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Corrects output glitches: channel de sync and improper border beginnings.

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This commit is contained in:
Thomas Harte 2019-11-06 22:37:05 -05:00
parent 0971bbeebe
commit ec68bc5047
1 changed files with 10 additions and 2 deletions
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12
Machines/AtariST/Video.cpp
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@ -138,9 +138,11 @@ void Video::run_for(HalfCycles duration) {
} else {
if(run_length < 32) {
shift_out(run_length); // TODO: this might end up overrunning.
if(!output_shifter) pixel_buffer_.flush(crt_);
} else {
shift_out(32);
output_shifter = 0;
pixel_buffer_.flush(crt_);
output_border(run_length - 32);
}
}
@ -152,6 +154,12 @@ void Video::run_for(HalfCycles duration) {
int start_column = x >> 3;
const int end_column = (x + run_length) >> 3;
// Rules obeyed below:
//
// Video fetches occur as the first act of business in a column. Each
// fetch is then followed by 8 shift clocks. Whether or not the shifter
// was reloaded by the fetch depends on the FIFO.
if(start_column == end_column) {
shift_out(run_length);
} else {
@ -162,18 +170,18 @@ void Video::run_for(HalfCycles duration) {
// so go for the entirety of it.
shift_out(8 - (x & 7));
++start_column;
latch_word();
}
// Run for all columns that have their starts in this time period.
int complete_columns = end_column - start_column;
while(complete_columns--) {
latch_word();
shift_out(8);
latch_word();
}
// Output the start of the next column, if necessary.
if(start_column != end_column && (x + run_length) & 7) {
latch_word();
shift_out((x + run_length) & 7);
}
}