Add CSND::AcquireSoundChannels

include/services/csnd.hpp

@@ -19,6 +19,7 @@ class CSNDService {
 	std::optional<Handle> csndMutex = std::nullopt;
 
 	// Service functions
+	void acquireSoundChannels(u32 messagePointer);
 	void initialize(u32 messagePointer);
 
   public:

src/core/services/csnd.cpp

@@ -7,6 +7,7 @@
 namespace CSNDCommands {
 	enum : u32 {
 		Initialize = 0x00010140,
+		AcquireSoundChannels = 0x00050000,
 	};
 }
 
@@ -19,6 +20,7 @@ void CSNDService::handleSyncRequest(u32 messagePointer) {
 	const u32 command = mem.read32(messagePointer);
 
 	switch (command) {
+		case CSNDCommands::AcquireSoundChannels: acquireSoundChannels(messagePointer); break;
 		case CSNDCommands::Initialize: initialize(messagePointer); break;
 
 		default:
@@ -28,6 +30,17 @@ void CSNDService::handleSyncRequest(u32 messagePointer) {
 	}
 }
 
+void CSNDService::acquireSoundChannels(u32 messagePointer) {
+	log("CSND::AcquireSoundChannels\n");
+	// The CSND service talks to the DSP using the DSP FIFO to negotiate what CSND channels are allocated to the DSP, and this seems to be channels 0-7 (usually). The rest are dedicated to CSND services.
+	// https://www.3dbrew.org/wiki/CSND_Services
+	constexpr u32 csndChannelMask = 0xFFFFFF00;
+
+	mem.write32(messagePointer, IPC::responseHeader(0x5, 2, 0));
+	mem.write32(messagePointer + 4, Result::Success);
+	mem.write32(messagePointer + 8, csndChannelMask);
+}
+
 void CSNDService::initialize(u32 messagePointer) {
 	u32 blockSize = mem.read32(messagePointer + 4);
 	const u32 offset0 = mem.read32(messagePointer + 8);