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Edges towards working counters.

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This commit is contained in:
Thomas Harte
2021-07-23 22:43:47 -04:00
parent c733a4dbf8
commit 77a8ddb95c
2 changed files with 76 additions and 19 deletions
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Components/6526/Implementation/6526Storage.hpp
+27 -3
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@@ -21,8 +21,6 @@ struct MOS6526Storage {
uint8_t interrupt_control_ = 0;
uint8_t interrupt_state_ = 0;
uint8_t control_[2] = {0, 0};
uint32_t tod_increment_mask_ = uint32_t(~0);
uint32_t tod_latch_ = 0;
uint32_t tod_ = 0;
@@ -31,7 +29,33 @@ struct MOS6526Storage {
struct Counter {
uint16_t reload = 0;
uint16_t value = 0;
} counters_[2];
uint8_t control = 0;
// int one_shot_mask = 0;
int subtract(int count) {
if(control & 8) {
// One-shot.
// value -= count;
// if(value < 0) {
// const int underflows = one_shot_mask;
// value = 0;
// one_shot_mask = 0;
// return underflows;
// }
return 0;
} else {
// Continuous.
value -= count;
value -= (reload + 1);
const int underflows = -value / (reload + 1);
value %= (reload + 1);
value += (reload + 1);
return underflows;
}
}
} counter_[2];
};
}