I am working with gcc in linux, I have an implementation of an asm inline function, which adds two numbers in floating point and returns them by reference in the variable r also passed as a parameter, compiles but the result of the sum is 0.0 , someone could help me, thanks :) here my function:
#define suma(r, a, b)\
__asm__("fldz \n\t fld %1\n\t fadd %2\n\t fstp %0":"=&t"(r):"f"(a),"f"(b));
With a couple of changes I've made it work, at least on my machine:
#define suma(r, a, b)\
__asm__("FLD %1 \n FADD %2 \n FSTP %0 \n" : "=m"(r) : "m"(f1), "m"(f2) : );
#include <stdio.h>
int main()
{
float f;
float f1 = 4, f2 = 5;
suma(f,f1,f2);
printf("%f, %f, %f",f,f1,f2);
}
The restrictions used for the variables did not seem to be correct and you were also doing unnecessary operations: fldz