RP5C01.cc

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#include "RP5C01.hh"
#include "SRAM.hh"
#include "one_of.hh"
#include "serialize.hh"
#include <cassert>
#include <ctime>
 
namespace openmsx {
 
// TODO  ALARM is not implemented        (not connected on MSX)
// TODO  1Hz 16Hz output not implemented (not connected on MSX)
 
constexpr nibble MODE_REG  = 13;
constexpr nibble TEST_REG  = 14;
constexpr nibble RESET_REG = 15;
 
constexpr nibble TIME_BLOCK  = 0;
constexpr nibble ALARM_BLOCK = 1;
 
constexpr nibble MODE_BLOKSELECT  = 0x3;
constexpr nibble MODE_ALARMENABLE = 0x4;
constexpr nibble MODE_TIMERENABLE = 0x8;
 
constexpr nibble TEST_SECONDS = 0x1;
constexpr nibble TEST_MINUTES = 0x2;
constexpr nibble TEST_DAYS    = 0x4;
constexpr nibble TEST_YEARS   = 0x8;
 
constexpr nibble RESET_ALARM    = 0x1;
constexpr nibble RESET_FRACTION = 0x2;
 
 
// 0-bits are ignored on writing and return 0 on reading
constexpr nibble mask[4][13] = {
        { 0xf, 0x7, 0xf, 0x7, 0xf, 0x3, 0x7, 0xf, 0x3, 0xf, 0x1, 0xf, 0xf},
        { 0x0, 0x0, 0xf, 0x7, 0xf, 0x3, 0x7, 0xf, 0x3, 0x0, 0x1, 0x3, 0x0},
        { 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf},
        { 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf, 0xf}
};
 
RP5C01::RP5C01(CommandController& commandController, SRAM& regs_,
               EmuTime::param time, const std::string& name)
        : regs(regs_)
        , modeSetting(
                commandController,
                ((name == "Real time clock") ? std::string_view("rtcmode") // bw-compat
                                             : tmpStrCat(name + " mode")),
                "Real Time Clock mode", RP5C01::EMUTIME,
                EnumSetting<RP5C01::RTCMode>::Map{
                        {"EmuTime",  RP5C01::EMUTIME},
                        {"RealTime", RP5C01::REALTIME}})
        , reference(time)
{
        initializeTime();
        reset(time);
}
 
void RP5C01::reset(EmuTime::param time)
{
        modeReg = MODE_TIMERENABLE;
        testReg = 0;
        resetReg = 0;
        updateTimeRegs(time);
}
 
nibble RP5C01::readPort(nibble port, EmuTime::param time)
{
        switch (port) {
        case MODE_REG:
        case TEST_REG:
        case RESET_REG:
                // nothing
                break;
        default:
                unsigned block = modeReg & MODE_BLOKSELECT;
                if (block == one_of(TIME_BLOCK, ALARM_BLOCK)) {
                        updateTimeRegs(time);
                }
        }
        return peekPort(port);
}
 
nibble RP5C01::peekPort(nibble port) const
{
        assert(port <= 0x0f);
        switch (port) {
        case MODE_REG:
                return modeReg;
        case TEST_REG:
        case RESET_REG:
                // write only
                return 0x0f; // TODO check this
        default:
                unsigned block = modeReg & MODE_BLOKSELECT;
                nibble tmp = regs[block * 13 + port];
                return tmp & mask[block][port];
        }
}
 
void RP5C01::writePort(nibble port, nibble value, EmuTime::param time)
{
        assert (port <= 0x0f);
        switch (port) {
        case MODE_REG:
                updateTimeRegs(time);
                modeReg = value;
                break;
        case TEST_REG:
                updateTimeRegs(time);
                testReg = value;
                break;
        case RESET_REG:
                resetReg = value;
                if (value & RESET_ALARM) {
                        resetAlarm();
                }
                if (value & RESET_FRACTION) {
                        fraction = 0;
                }
                break;
        default:
                unsigned block = modeReg & MODE_BLOKSELECT;
                if (block == one_of(TIME_BLOCK, ALARM_BLOCK)) {
                        updateTimeRegs(time);
                }
                regs.write(block * 13 + port, value & mask[block][port]);
                if (block == one_of(TIME_BLOCK, ALARM_BLOCK)) {
                        regs2Time();
                }
        }
}
 
void RP5C01::initializeTime()
{
        time_t t = time(nullptr);
        struct tm *tm = localtime(&t);
        fraction = 0;                   // fractions of a second
        seconds  = tm->tm_sec;          // 0-59
        minutes  = tm->tm_min;          // 0-59
        hours    = tm->tm_hour;         // 0-23
        dayWeek  = tm->tm_wday;         // 0-6   0=sunday
        days     = tm->tm_mday-1;       // 0-30
        months   = tm->tm_mon;          // 0-11
        years    = tm->tm_year - 80;    // 0-99  0=1980
        leapYear = tm->tm_year % 4;     // 0-3   0=leap year
        time2Regs();
}
 
void RP5C01::regs2Time()
{
        seconds  = regs[TIME_BLOCK * 13 + 0] + 10 * regs[TIME_BLOCK * 13 + 1];
        minutes  = regs[TIME_BLOCK * 13 + 2] + 10 * regs[TIME_BLOCK * 13 + 3];
        hours    = regs[TIME_BLOCK * 13 + 4] + 10 * regs[TIME_BLOCK * 13 + 5];
        dayWeek  = regs[TIME_BLOCK * 13 + 6];
        days     = regs[TIME_BLOCK * 13 + 7] + 10 * regs[TIME_BLOCK * 13 + 8] - 1;
        months   = regs[TIME_BLOCK * 13 + 9] + 10 * regs[TIME_BLOCK * 13 +10] - 1;
        years    = regs[TIME_BLOCK * 13 +11] + 10 * regs[TIME_BLOCK * 13 +12];
        leapYear = regs[ALARM_BLOCK * 13 +11];
 
        if (!regs[ALARM_BLOCK * 13 + 10]) {
                // 12 hours mode
                if (hours >= 20) hours = (hours - 20) + 12;
        }
}
 
void RP5C01::time2Regs()
{
        unsigned hours_ = hours;
        if (!regs[ALARM_BLOCK * 13 + 10]) {
                // 12 hours mode
                if (hours >= 12) hours_ = (hours - 12) + 20;
        }
 
        regs.write(TIME_BLOCK  * 13 +  0,  seconds   % 10);
        regs.write(TIME_BLOCK  * 13 +  1,  seconds   / 10);
        regs.write(TIME_BLOCK  * 13 +  2,  minutes   % 10);
        regs.write(TIME_BLOCK  * 13 +  3,  minutes   / 10);
        regs.write(TIME_BLOCK  * 13 +  4,  hours_    % 10);
        regs.write(TIME_BLOCK  * 13 +  5,  hours_    / 10);
        regs.write(TIME_BLOCK  * 13 +  6,  dayWeek);
        regs.write(TIME_BLOCK  * 13 +  7, (days+1)   % 10); // 0-30 -> 1-31
        regs.write(TIME_BLOCK  * 13 +  8, (days+1)   / 10); // 0-11 -> 1-12
        regs.write(TIME_BLOCK  * 13 +  9, (months+1) % 10);
        regs.write(TIME_BLOCK  * 13 + 10, (months+1) / 10);
        regs.write(TIME_BLOCK  * 13 + 11,  years     % 10);
        regs.write(TIME_BLOCK  * 13 + 12,  years     / 10);
        regs.write(ALARM_BLOCK * 13 + 11,  leapYear);
}
 
static constexpr int daysInMonth(int month, unsigned leapYear)
{
        constexpr uint8_t daysInMonths[12] = {
                31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
        };
 
        month %= 12;
        return ((month == 1) && (leapYear == 0)) ? 29 : daysInMonths[month];
}
 
void RP5C01::updateTimeRegs(EmuTime::param time)
{
        if (modeSetting.getEnum() == EMUTIME) {
                // sync with EmuTime, perfect emulation
                auto elapsed = unsigned(reference.getTicksTill(time));
                reference.advance(time);
 
                // in test mode increase sec/min/.. at a rate of 16384Hz
                fraction += (modeReg & MODE_TIMERENABLE) ? elapsed : 0;
                unsigned carrySeconds = (testReg & TEST_SECONDS)
                                      ? elapsed : fraction / FREQ;
                seconds  += carrySeconds;
                unsigned carryMinutes = (testReg & TEST_MINUTES)
                                      ? elapsed : seconds / 60;
                minutes  += carryMinutes;
                hours    += minutes / 60;
                unsigned carryDays = (testReg & TEST_DAYS)
                                   ? elapsed : hours / 24;
                if (carryDays) {
                        // Only correct for number of days in a month when we
                        // actually advance the day. Because otherwise e.g. the
                        // following scenario goes wrong:
                        // - Suppose current date is 'xx/07/31' and we want to
                        //   change that to 'xx/12/31'.
                        // - Changing the months is done in two steps: first the
                        //   lower then the higher nibble.
                        // - So temporary we go via the (invalid) date 'xx/02/31'
                        //   (february does not have 32 days)
                        // - We must NOT roll over the days and advance to march.
                        days     += carryDays;
                        dayWeek  += carryDays;
                        while (days >= daysInMonth(months, leapYear)) {
                                // TODO not correct because leapYear is not updated
                                //      is only triggered when we update several months
                                //      at a time (but might happen in TEST_DAY mode)
                                days -= daysInMonth(months, leapYear);
                                months++;
                        }
                }
                unsigned carryYears = (testReg & TEST_YEARS)
                                    ? elapsed : unsigned(months / 12);
                years    += carryYears;
                leapYear += carryYears;
 
                fraction %= FREQ;
                seconds  %= 60;
                minutes  %= 60;
                hours    %= 24;
                dayWeek  %= 7;
                months   %= 12;
                years    %= 100;
                leapYear %= 4;
 
                time2Regs();
        } else {
                // sync with host clock
                //   writes to time, test and reset registers have no effect
                initializeTime();
        }
}
 
void RP5C01::resetAlarm()
{
        for (auto i : xrange(2, 9)) {
                regs.write(ALARM_BLOCK * 13 + i, 0);
        }
}
 
template<typename Archive>
void RP5C01::serialize(Archive& ar, unsigned /*version*/)
{
        ar.serialize("reference", reference,
                     "fraction",  fraction,
                     "seconds",   seconds,
                     "minutes",   minutes,
                     "hours",     hours,
                     "dayWeek",   dayWeek,
                     "years",     years,
                     "leapYear",  leapYear,
                     "days",      days,
                     "months",    months,
                     "modeReg",   modeReg,
                     "testReg",   testReg,
                     "resetReg",  resetReg);
}
INSTANTIATE_SERIALIZE_METHODS(RP5C01);
 
} // namespace openmsx