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From: kneller@cgl.ucsf.edu (Don Kneller)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Microsoft Quickc - Pointers to arbitrary memory location
Message-ID: <11135@cgl.ucsf.EDU>
Date: 12 Sep 88 18:23:08 GMT
References: <666@dogie.edu> <1920@titan.camcon.co.uk>
Sender: daemon@cgl.ucsf.edu
Reply-To: kneller@socrates.ucsf.edu.UUCP (Don Kneller)
Organization: UCSF Computer Graphics Lab
Lines: 28

In article <1920@titan.camcon.co.uk> mrh@camcon.co.uk (Mark Hughes) writes:
>From article <666@dogie.edu>, by dorl@vms.macc.wisc.edu (Michael Dorl - MACC):
>> I've been trying to reference screen memory directly from Quickc.
>> The stuff I've tried looks something like this
>> 
>>   char far *p;
>> 
>>   p = (char far *)0xb8000;
>> 
>Try defining a macro like:-
>
>#define fp(a) ( (( (long)(a) & 0xf0000 )<< 12) | ( (long(a) & 0xffff ) )
>

MSC supplies the macros you need with FP_SEG and FP_OFF, which can be
used to get the segment and offset of far (32-bit) pointers.  They can
also be used to SET the segment and offset:

	FP_SEG(p) = 0xB800;
	FP_OFF(p) = 0;

and away you go with p[0], p[1], etc.  The macros are in dos.h.

- don
-----
	Don Kneller
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