From 0d7646d42a2c70033fe0a3916b63f92deed27ef0 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 4 Dec 2023 09:45:32 -0500
Subject: [PATCH] Add a cursor-type template parameter.

---
 Components/6845/CRTC6845.hpp           | 15 ++++++++++++++-
 Machines/AmstradCPC/AmstradCPC.cpp     |  7 ++++---
 Machines/PCCompatible/PCCompatible.cpp | 18 +++++++++---------
 3 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/Components/6845/CRTC6845.hpp b/Components/6845/CRTC6845.hpp
index 67d065a25..a187c0dfb 100644
--- a/Components/6845/CRTC6845.hpp
+++ b/Components/6845/CRTC6845.hpp
@@ -50,9 +50,22 @@ enum Personality {
 	AMS40226	// Type 3. Status is get register, fixed-length VSYNC, no zero-length HSYNC.
 };
 
+// https://www.pcjs.org/blog/2018/03/20/ advises that "the behavior of bits 5 and 6 [of register 10, the cursor start
+// register is really card specific".
+//
+// This enum captures those specifics.
+enum CursorType {
+	/// No cursor signal is generated.
+	None,
+	/// MDA style: 00 => symmetric blinking; 01 or 10 => no blinking; 11 => short on, long off.
+	MDA,
+	/// EGA style: ignore the bits completely.
+	EGA,
+};
+
 // TODO UM6845R and R12/R13; see http://www.cpcwiki.eu/index.php/CRTC#CRTC_Differences
 
-template <class T> class CRTC6845 {
+template <class T, CursorType cursor> class CRTC6845 {
 	public:
 
 		CRTC6845(Personality p, T &bus_handler) noexcept :
diff --git a/Machines/AmstradCPC/AmstradCPC.cpp b/Machines/AmstradCPC/AmstradCPC.cpp
index d720303db..7c2848fee 100644
--- a/Machines/AmstradCPC/AmstradCPC.cpp
+++ b/Machines/AmstradCPC/AmstradCPC.cpp
@@ -585,6 +585,7 @@ class CRTCBusHandler {
 
 		InterruptTimer &interrupt_timer_;
 };
+using CRTC = Motorola::CRTC::CRTC6845<CRTCBusHandler, Motorola::CRTC::CursorType::None>;
 
 /*!
 	Holds and vends the current keyboard state, acting as the AY's port handler.
@@ -683,7 +684,7 @@ class i8255PortHandler : public Intel::i8255::PortHandler {
 	public:
 		i8255PortHandler(
 			KeyboardState &key_state,
-			const Motorola::CRTC::CRTC6845<CRTCBusHandler> &crtc,
+			const CRTC &crtc,
 			AYDeferrer &ay,
 			Storage::Tape::BinaryTapePlayer &tape_player) :
 				ay_(ay),
@@ -742,7 +743,7 @@ class i8255PortHandler : public Intel::i8255::PortHandler {
 
 	private:
 		AYDeferrer &ay_;
-		const Motorola::CRTC::CRTC6845<CRTCBusHandler> &crtc_;
+		const CRTC &crtc_;
 		KeyboardState &key_state_;
 		Storage::Tape::BinaryTapePlayer &tape_player_;
 };
@@ -1219,7 +1220,7 @@ template <bool has_fdc> class ConcreteMachine:
 		CPU::Z80::Processor<ConcreteMachine, false, true> z80_;
 
 		CRTCBusHandler crtc_bus_handler_;
-		Motorola::CRTC::CRTC6845<CRTCBusHandler> crtc_;
+		CRTC crtc_;
 
 		AYDeferrer ay_;
 		i8255PortHandler i8255_port_handler_;
diff --git a/Machines/PCCompatible/PCCompatible.cpp b/Machines/PCCompatible/PCCompatible.cpp
index aa2e3c61e..d525086c2 100644
--- a/Machines/PCCompatible/PCCompatible.cpp
+++ b/Machines/PCCompatible/PCCompatible.cpp
@@ -625,7 +625,7 @@ class MDA {
 			const uint8_t *ram = nullptr;
 			std::vector<uint8_t> font;
 		} outputter_;
-		Motorola::CRTC::CRTC6845<CRTCOutputter> crtc_;
+		Motorola::CRTC::CRTC6845<CRTCOutputter, Motorola::CRTC::CursorType::MDA> crtc_;
 
 		int full_clock_;
 };
@@ -885,14 +885,14 @@ class IO {
 					printf("Unhandled in: %04x\n", port);
 				break;
 
-				case 0x0000:	return dma_.controller.read<0>();
-				case 0x0001:	return dma_.controller.read<1>();
-				case 0x0002:	return dma_.controller.read<2>();
-				case 0x0003:	return dma_.controller.read<3>();
-				case 0x0004:	return dma_.controller.read<4>();
-				case 0x0005:	return dma_.controller.read<5>();
-				case 0x0006:	return dma_.controller.read<6>();
-				case 0x0007:	return dma_.controller.read<7>();
+				case 0x0000:	return dma_.controller.template read<0>();
+				case 0x0001:	return dma_.controller.template read<1>();
+				case 0x0002:	return dma_.controller.template read<2>();
+				case 0x0003:	return dma_.controller.template read<3>();
+				case 0x0004:	return dma_.controller.template read<4>();
+				case 0x0005:	return dma_.controller.template read<5>();
+				case 0x0006:	return dma_.controller.template read<6>();
+				case 0x0007:	return dma_.controller.template read<7>();
 
 				case 0x0008:	return dma_.controller.status();