Code Rätsel 4

void f(char *x, char *y, int z) {
    int z2 = (z+7)/8;
    switch(z%8) {
    case 0: do { *x++ = *y++;
    case 7: *x++ = *y++;
    case 6: *x++ = *y++;
    case 5: *x++ = *y++;
    case 4: *x++ = *y++;
    case 3: *x++ = *y++;
    case 2: *x++ = *y++;
    case 1:*x++ = *y++;
        } while(--z2 > 0);
    }
}