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Takes a guess at one-shot mode.

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Thomas Harte 2021-07-24 15:53:18 -04:00
parent e3bb9fc1d7
commit ceca32ceb3
2 changed files with 20 additions and 10 deletions
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12
Components/6526/Implementation/6526Implementation.hpp
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@ -69,9 +69,15 @@ void MOS6526<BusHandlerT, personality>::write(int address, uint8_t value) {
// Counters; writes set the reload values. // Counters; writes set the reload values.
case 4: counter_[0].reload = (counter_[0].reload & 0xff00) | uint16_t(value << 0); break; case 4: counter_[0].reload = (counter_[0].reload & 0xff00) | uint16_t(value << 0); break;
case 5: counter_[0].reload = (counter_[0].reload & 0x00ff) | uint16_t(value << 8); break; case 5:
counter_[0].reload = (counter_[0].reload & 0x00ff) | uint16_t(value << 8);
counter_[0].is_counting = true;
break;
case 6: counter_[1].reload = (counter_[1].reload & 0xff00) | uint16_t(value << 0); break; case 6: counter_[1].reload = (counter_[1].reload & 0xff00) | uint16_t(value << 0); break;
case 7: counter_[1].reload = (counter_[1].reload & 0x00ff) | uint16_t(value << 8); break; case 7:
counter_[1].reload = (counter_[1].reload & 0x00ff) | uint16_t(value << 8);
counter_[1].is_counting = true;
break;
// Time-of-day clock. // Time-of-day clock.
// //
@ -138,6 +144,7 @@ void MOS6526<BusHandlerT, personality>::write(int address, uint8_t value) {
case 14: case 14:
if(value & 0x10) { if(value & 0x10) {
counter_[0].value = counter_[0].reload; counter_[0].value = counter_[0].reload;
counter_[0].is_counting = true;
} }
counter_[0].control = value & 0xef; counter_[0].control = value & 0xef;
printf("Ignoring control A write: %02x\n", value); printf("Ignoring control A write: %02x\n", value);
@ -146,6 +153,7 @@ void MOS6526<BusHandlerT, personality>::write(int address, uint8_t value) {
case 15: case 15:
if(value & 0x10) { if(value & 0x10) {
counter_[1].value = counter_[1].reload; counter_[1].value = counter_[1].reload;
counter_[1].is_counting = true;
} }
counter_[1].control = value; counter_[1].control = value;
printf("Ignoring control B write: %02x\n", value); printf("Ignoring control B write: %02x\n", value);

18
Components/6526/Implementation/6526Storage.hpp
View File

@ -30,18 +30,20 @@ struct MOS6526Storage {
uint16_t reload = 0; uint16_t reload = 0;
uint16_t value = 0; uint16_t value = 0;
uint8_t control = 0; uint8_t control = 0;
// int one_shot_mask = 0; bool is_counting = false;
int subtract(int count) { int subtract(int count) {
if(control & 8) { if(control & 8) {
// One-shot. // One-shot.
// value -= count; if(is_counting) {
// if(value < 0) { if(value < count) {
// const int underflows = one_shot_mask; value = reload;
// value = 0; is_counting = false;
// one_shot_mask = 0; return 1;
// return underflows; } else {
// } value -= count;
}
}
return 0; return 0;
} else { } else {
// Continuous. // Continuous.