BSynth/BSoftSynth: implemented GetAudio().

Patch by Pete Goodeve (modified by me, hopefully for the better and
without introducing bugs) which implements BSynth::GetAudio().

headers/os/midi/Synth.h

@@ -34,8 +34,7 @@ class BMidiSynthFile;
 
 namespace BPrivate { class BSoftSynth; }
 
-class BSynth 
-{
+class BSynth {
 public:
 
 	BSynth();

src/kits/midi/SoftSynth.cpp

@@ -43,7 +43,10 @@ BSoftSynth::BSoftSynth()
 : 	fInitCheck(false),
 	fSynth(NULL),
 	fSettings(NULL),
-	fSoundPlayer(NULL)
+	fSoundPlayer(NULL),
+	fMonitor(NULL),
+	fMonitorSize(0),
+	fMonitorChans(-1)
 {
 	fInstrumentsFile = NULL;
 	SetDefaultInstrumentsFile();
@@ -65,6 +68,7 @@ BSoftSynth::~BSoftSynth()
 	// a big deal, but the Midi Kit will complain (on stdout) that we 
 	// didn't release our endpoints.
 
+	delete[] fMonitor;
 	Unload();
 }
 
@@ -527,13 +531,23 @@ BSoftSynth::PlayBuffer(void* cookie, void* data, size_t size,
 {
 	BSoftSynth* synth = (BSoftSynth*)cookie;
 
+	if (synth->fMonitor != NULL) {
+		delete[] synth->fMonitor;
+		synth->fMonitor = NULL;
+	}
 	// we use float samples
-	
 	if (synth->fSynth) {
 		fluid_synth_write_float(
 			synth->fSynth, size / sizeof(float) / format.channel_count,
 			data, 0, format.channel_count,
 			data, 1, format.channel_count);
+
+		synth->fMonitor = new float[size];
+		synth->fMonitorSize = size;
+		synth->fMonitorChans = format.channel_count;
+		memcpy(synth->fMonitor, data, size);
 	}
+
+
 }
 

src/kits/midi/SoftSynth.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006, Haiku.
+ * Copyright 2006-2014, Haiku.
  * 
  * Copyright (c) 2004-2005 Matthijs Hollemans
  * Copyright (c) 2003 Jerome Leveque
@@ -9,6 +9,7 @@
  * 		Jérôme Duval
  *		Jérôme Leveque
  *		Matthijs Hollemans
+ *		Pete Goodeve
  */
 
 #ifndef _SOFT_SYNTH_H
@@ -107,6 +108,10 @@ private:
 	fluid_settings_t* fSettings;
 
 	BSoundPlayer* fSoundPlayer;
+
+	float* fMonitor;
+	size_t fMonitorSize;
+	int16 fMonitorChans;
 };
 
 } // namespace BPrivate

src/kits/midi/Synth.cpp

@@ -220,11 +220,23 @@ BSynth::GetAudio(int16* pLeft, int16* pRight, int32 max_samples) const
 {
 	// We don't print a "not supported" message here. That would cause
 	// significant slowdowns because applications ask for this many times.
+
+	if (fSynth->fMonitorSize <= 0) {
+		memset(pLeft, 0, max_samples * sizeof(int16));
+		memset(pRight, 0, max_samples * sizeof(int16));
+		return max_samples;
+	}
 	
-	memset(pLeft, 0, max_samples * sizeof(int16));
-	memset(pRight, 0, max_samples * sizeof(int16));
-	
-	return max_samples;
+	int32 nSamples = fSynth->fMonitorSize / sizeof(float)
+			/ fSynth->fMonitorChans;
+	if (nSamples > max_samples)
+		nSamples = max_samples;
+	float* sPtr = fSynth->fMonitor;
+	for (int32 i = 0; i < nSamples; i++, sPtr += fSynth->fMonitorChans) {
+		*pLeft++ = (int16)(*sPtr * 32768);
+		*pRight++ = (int16)(*(sPtr + 1) * 32768);
+	}
+	return nSamples;
 }