From 131784d0076cd065045b82f37d1035d2bbcbdc41 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 13 Mar 2023 22:51:01 -0400
Subject: [PATCH] Generalise PointSet to read or write.

---
 Components/9918/Implementation/9918.cpp       | 24 ++++++++++---------
 Components/9918/Implementation/9918Base.hpp   |  7 ++++++
 Components/9918/Implementation/Storage.hpp    |  9 +++++++
 .../9918/Implementation/YamahaCommands.hpp    | 12 +++++-----
 4 files changed, 35 insertions(+), 17 deletions(-)

diff --git a/Components/9918/Implementation/9918.cpp b/Components/9918/Implementation/9918.cpp
index 4368f7647..1153467ff 100644
--- a/Components/9918/Implementation/9918.cpp
+++ b/Components/9918/Implementation/9918.cpp
@@ -924,20 +924,20 @@ void Base<personality>::commit_register(int reg, uint8_t value) {
 					default:
 					case 0b0000: 	Storage<personality>::command_ = nullptr;	break;	// STOP.
 
-					case 0b0100:	break;	// TODO: point.	[read a pixel colour]
-					case 0b0101:	Begin(PointSet);					break;	// PSET [plot a pixel].
+					case 0b0100:	Begin(Point<true>);							break;	// POINT [read a pixel colour].
+					case 0b0101:	Begin(Point<false>);						break;	// PSET [plot a pixel].
 					case 0b0110:	break;	// TODO: srch.	[search horizontally for a colour]
-					case 0b0111:	Begin(Line);						break;	// LINE [draw a Bresenham line].
+					case 0b0111:	Begin(Line);								break;	// LINE [draw a Bresenham line].
 
-					case 0b1000:	Begin(LogicalFill);					break;	// LMMV [logical move, VDP to VRAM, i.e. solid-colour fill].
-					case 0b1001:	Begin(Move<MoveType::Logical>);		break;	// LMMM [logical move, VRAM to VRAM].
+					case 0b1000:	Begin(LogicalFill);							break;	// LMMV [logical move, VDP to VRAM, i.e. solid-colour fill].
+					case 0b1001:	Begin(Move<MoveType::Logical>);				break;	// LMMM [logical move, VRAM to VRAM].
 					case 0b1010:	break;	// TODO: lmcm.	[logical move, VRAM to CPU]
-					case 0b1011:	Begin(MoveFromCPU<true>);			break;	// LMMC [logical move, CPU to VRAM].
+					case 0b1011:	Begin(MoveFromCPU<true>);					break;	// LMMC [logical move, CPU to VRAM].
 
-					case 0b1100:	Begin(HighSpeedFill);				break;	// HMMV [high-speed move, VDP to VRAM, i.e. single-byte fill].
-					case 0b1101:	Begin(Move<MoveType::HighSpeed>);	break;	// HMMM [high-speed move, VRAM to VRAM].
-					case 0b1110:	Begin(Move<MoveType::YOnly>);		break;	// YMMM [high-speed move, y only, VRAM to VRAM].
-					case 0b1111:	Begin(MoveFromCPU<false>);			break;	// HMMC [high-speed move, CPU to VRAM].
+					case 0b1100:	Begin(HighSpeedFill);						break;	// HMMV [high-speed move, VDP to VRAM, i.e. single-byte fill].
+					case 0b1101:	Begin(Move<MoveType::HighSpeed>);			break;	// HMMM [high-speed move, VRAM to VRAM].
+					case 0b1110:	Begin(Move<MoveType::YOnly>);				break;	// YMMM [high-speed move, y only, VRAM to VRAM].
+					case 0b1111:	Begin(MoveFromCPU<false>);					break;	// HMMC [high-speed move, CPU to VRAM].
 				}
 #undef Begin
 
@@ -1113,7 +1113,9 @@ uint8_t Base<personality>::read_register() {
 			case 4:	LOG("TODO: Yamaha status 4");	break;
 			case 5:	LOG("TODO: Yamaha status 5");	break;
 			case 6:	LOG("TODO: Yamaha status 6");	break;
-			case 7:	LOG("TODO: Yamaha status 7");	break;
+
+			case 7:	return Storage<personality>::colour_status_;
+
 			case 8:	LOG("TODO: Yamaha status 8");	break;
 			case 9:	LOG("TODO: Yamaha status 9");	break;
 		}
diff --git a/Components/9918/Implementation/9918Base.hpp b/Components/9918/Implementation/9918Base.hpp
index 88983a646..bdf698b9d 100644
--- a/Components/9918/Implementation/9918Base.hpp
+++ b/Components/9918/Implementation/9918Base.hpp
@@ -390,6 +390,13 @@ template <Personality personality> struct Base: public Storage<personality> {
 					case CommandStep::None:
 					break;
 
+					case CommandStep::CopySourcePixelToStatus:
+						Storage<personality>::colour_status_ = extract_colour(source[command_address(context.source, context.arguments & 0x10)], context.source);
+
+						Storage<personality>::command_->advance(pixels_per_byte(this->underlying_mode_));
+						Storage<personality>::update_command_step(access_column);
+					break;
+
 					case CommandStep::ReadSourcePixel:
 						context.latched_colour.set(extract_colour(source[command_address(context.source, context.arguments & 0x10)], context.source));
 
diff --git a/Components/9918/Implementation/Storage.hpp b/Components/9918/Implementation/Storage.hpp
index f83d8acac..f88d2eb70 100644
--- a/Components/9918/Implementation/Storage.hpp
+++ b/Components/9918/Implementation/Storage.hpp
@@ -100,6 +100,9 @@ template <Personality personality> struct Storage<personality, std::enable_if_t<
 	// Sprite collection state.
 	bool sprites_enabled_ = true;
 
+	// Additional status.
+	uint8_t colour_status_ = 0;
+
 	/// Resets line-ephemeral state for a new line.
 	void begin_line(ScreenMode mode, bool is_refresh) {
 		if(is_refresh) {
@@ -134,6 +137,8 @@ template <Personality personality> struct Storage<personality, std::enable_if_t<
 	enum class CommandStep {
 		None,
 
+		CopySourcePixelToStatus,
+
 		ReadSourcePixel,
 		ReadDestinationPixel,
 		WritePixel,
@@ -158,6 +163,10 @@ template <Personality personality> struct Storage<personality, std::enable_if_t<
 
 		minimum_command_column_ = current_column + command_->cycles;
 		switch(command_->access) {
+			case Command::AccessType::ReadPoint:
+				next_command_step_ = CommandStep::CopySourcePixelToStatus;
+			break;
+
 			case Command::AccessType::CopyPoint:
 				next_command_step_ = CommandStep::ReadSourcePixel;
 			break;
diff --git a/Components/9918/Implementation/YamahaCommands.hpp b/Components/9918/Implementation/YamahaCommands.hpp
index 6e27d67bf..7545180cb 100644
--- a/Components/9918/Implementation/YamahaCommands.hpp
+++ b/Components/9918/Implementation/YamahaCommands.hpp
@@ -111,7 +111,9 @@ struct Command {
 		/// being a read, a 24-cycle gap, then a write.
 		CopyByte,
 
-//		ReadPoint,
+		/// Copies a single pixel from @c source to the colour status register.
+		ReadPoint,
+
 //		ReadByte,
 //		WaitForColourSend,
 	};
@@ -211,11 +213,11 @@ struct Line: public Command {
 /// Implements the PSET command, which plots a single pixel.
 ///
 /// No timings are documented, so this'll output as quickly as possible.
-struct PointSet: public Command {
+template <bool is_read> struct Point: public Command {
 	public:
-		PointSet(CommandContext &context) : Command(context) {
+		Point(CommandContext &context) : Command(context) {
 			cycles = 0;	// TODO.
-			access = AccessType::PlotPoint;
+			access = is_read ? AccessType::ReadPoint : AccessType::PlotPoint;
 		}
 
 		bool done() final {
@@ -230,8 +232,6 @@ struct PointSet: public Command {
 		bool done_ = false;
 };
 
-// TODO: point.
-
 // MARK: - Rectangular base.
 
 /// Useful base class for anything that does logical work in a rectangle.