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Moves beginning and end of vertical sync to what I now believe is its proper place.

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At least one demo now successfully opens the top border.
This commit is contained in:
Thomas Harte 2019-11-19 20:13:47 -05:00
parent c91495d068
commit 894066984c
1 changed files with 21 additions and 12 deletions
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33
Machines/Atari/ST/Video.cpp
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@ -28,7 +28,7 @@ const struct VerticalParams {
const int height;
} vertical_params[3] = {
{63, 263, 313}, // 47 rather than 63 on early machines.
{34, 234, 262}, // TODO: is 262 correct? If it's 263, how does that interact with opening the bottom border?
{34, 234, 263}, // TODO: is 262 correct? If it's 263, how does that interact with opening the bottom border?
{1, 401, 500} // 72 Hz mode: who knows?
};
@ -87,7 +87,11 @@ struct Checker {
} checker;
#endif
const int de_delay_period = 28*2;
const int de_delay_period = 28*2; // Number of half cycles after DE that observed DE changes.
const int vsync_x_position = 54*2; // Horizontal cycle on which vertical sync changes happen.
// "VSYNC starts 104 cycles after the start of the previous line's HSYNC, so that's 4 cycles before DE would be activated. ";
// hsync is at -50, so that's +54
}
@ -147,8 +151,8 @@ void Video::run_for(HalfCycles duration) {
if(line_length_ - 10*2 > x_) next_event = std::min(next_event, line_length_ - 10*2);
// Also, a vertical sync event might intercede.
if(vertical_.sync_schedule != VerticalState::SyncSchedule::None && x_ < 30*2 && next_event >= 30*2) {
next_event = 30*2;
if(vertical_.sync_schedule != VerticalState::SyncSchedule::None && x_ < vsync_x_position && next_event >= vsync_x_position) {
next_event = vsync_x_position;
}
// Determine current output mode and number of cycles to output for.
@ -208,16 +212,21 @@ void Video::run_for(HalfCycles duration) {
next_vertical_ = vertical_;
next_vertical_.sync_schedule = VerticalState::SyncSchedule::None;
// Use vertical_parameters to get parameters for the current output frequency.
if(next_y_ == vertical_timings.set_enable) {
// Use vertical_parameters to get parameters for the current output frequency;
// quick note: things other than the total frame size are counted in terms
// of the line they're evaluated on — i.e. the test is this line, not the next
// one. The total height constraint is obviously whether the next one would be
// too far.
if(y_ == vertical_timings.set_enable) {
next_vertical_.enable = true;
} else if(next_y_ == vertical_timings.reset_enable) {
} else if(y_ == vertical_timings.reset_enable) {
next_vertical_.enable = false;
} else if(next_y_ == vertical_timings.height) {
next_y_ = 0;
next_vertical_.sync_schedule = VerticalState::SyncSchedule::Begin;
current_address_ = base_address_ >> 1;
} else if(next_y_ == 3) {
} else if(y_ == 0) {
next_vertical_.sync_schedule = VerticalState::SyncSchedule::Begin;
} else if(y_ == 3) {
next_vertical_.sync_schedule = VerticalState::SyncSchedule::End;
}
}
@ -235,7 +244,7 @@ void Video::run_for(HalfCycles duration) {
else if(line_length_ - 10*2 == x_) horizontal_.sync = false;
// Check vertical events.
if(vertical_.sync_schedule != VerticalState::SyncSchedule::None && x_ == 30*2) {
if(vertical_.sync_schedule != VerticalState::SyncSchedule::None && x_ == vsync_x_position) {
vertical_.sync = vertical_.sync_schedule == VerticalState::SyncSchedule::Begin;
vertical_.enable &= !vertical_.sync;
}
@ -320,8 +329,8 @@ HalfCycles Video::get_next_sequence_point() {
}
// If a vertical sync event is scheduled, test for that.
if(vertical_.sync_schedule != VerticalState::SyncSchedule::None && (x_ < 30*2)) {
event_time = std::min(event_time, 30*2);
if(vertical_.sync_schedule != VerticalState::SyncSchedule::None && (x_ < vsync_x_position)) {
event_time = std::min(event_time, vsync_x_position);
}
// Test for beginning and end of horizontal sync.