mimxrt/machine_rtc: Change RTC.datetime() tuple to match other ports.

This change moves the datetime tuple format back to the one used by all the
other ports:

    (year, month, day, weekday, hour, minute, second, microsecond)

Weekday is a number between 0 and 6, with 0 assigned to Monday.  It has to
be provided when setting the RTC with datetime(), but will be ignored on
entry and calculated when needed.

The weekday() method was removed, since that is now again a part of the
datetime tuple.

The now() method was updated so it continues to return a tuple that matches
CPython's datetime module.

ports/mimxrt/machine_rtc.c

@@ -39,10 +39,10 @@ typedef struct _machine_rtc_obj_t {
 STATIC const machine_rtc_obj_t machine_rtc_obj = {{&machine_rtc_type}};
 
 // Calculate the weekday from the date.
-// The result is zero based with 0 = Sunday.
+// The result is zero based with 0 = Monday.
 // by Michael Keith and Tom Craver, 1990.
 static int calc_weekday(int y, int m, int d) {
-    return (d += m < 3 ? y-- : y - 2, 23 * m / 9 + d + 4 + y / 4 - y / 100 + y / 400) % 7;
+    return ((d += m < 3 ? y-- : y - 2, 23 * m / 9 + d + 4 + y / 4 - y / 100 + y / 400) + 6) % 7;
 }
 
 STATIC mp_obj_t machine_rtc_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
@@ -66,11 +66,11 @@ STATIC mp_obj_t machine_rtc_datetime_helper(size_t n_args, const mp_obj_t *args)
             mp_obj_new_int(srtc_date.year),
             mp_obj_new_int(srtc_date.month),
             mp_obj_new_int(srtc_date.day),
+            mp_obj_new_int(calc_weekday(srtc_date.year, srtc_date.month, srtc_date.day)),
             mp_obj_new_int(srtc_date.hour),
             mp_obj_new_int(srtc_date.minute),
             mp_obj_new_int(srtc_date.second),
             mp_obj_new_int(ticks_us64() % 1000000),
-            mp_const_none,
         };
         return mp_obj_new_tuple(8, tuple);
     } else {
@@ -84,9 +84,10 @@ STATIC mp_obj_t machine_rtc_datetime_helper(size_t n_args, const mp_obj_t *args)
         srtc_date.year = year >= 100 ? year : year + 2000; // allow 21 for 2021
         srtc_date.month = mp_obj_get_int(items[1]);
         srtc_date.day = mp_obj_get_int(items[2]);
-        srtc_date.hour = mp_obj_get_int(items[3]);
-        srtc_date.minute = mp_obj_get_int(items[4]);
-        srtc_date.second = mp_obj_get_int(items[5]);
+        // Ignore weekday at items[3]
+        srtc_date.hour = mp_obj_get_int(items[4]);
+        srtc_date.minute = mp_obj_get_int(items[5]);
+        srtc_date.second = mp_obj_get_int(items[6]);
         if (SNVS_LP_SRTC_SetDatetime(SNVS, &srtc_date) != kStatus_Success) {
             mp_raise_ValueError(NULL);
         }
@@ -101,7 +102,21 @@ STATIC mp_obj_t machine_rtc_datetime(mp_uint_t n_args, const mp_obj_t *args) {
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(machine_rtc_datetime_obj, 1, 2, machine_rtc_datetime);
 
 STATIC mp_obj_t machine_rtc_now(mp_obj_t self_in) {
-    return machine_rtc_datetime_helper(1, &self_in);
+    // Get date and time in CPython order.
+    snvs_lp_srtc_datetime_t srtc_date;
+    SNVS_LP_SRTC_GetDatetime(SNVS, &srtc_date);
+
+    mp_obj_t tuple[8] = {
+        mp_obj_new_int(srtc_date.year),
+        mp_obj_new_int(srtc_date.month),
+        mp_obj_new_int(srtc_date.day),
+        mp_obj_new_int(srtc_date.hour),
+        mp_obj_new_int(srtc_date.minute),
+        mp_obj_new_int(srtc_date.second),
+        mp_obj_new_int((ticks_us64() + us_offset) % 1000000),
+        mp_const_none,
+    };
+    return mp_obj_new_tuple(8, tuple);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_rtc_now_obj, machine_rtc_now);
 
@@ -112,16 +127,6 @@ STATIC mp_obj_t machine_rtc_init(mp_obj_t self_in, mp_obj_t date) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(machine_rtc_init_obj, machine_rtc_init);
 
-STATIC mp_obj_t machine_rtc_weekday(mp_obj_t self_in) {
-    (void)self_in; // unused
-    int day;
-    snvs_lp_srtc_datetime_t srtc_date;
-    SNVS_LP_SRTC_GetDatetime(SNVS, &srtc_date);
-    day = calc_weekday(srtc_date.year, srtc_date.month, srtc_date.day);
-    return MP_OBJ_NEW_SMALL_INT((day + 6) % 7);
-}
-STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_rtc_weekday_obj, machine_rtc_weekday);
-
 // calibration(cal)
 // When the argument is a number in the range [-16 to 15], set the calibration value.
 STATIC mp_obj_t machine_rtc_calibration(mp_obj_t self_in, mp_obj_t cal_in) {
@@ -143,7 +148,6 @@ STATIC const mp_rom_map_elem_t machine_rtc_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_init), MP_ROM_PTR(&machine_rtc_init_obj) },
     { MP_ROM_QSTR(MP_QSTR_datetime), MP_ROM_PTR(&machine_rtc_datetime_obj) },
     { MP_ROM_QSTR(MP_QSTR_now), MP_ROM_PTR(&machine_rtc_now_obj) },
-    { MP_ROM_QSTR(MP_QSTR_weekday), MP_ROM_PTR(&machine_rtc_weekday_obj) },
     { MP_ROM_QSTR(MP_QSTR_calibration), MP_ROM_PTR(&machine_rtc_calibration_obj) },
 };
 STATIC MP_DEFINE_CONST_DICT(machine_rtc_locals_dict, machine_rtc_locals_dict_table);