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sweep.cpp
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sweep.cpp
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bool APU::Sweep::check_period() {
if(pulse_period > 0x7ff) return false;
if(decrement == 0) {
if((pulse_period + (pulse_period >> shift)) & 0x800) return false;
}
return true;
}
void APU::Sweep::clock(unsigned channel) {
if(--counter == 0) {
counter = period + 1;
if(enable && shift && pulse_period > 8) {
signed delta = pulse_period >> shift;
if(decrement) {
pulse_period -= delta;
if(channel == 0) pulse_period--;
} else if((pulse_period + delta) < 0x800) {
pulse_period += delta;
}
}
}
if(reload) {
reload = false;
counter = period + 1;
}
}
void APU::Sweep::power() {
shift = 0;
decrement = 0;
period = 0;
counter = 1;
enable = 0;
reload = 0;
pulse_period = 0;
}
void APU::Sweep::reset() {
}
void APU::Sweep::serialize(serializer& s) {
s.integer(shift);
s.integer(decrement);
s.integer(period);
s.integer(counter);
s.integer(enable);
s.integer(reload);
s.integer(pulse_period);
}