fix for compounding/cascading filters

'data' needs to be reset inside the 'flag' controlled loop or
*undefined* behavior is likely when user sets 'flag' and loop repeats
without resetting 'data' to beginning of block.

filter_biquad.cpp

@@ -37,10 +37,10 @@ void AudioFilterBiquad::update(void)
 
 	block = receiveWritable();
 	if (!block) return;
-	data = (uint32_t *)(block->data);
 	end = data + AUDIO_BLOCK_SAMPLES/2;
 	state = (int32_t *)definition;
 	do {
+		data = (uint32_t *)(block->data); // needs to be done inside the loop, end need not be reset.
 		a0 = *state++;
 		a1 = *state++;
 		a2 = *state++;
@@ -78,14 +78,20 @@ void AudioFilterBiquad::update(void)
 	release(block);
 }
 
-void AudioFilterBiquad::updateCoefs(int *source, bool doReset)
+void AudioFilterBiquad::updateCoefs(uint8_t set,int *source, bool doReset)
 {
 	int32_t *dest=(int32_t *)definition;
-	int32_t *src=(int32_t *)source;
+	while(set)
+	{
+		*dest+=7;
+		if(!(*dest&0x80000000)) return;
+		*dest++;
+		set--;
+	}
 	__disable_irq();
 	for(uint8_t index=0;index<5;index++)
 	{
-		*dest++=*src++;
+		*dest++=*source++;
 	}
 	if(doReset)
 	{
@@ -96,8 +102,3 @@ void AudioFilterBiquad::updateCoefs(int *source, bool doReset)
 	__enable_irq();
 }
 
-void AudioFilterBiquad::updateCoefs(int *source)
-{
-	updateCoefs(source,false);
-}
-

filter_biquad.h

@@ -36,8 +36,11 @@ public:
 	   : AudioStream(1, inputQueueArray), definition(parameters) { }
 	virtual void update(void);
 	
-	void updateCoefs(int *source, bool doReset);
-	void updateCoefs(int *source);
+	void updateCoefs(uint8_t set,int *source, bool doReset);
+
+	void updateCoefs(uint8_t set,int *source) { updateCoefs(set,source,false); }
+	void updateCoefs(int *source, bool doReset) { updateCoefs(0,source,doReset); }
+	void updateCoefs(int *source) { updateCoefs(0,source,false); }
 private:
 	int *definition;
 	audio_block_t *inputQueueArray[1];