Add freeverb adjustable roomsize & damping

effect_freeverb.cpp

@@ -24,6 +24,10 @@
  * THE SOFTWARE.
  */
 
+// A fixed point implementation of Freeverb by Jezar at Dreampoint
+//  http://blog.bjornroche.com/2012/06/freeverb-original-public-domain-code-by.html
+//  https://music.columbia.edu/pipermail/music-dsp/2001-October/045433.html
+
 #include <Arduino.h>
 #include "effect_freeverb.h"
 #include "utility/dspinst.h"
@@ -83,28 +87,54 @@ static int16_t sat16(int32_t n, int rshift)
 }
 #endif
 
+// TODO: move this to one of the data files, use in output_adat.cpp, output_tdm.cpp, etc
+static const audio_block_t zeroblock = {
+0, 0, 0, {
+0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+#if AUDIO_BLOCK_SAMPLES > 16
+0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+#endif
+#if AUDIO_BLOCK_SAMPLES > 32
+0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+#endif
+#if AUDIO_BLOCK_SAMPLES > 48
+0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+#endif
+#if AUDIO_BLOCK_SAMPLES > 64
+0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+#endif
+#if AUDIO_BLOCK_SAMPLES > 80
+0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+#endif
+#if AUDIO_BLOCK_SAMPLES > 96
+0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+#endif
+#if AUDIO_BLOCK_SAMPLES > 112
+0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+#endif
+} };
+
 void AudioEffectFreeverb::update()
 {
 #if defined(KINETISK)
-	audio_block_t *block, *outblock;
+	const audio_block_t *block;
+	audio_block_t *outblock;
 	int i;
 	int16_t input, bufout, output;
 	int32_t sum;
 
 	outblock = allocate();
 	if (!outblock) {
-		block = receiveReadOnly(0);
-		if (block) release(block);
+		audio_block_t *tmp = receiveReadOnly(0);
+		if (tmp) release(tmp);
 		return;
 	}
 	block = receiveReadOnly(0);
-	if (!block) {
-		release(outblock);
-		return;
-		// TODO: pointer to zero block
-	}
-	for (i=0; i < 128; i++) {
-		input = sat16(block->data[i] * 21845, 17); // div by 6, for numerical headroom
+	if (!block) block = &zeroblock;
+
+	for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
+		// TODO: scale numerical range depending on roomsize & damping
+		input = sat16(block->data[i] * 8738, 17); // for numerical headroom
 		sum = 0;
 
 		bufout = comb1buf[comb1index];
@@ -177,11 +207,11 @@ void AudioEffectFreeverb::update()
 		output = sat16(bufout - output, 1);
 		if (++allpass4index >= sizeof(allpass4buf)/sizeof(int16_t)) allpass4index = 0;
 
-		outblock->data[i] = sat16(output * 12, 0);
+		outblock->data[i] = sat16(output * 30, 0);
 	}
 	transmit(outblock);
 	release(outblock);
-	release(block);
+	if (block != &zeroblock) release((audio_block_t *)block);
 
 #elif defined(KINETISL)
 	audio_block_t *block;

effect_freeverb.h

@@ -32,9 +32,23 @@
 class AudioEffectFreeverb : public AudioStream
 {
 public:
-	//AudioEffectFreeverb() : AudioStream(1, inputQueueArray);
 	AudioEffectFreeverb();
 	virtual void update();
+	void roomsize(float n) {
+		if (n > 1.0f) n = 1.0f;
+		else if (n < 0.0) n = 0.0f;
+		combfeeback = (int)(n * 9175.04f) + 22937;
+	}
+	void damping(float n) {
+		if (n > 1.0f) n = 1.0f;
+		else if (n < 0.0) n = 0.0f;
+		int x1 = (int)(n * 13107.2f);
+		int x2 = 32768 - x1;
+		__disable_irq();
+		combdamp1 = x1;
+		combdamp2 = x2;
+		__enable_irq();
+	}
 private:
 	audio_block_t *inputQueueArray[2];
 	int16_t comb1buf[1116];

keywords.txt

@@ -89,6 +89,8 @@ unmuteInput	KEYWORD2
 enableDither	KEYWORD2
 disableDither	KEYWORD2
 reverbTime	KEYWORD2
+roomsize	KEYWORD2
+damping	KEYWORD2
 frequency	KEYWORD2
 phase	KEYWORD2
 amplitude	KEYWORD2