6502/CLK
1
0
Fork 0
mirror of https://github.com/TomHarte/CLK.git synced 2024-06-25 18:30:07 +00:00
Code Issues Projects Releases Wiki Activity

Gets a bit more rigorous about the clocking stage.

Browse Source 
Albeit without advancing relative to the test.
This commit is contained in:
Thomas Harte 2021-08-02 21:04:00 -04:00
parent 15de5e98c4
commit ef58ce6277
2 changed files with 41 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Components/6526/Implementation/6526Implementation.hpp
View File

@ -248,10 +248,10 @@ void MOS6526<BusHandlerT, personality>::run_for(const HalfCycles half_cycles) {
pending_ &= PendingClearMask;
// TODO: use CNT potentially to clock timer A, elimiante conditional above.
const bool timer1_did_reload = counter_[0].advance(false);
const bool timer1_did_reload = counter_[0].template advance<false>(false);
const bool timer1_carry = timer1_did_reload && (counter_[1].control & 0x60) == 0x40;
const bool timer2_did_reload = counter_[1].advance(timer1_carry);
const bool timer2_did_reload = counter_[1].template advance<true>(timer1_carry);
posit_interrupt((timer1_did_reload ? 0x01 : 0x00) | (timer2_did_reload ? 0x02 : 0x00));
}
}

55
Components/6526/Implementation/6526Storage.hpp
View File

@ -45,7 +45,7 @@ struct MOS6526Storage {
control = v;
}
bool advance(bool chained_input) {
template <bool is_counter_2> bool advance(bool chained_input) {
// TODO: remove most of the conditionals here.
pending <<= 1;
@ -54,15 +54,38 @@ struct MOS6526Storage {
// Apply feeder states inputs: anything that
// will take effect in the future.
//
// Schedule a force reload if requested.
if(control & 0x10) {
pending |= ReloadInOne;
control &= ~0x10;
}
if((control & 0x01) || chained_input) {
// Determine whether an input clock is applicable.
if constexpr(is_counter_2) {
switch(control&0x60) {
case 0x00:
pending |= TestInputInOne;
break;
default:
// TODO: all other forms of input.
assert(false);
break;
}
} else {
if(!(control&0x20)) {
pending |= TestInputNow;
} else if (chained_input) { // TODO: check CNT directly, probably?
pending |= TestInputInOne;
}
}
if(pending&TestInputNow && control&1) {
pending |= ApplyClockInTwo;
}
// Keep a history of the one-shot bit.
if(control & 0x08) {
pending |= OneShotInOne;
pending |= OneShotInOne | OneShotNow;
}
@ -72,6 +95,7 @@ struct MOS6526Storage {
if(pending & ApplyClockNow) {
--value;
}
const bool should_reload = !value && (pending & ApplyClockInOne);
// Schedule a reload if so ordered.
@ -82,14 +106,14 @@ struct MOS6526Storage {
// If this was one-shot, stop.
if(pending&(OneShotInOne | OneShotNow)) {
control &= ~1;
pending &= ~(ApplyClockInOne|ApplyClockInTwo);
pending &= ~(ApplyClockInOne|ApplyClockInTwo); // Cancel scheculed ticks.
}
}
// Reload if scheduled.
if(pending & ReloadNow) {
value = reload;
pending &= ~ApplyClockInOne; // Skip one decrement.
pending &= ~ApplyClockInOne; // Skip next decrement.
}
@ -104,19 +128,18 @@ struct MOS6526Storage {
private:
int pending = 0;
// static constexpr int ReloadInThree = 1 << 0;
// static constexpr int ReloadInTwo = 1 << 1;
static constexpr int ReloadInOne = 1 << 2;
static constexpr int ReloadNow = 1 << 3;
static constexpr int ReloadInOne = 1 << 0;
static constexpr int ReloadNow = 1 << 1;
// static constexpr int OneShotInTwo = 1 << 4;
static constexpr int OneShotInOne = 1 << 5;
static constexpr int OneShotNow = 1 << 6;
static constexpr int OneShotInOne = 1 << 2;
static constexpr int OneShotNow = 1 << 3;
static constexpr int ApplyClockInThree = 1 << 7;
static constexpr int ApplyClockInTwo = 1 << 8;
static constexpr int ApplyClockInOne = 1 << 9;
static constexpr int ApplyClockNow = 1 << 10;
static constexpr int ApplyClockInTwo = 1 << 4;
static constexpr int ApplyClockInOne = 1 << 5;
static constexpr int ApplyClockNow = 1 << 6;
static constexpr int TestInputInOne = 1 << 7;
static constexpr int TestInputNow = 1 << 8;
static constexpr int PendingClearMask = ~(ReloadNow | OneShotNow | ApplyClockNow);