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Removes double DE edge test.

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This commit is contained in:
Thomas Harte 2019-12-12 22:50:35 -05:00
parent 95b5db4d87
commit f6f2b4b90f
1 changed files with 14 additions and 21 deletions
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35
Machines/Atari/ST/Video.cpp
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@ -269,12 +269,6 @@ void Video::run_for(HalfCycles duration) {
load_base_ = x_;
}
// Check for an upcoming load toggle; that is, a time at which load_ will be either
// disabled or enabled. These occur with a brief latency.
if((horizontal_.enable && vertical_.enable) != load_ && next_load_toggle_ == -1) {
next_load_toggle_ = x_ + 8; // 4 cycles = 8 half-cycles
}
// Check vertical events.
if(vertical_.sync_schedule != VerticalState::SyncSchedule::None && x_ == vsync_x_position) {
vertical_.sync = vertical_.sync_schedule == VerticalState::SyncSchedule::Begin;
@ -292,7 +286,11 @@ void Video::run_for(HalfCycles duration) {
// Chuck any deferred output changes into the queue.
const bool next_display_enable = vertical_.enable && horizontal_.enable;
if(display_enable != next_display_enable) {
// Schedule change in outwardly-visible DE line.
add_event(de_delay_period - integer_duration, next_display_enable ? Event::Type::SetDisplayEnable : Event::Type::ResetDisplayEnable);
// Schedule change in inwardly-visible effect.
next_load_toggle_ = x_ + 8; // 4 cycles = 8 half-cycles
}
}
}
@ -434,30 +432,25 @@ void Video::write(int address, uint16_t value) {
}
void Video::update_output_mode() {
// All I know about this is: "the 71-Hz-switch does something like a shifter-reset."
const auto old_frequency = field_frequency_;
const auto old_bpp_ = output_bpp_;
// If this is black and white mode, that's that.
switch((video_mode_ >> 8) & 3) {
case 0: output_bpp_ = OutputBpp::Four; break;
case 1: output_bpp_ = OutputBpp::Two; break;
// 1bpp mode ignores the otherwise-programmed frequency.
default:
case 2:
output_bpp_ = OutputBpp::One;
field_frequency_ = FieldFrequency::SeventyTwo;
if(field_frequency_ != old_frequency) {
reset_fifo();
// printf("%d, %d -> %d\n", x_, y_, field_frequency_);
}
return;
case 2: output_bpp_ = OutputBpp::One; break;
}
field_frequency_ = (sync_mode_ & 0x200) ? FieldFrequency::Fifty : FieldFrequency::Sixty;
if(field_frequency_ != old_frequency && old_frequency == FieldFrequency::SeventyTwo) {
// 1bpp mode ignores the otherwise-programmed frequency.
if(output_bpp_ == OutputBpp::One) {
field_frequency_ = FieldFrequency::SeventyTwo;
} else {
field_frequency_ = (sync_mode_ & 0x200) ? FieldFrequency::Fifty : FieldFrequency::Sixty;
}
if(output_bpp_ != old_bpp_) {
// "the 71-Hz-switch does something like a shifter-reset." (and some people use a high-low resolutions switch instead)
reset_fifo();
// printf("%d, %d -> %d\n", x_, y_, field_frequency_);
}
}