Add PulseGenerator to digital.hpp

include/dsp.hpp

@@ -9,6 +9,7 @@
 #include "dsp/decimator.hpp"
 #include "dsp/filter.hpp"
 #include "dsp/minblep.hpp"
+#include "dsp/digital.hpp"
 
 
 #include <assert.h>

include/dsp/digital.hpp

@@ -0,0 +1,68 @@
+#pragma once
+
+#include "math.hpp"
+
+
+namespace rack {
+
+
+/** Turns high when value reaches the high threshold, turns low when value reaches the low threshold */
+struct SchmittTrigger {
+	// UNKNOWN is used to represent a stable state when the previous state is not yet set
+	enum {UNKNOWN, LOW, HIGH} state = UNKNOWN;
+	float low = 0.0;
+	float high = 1.0;
+	void setThresholds(float low, float high) {
+		this->low = low;
+		this->high = high;
+	}
+	/** Returns true if triggered */
+	bool process(float in) {
+		switch (state) {
+			case LOW:
+				if (in >= high) {
+					state = HIGH;
+					return true;
+				}
+				break;
+			case HIGH:
+				if (in <= low) {
+					state = LOW;
+				}
+				break;
+			default:
+				if (in >= high) {
+					state = HIGH;
+				}
+				else if (in <= low) {
+					state = LOW;
+				}
+				break;
+		}
+		return false;
+	}
+	void reset() {
+		state = UNKNOWN;
+	}
+};
+
+
+/** When triggered, holds a high value for a specified time before going low again */
+struct PulseGenerator {
+	float time = 0.0;
+	float pulseTime = 0.0;
+	bool process(float deltaTime) {
+		time += deltaTime;
+		return time < pulseTime;
+	}
+	void trigger(float pulseTime) {
+		// Keep the previous pulseTime if the existing pulse would be held longer than the currently requested one.
+		if (time + pulseTime >= this->pulseTime) {
+			time = 0.0;
+			this->pulseTime = pulseTime;
+		}
+	}
+};
+
+
+} // namespace rack

include/dsp/filter.hpp

@@ -59,31 +59,4 @@ struct SlewLimiter {
 };
 
 
-struct SchmittTrigger {
-	/** 0 unknown, 1 low, 2 high */
-	int state = 0;
-	float low = 0.0;
-	float high = 1.0;
-	void setThresholds(float low, float high) {
-		this->low = low;
-		this->high = high;
-	}
-	/** Returns true if triggered */
-	bool process(float in) {
-		bool triggered = false;
-		if (in >= high) {
-			if (state == 1)
-				triggered = true;
-			state = 2;
-		}
-		else if (in <= low) {
-			state = 1;
-		}
-		return triggered;
-	}
-	void reset() {
-		state = 0;
-	}
-};
-
 } // namespace rack