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From: berryc@arcturus.uucp (Craig D. Berry (x1710))
Newsgroups: comp.lang.c
Subject: Re: Direct memory addressing in TURBO C/C++
Message-ID: <1991Mar8.210732.20269@arcturus.uucp>
Date: 8 Mar 91 21:07:32 GMT
References: <MORGAN.91Feb27195403@chaos.cs.brandeis.edu> <1991Mar3.031653.26871@NCoast.ORG>
Distribution: comp
Organization: Rockwell International
Lines: 24

catfood@NCoast.ORG (Mark W. Schumann) writes:

>In article <MORGAN.91Feb27195403@chaos.cs.brandeis.edu> morgan@chaos.cs.brandeis.edu (Dylan Kaufman) writes:
>>I have been trying to figure out how to do direct memory addressing in
>>C++.  The addressing I am thinking about in particular is done with
>>the keyword absolute in TURBO Pascal.  For example, to turn the Num
>>Lock key off :
>>var
>>  Key_Status_Bit : word absolute $0040:$0017;
>>begin
>>  Key_Status_Bits := (Key_Status_Bits and $DF);
>>end.
>>
>You can do this with--
>    * (unsigned int *) MK_FP (0x0040, 0x0017);
>MK_FP() is a macro that is defined in Turbo C (2.0 at least) and
>Mix Power C.  I think it is defined in MC.  This is NOT considered
>part of ANSI but it looks as if you are trying to do some very
>machine-dependent stuff anyway.

Note that for total safety, that should be (unsigned int far *).  This
would be the default in a large model program compilation, but it never
hurts to be careful...