new additions

middleware/include/high_pass.h

@@ -3,6 +3,23 @@
 
 #include <stdio.h>
 
-int high_pass(int alpha, int scale);
+typedef struct {
+	//Function Parameters
+	float alpha;
+	float scale;
+
+	float prev_output;
+
+} high_pass_st;
+
+void high_pass_init(float alpha, float scale, high_pass_st filter);
+/**
+@brief Initialization for high pass values
+ */
+
+float high_pass(high_pass_st filter, float input);
+/**
+@brief Function for high pass filter
+ */
 
 #endif

middleware/src/high_pass.c

@@ -17,36 +17,27 @@ output = alpha * last_output + (1-alpha) * input
 output = alpha * last_output + alpha * (avg - prev_avg)
 
 */
-#include "high_pass.h"
 
-//Samples can be modified
-#define SAMPLES 12
+#include "high_pass.h"
 
-//Scale Var allows adjustment of output strength
-//Alpha Var controls weight of prev input & sum difference
-float high_pass(int alpha, int scale)
+void high_pass_init(float alpha, float scale, high_pass_st filter)
 {
-	static float buffer[SAMPLES] = { 0 }; //initialize changing buffer
-	static int index = 0;
-	static float prev_sum = 0.0;
-
-	//buffer[index] = freq; //-> adding the freq input into the
-
-	index = (index + 1) % SAMPLES;
+	filter->alpha = alpha;
+	filter->scale = scale;
 
-	float sum = 0.0;
-
-	//Iterates through all indices
-	for (int i = 0; i < SAMPLES; i++) {
-		sum += buffer[i];
-	}
+	filter->prev_output = 0.0;
+}
 
-	//Algorithm
-	//
+//y[n]=x[n]−SMA[n]
+//The output is equal to the input - the moving average
+float high_pass(high_pass_st filter, float input)
+{
 	float output =
-		scale * (alpha * buffer[index - 1] + alpha * (sum - prev_sum));
+		filter->scale(input - (filter->alpha * input +
+				       (1 - filter->alpha) * prev_output));
 
-	prev_sum = sum; //updates the prev_sum
+	filter->prev_output =
+		filter->alpha * input + (1 - filter->alpha) * prev_output;
 
 	return output;
 }