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Implement blinking text.

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This commit is contained in:
Thomas Harte 2023-12-04 22:02:38 -05:00
parent 9f65587a1d
commit 9601c69e12
2 changed files with 17 additions and 11 deletions
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22
Components/6845/CRTC6845.hpp
View File

@ -23,6 +23,10 @@ struct BusState {
bool cursor = false;
uint16_t refresh_address = 0;
uint16_t row_address = 0;
// Not strictly part of the bus state; provided because the partition between 6845 and bus handler
// doesn't quite hold up in some emulated systems where the two are integrated and share more state.
int field_count = 0;
};
class BusHandler {
@ -262,13 +266,15 @@ template <class T, CursorType cursor_type> class CRTC6845 {
is_cursor_line_ |= bus_state_.row_address == (registers_[10] & 0x1f);
switch(cursor_type) {
// MDA-style blinking; timings are a bit of a guess for now.
// MDA-style blinking.
// https://retrocomputing.stackexchange.com/questions/27803/what-are-the-blinking-rates-of-the-caret-and-of-blinking-text-on-pc-graphics-car
// gives an 8/8 pattern for regular blinking though mode 11 is then just a guess.
case CursorType::MDA:
switch(registers_[10] >> 5) {
case 0b11: is_cursor_line_ &= (field_count_ & 15) < 5; break;
case 0b00: is_cursor_line_ &= bool(field_count_ & 16); break;
case 0b01: is_cursor_line_ = false; break;
case 0b10: is_cursor_line_ = true; break;
case 0b11: is_cursor_line_ &= (bus_state_.field_count & 8) < 3; break;
case 0b00: is_cursor_line_ &= bool(bus_state_.field_count & 8); break;
case 0b01: is_cursor_line_ = false; break;
case 0b10: is_cursor_line_ = true; break;
default: break;
}
break;
@ -281,9 +287,7 @@ template <class T, CursorType cursor_type> class CRTC6845 {
line_is_visible_ = true;
line_address_ = uint16_t((registers_[12] << 8) | registers_[13]);
bus_state_.refresh_address = line_address_;
if constexpr (cursor_type != CursorType::None) {
++field_count_;
}
++bus_state_.field_count;
}
Personality personality_;
@ -311,8 +315,6 @@ template <class T, CursorType cursor_type> class CRTC6845 {
unsigned int character_is_visible_shifter_ = 0;
bool is_cursor_line_ = false;
int field_count_ = 0;
};
}

6
Machines/PCCompatible/PCCompatible.cpp
View File

@ -595,7 +595,11 @@ class MDA {
break;
}
// TODO: blink.
// Apply blink if enabled.
if((control_ & 0x20) && (attributes & 0x80) && (state.field_count & 16)) {
row ^= 0xff;
blank = (blank == off) ? intensity : off;
}
if(((attributes & 7) == 1) && state.row_address == 13) {
// Draw as underline.