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Ensures the MFP requests and receives real-time clocking when needed.

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This commit is contained in:
Thomas Harte
2019-10-30 22:42:06 -04:00
parent 4857ceb3eb
commit 635e18a50d
3 changed files with 71 additions and 40 deletions
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Components/68901/MFP68901.cpp
+44 -33
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@@ -16,6 +16,17 @@
using namespace Motorola::MFP68901;
ClockingHint::Preference MFP68901::preferred_clocking() {
// Rule applied: if any timer is actively running and permitted to produce an
// interrupt, request real-time running.
return
(timers_[0].mode >= TimerMode::Delay && interrupt_enable_&Interrupt::TimerA) ||
(timers_[1].mode >= TimerMode::Delay && interrupt_enable_&Interrupt::TimerB) ||
(timers_[2].mode >= TimerMode::Delay && interrupt_enable_&Interrupt::TimerC) ||
(timers_[3].mode >= TimerMode::Delay && interrupt_enable_&Interrupt::TimerD)
? ClockingHint::Preference::RealTime : ClockingHint::Preference::JustInTime;
}
uint8_t MFP68901::read(int address) {
address &= 0x1f;
@@ -94,9 +105,14 @@ void MFP68901::write(int address, uint8_t value) {
// Whatever just happened may have affected the state of the interrupt line.
update_interrupts();
update_clocking_observer();
return;
}
const int timer_prescales[] = {
1, 4, 10, 16, 50, 64, 100, 200
};
switch(address) {
// GPIP block: output and configuration of active edge and direction values.
case 0x00:
@@ -141,26 +157,8 @@ void MFP68901::write(int address, uint8_t value) {
} break;
case 0x0e:
timer_cd_control_ = value;
switch(value & 7) {
case 0: set_timer_mode(3, TimerMode::Stopped, 1, false); break;
case 1: set_timer_mode(3, TimerMode::Delay, 4, false); break;
case 2: set_timer_mode(3, TimerMode::Delay, 10, false); break;
case 3: set_timer_mode(3, TimerMode::Delay, 16, false); break;
case 4: set_timer_mode(3, TimerMode::Delay, 50, false); break;
case 5: set_timer_mode(3, TimerMode::Delay, 64, false); break;
case 6: set_timer_mode(3, TimerMode::Delay, 100, false); break;
case 7: set_timer_mode(3, TimerMode::Delay, 200, false); break;
}
switch((value >> 4) & 7) {
case 0: set_timer_mode(2, TimerMode::Stopped, 1, false); break;
case 1: set_timer_mode(2, TimerMode::Delay, 4, false); break;
case 2: set_timer_mode(2, TimerMode::Delay, 10, false); break;
case 3: set_timer_mode(2, TimerMode::Delay, 16, false); break;
case 4: set_timer_mode(2, TimerMode::Delay, 50, false); break;
case 5: set_timer_mode(2, TimerMode::Delay, 64, false); break;
case 6: set_timer_mode(2, TimerMode::Delay, 100, false); break;
case 7: set_timer_mode(2, TimerMode::Delay, 200, false); break;
}
set_timer_mode(3, (value & 7) ? TimerMode::Delay : TimerMode::Stopped, timer_prescales[value & 7], false);
set_timer_mode(2, ((value >> 4) & 7) ? TimerMode::Delay : TimerMode::Stopped, timer_prescales[(value >> 4) & 7], false);
break;
case 0x0f: case 0x10: case 0x11: case 0x12:
set_timer_data(address - 0xf, value);
@@ -173,6 +171,8 @@ void MFP68901::write(int address, uint8_t value) {
case 0x16: LOG("Write: transmitter status"); break;
case 0x17: LOG("Write: USART data"); break;
}
update_clocking_observer();
}
void MFP68901::run_for(HalfCycles time) {
@@ -186,11 +186,20 @@ void MFP68901::run_for(HalfCycles time) {
--timers_[c].divisor;
if(!timers_[c].divisor) {
timers_[c].divisor = timers_[c].prescale;
decrement_timer(c);
decrement_timer(c, 1);
}
}
}
}
// const int cycles = int(cycles_left_.flush<Cycles>().as_integral());
// for(int c = 0; c < 4; ++c) {
// if(timers_[c].mode >= TimerMode::Delay) {
// const int dividend = (cycles + timers_[c].prescale - timers_[c].divisor);
// const int decrements = dividend / timers_[c].prescale;
// timers_[c].divisor = timers_[c].prescale - (dividend % timers_[c].prescale);
// if(decrements) decrement_timer(c, decrements);
// }
// }
}
HalfCycles MFP68901::get_next_sequence_point() {
@@ -224,21 +233,23 @@ void MFP68901::set_timer_event_input(int channel, bool value) {
timers_[channel].event_input = value;
if(timers_[channel].mode == TimerMode::EventCount && !value) { /* TODO: which edge is counted? "as defined by the associated Interrupt Channel’s edge bit"? */
decrement_timer(channel);
decrement_timer(channel, 1);
}
}
void MFP68901::decrement_timer(int timer) {
--timers_[timer].value;
if(!timers_[timer].value) {
switch(timer) {
case 0: begin_interrupts(Interrupt::TimerA); break;
case 1: begin_interrupts(Interrupt::TimerB); break;
case 2: begin_interrupts(Interrupt::TimerC); break;
case 3: begin_interrupts(Interrupt::TimerD); break;
}
if(timers_[timer].mode == TimerMode::Delay) {
timers_[timer].value = timers_[timer].reload_value;
void MFP68901::decrement_timer(int timer, int amount) {
while(amount--) {
--timers_[timer].value;
if(timers_[timer].value < 1) {
switch(timer) {
case 0: begin_interrupts(Interrupt::TimerA); break;
case 1: begin_interrupts(Interrupt::TimerB); break;
case 2: begin_interrupts(Interrupt::TimerC); break;
case 3: begin_interrupts(Interrupt::TimerD); break;
}
if(timers_[timer].mode == TimerMode::Delay) {
timers_[timer].value += timers_[timer].reload_value; // TODO: properly.
}
}
}
}