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Fix: signal is 'flyback', not sync.

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This commit is contained in:
Thomas Harte 2024-04-10 21:53:38 -04:00
parent 6c6cda3db5
commit c134c7bdc2
2 changed files with 18 additions and 16 deletions
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2
Machines/Acorn/Archimedes/InputOutputController.hpp
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@ -202,7 +202,7 @@ struct InputOutputController: public ClockingHint::Observer {
uint8_t value = control_ | 0xc0;
value &= ~(i2c_.clock() ? 0x02 : 0x00);
value &= ~(i2c_.data() ? 0x01 : 0x00);
value &= ~(video_.vsync_active() ? 0x80 : 0x00);
value &= ~(video_.flyback_active() ? 0x00 : 0x80); // i.e. high during flyback.
set_byte(value);
// logger.error().append("IOC control read: C:%d D:%d", !(value & 2), !(value & 1));
} break;

32
Machines/Acorn/Archimedes/Video.hpp
View File

@ -134,18 +134,20 @@ struct Video {
const auto old_phase = vertical_state_.phase();
vertical_state_.increment_position(vertical_timing_);
pixel_count_ = 0;
if(vertical_state_.did_restart()) {
entered_sync_ = true;
interrupt_observer_.update_interrupts();
}
// I don't have good information on this; first guess: copy frame and
// cursor start addresses into counters at the start of the first vertical
// display line.
const auto phase = vertical_state_.phase();
if(phase != old_phase && phase == Phase::Display) {
address_ = frame_start_;
cursor_address_ = cursor_start_;
if(phase != old_phase) {
// I don't have good information on this; first guess: copy frame and
// cursor start addresses into counters at the start of the first vertical
// display line.
if(phase == Phase::Display) {
address_ = frame_start_;
cursor_address_ = cursor_start_;
}
if(old_phase == Phase::Display) {
entered_flyback_ = true;
interrupt_observer_.update_interrupts();
}
}
// Determine which next 8 bytes will be the cursor image for this line.
@ -321,13 +323,13 @@ struct Video {
/// @returns @c true if a vertical retrace interrupt has been signalled since the last call to @c interrupt(); @c false otherwise.
bool interrupt() {
// Guess: edge triggered?
const bool interrupt = entered_sync_;
entered_sync_ = false;
const bool interrupt = entered_flyback_;
entered_flyback_ = false;
return interrupt;
}
bool vsync_active() const {
return vertical_state_.phase() == Phase::Sync;
bool flyback_active() const {
return vertical_state_.phase() != Phase::Display;
}
void set_frame_start(uint32_t address) { frame_start_ = address; }
@ -461,7 +463,7 @@ private:
// An interrupt flag; more closely related to the interface by which
// my implementation of the IOC picks up an interrupt request than
// to hardware.
bool entered_sync_ = false;
bool entered_flyback_ = false;
// The divider that would need to be applied to a 24Mhz clock to
// get half the current pixel clock; counting is in units of half