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Actually, this is probably more correct: increment and then compare, but increment the refresh address once more after the final character, to avoid repeating it.

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This commit is contained in:
Thomas Harte 2017-08-01 15:29:37 -04:00
parent ee27e16fb1
commit 1d99c116e7
1 changed files with 13 additions and 9 deletions
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22
Components/6845/CRTC6845.hpp
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@ -41,6 +41,12 @@ template <class T> class CRTC6845 {
}
}
// check for end of line
bool is_end_of_line = character_counter_ == registers_[0];
// increment counter
character_counter_++;
// check for start of horizontal sync
if(character_counter_ == registers_[2]) {
hsync_down_counter_ = registers_[3] & 15;
@ -49,16 +55,17 @@ template <class T> class CRTC6845 {
// check for end of visible characters
if(character_counter_ == registers_[1]) {
character_is_visible_ = false;
}
// update refresh address
if(character_is_visible_) {
bus_state_.refresh_address++;
character_is_visible_ = false;
} else {
// update refresh address
if(character_is_visible_) {
bus_state_.refresh_address++;
}
}
// check for end-of-line
if(character_counter_ == registers_[0]) {
if(is_end_of_line) {
character_counter_ = 0;
character_is_visible_ = true;
@ -114,9 +121,6 @@ template <class T> class CRTC6845 {
bus_state_.refresh_address = line_address_;
}
}
} else {
// advance horizontal counter
character_counter_++;
}
bus_state_.display_enable = character_is_visible_ && line_is_visible_;