[C] bit order?

struct tsHeader {
        unsigned ID1 : 3;
        unsigned ID2 : 13;
};

int main(int argc, char *argv[]) {
  unsigned char recv_str[100];
  recv_str[0] = 0x00;
  recv_str[1] = 0x01;

  struct tsHeader * tshdr;
  tshdr = malloc(sizeof(struct tsHeader));
  tshdr = (struct tsHeader *) recv_str;
  printf("ID2 = %d\n", tshdr->ID2);
}

#############################
# gcc -o test test.c
# ./test
ID2 = 32

struct tsHeader {
#if BYTE_ORDER == BIG_ENDIAN
unsigned ID1 : 3;
unsigned ID2_hi : 5;
#else
unsigned ID2_hi : 5;
unsigned ID1 : 3;
#endif
unsigned ID2_lo : 8;
};