void float_test(void) {
    int i;
    double a = -84.0;

    uint8_t * sweep = (uint8_t *)&a;

    for (i = 0; i < sizeof(a); i++)
        printf("%02x ", sweep[i]);
    printf("\r\n");

    printf("a is %f\r\n", a);

    uint64_t * aflip = (uint64_t *)&a;
    *aflip = *aflip << 32 | *aflip >> 32;

    for (i = 0; i < sizeof(a); i++)
        printf("%02x ", sweep[i]);
    printf("\r\n");

    printf("a (flipped) is %f\r\n", a);
}