#include <stdio.h>
#include <stddef.h>
#include <stdint.h>


typedef struct __attribute__((packed)) {
  uint8_t dir;            // 'F' = CW, 'R' = CCW
  uint32_t rev;           // number of revolutions
  uint8_t filler[3];      // filler
} stepper_data_t;

int main(void) {

	printf("offset of dir: %d\n", offsetof(stepper_data_t, dir));
	printf("offset of rev: %d\n", offsetof(stepper_data_t, rev));
	printf("offset of filler: %d\n", offsetof(stepper_data_t, filler));

	return 0;
}