marshal_dump

static VALUE
time_mdump(VALUE time)
{
    struct time_object *tobj;
    struct tm *tm;
    unsigned long p, s;
    char buf[8];
    time_t t;
    int nsec;
    int i;
    VALUE str;
    IF_HAVE_GMTIME_R(struct tm result);

    GetTimeval(time, tobj);

    t = tobj->ts.tv_sec;
    tm = GMTIME(&t, result);

    if ((tm->tm_year & 0xffff) != tm->tm_year)
        rb_raise(rb_eArgError, "year too big to marshal: %ld", (long)tm->tm_year);

    p = 0x1UL        << 31 | /*  1 */
        tobj->gmt    << 30 | /*  1 */
        tm->tm_year  << 14 | /* 16 */
        tm->tm_mon   << 10 | /*  4 */
        tm->tm_mday  <<  5 | /*  5 */
        tm->tm_hour;         /*  5 */
    s = tm->tm_min   << 26 | /*  6 */
        tm->tm_sec   << 20 | /*  6 */
        tobj->ts.tv_nsec / 1000;    /* 20 */
    nsec = tobj->ts.tv_nsec % 1000;

    for (i=0; i<4; i++) {
        buf[i] = p & 0xff;
        p = RSHIFT(p, 8);
    }
    for (i=4; i<8; i++) {
        buf[i] = s & 0xff;
        s = RSHIFT(s, 8);
    }

    str = rb_str_new(buf, 8);
    rb_copy_generic_ivar(str, time);
    if (nsec) {
        /*
         * submicro is formatted in fixed-point packed BCD (without sign).
         * It represent digits under microsecond.
         * For nanosecond resolution, 3 digits (2 bytes) are used.
         * However it can be longer.
         * Extra digits are ignored for loading.
         */
        unsigned char buf[2];
        int len = sizeof(buf);
        buf[1] = (nsec % 10) << 4;
        nsec /= 10;
        buf[0] = nsec % 10;
        nsec /= 10;
        buf[0] |= (nsec % 10) << 4;
        if (buf[1] == 0)
            len = 1;
        rb_ivar_set(str, id_submicro, rb_str_new((char *)buf, len));
    }
    return str;
}