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gb.cpp: Improved MBC3 RTC handling. (#9035)

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wilbertpol 2021-12-25 00:05:48 +00:00 committed by GitHub
parent 1e32a43b50
commit 76152ba35e
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2 changed files with 107 additions and 32 deletions
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123
src/devices/bus/gameboy/mbc.cpp
View File

@ -4,8 +4,8 @@
Game Boy carts with MBC (Memory Bank Controller)
TODO: RTC runs too fast while in-game, in MBC-3 games... find the problem!
TODO:
- The MBC3 RTC should count the time that passed since the game was last played.
***********************************************************************************************************/
@ -189,12 +189,26 @@ void gb_rom_mbc3_device::device_start()
shared_start();
save_item(NAME(m_rtc_regs));
save_item(NAME(m_rtc_ready));
save_item(NAME(m_rtc_ticks));
save_item(NAME(m_latched_regs));
m_rtc_ticks = 0;
system_time curtime;
machine().current_datetime(curtime);
m_rtc_regs[REG_SECONDS] = curtime.local_time.second;
m_rtc_regs[REG_MINUTES] = curtime.local_time.minute;
m_rtc_regs[REG_HOURS] = curtime.local_time.hour;
m_rtc_regs[REG_DAYS] = curtime.local_time.day & 0xff;
m_rtc_regs[REG_CONTROL] = (curtime.local_time.day >> 8) & 0x01;
m_rtc_timer = machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(gb_rom_mbc3_device::rtc_tick),this));
m_rtc_timer->adjust(attotime::from_hz(RTC_FREQUENCY), 0, attotime::from_hz(RTC_FREQUENCY));
}
void gb_rom_mbc3_device::device_reset()
{
shared_reset();
memset(m_rtc_regs, 0, sizeof(m_rtc_regs));
m_rtc_ready = 0;
}
@ -468,16 +482,39 @@ void gb_rom_mbc2_device::write_ram(offs_t offset, uint8_t data)
// MBC3
void gb_rom_mbc3_device::update_rtc()
TIMER_CALLBACK_MEMBER(gb_rom_mbc3_device::rtc_tick)
{
system_time curtime;
machine().current_datetime(curtime);
m_rtc_regs[0] = curtime.local_time.second;
m_rtc_regs[1] = curtime.local_time.minute;
m_rtc_regs[2] = curtime.local_time.hour;
m_rtc_regs[3] = curtime.local_time.day & 0xff;
m_rtc_regs[4] = (m_rtc_regs[4] & 0xf0) | (curtime.local_time.day >> 8);
if (BIT(m_rtc_regs[REG_CONTROL], 6)) {
return;
}
m_rtc_ticks++;
if (m_rtc_ticks >= RTC_FREQUENCY)
{
m_rtc_ticks = 0;
m_rtc_regs[REG_SECONDS] = (m_rtc_regs[REG_SECONDS] + 1) & 0x3f;
if (m_rtc_regs[REG_SECONDS] == 60)
{
m_rtc_regs[REG_SECONDS] = 0;
m_rtc_regs[REG_MINUTES] = (m_rtc_regs[REG_MINUTES] + 1) & 0x3f;
if (m_rtc_regs[REG_MINUTES] == 60)
{
m_rtc_regs[REG_MINUTES] -= 60;
m_rtc_regs[REG_HOURS] = (m_rtc_regs[REG_HOURS] + 1) & 0x1f;
if (m_rtc_regs[REG_HOURS] == 24)
{
m_rtc_regs[REG_HOURS] = 0;
m_rtc_regs[REG_DAYS]++;
if (m_rtc_regs[REG_DAYS] == 0)
{
m_rtc_regs[REG_CONTROL] = (m_rtc_regs[REG_CONTROL] & 0xfe) | ((m_rtc_regs[REG_CONTROL] + 1) & 0x01);
if (!(m_rtc_regs[REG_CONTROL] & 0x01)) {
m_rtc_regs[REG_CONTROL] |= RTC_CARRY;
}
}
}
}
}
}
}
uint8_t gb_rom_mbc3_device::read_rom(offs_t offset)
@ -512,42 +549,66 @@ void gb_rom_mbc3_device::write_bank(offs_t offset, uint8_t data)
m_rtc_ready = 0;
if (m_rtc_ready == 0 && data == 1)
{
m_latched_regs[REG_SECONDS] = m_rtc_regs[REG_SECONDS];
m_latched_regs[REG_MINUTES] = m_rtc_regs[REG_MINUTES];
m_latched_regs[REG_HOURS] = m_rtc_regs[REG_HOURS];
m_latched_regs[REG_DAYS] = m_rtc_regs[REG_DAYS];
m_latched_regs[REG_CONTROL] = m_rtc_regs[REG_CONTROL];
m_rtc_ready = 1;
update_rtc();
}
}
}
uint8_t gb_rom_mbc3_device::read_ram(offs_t offset)
{
if (m_ram_bank < 4 && m_ram_enable)
if (m_ram_enable)
{
// RAM
if (!m_ram.empty())
if (m_ram_bank < 4 && !m_ram.empty())
{
// RAM
return m_ram[ram_bank_map[m_ram_bank] * 0x2000 + (offset & 0x1fff)];
}
if (m_ram_bank >= 0x8 && m_ram_bank <= 0xc)
{
// RTC registers
if (has_timer)
return m_rtc_regs[m_ram_bank - 8];
}
else if (m_ram_bank >= 0x08 && m_ram_bank <= 0x0c && has_timer)
{
// RTC registers
return m_latched_regs[m_ram_bank - 8];
}
}
return 0xff;
}
void gb_rom_mbc3_device::write_ram(offs_t offset, uint8_t data)
{
if (m_ram_bank < 4 && m_ram_enable)
if (m_ram_enable)
{
// RAM
if (!m_ram.empty())
if (m_ram_bank < 4 && !m_ram.empty())
{
// RAM
m_ram[ram_bank_map[m_ram_bank] * 0x2000 + (offset & 0x1fff)] = data;
}
if (m_ram_bank >= 0x8 && m_ram_bank <= 0xc && m_ram_enable)
{
// RTC registers are writeable too
if (has_timer)
m_rtc_regs[m_ram_bank - 8] = data;
}
else if (m_ram_bank >= 0x08 && m_ram_bank <= 0x0c && has_timer)
{
// RTC registers are writeable too
uint8_t reg = m_ram_bank - 8;
switch(reg)
{
case REG_SECONDS:
case REG_MINUTES:
data &= 0x3f;
break;
case REG_HOURS:
data &= 0x1f;
break;
case REG_CONTROL:
data &= 0xc1;
break;
}
m_rtc_regs[reg] = data;
if (reg == REG_SECONDS)
{
m_rtc_ticks = 0;
}
}
}
}

16
src/devices/bus/gameboy/mbc.h
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@ -100,9 +100,23 @@ protected:
virtual void device_reset() override;
private:
void update_rtc();
static constexpr uint32_t RTC_FREQUENCY = 32'768;
static constexpr uint8_t RTC_CARRY = 0x80;
static constexpr uint8_t RTC_HALT = 0x40;
static constexpr uint8_t REG_SECONDS = 0;
static constexpr uint8_t REG_MINUTES = 1;
static constexpr uint8_t REG_HOURS = 2;
static constexpr uint8_t REG_DAYS = 3;
static constexpr uint8_t REG_CONTROL = 4;
emu_timer *m_rtc_timer;
uint32_t m_rtc_ticks;
uint8_t m_rtc_regs[5];
uint8_t m_latched_regs[5];
int m_rtc_ready;
TIMER_CALLBACK_MEMBER(rtc_tick);
};
// ======================> gb_rom_mbc5_device