G2 support

src/core/gen2/Clock.lua

@@ -0,0 +1,131 @@
+-- The game clock, as the cart keeps it (home/time.asm, engine/rtc/timeset.asm).
+--
+-- Gold does not store "the time".  It stores wStartHour / wStartMinute /
+-- wStartDay -- the RTC reading at the moment the player answered Oak -- and
+-- every read is CalcNSecsHoursDaysSince: the RTC now, MINUS that base, plus
+-- what the player said it was.  That is why setting the clock to 10 AM does
+-- not stop it: it only re-anchors the offset the RTC is read through.
+--
+-- The port has no battery-backed RTC to read, so `now` is the host clock and
+-- the base is the host clock at the moment the player answered.  The stored
+-- pair is the same pair the cart stores, so the arithmetic below IS
+-- InitTime's, not a second clock: a save with no base at all reads the host
+-- clock straight through, which is what every save made before this did.
+--
+-- Lives here rather than on World because two screens and one special write
+-- it (src/ui/gen2/InitClock.lua, src/script/gen2/Specials.lua SetDayOfWeek)
+-- and World only ever reads it.
+
+local Runtime = require("src.mods.Runtime")
+
+local Clock = {}
+
+Clock.MINUTES_PER_DAY = 24 * 60
+Clock.DAYS = 7
+
+-- InitClock's own default: `ld a, 10 ; default hour = 10 AM`, with the minute
+-- buffer left at the zero ByteFill put there.
+Clock.DEFAULT_HOUR = 10
+Clock.DEFAULT_MINUTE = 0
+
+local function hostMinutes()
+  local hour = tonumber(os.date("%H")) or 0
+  local minute = tonumber(os.date("%M")) or 0
+  return (hour * 60 + minute) % Clock.MINUTES_PER_DAY
+end
+
+local function hostWeekday()
+  -- os.date("%w") is Sunday 0, and constants/misc_constants.asm's SUNDAY is 0
+  -- too, so the two agree without a shift.
+  return (tonumber(os.date("%w")) or 0) % Clock.DAYS
+end
+
+Clock.hostMinutes = hostMinutes
+Clock.hostWeekday = hostWeekday
+
+local function rtc(save)
+  return type(save) == "table" and save.rtc or nil
+end
+
+-- clock.day_changed, a Gen 2 invention: Gen 1 has no clock at all, so there is
+-- no name to share.  The cart has no "day changed" routine either -- everything
+-- daily is a countdown compared against wCurDay when it is next read -- so the
+-- event is raised off the read that IS GetWeekday: every consumer of the day
+-- (VAR_WEEKDAY, the world.tod ctx, the Pokegear clock card, the daily resets)
+-- goes through Clock.weekday, so a rollover cannot get past this.
+--
+--   day       the weekday now, SUNDAY 0 .. SATURDAY 6
+--   previous  the weekday the last read answered
+--   reason    "rollover" for the host clock crossing midnight, "set" for
+--             Mom's wheel re-anchoring the day (src/ui/gen2/InitClock.lua)
+--
+-- The last-seen day is process-local rather than saved: the first read after a
+-- boot has nothing to compare against and reports nothing, which is why a
+-- Gold boot does not open with a spurious day change.  It is only maintained
+-- while somebody is subscribed, which is what keeps a mod-free boot free.
+local lastDay = nil
+
+local function noteDay(day, reason)
+  if not Runtime.wants("clock.day_changed") then
+    lastDay = nil
+    return day
+  end
+  local previous = lastDay
+  lastDay = day
+  if previous ~= nil and previous ~= day then
+    Runtime.emit("clock.day_changed",
+      { day = day, previous = previous, reason = reason })
+  end
+  return day
+end
+
+-- _InitTime: store the base so that reading it back answers `hour:minute`.
+function Clock.setTime(save, hour, minute)
+  if type(save) ~= "table" then return false end
+  save.rtc = save.rtc or {}
+  local wanted = (math.floor(hour or 0) % 24) * 60
+    + (math.floor(minute or 0) % 60)
+  save.rtc.startMinute = (wanted - hostMinutes()) % Clock.MINUTES_PER_DAY
+  return true
+end
+
+-- InitDayOfWeek, which is the same anchor for wCurDay.
+function Clock.setWeekday(save, day)
+  if type(save) ~= "table" then return false end
+  save.rtc = save.rtc or {}
+  save.rtc.startDay = (math.floor(day or 0) - hostWeekday()) % Clock.DAYS
+  save.rtc.dayOfWeek = math.floor(day or 0) % Clock.DAYS
+  noteDay(save.rtc.dayOfWeek, "set")
+  return true
+end
+
+-- The clock the game reads: the host clock through the stored offset.
+function Clock.minutes(save)
+  local r = rtc(save)
+  local offset = r and tonumber(r.startMinute) or 0
+  return (hostMinutes() + offset) % Clock.MINUTES_PER_DAY
+end
+
+function Clock.hour(save)
+  return math.floor(Clock.minutes(save) / 60)
+end
+
+function Clock.minute(save)
+  return Clock.minutes(save) % 60
+end
+
+-- GetWeekday, and the poll site clock.day_changed is raised from (see noteDay).
+function Clock.weekday(save)
+  local r = rtc(save)
+  local offset = r and tonumber(r.startDay) or 0
+  return noteDay((hostWeekday() + offset) % Clock.DAYS, "rollover")
+end
+
+-- True once the player has actually answered Oak, so a caller can tell "10 AM
+-- because that is what the host says" from "10 AM because the player set it".
+function Clock.isSet(save)
+  local r = rtc(save)
+  return r ~= nil and r.startMinute ~= nil
+end
+
+return Clock