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Tweaks timings yet further, adds a FIFO reset.

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The accuracy of this may require further research.
This commit is contained in:
Thomas Harte 2019-12-11 23:22:20 -05:00
parent de4403e021
commit 95b5db4d87
2 changed files with 30 additions and 18 deletions
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47
Machines/Atari/ST/Video.cpp
View File

@ -38,6 +38,7 @@ const VerticalParams &vertical_parameters(Video::FieldFrequency frequency) {
}
#define CYCLE(x) ((x) * 2)
/*!
Defines the horizontal counts at which mode-specific events will occur:
horizontal enable being set and being reset, blank being set and reset, and the
@ -58,9 +59,9 @@ const struct HorizontalParams {
const int length;
} horizontal_params[3] = {
{56*2, 376*2, 448*2, 28*2, 512*2},
{52*2, 372*2, 448*2, 24*2, 508*2},
{4*2, 164*2, 999*2, 999*2, 224*2} // 72Hz mode doesn't set or reset blank.
{CYCLE(56), CYCLE(376), CYCLE(450), CYCLE(28), CYCLE(512)},
{CYCLE(52), CYCLE(372), CYCLE(450), CYCLE(24), CYCLE(508)},
{CYCLE(4), CYCLE(164), CYCLE(999), CYCLE(999), CYCLE(224)} // 72Hz mode doesn't set or reset blank.
};
const HorizontalParams &horizontal_parameters(Video::FieldFrequency frequency) {
@ -93,8 +94,10 @@ struct Checker {
} checker;
#endif
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.
const int de_delay_period = CYCLE(28); // Number of half cycles after DE that observed DE changes.
const int vsync_x_position = CYCLE(54); // 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.
// "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
@ -154,8 +157,8 @@ void Video::run_for(HalfCycles duration) {
if(next_load_toggle_ > x_) next_event = std::min(next_event, next_load_toggle_);
// Check for events that are relative to existing latched state.
if(line_length_ - 50*2 > x_) next_event = std::min(next_event, line_length_ - 50*2);
if(line_length_ - 10*2 > x_) next_event = std::min(next_event, line_length_ - 10*2);
if(line_length_ - hsync_start > x_) next_event = std::min(next_event, line_length_ - hsync_start);
if(line_length_ - hsync_end > x_) next_event = std::min(next_event, line_length_ - hsync_end);
// Also, a vertical sync event might intercede.
if(vertical_.sync_schedule != VerticalState::SyncSchedule::None && x_ < vsync_x_position && next_event >= vsync_x_position) {
@ -213,10 +216,10 @@ void Video::run_for(HalfCycles duration) {
}
// Check for whether line length should have been latched during this run.
if(x_ <= 54*2 && (x_ + run_length) > 54*2) line_length_ = horizontal_timings.length;
if(x_ <= CYCLE(54) && (x_ + run_length) > CYCLE(54)) line_length_ = horizontal_timings.length;
// Make a decision about vertical state on cycle 502.
if(x_ <= 502*2 && (x_ + run_length) > 502*2) {
if(x_ <= CYCLE(502) && (x_ + run_length) > CYCLE(502)) {
next_y_ = y_ + 1;
next_vertical_ = vertical_;
next_vertical_.sync_schedule = VerticalState::SyncSchedule::None;
@ -233,6 +236,7 @@ void Video::run_for(HalfCycles duration) {
} else if(next_y_ == vertical_timings.height) {
next_y_ = 0;
current_address_ = base_address_ >> 1;
reset_fifo(); // TODO: remove this, I think, once otherwise stable.
// Consider a shout out to the range observer.
if(previous_base_address_ != base_address_) {
@ -257,8 +261,8 @@ void Video::run_for(HalfCycles duration) {
else if(horizontal_timings.set_blank == x_) horizontal_.blank = true;
else if(horizontal_timings.reset_enable == x_) horizontal_.enable = false;
else if(horizontal_timings.set_enable == x_) horizontal_.enable = true;
else if(line_length_ - 50*2 == x_) { horizontal_.sync = true; horizontal_.enable = false; }
else if(line_length_ - 10*2 == x_) horizontal_.sync = false;
else if(line_length_ - hsync_start == x_) { horizontal_.sync = true; horizontal_.enable = false; }
else if(line_length_ - hsync_end == x_) horizontal_.sync = false;
else if(next_load_toggle_ == x_) {
next_load_toggle_ = -1;
load_ ^= true;
@ -308,6 +312,10 @@ void Video::latch_word() {
}
}
void Video::reset_fifo() {
data_latch_position_ = 0;
}
bool Video::hsync() {
return horizontal_.sync;
}
@ -362,8 +370,8 @@ HalfCycles Video::get_next_sequence_point() {
}
// Test for beginning and end of horizontal sync.
if(x_ < line_length_ - 50*2) event_time = std::min(line_length_ - 50*2, event_time);
else if(x_ < line_length_ - 10*2) event_time = std::min(line_length_ - 10*2, event_time);
if(x_ < line_length_ - hsync_start) event_time = std::min(line_length_ - hsync_start, event_time);
else if(x_ < line_length_ - hsync_end) event_time = std::min(line_length_ - hsync_end, event_time);
// It wasn't any of those, so as a temporary expedient, just supply end of line.
return HalfCycles(event_time - x_);
@ -426,7 +434,8 @@ void Video::write(int address, uint16_t value) {
}
void Video::update_output_mode() {
// const auto old_frequency = field_frequency_;
// All I know about this is: "the 71-Hz-switch does something like a shifter-reset."
const auto old_frequency = field_frequency_;
// If this is black and white mode, that's that.
switch((video_mode_ >> 8) & 3) {
@ -438,16 +447,18 @@ void Video::update_output_mode() {
case 2:
output_bpp_ = OutputBpp::One;
field_frequency_ = FieldFrequency::SeventyTwo;
// if(field_frequency_ != old_frequency) {
if(field_frequency_ != old_frequency) {
reset_fifo();
// printf("%d, %d -> %d\n", x_, y_, field_frequency_);
// }
}
return;
}
field_frequency_ = (sync_mode_ & 0x200) ? FieldFrequency::Fifty : FieldFrequency::Sixty;
// if(field_frequency_ != old_frequency) {
if(field_frequency_ != old_frequency && old_frequency == FieldFrequency::SeventyTwo) {
reset_fifo();
// printf("%d, %d -> %d\n", x_, y_, field_frequency_);
// }
}
}
// MARK: - The shifter

1
Machines/Atari/ST/Video.hpp
View File

@ -153,6 +153,7 @@ class Video {
int data_latch_position_ = 0;
uint16_t data_latch_[4] = {0, 0, 0, 0};
void latch_word();
void reset_fifo();
class Shifter {
public: