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Takes a shot at other display outputs.

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Thomas Harte 2019-10-08 22:29:58 -04:00
parent 5d06930df4
commit dbde8f2ee7
1 changed files with 57 additions and 0 deletions
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57
Machines/AtariST/Video.cpp
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@ -120,3 +120,60 @@ void Video::output_border(int duration) {
if(colour_pointer) *colour_pointer = 0x333;
crt_.output_level(duration);
}
bool Video::hsync() {
const auto mode_params = mode_params_for_mode();
return x >= mode_params.start_of_hsync && x < mode_params.end_of_hsync;
}
bool Video::vsync() {
return y < 3;
}
bool Video::display_enabled() {
const auto mode_params = mode_params_for_mode();
return y >= mode_params.first_video_line && y < mode_params.final_video_line && x >= mode_params.start_of_display_enable && x < mode_params.end_of_display_enable;
}
HalfCycles Video::get_next_sequence_point() {
// The next hsync transition will occur either this line or the next.
const auto mode_params = mode_params_for_mode();
HalfCycles cycles_until_hsync;
if(x < mode_params.start_of_hsync) {
cycles_until_hsync = HalfCycles(mode_params.start_of_hsync - x);
} else if(x < mode_params.end_of_hsync) {
cycles_until_hsync = HalfCycles(mode_params.end_of_hsync - x);
} else {
cycles_until_hsync = HalfCycles(mode_params.start_of_hsync + mode_params.line_length - x);
}
// The next vsync transition depends purely on the current y.
HalfCycles cycles_until_vsync;
if(y < 3) {
cycles_until_vsync = HalfCycles(mode_params.line_length - x + (2 - y)*mode_params.line_length);
} else {
cycles_until_vsync = HalfCycles(mode_params.line_length - x + (mode_params.lines_per_frame - 1 - y)*mode_params.line_length);
}
// The next display enable transition will occur only in the visible area.
HalfCycles cycles_until_display_enable;
if(display_enabled()) {
cycles_until_display_enable = HalfCycles(mode_params.end_of_display_enable - x);
} else {
const auto horizontal_cycles = mode_params.start_of_display_enable - x;
int vertical_lines = 0;
if(y < mode_params.first_video_line) {
vertical_lines = mode_params.first_video_line - y;
} else if(y >= mode_params.final_video_line ) {
vertical_lines = mode_params.first_video_line + mode_params.lines_per_frame - y;
}
cycles_until_display_enable = HalfCycles(horizontal_cycles + vertical_lines * mode_params.line_length);
}
// Determine the minimum of the three
if(cycles_until_hsync < cycles_until_vsync && cycles_until_hsync < cycles_until_display_enable) {
return cycles_until_hsync;
} else {
return (cycles_until_vsync < cycles_until_display_enable) ? cycles_until_vsync : cycles_until_display_enable;
}
}