Function convert_datetimestruct_to_datetime

numpy/core/src/multiarray/datetime.c:280–413

* Converts a datetime from a datetimestruct to a datetime based * on some metadata. The date is assumed to be valid. * * TODO: If meta->num is really big, there could be overflow * * Returns 0 on success, -1 on failure. */

 * Returns 0 on success, -1 on failure.
 */
NPY_NO_EXPORT int
convert_datetimestruct_to_datetime(PyArray_DatetimeMetaData *meta,
                                    const npy_datetimestruct *dts,
                                    npy_datetime *out)
{
    npy_datetime ret;
    NPY_DATETIMEUNIT base = meta->base;

    /* If the datetimestruct is NaT, return NaT */
    if (dts->year == NPY_DATETIME_NAT) {
        *out = NPY_DATETIME_NAT;
        return 0;
    }

    /* Cannot instantiate a datetime with generic units */
    if (meta->base == NPY_FR_GENERIC) {
        PyErr_SetString(PyExc_ValueError,
                    "Cannot create a NumPy datetime other than NaT "
                    "with generic units");
        return -1;
    }

    if (base == NPY_FR_Y) {
        /* Truncate to the year */
        ret = dts->year - 1970;
    }
    else if (base == NPY_FR_M) {
        /* Truncate to the month */
        ret = 12 * (dts->year - 1970) + (dts->month - 1);
    }
    else {
        /* Otherwise calculate the number of days to start */
        npy_int64 days = get_datetimestruct_days(dts);

        switch (base) {
            case NPY_FR_W:
                /* Truncate to weeks */
                if (days >= 0) {
                    ret = days / 7;
                }
                else {
                    ret = (days - 6) / 7;
                }
                break;
            case NPY_FR_D:
                ret = days;
                break;
            case NPY_FR_h:
                ret = days * 24 +
                      dts->hour;
                break;
            case NPY_FR_m:
                ret = (days * 24 +
                      dts->hour) * 60 +
                      dts->min;
                break;
            case NPY_FR_s:
                ret = ((days * 24 +