From a315384e30d093dcfc18beab751ab08c7689da6c Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Tue, 31 Jan 2023 21:29:55 -0500
Subject: [PATCH] Provide context for byte-by-byte commands.

---
 Components/9918/Implementation/9918.cpp       |  2 +-
 Components/9918/Implementation/9918Base.hpp   |  6 ++--
 .../9918/Implementation/AccessEnums.hpp       | 17 ++++++++++
 .../9918/Implementation/YamahaCommands.hpp    | 33 ++++++++++++++-----
 4 files changed, 44 insertions(+), 14 deletions(-)

diff --git a/Components/9918/Implementation/9918.cpp b/Components/9918/Implementation/9918.cpp
index 178e45d60..510b5ed1c 100644
--- a/Components/9918/Implementation/9918.cpp
+++ b/Components/9918/Implementation/9918.cpp
@@ -871,7 +871,7 @@ void Base<personality>::commit_register(int reg, uint8_t value) {
 					Storage<personality>::command_ &&
 					Storage<personality>::command_->access == Command::AccessType::WaitForColourReceipt
 				) {
-					Storage<personality>::command_->advance();
+					Storage<personality>::command_->advance(pixels_per_byte(this->screen_mode_));
 					Storage<personality>::update_command_step(fetch_pointer_.column);
 				}
 			break;
diff --git a/Components/9918/Implementation/9918Base.hpp b/Components/9918/Implementation/9918Base.hpp
index 3ec608949..8d5b36309 100644
--- a/Components/9918/Implementation/9918Base.hpp
+++ b/Components/9918/Implementation/9918Base.hpp
@@ -365,8 +365,6 @@ template <Personality personality> struct Storage<personality, std::enable_if_t<
 	uint32_t colour_ram_[32];
 	bool cram_is_selected_ = false;
 
-	// Fields below affect only the Master System output mode.
-
 	// Programmer-set flags.
 	bool vertical_scroll_lock_ = false;
 	bool horizontal_scroll_lock_ = false;
@@ -707,13 +705,13 @@ template <Personality personality> struct Base: public Storage<personality> {
 
 						ram_[address] = Storage<personality>::command_latch_;
 
-						Storage<personality>::command_->advance();
+						Storage<personality>::command_->advance(pixels_per_byte(this->screen_mode_));
 						Storage<personality>::update_command_step(access_column);
 					} break;
 
 					case CommandStep::WriteByte:
 						ram_[command_address()] = Storage<personality>::command_context_.colour;
-						Storage<personality>::command_->advance();
+						Storage<personality>::command_->advance(pixels_per_byte(this->screen_mode_));
 						Storage<personality>::update_command_step(access_column);
 					break;
 				}
diff --git a/Components/9918/Implementation/AccessEnums.hpp b/Components/9918/Implementation/AccessEnums.hpp
index 66a80ec1e..a2a079b64 100644
--- a/Components/9918/Implementation/AccessEnums.hpp
+++ b/Components/9918/Implementation/AccessEnums.hpp
@@ -39,6 +39,23 @@ enum class ScreenMode {
 	YamahaGraphics2 = Graphics,
 };
 
+constexpr int pixels_per_byte(ScreenMode mode) {
+	switch(mode) {
+		case ScreenMode::Blank:				return 0;
+		case ScreenMode::Text:				return 6;
+		case ScreenMode::MultiColour:		return 2;
+		case ScreenMode::ColouredText:		return 8;
+		case ScreenMode::Graphics:			return 8;
+		case ScreenMode::SMSMode4:			return 2;
+		case ScreenMode::YamahaText80:		return 6;
+		case ScreenMode::YamahaGraphics3:	return 8;
+		case ScreenMode::YamahaGraphics4:	return 2;
+		case ScreenMode::YamahaGraphics5:	return 4;
+		case ScreenMode::YamahaGraphics6:	return 2;
+		case ScreenMode::YamahaGraphics7:	return 1;
+	}
+}
+
 enum class FetchMode {
 	Text,
 	Character,
diff --git a/Components/9918/Implementation/YamahaCommands.hpp b/Components/9918/Implementation/YamahaCommands.hpp
index 291066ea1..6eb9fa13d 100644
--- a/Components/9918/Implementation/YamahaCommands.hpp
+++ b/Components/9918/Implementation/YamahaCommands.hpp
@@ -95,14 +95,14 @@ struct Command {
 	/// @returns @c true if all output from this command is done; @c false otherwise.
 	virtual bool done() = 0;
 
-	/// Repopulates the fields above with the next action to take.
-	virtual void advance() = 0;
+	/// Repopulates the fields above with the next action to take, being provided with the
+	/// number of pixels per byte in the current screen mode.
+	virtual void advance(int pixels_per_byte) = 0;
 
 	protected:
-		template <int axis> void advance_axis() {
-			context.destination.add<axis>(context.arguments & (0x4 << axis) ? -1 : 1);
+		template <int axis> void advance_axis(int offset = 1) {
+			context.destination.add<axis>(context.arguments & (0x4 << axis) ? -offset : offset);
 		}
-
 };
 
 // MARK: - Line drawing.
@@ -136,7 +136,7 @@ struct Line: public Command {
 			return !context.size.v[0];
 		}
 
-		void advance() final {
+		void advance(int) final {
 			--context.size.v[0];
 			cycles = 88;
 
@@ -186,7 +186,7 @@ struct PointSet: public Command {
 			return done_;
 		}
 
-		void advance() final {
+		void advance(int) final {
 			done_ = true;
 		}
 
@@ -208,7 +208,7 @@ struct LogicalMoveFromCPU: public Command {
 			location = context.destination;
 		}
 
-		void advance() final {
+		void advance(int) final {
 			switch(access) {
 				default: break;
 
@@ -258,8 +258,23 @@ struct HighSpeedFill: public Command {
 		return true;
 	}
 
-	void advance() final {
+	void advance(int pixels_per_byte) final {
 		cycles = 48;
+
+		// TODO: step at byte speed, not pixel speed.
+		advance_axis<0>(pixels_per_byte);
+		--context.size.v[0];
+
+		if(!context.size.v[0]) {
+			cycles += 56;
+			context.size.v[0] = width_;
+			context.destination.v[0] = start_x_;
+
+			advance_axis<1>();
+			--context.size.v[1];
+		}
+
+		location = context.destination;
 	}
 
 	private: