Add RTC_DAY_CYCLE constant for the 140-day RTC wrap (#1267)

constants/misc_constants.asm

@@ -29,6 +29,9 @@ DEF SAVE_CHECK_VALUE_2 EQU 127
 ; RTC halted check value
 DEF RTC_HALT_VALUE EQU $1234
 
+; the RTC day count wraps after 20 weeks, preserving the day of the week
+DEF RTC_DAY_CYCLE EQU 20 * 7
+
 ; time of day boundaries
 DEF MORN_HOUR EQU 4  ; 4 AM
 DEF DAY_HOUR  EQU 10 ; 10 AM

engine/events/battle_tower/battle_tower.asm

@@ -1110,7 +1110,7 @@ BattleTowerAction_17:
 
 .asm_170849
 	ld hl, wCurDay
-	ld a, 140
+	ld a, RTC_DAY_CYCLE
 	sub c
 	add [hl]
 	cp 11

engine/rtc/rtc.asm

@@ -185,7 +185,7 @@ _InitTime::
 	sbc [hl]
 	dec hl
 	jr nc, .okay_days
-	add 140
+	add RTC_DAY_CYCLE
 	ld c, 7
 	call SimpleDivide
 

home/time.asm

@@ -82,12 +82,12 @@ FixDays::
 ; mod twice since bit 8 (DH) was set
 	ldh a, [hRTCDayLo]
 .modh
-	sub 140
+	sub RTC_DAY_CYCLE
 	jr nc, .modh
 .modl
-	sub 140
+	sub RTC_DAY_CYCLE
 	jr nc, .modl
-	add 140
+	add RTC_DAY_CYCLE
 
 ; update dl
 	ldh [hRTCDayLo], a
@@ -99,14 +99,14 @@ FixDays::
 .daylo
 ; quit if fewer than 140 days have passed
 	ldh a, [hRTCDayLo]
-	cp 140
+	cp RTC_DAY_CYCLE
 	jr c, .quit
 
 ; mod 140
 .mod
-	sub 140
+	sub RTC_DAY_CYCLE
 	jr nc, .mod
-	add 140
+	add RTC_DAY_CYCLE
 
 ; update dl
 	ldh [hRTCDayLo], a