Subject:
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How to make shared memory....not
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Newsgroups:
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lugnet.robotics.rcx.legos
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Date:
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Sat, 22 Dec 2001 11:10:12 GMT
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Viewed:
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1703 times
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> SO... how do I do that? (I need commands here!)
You ask for it, you get it. BUT: It works, sort of. It will not survive any
multitasking problems. Shared memory has to be handled by the OS, not by a
user program.
I split your problem to 3 programs. Program 1 allocates the memory and prints
it address. Program 2 writes to this memory, program 3 reads from it. When
you start program 3 after running program 1 again, you will get all zeros.
But you have to hardwire the address of the memory to program 2 and three.
-------------- snip -------- program 1 ---------------------------
#include <conio.h>
typedef struct {
int i, j, k;
} shared;
shared sh;
main()
{
cputw( &sh );
sh.i = sh.j = sh.k = 0;
return 0;
}
----------- snip -------- program 2 -------------------------------
#include <conio.h>
typedef struct {
int i, j, k;
} shared;
shared *psh;
main()
{
psh = (shared *)0xb0a2; /* enter YOUR result of prg1 here!! */
psh->i = 123;
psh->j = 234;
psh->k = 345;
lcd_int( psh->i ); sleep( 1 );
lcd_int( psh->j ); sleep( 1 );
lcd_int( psh->k );
return 0;
}
------------- snip --------- program 3 --------------------------------
#include <conio.h>
typedef struct {
int i, j, k;
} shared;
shared *psh;
main()
{
psh = (shared *)0xb0a2; /* enter YOUR result from prg1 here!! */
lcd_int( psh->i ); sleep( 1 );
lcd_int( psh->j ); sleep( 1 );
lcd_int( psh->k );
return 0;
}
----------- snip ------- end of programs ----------------------------
Hope it hels,
Mike
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Message has 1 Reply:
 | | Re: How to make shared memory....not
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| (...) Thanks, Michael. This appears to be exactly what I'm looking for. I assume if I want to store more values, I can just change the 'shared' struct, right? (add l, m, n...) When you say 'multitasking problems', you're talking about storing & (...) (23 years ago, 27-Dec-01, to lugnet.robotics.rcx.legos)
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Message is in Reply To:
| | Re: Storing Data
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| (...) It was suggested by some of my 'c++' co-workers that this was the case (shared memory was available). However, I don't deal with that in my Visual Basic world. They also suggested there were 'unused' memory blocks in LegOS where data could be (...) (23 years ago, 21-Dec-01, to lugnet.robotics.rcx.legos)
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