Trying to run assembly in C, but won't compile with gcc
main.c
#include <stdio.h>
#include "assem.s"
void extern testing(int * a);
int main(){
int b = 8;
int * a = &b;
testing(a);
printf("%d",*a);
}
assem.s
.globl testing
testing:
ret
gcc
gcc main.c assem.s -o test.exe
error
expected identifier or '(' before '.' token .globl testing
When you do #include "assem.s" it takes the contents of the file assem.s and places it into the C at that point. The result would have the compiler trying to compile this:
#include <stdio.h>
.globl testing
testing:
ret
void extern testing(int * a);
int main(){
int b = 8;
int * a = &b;
testing(a);
printf("%d",*a);
}
Of course that's not what you want. The compiler attempted to compile the line .globl testing and it failed because it isn't proper C syntax and results in the error you got. All you have to do is remove #include "assem.s".
assem.s will be assembled and then linked into the executable with the command gcc main.c assem.s -o test.exe. This one GCC command is the equivalent of the following except that intermediate object files won't be generated:
gcc -c main.c -o main.o
gcc -c assem.s -o assem.o
gcc main.o assem.o -o test.exe
You assemble/compile .s and .S files in the same fashion as .c files. .s and .S files should not be used with the C #include directive. There is a misconception among some new GCC users that they should be included and not assembled/linked separately.
You should change main.c like this. Then they could work.
#include <stdio.h>
//#include "assem.s"
void extern testing(int * a);
int main(){
int b = 8;
int * a = &b;
testing(a);
printf("%d",*a);
return 0;
}
