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Transfers full TOD responsibility onto the chip-specific templates.
This commit is contained in:
Thomas Harte
parent
0245b040b0
commit
6210605bc7
@ -73,61 +73,16 @@ void MOS6526<BusHandlerT, personality>::write(int address, uint8_t value) {
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break;
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// Counters; writes set the reload values.
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case 4: counter_[0].template set_reload<0>(value); break;
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case 5: counter_[0].template set_reload<8>(value); break;
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case 6: counter_[1].template set_reload<0>(value); break;
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case 7: counter_[1].template set_reload<8>(value); break;
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case 4: counter_[0].template set_reload<0>(value); break;
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case 5: counter_[0].template set_reload<8>(value); break;
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case 6: counter_[1].template set_reload<0>(value); break;
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case 7: counter_[1].template set_reload<8>(value); break;
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// Time-of-day clock.
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//
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// 8520: a binary counter; stopped on any write, restarted
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// upon a write to the LSB.
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case 8:
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if constexpr (personality == Personality::P8250) {
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if(counter_[1].control & 0x80) {
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tod_.alarm = (tod_.alarm & 0xffff00) | uint32_t(value);
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} else {
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tod_.value = (tod_.value & 0xffff00) | uint32_t(value);
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tod_.increment_mask = uint32_t(~0);
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}
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} else {
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printf("6526 TOD clock not implemented\n");
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assert(false);
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}
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break;
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case 9:
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if constexpr (personality == Personality::P8250) {
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if(counter_[1].control & 0x80) {
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tod_.alarm = (tod_.alarm & 0xff00ff) | uint32_t(value << 8);
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} else {
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tod_.value = (tod_.value & 0xff00ff) | uint32_t(value << 8);
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tod_.increment_mask = 0;
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}
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} else {
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printf("6526 TOD clock not implemented\n");
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assert(false);
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}
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break;
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case 10:
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if constexpr (personality == Personality::P8250) {
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if(counter_[1].control & 0x80) {
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tod_.alarm = (tod_.alarm & 0x00ffff) | uint32_t(value << 16);
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} else {
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tod_.value = (tod_.value & 0x00ffff) | uint32_t(value << 16);
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tod_.increment_mask = 0;
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}
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} else {
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printf("6526 TOD clock not implemented\n");
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assert(false);
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}
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break;
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case 11:
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if constexpr (personality != Personality::P8250) {
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printf("6526 TOD clock not implemented\n");
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assert(false);
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}
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break;
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case 8: tod_.template write<0>(value); break;
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case 9: tod_.template write<1>(value); break;
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case 10: tod_.template write<2>(value); break;
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case 11: tod_.template write<3>(value); break;
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// Interrupt control.
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case 13: {
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@ -139,9 +94,15 @@ void MOS6526<BusHandlerT, personality>::write(int address, uint8_t value) {
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update_interrupts();
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} break;
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// Control.
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case 14: counter_[0].template set_control<false>(value); break;
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case 15: counter_[1].template set_control<true>(value); break;
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// Control. Posted to both the counters and the clock as it affects both.
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case 14:
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counter_[0].template set_control<false>(value);
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tod_.template set_control<false>(value);
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break;
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case 15:
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counter_[1].template set_control<true>(value);
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tod_.template set_control<true>(value);
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break;
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default:
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printf("Unhandled 6526 write: %02x to %d\n", value, address);
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@ -179,53 +140,10 @@ uint8_t MOS6526<BusHandlerT, personality>::read(int address) {
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return counter_[address - 14].control;
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// Time-of-day clock.
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//
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// 8250: Latch on MSB. Unlatch on LSB. Read raw if not latched.
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case 8:
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if constexpr (personality == Personality::P8250) {
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if(tod_.latch) {
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const uint8_t result = tod_.latch & 0xff;
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tod_.latch = 0;
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return result;
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} else {
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return tod_.value & 0xff;
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}
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} else {
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printf("6526 TOD clock not implemented\n");
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assert(false);
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}
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break;
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case 9:
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if constexpr (personality == Personality::P8250) {
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if(tod_.latch) {
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return (tod_.latch >> 8) & 0xff;
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} else {
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return (tod_.value >> 8) & 0xff;
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}
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} else {
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printf("6526 TOD clock not implemented\n");
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assert(false);
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}
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break;
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case 10:
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if constexpr (personality == Personality::P8250) {
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tod_.latch = tod_.value | 0xff00'0000;
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return (tod_.value >> 16) & 0xff;
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} else {
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printf("6526 TOD clock not implemented\n");
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assert(false);
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}
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break;
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case 11:
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if constexpr (personality == Personality::P8250) {
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return 0x00; // Assumed. Just a guss.
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} else {
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printf("6526 TOD clock not implemented\n");
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assert(false);
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}
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break;
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case 8: return tod_.template read<0>();
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case 9: return tod_.template read<1>();
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case 10: return tod_.template read<2>();
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case 11: return tod_.template read<3>();
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default:
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printf("Unhandled 6526 read from %d\n", address);
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@ -259,18 +177,8 @@ void MOS6526<BusHandlerT, personality>::run_for(const HalfCycles half_cycles) {
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template <typename BusHandlerT, Personality personality>
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void MOS6526<BusHandlerT, personality>::advance_tod(int count) {
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if(!count) return;
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if constexpr(personality == Personality::P8250) {
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// The 8250 uses a simple binary counter to replace the
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// 6526's time-of-day clock. So this is easy.
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const uint32_t distance_to_alarm = (tod_.alarm - tod_.value) & 0xffffff;
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tod_.value += uint32_t(count) & tod_.increment_mask;
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if(distance_to_alarm <= uint32_t(count)) {
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posit_interrupt(0x04);
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}
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} else {
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// The 6526 uses a time-of-day clock. This may or may not
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// be accurate.
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if(tod_.advance(count)) {
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posit_interrupt(0x04);
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}
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}
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@ -12,15 +12,95 @@
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namespace MOS {
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namespace MOS6526 {
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template <bool is_8250> struct TODStorage {};
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template <> struct TODStorage<false> {
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// TODO.
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class TODBase {
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public:
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template <bool is_timer2> void set_control(uint8_t value) {
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if constexpr (is_timer2) {
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write_alarm = value & 0x80;
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} else {
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is_50Hz = value & 0x80;
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}
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}
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protected:
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bool write_alarm = false, is_50Hz = false;
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};
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template <> struct TODStorage<true> {
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uint32_t increment_mask = uint32_t(~0);
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uint32_t latch = 0;
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uint32_t value = 0;
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uint32_t alarm = 0;
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template <bool is_8250> class TODStorage {};
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template <> class TODStorage<false>: public TODBase {
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public:
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// TODO.
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template <int byte> void write(uint8_t) {
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printf("6526 TOD clock not implemented\n");
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assert(false);
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}
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template <int byte> uint8_t read() {
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printf("6526 TOD clock not implemented\n");
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assert(false);
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}
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bool advance(int) {
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printf("6526 TOD clock not implemented\n");
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assert(false);
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}
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};
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template <> class TODStorage<true>: public TODBase {
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private:
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uint32_t increment_mask_ = uint32_t(~0);
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uint32_t latch_ = 0;
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uint32_t value_ = 0;
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uint32_t alarm_ = 0;
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public:
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template <int byte> void write(uint8_t v) {
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if constexpr (byte == 3) {
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return;
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}
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constexpr int shift = byte << 3;
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// Write to either the alarm or the current value as directed;
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// writing to any part of the current value other than the LSB
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// pauses incrementing until the LSB is written.
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if(write_alarm) {
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alarm_ = (alarm_ & (0x00ff'ffff >> (24 - shift))) | uint32_t(v << shift);
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} else {
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value_ = (alarm_ & (0x00ff'ffff >> (24 - shift))) | uint32_t(v << shift);
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increment_mask_ = (shift == 0) ? uint32_t(~0) : 0;
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}
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}
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template <int byte> uint8_t read() {
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if constexpr (byte == 3) {
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return 0xff; // Assumed. Just a guss.
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}
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constexpr int shift = byte << 3;
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if(latch_) {
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// Latching: if this is a latched read from the LSB,
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// empty the latch.
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const uint8_t result = uint8_t((latch_ >> shift) & 0xff);
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if constexpr (shift == 0) {
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latch_ = 0;
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}
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return result;
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} else {
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// Latching: if this is a read from the MSB, latch now.
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if constexpr (shift == 16) {
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latch_ = value_ | 0xff00'0000;
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}
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return uint8_t((value_ >> shift) & 0xff);
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}
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}
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bool advance(int count) {
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// The 8250 uses a simple binary counter to replace the
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// 6526's time-of-day clock. So this is easy.
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const uint32_t distance_to_alarm = (alarm_ - value_) & 0xffffff;
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value_ += uint32_t(count) & increment_mask_;
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return distance_to_alarm <= uint32_t(count);
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}
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};
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struct MOS6526Storage {
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