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From: anon@att.net
Newsgroups: comp.lang.ada
Subject: Re: How do I write directly to a memory address?
Date: Sun, 13 Feb 2011 01:04:07 +0000 (UTC)
Organization: ETT newsserver
Message-ID: <ij7am6$13m5$1@news.ett.com.ua>
References: 
 <67063a5b-f588-45ea-bf22-ca4ba0196ee6@l11g2000yqb.googlegroups.com>
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Date: 2011-02-13T01:04:07+00:00
List-Id: <comp.lang.ada>

I have watch a number of people showing ways of using the representation 
clause's "attribute_definition_clause" or the "at_clause" to define a 
memory location.  But they forget to say that aome OSs may restrict or 
reject access to real memory even the video memory.

The main problem in using this type of programming is that most OSs used 
today protects their real memory. And also some OSs use framebuffers for 
video memory. So, you may need to alter your code to create a Ada device 
driver server program for your video needs with the main program being a 
client that links to this server to send data to the video. That way you can 
have both the privilege to write to the video memory and/or to correctly 
access the right framebuffer.




In <67063a5b-f588-45ea-bf22-ca4ba0196ee6@l11g2000yqb.googlegroups.com>, Syntax Issues <syntax.issues@gmail.com> writes:
>I am planning to start learning lower-level programming with ada,
>however, I was unable to find a solid tutorial on writing directly to
>a memory address or interfacing with assembly. Does anyone know where
>I can find a reference to some tutorials/information? Below is an
>example of code I would like to be able to implement.
>
>....
>unsigned int print(char *message, unsigned int line)
>{
>	char *vidmem = (char *) 0xb8000;
>	unsigned int i= 0;
>
>	i=(line*80*2);
>
>	while(*message!=0) // 24h
>	{
>		vidmem[i]= *message;
>		*message++;
>		i++;
>		vidmem[i]= 0x7;
>		i++;
>	};
>
>	return(1);
>};
>....
>
>