Function cast_timedelta_to_timedelta

numpy/core/src/multiarray/datetime.c:3046–3077

* Casts a single timedelta from having src_meta metadata into * dst_meta metadata. * * Returns 0 on success, -1 on failure. */

 * Returns 0 on success, -1 on failure.
 */
NPY_NO_EXPORT int
cast_timedelta_to_timedelta(PyArray_DatetimeMetaData *src_meta,
                          PyArray_DatetimeMetaData *dst_meta,
                          npy_timedelta src_dt,
                          npy_timedelta *dst_dt)
{
    npy_int64 num = 0, denom = 0;

    /* If the metadata is the same, short-circuit the conversion */
    if (src_meta->base == dst_meta->base &&
            src_meta->num == dst_meta->num) {
        *dst_dt = src_dt;
        return 0;
    }

    /* Get the conversion factor */
    get_datetime_conversion_factor(src_meta, dst_meta, &num, &denom);

    if (num == 0) {
        return -1;
    }

    /* Apply the scaling */
    if (src_dt < 0) {
        *dst_dt = (src_dt * num - (denom - 1)) / denom;
    }
    else {
        *dst_dt = src_dt * num / denom;
    }

    return 0;
}

/*
 * Returns true if the object is something that is best considered