Ensured the video subsystem correctly handles requests to run over a frame boundary.

Machines/Electron/Electron.cpp

@@ -104,10 +104,6 @@ unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uin
 	}
 	else
 	{
-//		if((address >> 8) == 0xfc)
-//		{
-//			printf("d");
-//		}
 		switch(address & 0xff0f)
 		{
 			case 0xfe00:
@@ -122,6 +118,26 @@ unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uin
 					evaluate_interrupts();
 				}
 			break;
+			case 0xfe07:
+				if(!isReadOperation(operation))
+				{
+					// update speaker mode
+					bool new_speaker_is_enabled = (*value & 6) == 2;
+					if(new_speaker_is_enabled != speaker_is_enabled_)
+					{
+						update_audio();
+						speaker_->set_is_enabled(new_speaker_is_enabled);
+						speaker_is_enabled_ = new_speaker_is_enabled;
+					}
+
+					tape_.set_is_enabled((*value & 6) != 6);
+					tape_.set_is_in_input_mode((*value & 6) == 0);
+					tape_.set_is_running(((*value)&0x40) ? true : false);
+
+					// TODO: caps lock LED
+				}
+
+			// deliberate fallthrough
 			case 0xfe02: case 0xfe03:
 			case 0xfe08: case 0xfe09: case 0xfe0a: case 0xfe0b:
 			case 0xfe0c: case 0xfe0d: case 0xfe0e: case 0xfe0f:
@@ -184,28 +200,6 @@ unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uin
 					tape_.set_counter(*value);
 				}
 			break;
-			case 0xfe07:
-				if(!isReadOperation(operation))
-				{
-					update_display();
-					video_output_->set_register(address, *value);
-
-					// update speaker mode
-					bool new_speaker_is_enabled = (*value & 6) == 2;
-					if(new_speaker_is_enabled != speaker_is_enabled_)
-					{
-						update_audio();
-						speaker_->set_is_enabled(new_speaker_is_enabled);
-						speaker_is_enabled_ = new_speaker_is_enabled;
-					}
-
-					tape_.set_is_enabled((*value & 6) != 6);
-					tape_.set_is_in_input_mode((*value & 6) == 0);
-					tape_.set_is_running(((*value)&0x40) ? true : false);
-
-					// TODO: caps lock LED
-				}
-			break;
 
 			case 0xfc04: case 0xfc05: case 0xfc06: case 0xfc07:
 				if(plus3_ && (address&0x00f0) == 0x00c0)
@@ -326,11 +320,6 @@ unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uin
 		}
 	}
 
-//	if(operation == CPU6502::BusOperation::ReadOpcode)
-//	{
-//		printf("%04x: %02x (%d)\n", address, *value, _fieldCycles);
-//	}
-
 //	const int end_of_field =
 //	if(frame_cycles_ < (256 + first_graphics_line) << 7))
 
@@ -484,7 +473,7 @@ inline void Machine::evaluate_interrupts()
 
 inline void Machine::update_display()
 {
-	video_output_->run_for_cycles(frame_cycles_ - display_output_position_);
+	video_output_->run_for_cycles((int)(frame_cycles_ - display_output_position_));
 	display_output_position_ = frame_cycles_;
 }
 

Machines/Electron/Electron.hpp

@@ -120,12 +120,14 @@ class Machine:
 		uint8_t os_[16384], ram_[32768];
 		std::vector<uint8_t> dfs_, adfs_;
 
-		// Things affected by registers, explicitly or otherwise.
+		// Paging
-		uint8_t interrupt_status_, interrupt_control_;
-		uint8_t key_states_[14];
 		ROMSlot active_rom_;
 		bool keyboard_is_active_, basic_is_active_;
 
+		// Interrupt and keyboard state
+		uint8_t interrupt_status_, interrupt_control_;
+		uint8_t key_states_[14];
+
 		// Counters related to simultaneous subsystems
 		unsigned int frame_cycles_, display_output_position_;
 		unsigned int audio_output_position_, audio_output_position_error_;

Machines/Electron/Video.cpp

@@ -13,7 +13,7 @@ using namespace Electron;
 namespace {
 	static const unsigned int cycles_per_line = 128;
 	static const unsigned int lines_per_frame = 625;
-	static const unsigned int cycles_per_frame = lines_per_frame * cycles_per_line;
+	static const int cycles_per_frame = lines_per_frame * cycles_per_line;
 	static const unsigned int crt_cycles_multiplier = 8;
 	static const unsigned int crt_cycles_per_line = crt_cycles_multiplier * cycles_per_line;
 
@@ -255,130 +255,138 @@ void VideoOutput::run_for_cycles(int number_of_cycles)
 
 	*/
 	int final_position = output_position_ + number_of_cycles;
-	int final_line = final_position >> 7;
+
-	while(output_position_ < final_position)
+	int number_of_frames = 1 + (final_position / cycles_per_frame);
+
+	while(number_of_frames--)
 	{
-		int line = output_position_ >> 7;
+		int frame_final = number_of_frames ? cycles_per_frame : (final_position % cycles_per_frame);
+		int final_line = frame_final >> 7;
 
-		// Priority one: sync.
+		while(output_position_ < frame_final)
-		// ===================
-
-		// full sync lines are 0, 1, field_divider_line+1 and field_divider_line+2
-		if(line == 0 || line == 1 || line == field_divider_line+1 || line == field_divider_line+2)
 		{
-			// wait for the line to complete before signalling
+			int line = output_position_ >> 7;
-			if(final_line == line) return;
-			crt_->output_sync(128 * crt_cycles_multiplier);
-			output_position_ += 128;
-			continue;
-		}
 
-		// line 2 is a left-sync line
+			// Priority one: sync.
-		if(line == 2)
+			// ===================
-		{
-			// wait for the line to complete before signalling
-			if(final_line == line) return;
-			crt_->output_sync(64 * crt_cycles_multiplier);
-			crt_->output_blank(64 * crt_cycles_multiplier);
-			output_position_ += 128;
-			continue;
-		}
 
-		// line field_divider_line is a right-sync line
+			// full sync lines are 0, 1, field_divider_line+1 and field_divider_line+2
-		if(line == field_divider_line)
+			if(line == 0 || line == 1 || line == field_divider_line+1 || line == field_divider_line+2)
-		{
-			// wait for the line to complete before signalling
-			if(final_line == line) return;
-			crt_->output_sync(9 * crt_cycles_multiplier);
-			crt_->output_blank(55 * crt_cycles_multiplier);
-			crt_->output_sync(64 * crt_cycles_multiplier);
-			output_position_ += 128;
-			continue;
-		}
-
-		// Priority two: blank lines.
-		// ==========================
-		//
-		// Given that it is not a sync line, this is a blank line if it is less than first_graphics_line, or greater
-		// than first_graphics_line+255 and less than first_graphics_line+field_divider_line, or greater than
-		// first_graphics_line+field_divider_line+255 (TODO: or this is Mode 3 or 6 and this should be blank)
-		if(
-			line < first_graphics_line ||
-			(line > first_graphics_line+255 && line < first_graphics_line+field_divider_line) ||
-			line > first_graphics_line+field_divider_line+255)
-		{
-			if(final_line == line) return;
-			crt_->output_sync(9 * crt_cycles_multiplier);
-			crt_->output_blank(119 * crt_cycles_multiplier);
-			output_position_ += 128;
-			continue;
-		}
-
-		// Final possibility: this is a pixel line.
-		// ========================================
-
-		// determine how far we're going from left to right
-		unsigned int this_cycle = output_position_&127;
-		unsigned int final_cycle = final_position&127;
-		if(final_line > line)
-		{
-			final_cycle = 128;
-		}
-
-		// output format is:
-		// 9 cycles: sync
-		// ... to 24 cycles: colour burst
-		// ... to first_graphics_cycle: blank
-		// ... for 80 cycles: pixels
-		// ... until end of line: blank
-		while(this_cycle < final_cycle)
-		{
-			if(this_cycle < 9)
 			{
-				if(final_cycle < 9) return;
+				// wait for the line to complete before signalling
+				if(final_line == line) return;
+				crt_->output_sync(128 * crt_cycles_multiplier);
+				output_position_ += 128;
+				continue;
+			}
+
+			// line 2 is a left-sync line
+			if(line == 2)
+			{
+				// wait for the line to complete before signalling
+				if(final_line == line) return;
+				crt_->output_sync(64 * crt_cycles_multiplier);
+				crt_->output_blank(64 * crt_cycles_multiplier);
+				output_position_ += 128;
+				continue;
+			}
+
+			// line field_divider_line is a right-sync line
+			if(line == field_divider_line)
+			{
+				// wait for the line to complete before signalling
+				if(final_line == line) return;
 				crt_->output_sync(9 * crt_cycles_multiplier);
-				output_position_ += 9;
+				crt_->output_blank(55 * crt_cycles_multiplier);
-				this_cycle = 9;
+				crt_->output_sync(64 * crt_cycles_multiplier);
+				output_position_ += 128;
+				continue;
 			}
 
-			if(this_cycle < 24)
+			// Priority two: blank lines.
+			// ==========================
+			//
+			// Given that it is not a sync line, this is a blank line if it is less than first_graphics_line, or greater
+			// than first_graphics_line+255 and less than first_graphics_line+field_divider_line, or greater than
+			// first_graphics_line+field_divider_line+255 (TODO: or this is Mode 3 or 6 and this should be blank)
+			if(
+				line < first_graphics_line ||
+				(line > first_graphics_line+255 && line < first_graphics_line+field_divider_line) ||
+				line > first_graphics_line+field_divider_line+255)
 			{
-				if(final_cycle < 24) return;
+				if(final_line == line) return;
-				crt_->output_default_colour_burst((24-9) * crt_cycles_multiplier);
+				crt_->output_sync(9 * crt_cycles_multiplier);
-				output_position_ += 24-9;
+				crt_->output_blank(119 * crt_cycles_multiplier);
-				this_cycle = 24;
+				output_position_ += 128;
-				// TODO: phase shouldn't be zero on every line
+				continue;
 			}
 
-			if(this_cycle < first_graphics_cycle)
+			// Final possibility: this is a pixel line.
+			// ========================================
+
+			// determine how far we're going from left to right
+			unsigned int this_cycle = output_position_&127;
+			unsigned int final_cycle = frame_final&127;
+			if(final_line > line)
 			{
-				if(final_cycle < first_graphics_cycle) return;
+				final_cycle = 128;
-				crt_->output_blank((first_graphics_cycle - 24) * crt_cycles_multiplier);
-				output_position_ += first_graphics_cycle - 24;
-				this_cycle = first_graphics_cycle;
-				start_pixel_line();
 			}
 
-			if(this_cycle < first_graphics_cycle + 80)
+			// output format is:
+			// 9 cycles: sync
+			// ... to 24 cycles: colour burst
+			// ... to first_graphics_cycle: blank
+			// ... for 80 cycles: pixels
+			// ... until end of line: blank
+			while(this_cycle < final_cycle)
 			{
-				unsigned int length_to_output = std::min(final_cycle, (first_graphics_cycle + 80)) - this_cycle;
+				if(this_cycle < 9)
-				output_pixels(length_to_output);
+				{
-				output_position_ += length_to_output;
+					if(final_cycle < 9) return;
-				this_cycle += length_to_output;
+					crt_->output_sync(9 * crt_cycles_multiplier);
-			}
+					output_position_ += 9;
+					this_cycle = 9;
+				}
 
-			if(this_cycle >= first_graphics_cycle + 80)
+				if(this_cycle < 24)
-			{
+				{
-				if(final_cycle < 128) return;
+					if(final_cycle < 24) return;
-				end_pixel_line();
+					crt_->output_default_colour_burst((24-9) * crt_cycles_multiplier);
-				crt_->output_blank((128 - (first_graphics_cycle + 80)) * crt_cycles_multiplier);
+					output_position_ += 24-9;
-				output_position_ += 128 - (first_graphics_cycle + 80);
+					this_cycle = 24;
-				this_cycle = 128;
+					// TODO: phase shouldn't be zero on every line
+				}
+
+				if(this_cycle < first_graphics_cycle)
+				{
+					if(final_cycle < first_graphics_cycle) return;
+					crt_->output_blank((first_graphics_cycle - 24) * crt_cycles_multiplier);
+					output_position_ += first_graphics_cycle - 24;
+					this_cycle = first_graphics_cycle;
+					start_pixel_line();
+				}
+
+				if(this_cycle < first_graphics_cycle + 80)
+				{
+					unsigned int length_to_output = std::min(final_cycle, (first_graphics_cycle + 80)) - this_cycle;
+					output_pixels(length_to_output);
+					output_position_ += length_to_output;
+					this_cycle += length_to_output;
+				}
+
+				if(this_cycle >= first_graphics_cycle + 80)
+				{
+					if(final_cycle < 128) return;
+					end_pixel_line();
+					crt_->output_blank((128 - (first_graphics_cycle + 80)) * crt_cycles_multiplier);
+					output_position_ += 128 - (first_graphics_cycle + 80);
+					this_cycle = 128;
+				}
 			}
 		}
-	}
 
-	output_position_ %= cycles_per_frame;
+		output_position_ %= cycles_per_frame;
+	}
 }
 
 void VideoOutput::set_register(int address, uint8_t value)
@@ -470,3 +478,15 @@ void VideoOutput::set_register(int address, uint8_t value)
 		break;
 	}
 }
+
+#pragma mark - Interrupts
+
+int VideoOutput::get_cycles_until_next_interrupt()
+{
+	return 0;
+}
+
+Interrupt VideoOutput::get_next_interrupt()
+{
+	return DisplayEnd;
+}