• Noob_programmer <Noob_programmer_member pathlink.com> Jun 11 2004

Noob_programmer <Noob_programmer_member pathlink.com> writes:

hi,
I am trying to call an assembly function I made, from a c++ program.  I get an
error message from the DM compiler that states

diag01.obj(diag01)
Error 42: Symbol Undefined _memSize

--- errorlevel 1

I use the command:
dmc diag01.cpp -msd

But it creates an executable that seems to run.

Here is the assembly code:

Public _memSize

data

buffer1 BYTE 20 DUP(?)
count	DWORD 0

code

_memSize PROC NEAR, C
PUSH EBP
MOV EBX, 00000000h
MOV AX, SEG buffer1
MOV ES, AX
MOV AX, OFFSET buffer1
MOV DI, AX
L1:
MOV EAX, 0000E820h
MOV EDX, 534D4150h		;'SMAP'
MOV ECX, SIZEOF buffer1		
INT 15h
JC L2
CMP EBX, 0
JZ L2
MOV EAX, OFFSET buffer1 + 8
MOV ECX, [EAX]			;Dereference EAX
ADD count, ECX
JMP L1
L2:
POP EBP
RET	
_memSize ENDP

END


And here is the C++ code:

#include <iostream.h>
#include <stdlib.h>

extern "C" void memSize();

int main()
{
unsigned int choice;
unsigned long count = 0;
system ("CLS");
do
{
cout << "Choose something. ";
cin >> choice;
switch(choice)
{
case 1:   system ("CLS");
cout << "Option 1\n";
break;
case 2:   system ("CLS");
cout << "Option 2\n";
memSize();
break;
case 3:   system ("CLS");
cout << "Option 3\n";
break;
case 0:   system ("CLS");
cout << "Exiting!!!\n";
break;
default:  system ("CLS");
cout << "Not a valid selection, please re-choose!\n";
}
}while(choice != 0);
return 0;
}


Could someone please look at my code and tell me what I am doing wrong.

Also, could someone tell me how to return values from the assembly funtion back
to the C++ calling program.

Thanks

BTW: The assembly funtion finds the total system memory(conventional, reserved,
and extended).