DATA( p, type ) (*((type *)(p))) >#define SUCC( p, type ) ((p) += sizeof(type)) > >a = DATA(p,int); >SUCC(a, int); >b = DATA(p,double); >SUCC(p, double); Or, if you want the effect of *(type *)(p)++: #define ACCESS(p, type) ((p) += sizeof (type), (type *)(p)[-1]) a = ACCESS(p, int); b = ACCESS(p, double); Note that any such mangling of pointer types is inherently machine dependent. You can reduce the dependency, but not eliminate it. -- In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690) UUCP: seismo!umcp-cs!chris CSNet: chris@umcp-cs ARPA: chris@mimsy.umd.edu
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: arc1-ca.pugleaf.net!utzoo!mnetor!seismo!umcp-cs!chris From: chris@umcp-cs.UUCP (Chris Torek) Newsgroups: net.lang.c Subject: Re: Generic pointers Message-ID: <4039@umcp-cs.UUCP> Date: Tue, 28-Oct-86 17:44:32 EST Article-I.D.: umcp-cs.4039 Posted: Tue Oct 28 17:44:32 1986 Date-Received: Tue, 28-Oct-86 23:27:01 EST References: <4763@brl-smoke.ARPA> <7800017@datacube> Reply-To: chris@umcp-cs.UUCP (Chris Torek) Organization: University of Maryland, Dept. of Computer Sci. Lines: 27