From c31ee968dfa58bd583f8e3e3a111f2e00b80e37b Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 2 Dec 2023 15:24:47 -0500
Subject: [PATCH] TC: start tending towards meaning.

---
 Machines/PCCompatible/DMA.hpp          | 48 +++++++++++++++++++++++++-
 Machines/PCCompatible/PCCompatible.cpp | 27 ---------------
 2 files changed, 47 insertions(+), 28 deletions(-)

diff --git a/Machines/PCCompatible/DMA.hpp b/Machines/PCCompatible/DMA.hpp
index 3e9795bbc..670286457 100644
--- a/Machines/PCCompatible/DMA.hpp
+++ b/Machines/PCCompatible/DMA.hpp
@@ -11,31 +11,41 @@
 
 #include "../../Numeric/RegisterSizes.hpp"
 
+#include "Memory.hpp"
+
 namespace PCCompatible {
 
 class i8237 {
 	public:
 		void flip_flop_reset() {
+			printf("DMA: Flip flop reset\n");
 			next_access_low_ = true;
 		}
 
 		void mask_reset() {
+			printf("DMA: Mask reset\n");
 			for(auto &channel : channels_) {
 				channel.mask = false;
 			}
 		}
 
 		void master_reset() {
+			printf("DMA: Master reset\n");
 			flip_flop_reset();
 			for(auto &channel : channels_) {
 				channel.mask = true;
-				channel.transfer_complete = true;
+				channel.transfer_complete = false;
 				channel.request = false;
 			}
+
+			// This is a bit of a hack; DMA channel 0 is supposed to be linked to the PIT,
+			// performing DRAM refresh. It isn't yet. So hack this, and hack that.
+			channels_[0].transfer_complete = true;
 		}
 
 		template <int address>
 		void write(uint8_t value) {
+			printf("DMA: Write %02x to %d\n", value, address);
 			constexpr int channel = (address >> 1) & 3;
 			constexpr bool is_count = address & 1;
 
@@ -57,6 +67,7 @@ class i8237 {
 
 		template <int address>
 		uint8_t read() {
+			printf("DMA: Read %d\n", address);
 			constexpr int channel = (address >> 1) & 3;
 			constexpr bool is_count = address & 1;
 
@@ -77,14 +88,17 @@ class i8237 {
 		}
 
 		void set_reset_mask(uint8_t value) {
+			printf("DMA: Set/reset mask %02x\n", value);
 			channels_[value & 3].mask = value & 4;
 		}
 
 		void set_reset_request(uint8_t value) {
+			printf("DMA: Set/reset request %02x\n", value);
 			channels_[value & 3].request = value & 4;
 		}
 
 		void set_mask(uint8_t value) {
+			printf("DMA: Set mask %02x\n", value);
 			channels_[0].mask = value & 1;
 			channels_[1].mask = value & 2;
 			channels_[2].mask = value & 4;
@@ -92,6 +106,7 @@ class i8237 {
 		}
 
 		void set_mode(uint8_t value) {
+			printf("DMA: Set mode %02x\n", value);
 			channels_[value & 3].transfer = Channel::Transfer((value >> 2) & 3);
 			channels_[value & 3].autoinitialise = value & 0x10;
 			channels_[value & 3].address_decrement = value & 0x20;
@@ -99,6 +114,7 @@ class i8237 {
 		}
 
 		void set_command(uint8_t value) {
+			printf("DMA: Set command %02x\n", value);
 			enable_memory_to_memory_ = value & 0x01;
 			enable_channel0_address_hold_ = value & 0x02;
 			enable_controller_ = value & 0x04;
@@ -124,6 +140,9 @@ class i8237 {
 			for(auto &channel : channels_) {
 				channel.transfer_complete = false;
 			}
+
+			printf("DMA: status is %02x\n", result);
+
 			return result;
 		}
 
@@ -227,6 +246,33 @@ class DMAPages {
 		}
 };
 
+class DMA {
+	public:
+		i8237 controller;
+		DMAPages pages;
+
+		// Memory is set posthoc to resolve a startup time.
+		void set_memory(Memory *memory) {
+			memory_ = memory;
+		}
+
+		// TODO: this permits only 8-bit DMA. Fix that.
+		bool write(size_t channel, uint8_t value) {
+			auto address = controller.access(channel, true);
+			if(address == i8237::NotAvailable) {
+				return false;
+			}
+
+			address |= uint32_t(pages.channel_page(channel) << 16);
+			*memory_->at(address) = value;
+
+			return true;
+		}
+
+	private:
+		Memory *memory_;
+};
+
 }
 
 #endif /* DMA_hpp */
diff --git a/Machines/PCCompatible/PCCompatible.cpp b/Machines/PCCompatible/PCCompatible.cpp
index f72314c63..d05701f7d 100644
--- a/Machines/PCCompatible/PCCompatible.cpp
+++ b/Machines/PCCompatible/PCCompatible.cpp
@@ -49,33 +49,6 @@ namespace PCCompatible {
 //bool log = false;
 //std::string previous;
 
-class DMA {
-	public:
-		i8237 controller;
-		DMAPages pages;
-
-		// Memory is set posthoc to resolve a startup time.
-		void set_memory(Memory *memory) {
-			memory_ = memory;
-		}
-
-		// TODO: this permits only 8-bit DMA. Fix that.
-		bool write(size_t channel, uint8_t value) {
-			auto address = controller.access(channel, true);
-			if(address == i8237::NotAvailable) {
-				return false;
-			}
-
-			address |= uint32_t(pages.channel_page(channel) << 16);
-			*memory_->at(address) = value;
-
-			return true;
-		}
-
-	private:
-		Memory *memory_;
-};
-
 class FloppyController {
 	public:
 		FloppyController(PIC &pic, DMA &dma) : pic_(pic), dma_(dma) {