#include <inttypes.h>
#include <string.h>
typedef struct
{
char type;
uint16_t P1;
uint16_t P2;
uint16_t res;
} Line_t, Arc_t;
int main ()
{
Line_t lines[10] = { 0 };
Arc_t arcs[10] = { 0 };
arcs[1] = lines[2];
lines[3] = arcs[5]; /* usw */
memcpy (lines, arcs, 10 * sizeof *lines);
}