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Begin CRTC rejig.
This commit is contained in:
Thomas Harte
parent
10f8318e79
commit
ea25dbfd1e
@ -185,55 +185,102 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
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status_ |= 0x40;
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}
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bool eof_latched_ = false;
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bool extra_scanline_ = false;
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uint8_t next_line_counter_ = 0;
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bool adjustment_in_progress_ = false;
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uint16_t next_row_address_ = 0;
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void run_for(Cycles cycles) {
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auto cyles_remaining = cycles.as_integral();
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while(cyles_remaining--) {
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// Check for end of visible characters.
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if(character_counter_ == layout_.horizontal.displayed) {
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// TODO: consider skew in character_is_visible_. Or maybe defer until perform_bus_cycle?
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character_is_visible_ = false;
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end_of_line_address_ = bus_state_.refresh_address;
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}
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const bool character_total_hit = character_counter_ == layout_.horizontal.total;
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const bool new_frame = character_total_hit && eof_latched_ && (layout_.interlace_mode_ == InterlaceMode::Off || !(bus_state_.field_count&1) || extra_scanline_);
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//
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// Horizontal.
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//
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// Check for end-of-line.
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if(character_total_hit) {
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character_counter_ = 0;
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character_is_visible_ = true;
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} else {
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character_counter_++;
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}
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// Check for end of visible characters.
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if(character_counter_ == layout_.horizontal.displayed) {
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character_is_visible_ = false;
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}
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// Update horizontal sync.
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if(bus_state_.hsync) {
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++hsync_counter_;
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bus_state_.hsync = hsync_counter_ != layout_.horizontal.sync_width;
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}
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if(character_counter_ == layout_.horizontal.start_sync) {
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hsync_counter_ = 0;
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bus_state_.hsync = true;
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}
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//
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// Vertical.
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//
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const bool line_total_hit = line_counter_ == layout_.vertical.displayed && !adjustment_in_progress_;
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// Line counter.
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if(new_frame) {
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line_counter_ = 0;
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} else if(character_total_hit) {
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line_counter_ = next_line_counter_;
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}
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if(line_total_hit) {
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next_line_counter_ = 0;
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} else if(layout_.interlace_mode_ != InterlaceMode::InterlaceSyncAndVideo || adjustment_in_progress_) {
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next_line_counter_ = line_counter_ + 1;
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} else {
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next_line_counter_ = (line_counter_ + 2) & ~1;
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}
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// Row counter.
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bus_state_.row_address = next_row_address_;
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if(new_frame) {
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next_row_address_ = 0;
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} else if(line_total_hit && character_total_hit) {
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next_row_address_ = bus_state_.row_address + 1;
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} else {
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next_row_address_ = bus_state_.row_address;
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}
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// Sync. [TODO]
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const bool vsync_hit = line_counter_ == layout_.vertical.start_sync;
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if(character_total_hit) {
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if(vsync_hit) {
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vsync_counter_ = 0;
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} else {
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++vsync_counter_;
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}
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}
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//
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// Addressing.
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//
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if(new_frame) {
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}
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// Do bus work.
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// bus_state_.refresh_address = (bus_state_.refresh_address + 1) & RefreshMask;
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//
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// bus_state_.cursor = is_cursor_line_ &&
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// bus_state_.refresh_address == layout_.cursor_address;
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perform_bus_cycle_phase1();
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bus_state_.refresh_address = (bus_state_.refresh_address + 1) & RefreshMask;
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bus_state_.cursor = is_cursor_line_ &&
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bus_state_.refresh_address == layout_.cursor_address;
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// Check for end-of-line.
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if(character_counter_ == layout_.horizontal.total) {
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character_counter_ = 0;
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do_end_of_line();
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character_is_visible_ = true;
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} else {
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// Increment counter.
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character_counter_++;
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}
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// Check for start of horizontal sync.
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if(character_counter_ == layout_.horizontal.start_sync) {
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hsync_counter_ = 0;
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bus_state_.hsync = true;
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}
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// Check for end of horizontal sync; note that a sync time of zero will result in an immediate
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// cancellation of the plan to perform sync if this is an HD6845S or UM6845R; otherwise zero
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// will end up counting as 16 as it won't be checked until after overflow.
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if(bus_state_.hsync) {
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switch(personality) {
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case Personality::HD6845S:
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case Personality::UM6845R:
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bus_state_.hsync = hsync_counter_ != layout_.horizontal.sync_width;
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hsync_counter_ = (hsync_counter_ + 1) & 15;
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break;
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default:
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hsync_counter_ = (hsync_counter_ + 1) & 15;
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bus_state_.hsync = hsync_counter_ != layout_.horizontal.sync_width;
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break;
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}
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}
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perform_bus_cycle_phase2();
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}
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}
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@ -256,100 +303,100 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
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bus_handler_.perform_bus_cycle_phase2(bus_state_);
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}
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inline void do_end_of_line() {
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if constexpr (cursor_type != CursorType::None) {
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// Check for cursor disable.
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// TODO: this is handled differently on the EGA, should I ever implement that.
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is_cursor_line_ &= bus_state_.row_address != layout_.vertical.end_cursor;
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}
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// Check for end of vertical sync.
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if(bus_state_.vsync) {
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vsync_counter_ = (vsync_counter_ + 1) & 15;
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// On the UM6845R and AMS40226, honour the programmed vertical sync time; on the other CRTCs
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// always use a vertical sync count of 16.
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switch(personality) {
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case Personality::HD6845S:
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case Personality::AMS40226:
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bus_state_.vsync = vsync_counter_ != layout_.vertical.sync_lines;
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break;
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default:
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bus_state_.vsync = vsync_counter_ != 0;
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break;
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}
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}
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if(is_in_adjustment_period_) {
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line_counter_++;
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if(line_counter_ == layout_.vertical.adjust) {
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is_in_adjustment_period_ = false;
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do_end_of_frame();
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}
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} else {
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// Advance vertical counter.
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if(bus_state_.row_address == layout_.vertical.end_row) {
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bus_state_.row_address = 0;
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line_address_ = end_of_line_address_;
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// Check for entry into the overflow area.
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if(line_counter_ == layout_.vertical.total) {
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if(layout_.vertical.adjust) {
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line_counter_ = 0;
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is_in_adjustment_period_ = true;
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} else {
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do_end_of_frame();
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}
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} else {
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line_counter_ = (line_counter_ + 1) & 0x7f;
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}
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// Check for start of vertical sync.
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if(line_counter_ == layout_.vertical.start_sync) {
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bus_state_.vsync = true;
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vsync_counter_ = 0;
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}
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// Check for end of visible lines.
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if(line_counter_ == layout_.vertical.displayed) {
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line_is_visible_ = false;
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}
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} else {
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bus_state_.row_address = (bus_state_.row_address + 1) & 0x1f;
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}
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}
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bus_state_.refresh_address = line_address_;
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character_counter_ = 0;
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character_is_visible_ = (layout_.horizontal.displayed != 0);
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if constexpr (cursor_type != CursorType::None) {
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// Check for cursor enable.
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is_cursor_line_ |= bus_state_.row_address == layout_.vertical.start_cursor;
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switch(cursor_type) {
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// MDA-style blinking.
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// https://retrocomputing.stackexchange.com/questions/27803/what-are-the-blinking-rates-of-the-caret-and-of-blinking-text-on-pc-graphics-car
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// gives an 8/8 pattern for regular blinking though mode 11 is then just a guess.
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case CursorType::MDA:
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switch(layout_.cursor_flags) {
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case 0b11: is_cursor_line_ &= (bus_state_.field_count & 8) < 3; break;
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case 0b00: is_cursor_line_ &= bool(bus_state_.field_count & 8); break;
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case 0b01: is_cursor_line_ = false; break;
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case 0b10: is_cursor_line_ = true; break;
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default: break;
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}
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break;
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}
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}
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}
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inline void do_end_of_frame() {
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line_counter_ = 0;
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line_is_visible_ = true;
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line_address_ = layout_.start_address;
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bus_state_.refresh_address = line_address_;
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++bus_state_.field_count;
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}
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// inline void do_end_of_line() {
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// if constexpr (cursor_type != CursorType::None) {
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// // Check for cursor disable.
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// // TODO: this is handled differently on the EGA, should I ever implement that.
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// is_cursor_line_ &= bus_state_.row_address != layout_.vertical.end_cursor;
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// }
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//
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// // Check for end of vertical sync.
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// if(bus_state_.vsync) {
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// vsync_counter_ = (vsync_counter_ + 1) & 15;
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// // On the UM6845R and AMS40226, honour the programmed vertical sync time; on the other CRTCs
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// // always use a vertical sync count of 16.
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// switch(personality) {
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// case Personality::HD6845S:
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// case Personality::AMS40226:
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// bus_state_.vsync = vsync_counter_ != layout_.vertical.sync_lines;
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// break;
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// default:
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// bus_state_.vsync = vsync_counter_ != 0;
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// break;
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// }
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// }
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//
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// if(is_in_adjustment_period_) {
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// line_counter_++;
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// if(line_counter_ == layout_.vertical.adjust) {
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// is_in_adjustment_period_ = false;
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// do_end_of_frame();
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// }
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// } else {
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// // Advance vertical counter.
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// if(bus_state_.row_address == layout_.end_row()) {
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// bus_state_.row_address = 0;
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// line_address_ = end_of_line_address_;
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//
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// // Check for entry into the overflow area.
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// if(line_counter_ == layout_.vertical.total) {
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// if(layout_.vertical.adjust) {
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// line_counter_ = 0;
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// is_in_adjustment_period_ = true;
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// } else {
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// do_end_of_frame();
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// }
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// } else {
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// line_counter_ = (line_counter_ + 1) & 0x7f;
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// }
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//
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// // Check for start of vertical sync.
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// if(line_counter_ == layout_.vertical.start_sync) {
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// bus_state_.vsync = true;
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// vsync_counter_ = 0;
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// }
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//
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// // Check for end of visible lines.
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// if(line_counter_ == layout_.vertical.displayed) {
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// line_is_visible_ = false;
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// }
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// } else {
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// bus_state_.row_address = (bus_state_.row_address + 1) & 0x1f;
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// }
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// }
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//
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// bus_state_.refresh_address = line_address_;
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// character_counter_ = 0;
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// character_is_visible_ = (layout_.horizontal.displayed != 0);
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//
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// if constexpr (cursor_type != CursorType::None) {
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// // Check for cursor enable.
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// is_cursor_line_ |= bus_state_.row_address == layout_.vertical.start_cursor;
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//
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// switch(cursor_type) {
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// // MDA-style blinking.
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// // https://retrocomputing.stackexchange.com/questions/27803/what-are-the-blinking-rates-of-the-caret-and-of-blinking-text-on-pc-graphics-car
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// // gives an 8/8 pattern for regular blinking though mode 11 is then just a guess.
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// case CursorType::MDA:
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// switch(layout_.cursor_flags) {
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// case 0b11: is_cursor_line_ &= (bus_state_.field_count & 8) < 3; break;
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// case 0b00: is_cursor_line_ &= bool(bus_state_.field_count & 8); break;
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// case 0b01: is_cursor_line_ = false; break;
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// case 0b10: is_cursor_line_ = true; break;
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// default: break;
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// }
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// break;
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// }
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// }
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// }
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//
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// inline void do_end_of_frame() {
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// line_counter_ = 0;
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// line_is_visible_ = true;
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// line_address_ = layout_.start_address;
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// bus_state_.refresh_address = line_address_;
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// ++bus_state_.field_count;
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// }
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BusHandlerT &bus_handler_;
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BusState bus_state_;
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@ -383,6 +430,10 @@ template <class BusHandlerT, Personality personality, CursorType cursor_type> cl
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} vertical;
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InterlaceMode interlace_mode_ = InterlaceMode::Off;
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uint8_t end_row() const {
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return interlace_mode_ == InterlaceMode::InterlaceSyncAndVideo ? vertical.end_row & ~1 : vertical.end_row;
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}
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uint16_t start_address;
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uint16_t cursor_address;
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uint16_t light_pen_address;
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