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From: berger@datacube.UUCP
Newsgroups: net.lang.c
Subject: Re: Re:  Re: Uses of \"short\" ?
Message-ID: <7800003@datacube.UUCP>
Date: Tue, 15-Oct-85 19:10:00 EDT
Article-I.D.: datacube.7800003
Posted: Tue Oct 15 19:10:00 1985
Date-Received: Fri, 18-Oct-85 01:30:32 EDT
References: <2081@brl-tgr.UUCP>
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Nf-ID: #R:brl-tgr:-208100:datacube:7800003:000:769
Nf-From: datacube!berger    Oct 15 19:10:00 1985


The main use would be when you create structures that describe the
layout of registers in hardware. In otherwords, when you are writing
a driver or something you might say:

struct deviceRegs {
	int8 csr0;
	int8 csr1;
	int16 dataport;
};

register struct deviceRegs *p = (struct deviceRegs *)0x40000;

	p->csr0 = 0xff;
		etc.

You want each structure element to be a particular size so you can access
particular 8 bit bytes or 16 bit words.  This does not protect you from
byte swapping and I suspect some compilers might throw in hidden alignments,
but in general it works and looks nice.

			Bob Berger 

Datacube Inc. 4 Dearborn Rd. Peabody, Ma 01960 	617-535-6644
	
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