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Switch to named values for everything except blink mode.

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This commit is contained in:
Thomas Harte 2024-01-09 22:03:24 -05:00
parent 177e741bca
commit 22b4b4d4e3
1 changed files with 49 additions and 5 deletions
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54
Components/6845/CRTC6845.hpp
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@ -105,6 +105,14 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
void set_register(uint8_t value) {
static constexpr bool is_ega = is_egavga(personality);
auto load_low = [value](uint16_t &target) {
target = (target & 0xff00) | value;
};
auto load_high = [value](uint16_t &target) {
constexpr uint8_t mask = RefreshMask >> 8;
target = uint16_t((target & 0x00ff) | ((value & mask) << 8));
};
switch(selected_register_) {
case 0: layout_.horizontal.total = value; break;
case 1: layout_.horizontal.displayed = value; break;
@ -127,6 +135,25 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
case 5: layout_.vertical.adjust = value & 0x1f; break;
case 6: layout_.vertical.displayed = value & 0x7f; break;
case 7: layout_.vertical.start_sync = value & 0x7f; break;
case 8:
switch(value & 3) {
default: layout_.interlace_mode_ = InterlaceMode::Off; break;
case 0b01: layout_.interlace_mode_ = InterlaceMode::InterlaceSync; break;
case 0b11: layout_.interlace_mode_ = InterlaceMode::InterlaceSyncAndVideo; break;
}
break;
case 9: layout_.vertical.end_row = value & 0x1f; break;
case 10:
layout_.vertical.start_cursor = value & 0x1f;
// TODO: blink mode.
break;
case 11:
layout_.vertical.end_cursor = value & 0x1f;
break;
case 12: load_high(layout_.start_address); break;
case 13: load_low(layout_.start_address); break;
case 14: load_high(layout_.cursor_address); break;
case 15: load_low(layout_.cursor_address); break;
}
static constexpr uint8_t masks[] = {
@ -181,7 +208,7 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
bus_state_.refresh_address = (bus_state_.refresh_address + 1) & RefreshMask;
bus_state_.cursor = is_cursor_line_ &&
bus_state_.refresh_address == (registers_[15] | (registers_[14] << 8));
bus_state_.refresh_address == layout_.cursor_address;
// Check for end-of-line.
if(character_counter_ == layout_.horizontal.total) {
@ -242,7 +269,7 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
if constexpr (cursor_type != CursorType::None) {
// Check for cursor disable.
// TODO: this is handled differently on the EGA, should I ever implement that.
is_cursor_line_ &= bus_state_.row_address != (registers_[11] & 0x1f);
is_cursor_line_ &= bus_state_.row_address != layout_.vertical.end_cursor;
}
// Check for end of vertical sync.
@ -269,7 +296,7 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
}
} else {
// Advance vertical counter.
if(bus_state_.row_address == registers_[9]) {
if(bus_state_.row_address == layout_.vertical.end_row) {
bus_state_.row_address = 0;
line_address_ = end_of_line_address_;
@ -306,7 +333,7 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
if constexpr (cursor_type != CursorType::None) {
// Check for cursor enable.
is_cursor_line_ |= bus_state_.row_address == (registers_[10] & 0x1f);
is_cursor_line_ |= bus_state_.row_address == layout_.vertical.start_cursor;
switch(cursor_type) {
// MDA-style blinking.
@ -328,7 +355,7 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
inline void do_end_of_frame() {
line_counter_ = 0;
line_is_visible_ = true;
line_address_ = uint16_t((registers_[12] << 8) | registers_[13]);
line_address_ = layout_.start_address;
bus_state_.refresh_address = line_address_;
++bus_state_.field_count;
}
@ -336,6 +363,14 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
BusHandlerT &bus_handler_;
BusState bus_state_;
enum class InterlaceMode {
Off,
InterlaceSync,
InterlaceSyncAndVideo,
};
enum class BlinkMode {
// TODO.
};
struct {
struct {
uint8_t total;
@ -350,7 +385,16 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
uint8_t start_sync;
uint8_t sync_lines;
uint8_t adjust;
uint8_t end_row;
uint8_t start_cursor;
uint8_t end_cursor;
} vertical;
InterlaceMode interlace_mode_ = InterlaceMode::Off;
uint16_t start_address;
uint16_t cursor_address;
uint16_t light_pen_address;
} layout_;
uint8_t registers_[18]{};