Audio Processor now uses atomics rather than mutex

Core/HLE/__sceAudio.cpp

@@ -29,8 +29,9 @@
 #include "FixedSizeQueue.h"
 #include "Common/Thread.h"
 
+
 // Should be used to lock anything related to the outAudioQueue.
-recursive_mutex section;
+std::atomic<bool> audioQueueLock;
 
 int eventAudioUpdate = -1;
 int eventHostAudioUpdate = -1;
@@ -55,6 +56,10 @@ static int chanQueueMinSizeFactor;
 // is bad mojo.
 FixedSizeQueue<s16, 512 * 16> outAudioQueue;
 
+
+bool __gainAudioQueueLock();
+
+
 static inline s16 clamp_s16(int i) {
 	if (i > 32767)
 		return 32767;
@@ -108,6 +113,8 @@ void __AudioInit() {
 
 	mixBuffer = new s32[hwBlockSize * 2];
 	memset(mixBuffer, 0, hwBlockSize * 2 * sizeof(s32));
+
+	audioQueueLock.store(false);
 }
 
 void __AudioDoState(PointerWrap &p) {
@@ -123,8 +130,15 @@ void __AudioDoState(PointerWrap &p) {
 	p.Do(mixFrequency);
 
 	{
-		lock_guard guard(section);
+		if(!__gainAudioQueueLock()){
+			return;
+		}
+
 		outAudioQueue.DoState(p);
+
+		//release the atomic lock
+		audioQueueLock.store(false);
+		
 	}
 
 	int chanCount = ARRAY_SIZE(chans);
@@ -322,11 +336,18 @@ void __AudioUpdate() {
 	}
 
 	if (g_Config.bEnableSound) {
-		lock_guard guard(section);
+
+		//looks like the heavy lifting is done here.
+		//we have to optimize this some more.
+		if(!__gainAudioQueueLock()){
+			return;
+		}
+
 		if (outAudioQueue.room() >= hwBlockSize * 2) {
 			s16 *buf1 = 0, *buf2 = 0;
 			size_t sz1, sz2;
 			outAudioQueue.pushPointers(hwBlockSize * 2, &buf1, &sz1, &buf2, &sz2);
+			
 			for (size_t s = 0; s < sz1; s++)
 				buf1[s] = clamp_s16(mixBuffer[s]);
 			if (buf2) {
@@ -337,6 +358,9 @@ void __AudioUpdate() {
 			// This happens quite a lot. There's still something slightly off
 			// about the amount of audio we produce.
 		}
+	
+		//release the atomic lock
+		audioQueueLock.store(false);
 	}
 }
 
@@ -352,12 +376,21 @@ int __AudioMix(short *outstereo, int numFrames)
 	const s16 *buf1 = 0, *buf2 = 0;
 	size_t sz1, sz2;
 	{
-		lock_guard guard(section);
+
+		if(!__gainAudioQueueLock()){
+			return numFrames;
+		}
+			
+		
 		outAudioQueue.popPointers(numFrames * 2, &buf1, &sz1, &buf2, &sz2);
+
 		memcpy(outstereo, buf1, sz1 * sizeof(s16));
 		if (buf2) {
 			memcpy(outstereo + sz1, buf2, sz2 * sizeof(s16));
 		}
+
+		//release the atomic lock
+		audioQueueLock.store(false);
 	}
 
 	int remains = (int)(numFrames * 2 - sz1 - sz2);
@@ -370,3 +403,13 @@ int __AudioMix(short *outstereo, int numFrames)
 	}
 	return underrun >= 0 ? underrun : numFrames;
 }
+
+
+bool __gainAudioQueueLock(){
+	if(audioQueueLock.load(std::memory_order::memory_order_relaxed) == true){
+		return false;
+	}
+
+	audioQueueLock.store(true, std::memory_order::memory_order_relaxed );
+	return true;
+};

Core/HLE/__sceAudio.h

@@ -16,8 +16,10 @@
 // https://github.com/hrydgard/ppsspp and http://www.ppsspp.org/.
 
 #pragma once
-
 #include "sceAudio.h"
+#include <atomic>
+
+
 
 // Easy interface for sceAudio to write to, to keep the complexity in check.