Hello. I have a simply programs that sums two numbers in assembler. I also have a c program with a .h file that must use that program.
But I always got as a result a 0.
This is my asm code
MyProc proc var1:REAL4, var2:REAL4
LOCAL retval:REAL4
PUBLIC MyProc
finit
fld var1
fld var2
fadd
fstp retval
fwait ;<- is this really needed?
mov eax, retval
ret
MyProc endp
This is my .h code
#ifndef _FLOTANTE_H
#define _FLOTANTE_H
extern "C" unsigned long __stdcall __MyProc(float, float);
float MyProc(float f1, float f2);
#endif
and this is my C code
void sum(void)
{
int ch;
float f1;
float f2;
printf("Enter first number\n\n");
scanf("%d",&f1);
printf("Enter second number\n\n");
scanf("%d",&f2);
float total2;
total2 = MyProc(f1, f2);
printf("Total is: %d", total2);
while ( (ch = getchar()) != '\n' && ch != EOF) ;
printf("\n\nPress ENTER to continue.");
while ( (ch = getchar()) != '\n' && ch != EOF)
;
if(ch=='\n' || ch==EOF)
{
printmenu();
}
}
Note that this is NOT a C forum, if you want to post questions about C coding, do it in the specific subforum for that task.
But it may be an error of my assembler program.
MyProc proc var1:REAL4, var2:REAL4
PUBLIC MyProc
LOCAL retval:REAL4
fld var1
fadd var2
fstp retval
mov eax, retval
ret
MyProc endp
#ifndef _FLOTANTE_H
#define _FLOTANTE_H
extern "C" float __stdcall __MyProc(float, float);
#endif
void sum(void)
{
int ch;
float f1;
float f2;
printf("Enter first number\n\n");
scanf("%f",&f1); // need %f for real4
printf("Enter second number\n\n");
scanf("%f",&f2);
float total2 = __MyProc(f1, f2); // need the __ part because that is the name of the external function
printf("Total is: %f", total2); // %f for real4
while ( (ch = getchar()) != '\n' && ch != EOF) ;
printf("\n\nPress ENTER to continue.");
while ( (ch = getchar()) != '\n' && ch != EOF)
;
if(ch=='\n' || ch==EOF)
{
printmenu();
}
}
I think it should work now.
Try leaving the float you want on the FPU, i know VB works that way.
Yeah I'm pretty sure you return floats and doubles on the stack, and have only the return value at TOS, nothing else.