[ace123]

declare the variable(s) you want to use outside of a function (outside any brackets).
Then, move the extern line(s) into a .h file (user_routines.h)
The extern lines are optional, and are only needed if you want to use them in more than one file (user_routines.c and user_routines_fast.c for autonomous)

After that, you can read and write to them from any function:

user_routines.c

#include "user_routines.h"
...
...
/* Only declare and initialize global variables *once*.*/
int x=0;
int y=0;
void func1(void) {
    x=1;
}
void func2(void) {
    y=x;
}
void Default_Routine(void) {
    /* caution: do not declare the global variables (or variables with the same name) inside a function again. This may cause strange behaviour if done by accident, and will not produce an error or even a warning in most cases.*/
    // int x; <-- NO COMPILE ERROR! 
    pwm01=y+127;
    pwm02=x+127;
}

user_routines.h

...
...
/* The extern allows *global variables* declared in one file to be usable in any other file. */
extern int x;
extern int y;
void func1(void);
void func2(void);
void Default_Routine(void);