Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!zaphod.mps.ohio-state.edu!mips!pacbell.com!pacbell!att!mcdchg!laidbak!obdient!igloo!ddsw1!corpane!disk!mangor
From: mangor@disk.UUCP (Darrell Kitchen)
Newsgroups: comp.lang.pascal
Subject: Re: help TP Pointers
Keywords: pointer, pointers, ofs, seg
Message-ID: <3973@disk.UUCP>
Date: 24 Aug 90 06:22:33 GMT
References: <24138@adm.BRL.MIL>
Reply-To: mangor@disk.UUCP (Mangor)
Organization: DISK, Louisville Ky
Lines: 49

In article <24138@adm.BRL.MIL> SNYDER%UCLACH.BITNET@cornellc.cit.cornell.edu writes:
>Dear Sir or Madam:
>
>We are having problems and hope we can get some help from someone
>with more programming skill.
>
>We need to know how to get the address that a newly allocated pointer
>(Turbo Pascal ver 4.0) points to for an application involving direct
>memory access (DMA). In particular, we are using a software routine
>for the DMA which requires the segment and offset of a variable and
>we are forced to use dynamic memory allocation and pointers because
>our sample density exceeds the 64K Turbo Pascal limit. If you know
>how to get the address of the newly allocated memory that the pointer
>points to we would greatly appreciate your assistance.
>
>Please send e-mail to snyder@uclac1.chem.ucla.edu or snyder@uclach.bitnet.
>Thank you very much.

Heres a very simple way to access any pointer that you may have.  Type doesn't
seem to differ.

type
     ptype = record case byte of
	  0 : (p     : pointer);
	  1 : (l     : longint);
	  2 : (ofs, seg : word);
     end;

var
     pt  : pointer;
     lnv : longint;
     ofs : word;
     seg : word;

(*  access offset and seg of pt through Turbo Pascal's powerful typecasting
    as

    ofs := ptype(pt).ofs;
    seg := ptype(pt).seg;
          likewise
    ptype(pt).ofs := ofs;
    ptype(pt).seg := seg;
	    also
    ptype(pt).l := lnv;
	    and
    lnv := ptype(pt).l;
*)

Darrell (mangor@disk.uucp)