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From: greg@gryphon.CTS.COM (Greg Laskin)
Newsgroups: comp.sys.ibm.pc,comp.lang.c
Subject: Re: Looking for C functions to access PC memory
Message-ID: <2292@gryphon.CTS.COM>
Date: Fri, 13-Nov-87 23:42:54 EST
Article-I.D.: gryphon.2292
Posted: Fri Nov 13 23:42:54 1987
Date-Received: Sun, 15-Nov-87 16:42:46 EST
References: <24261F3U@PSUVMB> <2312@emory.uucp>
Reply-To: greg@gryphon.CTS.COM (Greg Laskin)
Organization: Trailing Edge Technology, Redondo Beach, CA
Lines: 48
Xref: mnetor comp.sys.ibm.pc:10152 comp.lang.c:5413

>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 Mircrosoft C:

foo()
{
	char huge *blat =0;
	char far *p;
	char c; int i;

	/* assume n is the ABSOLUTE address of an object in physical
	   memory -- linear space, not segmented */
	long n = 0x0c0000;

	c = blat[n];
	i = ((int huge *)blat)[n];

	/* huge pointers are EXPENSIVE so if you're going to do lots of
	   stuff in a 64K segement, like video stuff, resolve the address
	   into a far pointer and use it instead thusly */
	p = &blat[0xb8000];

}

Note:

#ifndef M_LGDATA
#define huge
#define far
#endif

to remove the processor dependency of the code. (Yes.  I know about the
non-portability of the hard addressing)
-- 
Greg Laskin   
"When everybody's talking and nobody's listening, how can we decide?"
INTERNET:     Greg.Laskin@gryphon.CTS.COM
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