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Ensures that vertical sync and end-of-visible-lines conditions potentially trigger whenever line_counter_ changes, not only when it increments.

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This commit is contained in:
Thomas Harte 2017-08-26 17:54:54 -04:00
parent 6c5a03187b
commit 487fe83dca
1 changed files with 13 additions and 12 deletions
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25
Components/6845/CRTC6845.hpp
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@ -75,8 +75,9 @@ template <class T> class CRTC6845 {
0xff, 0x1f, 0x7f, 0x1f, 0x3f, 0xff, 0x3f, 0xff 0xff, 0x1f, 0x7f, 0x1f, 0x3f, 0xff, 0x3f, 0xff
}; };
if(selected_register_ < 16) if(selected_register_ < 16) {
registers_[selected_register_] = value & masks[selected_register_]; registers_[selected_register_] = value & masks[selected_register_];
}
} }
void trigger_light_pen() { void trigger_light_pen() {
@ -170,21 +171,21 @@ template <class T> class CRTC6845 {
} }
} else { } else {
line_counter_ = (line_counter_ + 1) & 0x7f; line_counter_ = (line_counter_ + 1) & 0x7f;
// check for start of vertical sync
if(line_counter_ == registers_[7]) {
bus_state_.vsync = true;
vsync_counter_ = 0;
}
// check for end of visible lines
if(line_counter_ == registers_[6]) {
line_is_visible_ = false;
}
} }
} else { } else {
bus_state_.row_address = (bus_state_.row_address + 1) & 0x1f; bus_state_.row_address = (bus_state_.row_address + 1) & 0x1f;
} }
// check for start of vertical sync
if(line_counter_ == registers_[7]) {
bus_state_.vsync = true;
vsync_counter_ = 0;
}
// check for end of visible lines
if(line_counter_ == registers_[6]) {
line_is_visible_ = false;
}
} }
bus_state_.refresh_address = line_address_; bus_state_.refresh_address = line_address_;