From c71fa02bf5c6a154d4d3a029664769e870d3394f Mon Sep 17 00:00:00 2001
From: Bastien Bouclet
Date: Tue, 15 Oct 2019 22:18:05 +0200
Subject: 3DS: Change the audio thread to wait for the audio buffers to
 complete

Fixes the regular pop sounds caused by buffer underruns / clobbering of
the previous implementation.
---
 backends/platform/3ds/osystem-audio.cpp | 34 +++++++++++++++------------------
 1 file changed, 15 insertions(+), 19 deletions(-)

(limited to 'backends/platform/3ds')

diff --git a/backends/platform/3ds/osystem-audio.cpp b/backends/platform/3ds/osystem-audio.cpp
index 58262372cc..043aaf1fe2 100644
--- a/backends/platform/3ds/osystem-audio.cpp
+++ b/backends/platform/3ds/osystem-audio.cpp
@@ -31,18 +31,16 @@ static void audioThreadFunc(void *arg) {
 	Audio::MixerImpl *mixer = (Audio::MixerImpl *)arg;
 	OSystem_3DS *osys = (OSystem_3DS *)g_system;
 
-	int i;
 	const int channel = 0;
 	int bufferIndex = 0;
-	const int bufferCount = 3;
-	const int bufferSize = 80000; // Can't be too small, based on delayMillis duration
+	const int bufferCount = 2;
 	const int sampleRate = mixer->getOutputRate();
-	int sampleLen = 0;
-	uint32 lastTime = osys->getMillis(true);
-	uint32 time = lastTime;
+	const int bufferSamples = 1024;
+	const int bufferSize = bufferSamples * 4;
+
 	ndspWaveBuf buffers[bufferCount];
 
-	for (i = 0; i < bufferCount; ++i) {
+	for (int i = 0; i < bufferCount; ++i) {
 		memset(&buffers[i], 0, sizeof(ndspWaveBuf));
 		buffers[i].data_vaddr = linearAlloc(bufferSize);
 		buffers[i].looping = false;
@@ -55,27 +53,25 @@ static void audioThreadFunc(void *arg) {
 	ndspChnSetFormat(channel, NDSP_FORMAT_STEREO_PCM16);
 
 	while (!osys->exiting) {
-		osys->delayMillis(100); // Note: Increasing the delay requires a bigger buffer
-
-		time = osys->getMillis(true);
-		sampleLen = (time - lastTime) * 22 * 4; // sampleRate / 1000 * channelCount * sizeof(int16);
-		lastTime = time;
+		svcSleepThread(5000 * 1000); // Wake up the thread every 5 ms
 
-		if (!osys->sleeping && sampleLen > 0) {
-			bufferIndex++;
-			bufferIndex %= bufferCount;
-			ndspWaveBuf *buf = &buffers[bufferIndex];
+		if (osys->sleeping) continue;
 
-			buf->nsamples = mixer->mixCallback(buf->data_adpcm, sampleLen);
+		ndspWaveBuf *buf = &buffers[bufferIndex];
+		if (buf->status == NDSP_WBUF_FREE || buf->status == NDSP_WBUF_DONE) {
+			buf->nsamples = mixer->mixCallback(buf->data_adpcm, bufferSize);
 			if (buf->nsamples > 0) {
 				DSP_FlushDataCache(buf->data_vaddr, bufferSize);
 				ndspChnWaveBufAdd(channel, buf);
 			}
+
+			bufferIndex++;
+			bufferIndex %= bufferCount;
 		}
 	}
 
-	for (i = 0; i < bufferCount; ++i)
-		linearFree(buffers[i].data_pcm8);
+	for (int i = 0; i < bufferCount; ++i)
+		linearFree(buffers[i].data_pcm16);
 }
 
 void OSystem_3DS::initAudio() {
-- 
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