Question

I wrote a function named absD that i want to return the absolute value of its argument..
I am using GCC inline assembly with cygwin..

I dont see why its not working. i m loading into memory. then into st(0)
where i am using fabs – absolute value. Do i have to allocate memory?

I am trying to learn assembly with C here so please be nice. Please give me good help.
Thank you

heres the code and then the error:

#include <stdio.h>
#include <stdlib.h>
#define PRECISION   3

double absD (double n)
{


asm(
        "fldl %[nIn]\n"
        "fabs\n"
        "fstpl %[nOut]\n"
        : [nOut] "=m" (n)
        : [nIn] "m" (n)
);



return n;


}

int main (int argc, char **argv)
{
double  n = 0.0;

printf("Absolute value\n");
if (argc > 1)
    n = atof(argv[1]);

printf("abs(%.*f) = %.*f\n", PRECISION, n, PRECISION, absD(n));

return 0;
}

here is the output:

~ $ gc a3
gcc -Wall -g a3.c -o a3
~ $ ./a3
Absolute value
abs(0.000) = 0.000
~ $

Not outputing its absolute value…
Thank you..

Answer 1

It is completely working..!! You are just forgetting to put values to argv. You can run the program with something like this:

./a3 -1.3

and it should return 1.3

you were done before posting it here…