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From: kneller@cgl.ucsf.edu (Don Kneller)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Looking for C functions to access PC memory
Message-ID: <10484@cgl.ucsf.EDU>
Date: Sun, 8-Nov-87 17:36:44 EST
Article-I.D.: cgl.10484
Posted: Sun Nov  8 17:36:44 1987
Date-Received: Tue, 10-Nov-87 06:22:27 EST
References: <24261F3U@PSUVMB> <2312@emory.uucp> <151@fxgrp.UUCP>
Sender: daemon@cgl.ucsf.edu
Reply-To: kneller@socrates.ucsf.edu.UUCP (Don Kneller)
Organization: UCSF Computer Graphics Lab
Lines: 43

>In article <24261F3U@PSUVMB> F3U@PSUVMB.BITNET writes:
>>I am looking for some functions when called from a C program, will:
>>      1)  read (peek) memory directly when supplied with
>>          an address.  Returns with the value at specified address.
>>  and
>>      2)  write (poke) memory directly when supplied with an
>>          address and a byte value.
>>     
>>I am using Microsoft C 4.0 on an AT&T 6300 PLUS.  Routines
>>in C or Assembler OK.

In MSC it's probably easiest to use the supplied FP_SEG and FP_OFF
macros to do this.  This works in all memory models:

#include <dos.h>

unsigned char
peek(segment, offset)
unsigned int segment, offset;
{
	unsigned char far *cp;

	FP_SEG(cp) = segment;
	FP_OFF(cp) = offset;
	return *cp;
}

void
poke(segment, offset, value)
unsigned int segment, offset;
unsigned char value;
{
	unsigned char far *cp;

	FP_SEG(cp) = segment;
	FP_OFF(cp) = offset;
	*cp = value;
}
-----
	Don Kneller
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