From 389541be6d8d8e0055e1153b220a3afca1c03ed3 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 20 Mar 2024 14:43:47 -0400
Subject: [PATCH] Pipe further sound parameters; obey divider.

---
 .../Acorn/Archimedes/MemoryController.hpp     |  6 ++--
 Machines/Acorn/Archimedes/Sound.hpp           | 17 +++++++++++
 Machines/Acorn/Archimedes/Video.hpp           | 29 +++++++++++++------
 3 files changed, 41 insertions(+), 11 deletions(-)

diff --git a/Machines/Acorn/Archimedes/MemoryController.hpp b/Machines/Acorn/Archimedes/MemoryController.hpp
index ff200b8f53..28c8cc5908 100644
--- a/Machines/Acorn/Archimedes/MemoryController.hpp
+++ b/Machines/Acorn/Archimedes/MemoryController.hpp
@@ -10,6 +10,7 @@
 
 #include "InputOutputController.hpp"
 #include "Video.hpp"
+#include "Sound.hpp"
 
 #include "../../../InstructionSets/ARM/Registers.hpp"
 #include "../../../Outputs/Log.hpp"
@@ -30,7 +31,8 @@ static_assert(BitMask<15, 14>::value == 49152);
 /// Models the MEMC, making this the Archimedes bus. Owns various other chips on the bus as a result.
 template <typename InterruptObserverT>
 struct MemoryController {
-	MemoryController(InterruptObserverT &delegate) : ioc_(delegate) {}
+	MemoryController(InterruptObserverT &observer) :
+		ioc_(observer), vidc_(observer, ioc_.sound()) {}
 
 	int interrupt_mask() const {
 		return ioc_.interrupt_mask();
@@ -251,7 +253,7 @@ struct MemoryController {
 		std::array<uint8_t, 4*1024*1024> ram_{};
 		std::array<uint8_t, 2*1024*1024> rom_;
 		InputOutputController<InterruptObserverT> ioc_;
-		Video vidc_;
+		Video<InterruptObserverT, Sound<InputOutputController<InterruptObserverT>>> vidc_;
 
 		template <typename IntT>
 		IntT &physical_ram(uint32_t address) {
diff --git a/Machines/Acorn/Archimedes/Sound.hpp b/Machines/Acorn/Archimedes/Sound.hpp
index aad9bd1f01..7241c2d591 100644
--- a/Machines/Acorn/Archimedes/Sound.hpp
+++ b/Machines/Acorn/Archimedes/Sound.hpp
@@ -8,8 +8,11 @@
 
 #pragma once
 
+#include <cstdint>
+
 namespace Archimedes {
 
+/// Models the Archimedes sound output; in a real machine this is a joint efort between the VIDC and the MEMC.
 template <typename InterruptObserverT>
 struct Sound {
 	Sound(InterruptObserverT &observer) : observer_(observer) {}
@@ -34,11 +37,23 @@ struct Sound {
 		halted_ = false;
 	}
 
+	void set_frequency(uint8_t frequency) {
+		divider_ = reload_ = frequency;
+	}
+
+	void set_stereo_image([[maybe_unused]] uint8_t channel, [[maybe_unused]] uint8_t value) {
+		// TODO.
+	}
+
 	void tick() {
 		if(halted_) {
 			return;
 		}
 
+		--divider_;
+		if(divider_) return;
+		divider_ = reload_;
+
 		current_.start += 16;
 		if(current_.start == current_.end) {
 			if(next_buffer_valid_) {
@@ -50,6 +65,8 @@ struct Sound {
 	}
 
 private:
+	uint8_t divider_ = 0, reload_ = 0;
+
 	void set_buffer_valid(bool valid) {
 		next_buffer_valid_ = valid;
 		observer_.update_sound_interrupt();
diff --git a/Machines/Acorn/Archimedes/Video.hpp b/Machines/Acorn/Archimedes/Video.hpp
index 3a69d0c030..1fd829e638 100644
--- a/Machines/Acorn/Archimedes/Video.hpp
+++ b/Machines/Acorn/Archimedes/Video.hpp
@@ -14,7 +14,11 @@
 
 namespace Archimedes {
 
+template <typename InterruptObserverT, typename SoundT>
 struct Video {
+	Video(InterruptObserverT &observer, SoundT &sound) :
+		observer_(observer), sound_(sound) {}
+
 	void write(uint32_t value) {
 		const auto target = (value >> 24) & 0xfc;
 
@@ -34,11 +38,6 @@ struct Video {
 				logger.error().append("TODO: Cursor colour %d to %03x", (target - 0x44) >> 2, value & 0x1fff);
 			break;
 
-			case 0x60:	case 0x64:	case 0x68:	case 0x6c:
-			case 0x70:	case 0x74:	case 0x78:	case 0x7c:
-				logger.error().append("TODO: Stereo image register %d to %03x", (target - 0x60) >> 2, value & 0x7);
-			break;
-
 			case 0x80:
 				logger.error().append("TODO: Video horizontal period: %d", (value >> 14) & 0x3ff);
 			break;
@@ -89,14 +88,24 @@ struct Video {
 				logger.error().append("TODO: Video vertical cursor end: %d", (value >> 14) & 0x3ff);
 			break;
 
-			case 0xc0:
-				logger.error().append("TODO: Sound frequency: %d", value & 0x7f);
-			break;
-
 			case 0xe0:
 				logger.error().append("TODO: video control: %08x", value);
 			break;
 
+			//
+			// Sound parameters.
+			//
+			case 0x60:	case 0x64:	case 0x68:	case 0x6c:
+			case 0x70:	case 0x74:	case 0x78:	case 0x7c: {
+				const uint8_t channel = ((value >> 26) + 7) & 7;
+				sound_.set_stereo_image(channel, value & 7);
+			} break;
+
+			case 0xc0:
+				sound_.set_frequency(value & 0x7f);
+			break;
+
+
 			default:
 				logger.error().append("TODO: unrecognised VIDC write of %08x", value);
 			break;
@@ -105,6 +114,8 @@ struct Video {
 
 private:
 	Log::Logger<Log::Source::ARMIOC> logger;
+	InterruptObserverT &observer_;
+	SoundT &sound_;
 };
 
 }