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Switch to faster timer implementation; it seems to work.

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This commit is contained in:
Thomas Harte 2019-12-09 19:23:08 -05:00
parent e1c7a140d0
commit c2646a415f
1 changed files with 7 additions and 20 deletions
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27
Components/68901/MFP68901.cpp
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@ -178,28 +178,15 @@ void MFP68901::write(int address, uint8_t value) {
void MFP68901::run_for(HalfCycles time) {
cycles_left_ += time;
// TODO: this is the stupidest possible implementation. Improve.
int cycles = int(cycles_left_.flush<Cycles>().as_integral());
while(cycles--) {
for(int c = 0; c < 4; ++c) {
if(timers_[c].mode >= TimerMode::Delay) {
--timers_[c].divisor;
if(!timers_[c].divisor) {
timers_[c].divisor = timers_[c].prescale;
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);
}
}
// 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() {