Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!sun-barr!cs.utexas.edu!uunet!mcvax!kth!sunic!liuida!prodix!jian
From: jian@prodix.liu.se (Jian Hu)
Newsgroups: comp.sys.ibm.pc
Subject: Re: ABSOLUTE ADDRESSING IN C
Message-ID: <107@prodix.liu.se>
Date: 5 Jul 89 14:04:57 GMT
References: <1344@sunset.MATH.UCLA.EDU>
Organization: Dept of Mechanical Engineering, Univ of Linkoping, Sweden
Lines: 31

In article <1344@sunset.MATH.UCLA.EDU> regwan@math.ucla.edu (Eliaho Regwan) writes:
>A friend is working on a IBM PC with a 80186 and it has an eprom of some sort.
>She needs to set a pointer to an ABSOLUTE ADDRESS (inside the eprom).  She
>is only able to get relative addresses with a block of memory.
>
>DOES ANYONE KNOW HOW TO DO THIS??  PLEASE.  THANKS.
>

I think this question belongs to comp.lang.c. But anyway, in MSC5.0
(<dos.h>) two macros are defined which should work under any compiler:

#define FP_SEG(fp) (*((unsigned *) &(fp)+1))
#define FP_OFF(fp) (*((unsigned *) &(fp)))

This is how to use it:

#include <dos.h> /* Or simply define the above macros */

void far *fp;

main ()
{ char var;

	FP_SEG(fp)=0x????; /* EPROM seg. address */
	FP_OFF(fp)=0x????; /* offset into the EPROM */
	var=(char) *fp;
}

I hope this is what you want.

-- J. H.