From 9215535beec67afff56447eca1987b7095d857f4 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 9 Aug 2021 17:35:09 -0400
Subject: [PATCH] Adds a container for the disk controller.

Thereby appears to prove that my Amiga is getting as far as attempting to load from floppy.
---
 Machines/Amiga/Chipset.cpp |  6 ++++-
 Machines/Amiga/Chipset.hpp | 48 ++++++++++++++++++++++++++++++++------
 2 files changed, 46 insertions(+), 8 deletions(-)

diff --git a/Machines/Amiga/Chipset.cpp b/Machines/Amiga/Chipset.cpp
index acf823468..42dc3d941 100644
--- a/Machines/Amiga/Chipset.cpp
+++ b/Machines/Amiga/Chipset.cpp
@@ -40,6 +40,7 @@ enum InterruptFlag: uint16_t {
 Chipset::Chipset(uint16_t *ram, size_t size) :
 	blitter_(ram, size),
 	copper_(*this, ram, size),
+	disk_(*this, ram, size),
 	crt_(908, 4, Outputs::Display::Type::PAL50, Outputs::Display::InputDataType::Red4Green4Blue4) {
 }
 
@@ -420,7 +421,10 @@ void Chipset::perform(const CPU::MC68000::Microcycle &cycle) {
 		break;
 
 		// Disk DMA.
-		case Write(0x020):	case Write(0x022):	case Write(0x024):
+		case Write(0x020):	disk_.set_address<16>(cycle.value16());	break;
+		case Write(0x022):	disk_.set_address<0>(cycle.value16());	break;
+		case Write(0x024):	disk_.set_length(cycle.value16());		break;
+
 		case Write(0x026):
 			LOG("TODO: disk DMA; " << PADHEX(4) << cycle.value16() << " to " << *cycle.address);
 		break;
diff --git a/Machines/Amiga/Chipset.hpp b/Machines/Amiga/Chipset.hpp
index cc8130f20..39d33deaa 100644
--- a/Machines/Amiga/Chipset.hpp
+++ b/Machines/Amiga/Chipset.hpp
@@ -61,6 +61,18 @@ class Chipset {
 		Outputs::Display::DisplayType get_display_type() const;
 
 	private:
+		// MARK: - Common base for DMA components.
+
+		class DMADevice {
+			public:
+				DMADevice(Chipset &chipset, uint16_t *ram, size_t size) : chipset_(chipset), ram_(ram), ram_mask_(uint32_t(size - 1)) {}
+
+			protected:
+				Chipset &chipset_;
+				uint16_t *ram_ = nullptr;
+				uint32_t ram_mask_ = 0;
+		};
+
 		// MARK: - Interrupts.
 
 		uint16_t interrupt_enable_ = 0;
@@ -103,9 +115,9 @@ class Chipset {
 
 		// MARK: - Copper.
 
-		class Copper {
+		class Copper: public DMADevice {
 			public:
-				Copper(Chipset &chipset, uint16_t *ram, size_t size) : chipset_(chipset), ram_(ram), ram_mask_(uint32_t(size - 1)) {}
+				using DMADevice::DMADevice;
 
 				/// Offers a DMA slot to the Copper, specifying the current beam position.
 				///
@@ -134,8 +146,6 @@ class Chipset {
 				}
 
 			private:
-				Chipset &chipset_;
-
 				uint32_t address_ = 0;
 				uint32_t addresses_[2]{};
 				uint16_t control_ = 0;
@@ -146,9 +156,6 @@ class Chipset {
 				bool skip_next_ = false;
 				uint16_t instruction_[2]{};
 				uint16_t position_mask_ = 0xffff;
-
-				uint16_t *ram_ = nullptr;
-				uint32_t ram_mask_ = 0;
 		} copper_;
 
 		// MARK: - Serial port.
@@ -163,6 +170,33 @@ class Chipset {
 				uint16_t status;
 		} serial_;
 
+		// MARK: - Disk drives.
+
+		class DiskDMA: public DMADevice {
+			public:
+				using DMADevice::DMADevice;
+
+				template <int shift> void set_address(uint16_t value) {
+					address_ = (address_ & (0xffff'0000 >> shift)) | uint32_t(value << shift);
+				}
+
+				void set_length(uint16_t value) {
+					dma_enable_ = value & 0x8000;
+					write_ = value & 0x4000;
+					length_ = value & 0x3fff;
+
+					if(dma_enable_) {
+						printf("Not yet implemented: disk DMA [%s of %d to %06x]\n", write_ ? "write" : "read", length_, address_);
+					}
+				}
+
+			private:
+				uint32_t address_;
+				uint16_t length_;
+				bool dma_enable_ = false;
+				bool write_ = false;
+		} disk_;
+
 		// MARK: - Pixel output.
 
 		Outputs::CRT::CRT crt_;