aa5
Subj : Re: Library built but Not working
To   : borland.public.cpp.borlandcpp
From : Bob Gonder
Date : Thu Oct 14 2004 06:52 pm

dkat wrote:

>I know globals are frowned upon but they really are necessary for ISR and
>the buffers it uses.  These must come from the main program.  I believe that
>this is where things are failing when I load the routines as a separate file
>with the previous global variables now being treated as externals in the
>Main program....  My problem is grasping where the scope of the variables
>are and how I should be declaring them...


Daq.h
 - - - -
#define	COUNTERS	2
#define	TIMERS		2
#define	MaxBSize	(4*1024);

	extern	int	counter[COUNTERS];
	extern	int	timer[TIMERS];
	extern	WORD	buffer[2][MaxBSize];	
/*	Other function and variable definitions		*/


Daq.c
 - - - -
#include	"daq.h"

	int	counter[COUNTERS];
	int	timer[TIMERS];
	WORD	buffer[2][MaxBSize];	
/*	Other code, and the ISR	*/


Program.c
 - - - - 
#include	"daq.h"

int main(void)
{
/*	just use the variables.	*/
	counter[0] = 15;
	return 0;
}



>  I am pulling out all of my old
>books but nothing really addresses when you are compiling routines outside
>of your main code.  I ended up declaring the buffer that holds the sound
>file as a double pointer in main and as a fixed array in the library.
>Perhaps this should be the other way around....

Whether it is in the library or in main is of no consequence.
The choice is "Who is responsable for maintaining the size of the
buffers?"
If you put the buffers in Main, then every application has to define
them. But if they belong to the library, then the application can't
forget to create them. Drawback is that Main can't then define larger
buffers.


That is, unless you make the sizes dynamic with a call to an
initialization routine: (Just a very rough sketch)

	long   DaqBuffersize;	/* global (main can see it) */
static	long   LocalBuffersize;	/* module (only daq can see it) */

bool DaqInit( int bufferssize, int numberofbuffers )
{	DaqBuffersize = buffersize *2;
	LocalBuffersize = buffersize;
	for( i=0; i<numberofbuffers; ++i )
	{	LocalBufferptr[i]=farmalloc(buffersize*sizeof(word));
		if( LocalBuffer[i] == NULL )
			release all allocs and return fail
	}
	/*other init stuff */
	return pass or fail;
}
Then, you would need a
	static	 word* LocalBufferptr[ something ];
and a function to return the buffer to main
char*GetBuffer(void)
{	return (char*) LocalBuffer[nextemptybuffer];
}

And Main would fill it with
	ReadFile( file, GetBuffer(), DaqBuffersize );

Much more code is involved in this approach, so maybe you'd better
stick with fixed sizes for now.

.

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