added presented demo files

1 files changed, 22 insertions, 0 deletions

diff --git a/gui/demos/2_iir_echo.cpp b/gui/demos/2_iir_echo.cpp
new file mode 100644
index 0000000..0bd7e9d
--- /dev/null
+++ b/gui/demos/2_iir_echo.cpp
@@ -0,0 +1,22 @@
+adcsample_t *process_data(adcsample_t *samples, unsigned int size)
+{
+	constexpr float alpha = 0.7;
+	constexpr unsigned int D = 2000;
+
+	static adcsample_t output[SIZE];
+	static adcsample_t prev[D]; // prev[0] = output[0 - D]
+
+	// Do calculations with previous output
+	for (unsigned int i = 0; i < D; i++)
+		output[i] = samples[i] + alpha * (prev[i] - 2048);
+
+	// Do calculations with current samples
+	for (unsigned int i = D; i < size; i++)
+		output[i] = samples[i] + alpha * (output[i - D] - 2048);
+
+	// Save outputs for next computation
+	for (unsigned int i = 0; i < D; i++)
+		prev[i] = output[size - (D - i)];
+
+	return output;
+}