fir

fir.c

@@ -0,0 +1,42 @@
+#include <stdio.h>
+
+#define N 5 // Number of taps (filter coefficients)
+
+// Example filter coefficients (simple low-pass averaging filter)
+float coeffs[N] = {
+    0.2, 0.2, 0.2, 0.2, 0.2 // Equal weights → moving average filter
+};
+
+float buffer[N] = {0}; // Circular buffer to store recent inputs
+int   bufIndex = 0;
+
+float fir_filter(float input) {
+    buffer[bufIndex] = input;
+
+    float output = 0.0;
+    int   index = bufIndex;
+
+    // Apply the convolution (dot product of input buffer and coefficients)
+    for (int i = 0; i < N; ++i) {
+        output += coeffs[i] * buffer[index];
+        if (--index < 0)
+            index = N - 1; // Wrap around circular buffer
+    }
+
+    bufIndex = (bufIndex + 1) % N;
+    return output;
+}
+
+int main() {
+    float noisy_signal[] = {1,   2, 3, 2,
+                            100, 3, 2, 1}; // A spike in the middle (100)
+    int   len = sizeof(noisy_signal) / sizeof(float);
+
+    printf("Filtered output:\n");
+    for (int i = 0; i < len; ++i) {
+        float filtered = fir_filter(noisy_signal[i]);
+        printf("%.2f\n", filtered);
+    }
+
+    return 0;
+}