1 files changed, 47 insertions, 0 deletions
diff --git a/examples/2_convolve_overlap_save.cpp b/examples/2_convolve_overlap_save.cpp
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+++ b/examples/2_convolve_overlap_save.cpp
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+/**
+ * 2_convolve_overlap_save.cpp
+ * Written by Clyne Sullivan.
+ *
+ * This convolution examples takes an overlap-save approach, where samples from the previous run
+ * are saved so that the overall operation is not interrupted (i.e. the observed output will
+ * transition smoothly between processed "chunks").
+ *
+ * Note that there are still improvements that can be made to the code; for example, notice every
+ * spot where an integer/float conversion is necessary. Operations like these may slow down the
+ * computation.
+ */
+
+Sample* process_data(Samples samples)
+{
+    static Samples buffer;
+
+    constexpr unsigned int filter_size = 3;
+	float filter[filter_size] = {
+        0.3333, 0.3333, 0.3333
+    };
+
+    // Keep a buffer of extra samples for overlap-save
+    static Sample prev[filter_size];
+
+    for (int n = 0; n < SIZE; n++) {
+        buffer[n] = 0;
+
+        for (int k = 0; k < filter_size; k++) {
+            int i = n - (filter_size - 1) + k;
+
+            // If i is >= 0, access current sample buffer.
+            // If i is < 0, provide the previous samples from the 'prev' buffer
+            if (i >= 0)
+                buffer[n] += samples[i] * filter[k];
+            else
+                buffer[n] += prev[filter_size - 1 + i] * filter[k];
+        }
+    }
+
+    // Save samples for the next convolution run
+    for (int i = 0; i < filter_size; i++)
+        prev[i] = samples[SIZE - filter_size + i];
+
+    return buffer;
+}
+