Xref: utzoo comp.sys.ibm.pc:44725 comp.lang.c:26048
Path: utzoo!attcan!telly!druid!darcy
From: darcy@druid.uucp (D'Arcy J.M. Cain)
Newsgroups: comp.sys.ibm.pc,comp.lang.c
Subject: Re: microsoft c isr question
Message-ID: <1990Feb18.174443.28133@druid.uucp>
Date: 18 Feb 90 17:44:43 GMT
References: <WIENER.90Feb17172147@stout.stout.UCAR.EDU>
Reply-To: darcy@druid.UUCP (D'Arcy J.M. Cain)
Distribution: usa
Organization: D'Arcy Cain Consulting, West Hill, Ontario
Lines: 44

In article <WIENER.90Feb17172147@stout.stout.UCAR.EDU> wiener@stout.UCAR.EDU (Gerry Wiener) writes:
>In the following code an interrupt handler for the keyboard is
>replaced by one that increments a counter then chains to the original
>handler.  Question:  Why doesn't "count" get incremented correctly?
>Please mail me the replies.
>
>	Gerry Wiener	  Email:wiener@stout.ucar.edu
>
>------------------------------------------------------------------------
>
>#include <dos.h>
>#include <stdio.h>
>
>#define KEYBD  0x16
>
>void (interrupt far *oldkb)(void);
>void interrupt far newkb(void);
>int count;
>
>main()
>{
>  int c;
>
>  oldkb = _dos_getvect(KEYBD);
>
>  _dos_setvect(KEYBD, newkb);
> [...]
>  _dos_setvect(KEYBD, oldkb);
>}
>
>void interrupt far newkb(void)
>{
>  count++;
>  _chain_intr(oldkb);
>}

This is just an untested guess since I no longer have MSC to try
it on but try declaring count as a far int.

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