Merge branch 'master' into SeparateFetchClock

Components/9918/Implementation/9918.cpp

@@ -30,30 +30,6 @@ Base<personality>::Base() :
 	// Unimaginatively, this class just passes RGB through to the shader. Investigation is needed
 	// into whether there's a more natural form. It feels unlikely given the diversity of chips modelled.
 
-	if constexpr (is_sega_vdp(personality)) {
-		// Cf. https://www.smspower.org/forums/8161-SMSDisplayTiming
-
-		// "For a line interrupt, /INT is pulled low 608 mclks into the appropriate scanline relative to pixel 0.
-		// This is 3 mclks before the rising edge of /HSYNC which starts the next scanline."
-		//
-		// i.e. it's 304 internal clocks after the end of the left border.
-		mode_timing_.line_interrupt_position = (LineLayout<personality>::EndOfLeftBorder + 304) % LineLayout<personality>::CyclesPerLine;
-
-		// For a frame interrupt, /INT is pulled low 607 mclks into scanline 192 (of scanlines 0 through 261) relative to pixel 0.
-		// This is 4 mclks before the rising edge of /HSYNC which starts the next scanline.
-		//
-		// i.e. it's 1/2 cycle before the line interrupt position, which I have rounded. Ugh.
-		mode_timing_.end_of_frame_interrupt_position.column = mode_timing_.line_interrupt_position - 1;
-		mode_timing_.end_of_frame_interrupt_position.row = 192 + (LineLayout<personality>::EndOfLeftBorder + 304) / LineLayout<personality>::CyclesPerLine;
-	}
-
-	if constexpr (is_yamaha_vdp(personality)) {
-		// TODO: this is used for interrupt _prediction_ but won't handle text modes correctly, and indeed
-		// can't be just a single value where the programmer has changed into or out of text modes during the
-		// middle of a line, since screen mode is latched (so it'll be one value for that line, another from then onwards).a
-		mode_timing_.line_interrupt_position = LineLayout<personality>::EndOfPixels;
-	}
-
 	// Establish that output is delayed after reading by `output_lag` cycles,
 	// i.e. the fetch pointer is currently _ahead_ of the output pointer.
 	output_pointer_.row = output_pointer_.column = 0;
@@ -61,6 +37,22 @@ Base<personality>::Base() :
 	fetch_pointer_ = output_pointer_;
 	fetch_pointer_.column += output_lag;
 
+	// The fetch pointer is interpreted such that its zero is at the mode-latch cycle.
+	// Conversely the output pointer has zero be at start of sync. So the following
+	// is a mere change-of-origin.
+	//
+	// Logically, any mode latch time greater than 0 — i.e. beyond the start of sync — will
+	// cause fetch_pointer_ to **regress**. It will be set to the value it was at the start
+	// of sync, ready to overflow to 0 upon mode latch. When it overflows, the fetch row
+	// will be incremented.
+	//
+	// Therefore the nominal output row at instantiation needs to be one greater than the
+	// fetch row, as that's the first row that'll actually be fetched.
+	fetch_pointer_.column = to_internal<personality, Origin::ModeLatch>(output_pointer_.column);
+	if(LineLayout<personality>::ModeLatchCycle) {
+		++output_pointer_.row;
+	}
+
 	fetch_line_buffer_ = line_buffers_.begin();
 	draw_line_buffer_ = line_buffers_.begin();
 	fetch_sprite_buffer_ = sprite_buffers_.begin();
@@ -224,7 +216,7 @@ void TMS9918<personality>::run_for(const HalfCycles cycles) {
 					// TODO: where did this magic constant come from? https://www.smspower.org/forums/17970-RoadRashHow#111000 mentioned in passing
 					// that "the vertical scroll register is latched at the start of the active display" and this is two clocks before that, so it's
 					// not uncompelling. I can just no longer find my source.
-					constexpr auto latch_time = LineLayout<personality>::EndOfLeftBorder - 2;
+					constexpr auto latch_time = to_internal<personality, Origin::ModeLatch>(LineLayout<personality>::EndOfLeftBorder - 2);
 					static_assert(latch_time > 0);
 					if(this->fetch_pointer_.column < latch_time && end_column >= latch_time) {
 						Storage<personality>::latched_vertical_scroll_ = Storage<personality>::vertical_scroll_;
@@ -283,13 +275,15 @@ void TMS9918<personality>::run_for(const HalfCycles cycles) {
 			// -------------------------------
 			// Check for interrupt conditions.
 			// -------------------------------
-			if constexpr (is_sega_vdp(personality)) {
+			if constexpr (LineLayout<personality>::HasFixedLineInterrupt) {
 				// The Sega VDP offers a decrementing counter for triggering line interrupts;
 				// it is reloaded either when it overflows or upon every non-pixel line after the first.
 				// It is otherwise decremented.
+
+				constexpr int FixedLineInterrupt = to_internal<personality, Origin::ModeLatch>(LineLayout<personality>::FixedLineInterrupt);
 				if(
-					this->fetch_pointer_.column < this->mode_timing_.line_interrupt_position &&
-					end_column >= this->mode_timing_.line_interrupt_position
+					this->fetch_pointer_.column < FixedLineInterrupt &&
+					end_column >= FixedLineInterrupt
 				) {
 					if(this->fetch_pointer_.row >= 0 && this->fetch_pointer_.row <= this->mode_timing_.pixel_lines) {
 						if(!this->line_interrupt_counter_) {

Components/9918/Implementation/9918Base.hpp

@@ -170,16 +170,6 @@ template <Personality personality> struct Base: public Storage<personality> {
 		// then the appropriate status information will be set.
 		int maximum_visible_sprites = 4;
 
-		// Set the position, in cycles, of the two interrupts,
-		// within a line.
-		//
-		// TODO: redetermine where this number came from.
-		struct {
-			int column = 313;
-			int row = 192;
-		} end_of_frame_interrupt_position;
-		int line_interrupt_position = -1;
-
 		// Enables or disabled the recognition of the sprite
 		// list terminator, and sets the terminator value.
 		bool allow_sprite_terminator = true;

Components/9918/Implementation/ClockConverter.hpp

@@ -24,9 +24,15 @@ enum class Clock {
 	TMSMemoryWindow,
 	/// A fixed 1368-cycle/line clock that is used to count output to the CRT.
 	CRT,
+};
+
+enum class Origin {
+	///
+	ModeLatch,
+
 	/// Provides the same clock rate as ::Internal but is relocated so that 0 is the start of horizontal sync — very not coincidentally,
 	/// where Grauw puts 0 on his detailed TMS and Yamaha timing diagrams.
-	FromStartOfSync,
+	StartOfSync,
 };
 
 template <Personality personality, Clock clk> constexpr int clock_rate() {
@@ -41,7 +47,6 @@ template <Personality personality, Clock clk> constexpr int clock_rate() {
 		case Clock::TMSMemoryWindow:	return 171;
 		case Clock::CRT:				return 1368;
 		case Clock::Internal:
-		case Clock::FromStartOfSync:
 			if constexpr (is_classic_vdp(personality)) {
 				return 342;
 			} else if constexpr (is_yamaha_vdp(personality)) {
@@ -52,36 +57,50 @@ template <Personality personality, Clock clk> constexpr int clock_rate() {
 	}
 }
 
-/// Statelessly converts @c length to the internal clock for @c personality; applies conversions per the list of clocks in left-to-right order.
-template <Personality personality, Clock head, Clock... tail> constexpr int to_internal(int length) {
-	if constexpr (head == Clock::FromStartOfSync) {
-		length = (length + LineLayout<personality>::StartOfSync) % LineLayout<personality>::CyclesPerLine;
-	} else {
-		length = length * clock_rate<personality, Clock::Internal>() / clock_rate<personality, head>();
-	}
-
-	if constexpr (!sizeof...(tail)) {
-		return length;
-	} else {
-		return to_internal<personality, tail...>(length);
-	}
+/// Scales @c length from @c clock to the internal clock rate.
+template <Personality personality, Clock clock> constexpr int to_internal(int length) {
+	return length * clock_rate<personality, Clock::Internal>() / clock_rate<personality, clock>();
 }
 
-/// Statelessly converts @c length to @c clock from the the internal clock used by VDPs of @c personality throwing away any remainder.
-template <Personality personality, Clock head, Clock... tail> constexpr int from_internal(int length) {
-	if constexpr (head == Clock::FromStartOfSync) {
-		length =
-			(length + LineLayout<personality>::CyclesPerLine - LineLayout<personality>::StartOfSync)
-				% LineLayout<personality>::CyclesPerLine;
-	} else {
-		length = length * clock_rate<personality, head>() / clock_rate<personality, Clock::Internal>();
+/// Moves @c position that is relative to @c Origin::StartOfSync so that it is relative to @c origin ;
+/// i.e. can be thought of as "to [internal with origin as specified]".
+template <Personality personality, Origin origin> constexpr int to_internal(int position) {
+	if constexpr (origin == Origin::ModeLatch) {
+		return (
+			position + LineLayout<personality>::CyclesPerLine - LineLayout<personality>::ModeLatchCycle
+		) % LineLayout<personality>::CyclesPerLine;
 	}
+	return position;
+}
 
-	if constexpr (!sizeof...(tail)) {
-		return length;
-	} else {
-		return to_internal<personality, tail...>(length);
+/// Converts @c position from one that is measured at the rate implied by @c clock and relative to @c Origin::StartOfSync
+/// to one that is at the internal clock rate and relative to @c origin.
+template <Personality personality, Origin origin, Clock clock> constexpr int to_internal(int position) {
+	position = to_internal<personality, clock>(position);
+	return to_internal<personality, origin>(position);
+}
+
+/// Scales @c length from the internal clock rate to @c clock.
+template <Personality personality, Clock clock> constexpr int from_internal(int length) {
+	return length * clock_rate<personality, clock>() / clock_rate<personality, Clock::Internal>();
+}
+
+/// Moves @c position that is relative to @c origin so that it is relative to @c Origin::StartOfSync ;
+/// i.e. can be thought of as "from [internal with origin as specified]".
+template <Personality personality, Origin origin> constexpr int from_internal(int length) {
+	if constexpr (origin == Origin::ModeLatch) {
+		return (
+			length + LineLayout<personality>::ModeLatchCycle
+		) % LineLayout<personality>::CyclesPerLine;
 	}
+	return length;
+}
+
+/// Converts @c position from one that is measured at the internal clock rate and relative to @c origin
+/// to one that is at the rate implied by @c clock and relative to @c Origin::StartOfSync 
+template <Personality personality, Origin origin, Clock clock> constexpr int from_internal(int position) {
+	position = from_internal<personality, origin>(position);
+	return from_internal<personality, clock>(position);
 }
 
 /*!

Components/9918/Implementation/Fetch.hpp

@@ -54,7 +54,7 @@ template<bool use_end, typename SequencerT> void Base<personality>::dispatch(Seq
 #define index(n)						\
 	if(use_end && end == n) return;		\
 	[[fallthrough]];					\
-	case n: fetcher.template fetch<from_internal<personality, Clock::FromStartOfSync>(n)>();
+	case n: fetcher.template fetch<from_internal<personality, Origin::StartOfSync>(n)>();
 
 	switch(start) {
 		default: assert(false);
@@ -373,7 +373,7 @@ struct RefreshSequencer {
 
 	template <int cycle> void fetch() {
 		if(cycle < 26 || (cycle & 1) || cycle >= 154) {
-			base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow, Clock::FromStartOfSync>(cycle));
+			base->do_external_slot(to_internal<personality, Origin::ModeLatch, Clock::TMSMemoryWindow>(cycle));
 		}
 	}
 
@@ -387,7 +387,7 @@ struct TextSequencer {
 	template <int cycle> void fetch() {
 		// The first 30 and the final 4 slots are external.
 		if constexpr (cycle < 30 || cycle >= 150) {
-			fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow, Clock::FromStartOfSync>(cycle));
+			fetcher.base->do_external_slot(to_internal<personality, Origin::ModeLatch, Clock::TMSMemoryWindow>(cycle));
 			return;
 		} else {
 			// For the 120 slots in between follow a three-step pattern of:
@@ -398,7 +398,7 @@ struct TextSequencer {
 					fetcher.fetch_name(column);
 				break;
 				case 1:		// (2) external slot.
-					fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow, Clock::FromStartOfSync>(cycle));
+					fetcher.base->do_external_slot(to_internal<personality, Origin::ModeLatch, Clock::TMSMemoryWindow>(cycle));
 				break;
 				case 2:		// (3) fetch tile pattern.
 					fetcher.fetch_pattern(column);
@@ -419,7 +419,7 @@ struct CharacterSequencer {
 
 	template <int cycle> void fetch() {
 		if(cycle < 5) {
-			character_fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow, Clock::FromStartOfSync>(cycle));
+			character_fetcher.base->do_external_slot(to_internal<personality, Origin::ModeLatch, Clock::TMSMemoryWindow>(cycle));
 		}
 
 		if(cycle == 5) {
@@ -430,7 +430,7 @@ struct CharacterSequencer {
 		}
 
 		if(cycle > 14 && cycle < 19) {
-			character_fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow, Clock::FromStartOfSync>(cycle));
+			character_fetcher.base->do_external_slot(to_internal<personality, Origin::ModeLatch, Clock::TMSMemoryWindow>(cycle));
 		}
 
 		// Fetch 8 new sprite Y coordinates, to begin selecting sprites for next line.
@@ -448,7 +448,7 @@ struct CharacterSequencer {
 				case 0:	character_fetcher.fetch_name(block);	break;
 				case 1:
 					if(!(block & 3)) {
-						character_fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow, Clock::FromStartOfSync>(cycle));
+						character_fetcher.base->do_external_slot(to_internal<personality, Origin::ModeLatch, Clock::TMSMemoryWindow>(cycle));
 					} else {
 						constexpr int sprite = 8 + ((block >> 2) * 3) + ((block & 3) - 1);
 						sprite_fetcher.fetch_y(sprite);
@@ -463,7 +463,7 @@ struct CharacterSequencer {
 		}
 
 		if(cycle >= 155 && cycle < 157) {
-			character_fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow, Clock::FromStartOfSync>(cycle));
+			character_fetcher.base->do_external_slot(to_internal<personality, Origin::ModeLatch, Clock::TMSMemoryWindow>(cycle));
 		}
 
 		if(cycle == 157) {
@@ -511,7 +511,7 @@ struct SMSSequencer {
 	// window 0 to HSYNC low.
 	template <int cycle> void fetch() {
 		if(cycle < 3) {
-			fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow, Clock::FromStartOfSync>(cycle));
+			fetcher.base->do_external_slot(to_internal<personality, Origin::ModeLatch, Clock::TMSMemoryWindow>(cycle));
 		}
 
 		if(cycle == 3) {
@@ -522,7 +522,7 @@ struct SMSSequencer {
 		}
 
 		if(cycle == 15 || cycle == 16) {
-			fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow, Clock::FromStartOfSync>(cycle));
+			fetcher.base->do_external_slot(to_internal<personality, Origin::ModeLatch, Clock::TMSMemoryWindow>(cycle));
 		}
 
 		if(cycle == 17) {
@@ -543,7 +543,7 @@ struct SMSSequencer {
 				case 0:	fetcher.fetch_tile_name(block);		break;
 				case 1:
 					if(!(block & 3)) {
-						fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow, Clock::FromStartOfSync>(cycle));
+						fetcher.base->do_external_slot(to_internal<personality, Origin::ModeLatch, Clock::TMSMemoryWindow>(cycle));
 					} else {
 						constexpr int sprite = (8 + ((block >> 2) * 3) + ((block & 3) - 1)) << 1;
 						fetcher.posit_sprite(sprite);
@@ -555,7 +555,7 @@ struct SMSSequencer {
 		}
 
 		if(cycle >= 153 && cycle < 157) {
-			fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow, Clock::FromStartOfSync>(cycle));
+			fetcher.base->do_external_slot(to_internal<personality, Origin::ModeLatch, Clock::TMSMemoryWindow>(cycle));
 		}
 
 		if(cycle == 157) {
@@ -566,7 +566,7 @@ struct SMSSequencer {
 		}
 
 		if(cycle >= 169) {
-			fetcher.base->do_external_slot(to_internal<personality, Clock::TMSMemoryWindow, Clock::FromStartOfSync>(cycle));
+			fetcher.base->do_external_slot(to_internal<personality, Origin::ModeLatch, Clock::TMSMemoryWindow>(cycle));
 		}
 	}
 

Components/9918/Implementation/LineLayout.hpp

@@ -28,8 +28,11 @@ template <Personality personality, typename Enable = void> struct LineLayout;
 //		* horizontal adjust on the Yamaha VDPs is applied to EndOfLeftBorder and EndOfPixels;
 //		* the Sega VDPs may programatically extend the left border; and
 //		* text mode on all VDPs adjusts border width.
+//
+//	ModeLaytchCycle is the cycle at which the video mode, blank disable/enable and
+//	sprite enable/disable are latched for the line.
 
-template <Personality personality> struct LineLayout<personality, std::enable_if_t<is_classic_vdp(personality)>> {
+template <Personality personality> struct LineLayout<personality, std::enable_if_t<is_classic_vdp(personality) && !is_sega_vdp(personality)>> {
 	constexpr static int StartOfSync		= 0;
 	constexpr static int EndOfSync			= 26;
 	constexpr static int StartOfColourBurst	= 29;
@@ -48,11 +51,34 @@ template <Personality personality> struct LineLayout<personality, std::enable_if
 													// and falls into the collection gap between the final sprite
 													// graphics and the initial tiles or pixels.
 
+	constexpr static bool HasDynamicLineInterrupt = false;
+	constexpr static bool HasFixedLineInterrupt = false;
+	constexpr static int EndOfFrameInterrupt = 313;
+
 	/// The number of internal cycles that must elapse between a request to read or write and
 	/// it becoming a candidate for action.
 	constexpr static int VRAMAccessDelay = 6;
 };
 
+template <Personality personality> struct LineLayout<personality, std::enable_if_t<is_sega_vdp(personality)>> :
+	public LineLayout<Personality::TMS9918A> {
+
+	// Cf. https://www.smspower.org/forums/8161-SMSDisplayTiming
+
+	// "For a line interrupt, /INT is pulled low 608 mclks into the appropriate scanline relative to pixel 0.
+	// This is 3 mclks before the rising edge of /HSYNC which starts the next scanline."
+	//
+	// i.e. it's 304 internal clocks after the end of the left border.
+	constexpr static bool HasFixedLineInterrupt = false;
+	constexpr static int FixedLineInterrupt = (EndOfLeftBorder + 304) % CyclesPerLine;
+
+	// For a frame interrupt, /INT is pulled low 607 mclks into scanline 192 (of scanlines 0 through 261) relative to pixel 0.
+	// This is 4 mclks before the rising edge of /HSYNC which starts the next scanline.
+	//
+	// i.e. it's 1/2 cycle before the line interrupt position, which I have rounded. Ugh.
+	constexpr static int EndOfFrameInterrupt = 313;
+};
+
 template <Personality personality> struct LineLayout<personality, std::enable_if_t<is_yamaha_vdp(personality)>> {
 	constexpr static int StartOfSync		= 0;
 	constexpr static int EndOfSync			= 100;
@@ -70,6 +96,10 @@ template <Personality personality> struct LineLayout<personality, std::enable_if
 
 	constexpr static int ModeLatchCycle		= 144;
 
+	constexpr static bool HasDynamicLineInterrupt = true;
+	constexpr static bool HasFixedLineInterrupt = false;
+	constexpr static int EndOfFrameInterrupt = 313;
+
 	/// The number of internal cycles that must elapse between a request to read or write and
 	/// it becoming a candidate for action.
 	constexpr static int VRAMAccessDelay = 16;

Components/9918/Implementation/Storage.hpp

@@ -87,7 +87,8 @@ struct YamahaFetcher {
 			size_t index = 0;
 			for(int c = 0; c < 1368; c++) { 
 				// Specific personality doesn't matter here; both Yamahas use the same internal timing.
-				const auto event = GeneratorT::event(from_internal<Personality::V9938, Clock::FromStartOfSync>(c));
+				const int mapped_location = from_internal<Personality::V9938, Origin::StartOfSync>(c);
+				const auto event = GeneratorT::event(mapped_location);
 				if(!event) {
 					continue;
 				}

OSBindings/Mac/Clock Signal.xcodeproj/xcshareddata/xcschemes/Clock Signal.xcscheme

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
    LastUpgradeVersion = "1400"
-   version = "1.3">
+   version = "1.8">
    <BuildAction
       parallelizeBuildables = "YES"
       buildImplicitDependencies = "YES">