From 82d6a5387f940954387ccea00766c4c1497d881f Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 29 Jul 2020 21:06:41 -0400
Subject: [PATCH] Gives Qt disk controllers independent ROM/RAM selection
 logic.

In particular, this fixes the Microdisc.
---
 Machines/Oric/BD500.hpp                    | 15 +++++++++++++++
 Machines/Oric/DiskController.hpp           | 22 ++++++----------------
 Machines/Oric/Jasmin.hpp                   | 10 ++++++++++
 Machines/Oric/Microdisc.cpp                | 15 ++++++++++-----
 Storage/Disk/Controller/DiskController.cpp |  4 ++--
 5 files changed, 43 insertions(+), 23 deletions(-)

diff --git a/Machines/Oric/BD500.hpp b/Machines/Oric/BD500.hpp
index f371dd506..89d839db1 100644
--- a/Machines/Oric/BD500.hpp
+++ b/Machines/Oric/BD500.hpp
@@ -18,6 +18,11 @@
 
 namespace Oric {
 
+/*!
+	Emulates a Byte Drive 500, at least to some extent. Very little is known about this interface,
+	and I'm in possession of only a single disk image. So much of the below is community guesswork;
+	see the thread at https://forum.defence-force.org/viewtopic.php?f=25&t=2055
+*/
 class BD500: public DiskController {
 	public:
 		BD500();
@@ -36,6 +41,16 @@ class BD500: public DiskController {
 
 		void access(int address);
 		void set_head_loaded(bool loaded);
+
+		bool enable_overlay_ram_ = false;
+		bool disable_basic_rom_ = false;
+		void select_paged_item() {
+			PagedItem item = PagedItem::RAM;
+			if(!enable_overlay_ram_) {
+				item = disable_basic_rom_ ? PagedItem::DiskROM : PagedItem::BASIC;
+			}
+			set_paged_item(item);
+		}
 };
 
 };
diff --git a/Machines/Oric/DiskController.hpp b/Machines/Oric/DiskController.hpp
index 6cee28d63..91056a9c9 100644
--- a/Machines/Oric/DiskController.hpp
+++ b/Machines/Oric/DiskController.hpp
@@ -44,28 +44,18 @@ class DiskController: public WD::WD1770 {
 	protected:
 		Delegate *delegate_ = nullptr;
 
-		bool enable_overlay_ram_ = false;
-		bool disable_basic_rom_ = false;
-		void select_paged_item() {
-			PagedItem item = PagedItem::RAM;
-			if(!enable_overlay_ram_) {
-				item = disable_basic_rom_ ? PagedItem::DiskROM : PagedItem::BASIC;
-			}
-			set_paged_item(item);
-		}
-
-	private:
-		PagedItem paged_item_ = PagedItem::DiskROM;
-		int clock_rate_;
-		Storage::Disk::Drive::ReadyType ready_type_;
-
-		inline void set_paged_item(PagedItem item) {
+		void set_paged_item(PagedItem item) {
 			if(paged_item_ == item) return;
 			paged_item_ = item;
 			if(delegate_) {
 				delegate_->disk_controller_did_change_paged_item(this);
 			}
 		}
+
+	private:
+		PagedItem paged_item_ = PagedItem::DiskROM;
+		int clock_rate_;
+		Storage::Disk::Drive::ReadyType ready_type_;
 };
 
 
diff --git a/Machines/Oric/Jasmin.hpp b/Machines/Oric/Jasmin.hpp
index c496d6e1e..9793b92cf 100644
--- a/Machines/Oric/Jasmin.hpp
+++ b/Machines/Oric/Jasmin.hpp
@@ -29,6 +29,16 @@ class Jasmin: public DiskController {
 		uint8_t selected_drives_ = 0;
 
 		Activity::Observer *observer_ = nullptr;
+
+		bool enable_overlay_ram_ = false;
+		bool disable_basic_rom_ = false;
+		void select_paged_item() {
+			PagedItem item = PagedItem::RAM;
+			if(!enable_overlay_ram_) {
+				item = disable_basic_rom_ ? PagedItem::DiskROM : PagedItem::BASIC;
+			}
+			set_paged_item(item);
+		}
 };
 
 };
diff --git a/Machines/Oric/Microdisc.cpp b/Machines/Oric/Microdisc.cpp
index 73c685507..4aac79ae7 100644
--- a/Machines/Oric/Microdisc.cpp
+++ b/Machines/Oric/Microdisc.cpp
@@ -38,7 +38,7 @@ void Microdisc::set_control_register(uint8_t control, uint8_t changes) {
 
 	// b4: side select
 	if(changes & 0x10) {
-		const int head = (control & 0x10) ? 1 : 0;
+		const int head = (control & 0x10) >> 4;
 		for_all_drives([head] (Storage::Disk::Drive &drive, size_t) {
 			drive.set_head(head);
 		});
@@ -52,7 +52,7 @@ void Microdisc::set_control_register(uint8_t control, uint8_t changes) {
 	// b0: IRQ enable
 	if(changes & 0x01) {
 		const bool had_irq = get_interrupt_request_line();
-		irq_enable_ = !!(control & 0x01);
+		irq_enable_ = bool(control & 0x01);
 		const bool has_irq = get_interrupt_request_line();
 		if(has_irq != had_irq && delegate_) {
 			delegate_->wd1770_did_change_output(this);
@@ -62,9 +62,14 @@ void Microdisc::set_control_register(uint8_t control, uint8_t changes) {
 	// b7: EPROM select (0 = select)
 	// b1: ROM disable (0 = disable)
 	if(changes & 0x82) {
-		enable_overlay_ram_ = control & 0x80;
-		disable_basic_rom_ = !(control & 0x02);
-		select_paged_item();
+		PagedItem item;
+		if(control & 0x02) item = PagedItem::BASIC;
+		else if(control & 0x80) {
+			item = PagedItem::RAM;
+		} else {
+			item = PagedItem::DiskROM;
+		}
+		set_paged_item(item);
 	}
 }
 
diff --git a/Storage/Disk/Controller/DiskController.cpp b/Storage/Disk/Controller/DiskController.cpp
index 5972e2dc6..1cba5d39a 100644
--- a/Storage/Disk/Controller/DiskController.cpp
+++ b/Storage/Disk/Controller/DiskController.cpp
@@ -90,7 +90,7 @@ void Controller::set_drive(int index_mask) {
 		return;
 	}
 
-	ClockingHint::Preference former_prefernece = preferred_clocking();
+	const ClockingHint::Preference former_preference = preferred_clocking();
 
 	// Stop receiving events from the current drive.
 	get_drive().set_event_delegate(nullptr);
@@ -114,7 +114,7 @@ void Controller::set_drive(int index_mask) {
 
 	get_drive().set_event_delegate(this);
 
-	if(preferred_clocking() != former_prefernece) {
+	if(preferred_clocking() != former_preference) {
 		update_clocking_observer();
 	}
 }