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From: arden@creed.tcom.stc.co.uk (Bruce Arden)
Newsgroups: comp.sys.ibm.pc,comp.lang.c
Subject: Segment & offset of pointers in MS C v4.0
Message-ID: <247@creed.tcom.stc.co.uk>
Date: Tue, 17-Mar-87 14:35:30 EST
Article-I.D.: creed.247
Posted: Tue Mar 17 14:35:30 1987
Date-Received: Thu, 19-Mar-87 05:11:29 EST
Organization: STC Telecommunications, London N11, UK
Lines: 24
Keywords: C pointers
Xref: mnetor comp.sys.ibm.pc:2564 comp.lang.c:1277

I want to have two macros P_SEG(p) and P_OFF(p) (cf FP_SEG & 
FP_OFF) that will let me get the segment and offset of p 
independant of the memory model.  Here is an example of their
intended use: 

    char scr[SCRSIZE];

    movedata(0xB000, 0x0000, P_SEG(scr), P_OFF(scr), sizeof scr);

I thought I had the answer to this question:

#define P_SEG(p)    (unsigned)((long)( (char far *)(p) ) >> 16)
#define P_OFF(p)    (unsigned)((long)( (char far *)(p) ))

This appeared to give the correct result (although it did 
generate some redundant code) with data pointers.  However it 
gave register DS as the segment of a near code pointer.

Has anyone solved this problem?

Thanks in advance
-- 
Bruce Arden
arden@creed.tcom.stc.co.uk