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Adds line length latching as a line event.

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This commit is contained in:
Thomas Harte 2020-01-28 20:22:37 -05:00
parent d0117556d1
commit 2c0cab9e4d
1 changed files with 10 additions and 4 deletions
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14
Machines/Atari/ST/Video.cpp
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@ -107,8 +107,7 @@ struct Checker {
const int de_delay_period = CYCLE(28); // Amount of time after DE that observed DE changes. NB: HACK HERE. This currently incorporates the MFP recognition delay. MUST FIX.
const int vsync_x_position = CYCLE(56); // Horizontal cycle on which vertical sync changes happen.
//const int hsync_start = CYCLE(48); // Cycles before end of line when hsync starts.
//const int hsync_end = CYCLE(8); // Cycles before end of line when hsync ends.
const int line_length_latch_position = CYCLE(54);
const int hsync_delay_period = CYCLE(8); // Signal hsync at the end of the line.
const int vsync_delay_period = hsync_delay_period; // Signal vsync with the same delay as hsync.
@ -265,10 +264,12 @@ void Video::advance(HalfCycles duration) {
}
// Check for whether line length should have been latched during this run.
if(x_ <= CYCLE(54) && (x_ + run_length) > CYCLE(54)) line_length_ = horizontal_timings.length;
if(x_ < line_length_latch_position && (x_ + run_length) >= line_length_latch_position) {
line_length_ = horizontal_timings.length;
}
// Make a decision about vertical state on the appropriate cycle.
if(x_ <= horizontal_timings.vertical_decision && (x_ + run_length) > horizontal_timings.vertical_decision) {
if(x_ < horizontal_timings.vertical_decision && (x_ + run_length) >= horizontal_timings.vertical_decision) {
next_y_ = y_ + 1;
next_vertical_ = vertical_;
next_vertical_.sync_schedule = VerticalState::SyncSchedule::None;
@ -440,6 +441,11 @@ HalfCycles Video::get_next_sequence_point() {
/* Hereby assumed: hsync end will be communicated at end of line: */
// static_assert(line_length_.hsync_end == hsync_delay_period);
// Also factor in the line length latching time.
if(x_ < line_length_latch_position) {
event_time = std::min(line_length_latch_position, event_time);
}
// It wasn't any of those, just supply end of line. That's when the static_assert above assumes a visible hsync transition.
return HalfCycles(event_time - x_);
}