From:	Ryzhenkov Ilya <ilya AT spy DOT isp DOT nsc DOT ru>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Dynamic Link Modules
Date:	Fri, 25 Oct 1996 15:01:43 -0700
Organization:	ISPh SB RAS
Lines:	91
Distribution:	world
Message-ID:	<327138C7.27BD@spy.isp.nsc.ru>
NNTP-Posting-Host:	arab.isp.nsc.ru
Mime-Version:	1.0
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Hi!

 I'm developing Dynamic Link Modules (DLM) environment for djgpp and now it's
 in a week from first release. 
 Breafly :
  1. It's a real run-time link. Modules can have unresolved external references and
     functions maybe called directly (i.e. not by pointer to function)
     Just to be sure that none of unresolved function & data actually uses, they
     are resolved to 0xffffffff address to cause a gpf on use. It maybe used
     in future, by catching exception and, for example, auto-loading desired DLM.
  2. DLM may reference each other in any way. (consider the following example)
  3. DLM's maybe loaded and unloaded dynamicaly, so they may be used as overlays.
  
 As now begins a period of testing (and actually writing stub which will load
 main DLM, export functions for DLM operating and start program), I need help
 and assistance. If anyone is interested and can help or suggest, or just talk about
 DLM - welcome to subscribe to the mailing list :
 mailto: maiser AT spy DOT isp DOT nsc DOT ru 
 in body : subscribe djgpp-dlm


 History of DLM developing is at http://spy.isp.nsc.ru/djgpp/dll.htm
 Here is example of using DLM :
 there were two files (test1.c & test2.c), each was converted into
 separate DLM, they were loaded and start() was called.
======= File test1.c =====
#include <stdio.h>

int i;
char *strings[4] = { "str1","str2","str3","str4" };

extern void test2(char *text);
void test1(void)
{
 printf("That's FINAL! This printf is from test1.dlm/test1()\n");
};

void start(void)
{
 printf("TEST1 started ....\n");
 printf("Printing strings from test1...\n");
 for (i=0; i<4; i++) printf("String : '%s' \n",strings[i]);
 printf("Now calling test2 ...\n");
 test2("<<TEST1 param>>");
 printf("back in test1...\n");
 printf("exiting...\n");
};
 
======= File test2.c =====
#include <stdio.h>

extern char *strings[];
extern i;
extern void test1(void);
void test2(char *text)
{
 printf("TEST2 called ! Param from test1 is '%s'\n",text);

 printf("Printing strings from test2...\n");
 for (i=0; i<4; i++) printf("String : '%s' \n",strings[i]);
 
 printf("Calling back test1 ...\n");
 test1();
 printf("Returned from test1 and now ");
 printf("exiting...\n");
};

======== OUTPUT =======
TEST1 started ....
Printing strings from test1...
String : 'str1' 
String : 'str2' 
String : 'str3' 
String : 'str4' 
Now calling test2 ...
TEST2 called ! Param from test1 is '<<TEST1 param>>'
Printing strings from test2...
String : 'str1' 
String : 'str2' 
String : 'str3' 
String : 'str4' 
Calling back test1 ...
That's FINAL! This printf is from test1.dlm/test1()
Returned from test1 and now exiting...
back in test1...
exiting...

-- 
							Sincerely yours, Ilya
mailto:ilya AT spy DOT isp DOT nsc DOT ru 
http://spy.isp.nsc.ru

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