Diff: SampleFilter.c

Revision:

1:1567f5a4e96f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SampleFilter.c	Mon Oct 30 16:12:27 2017 +0000
@@ -0,0 +1,38 @@
+#include "Samplefilter.h"
+
+static double filter_taps[SAMPLEFILTER_TAP_NUM] = {
+  0.009364555465021395,
+  0.04162548629009952,
+  0.08783132195564536,
+  0.14608632119801232,
+  0.19260258113649567,
+  0.21122159144894026,
+  0.19260258113649567,
+  0.14608632119801232,
+  0.08783132195564536,
+  0.04162548629009952,
+  0.009364555465021395
+};
+
+void SampleFilter_init(SampleFilter* f) {
+  int i;
+  for(i = 0; i < SAMPLEFILTER_TAP_NUM; ++i)
+    f->history[i] = 0;
+  f->last_index = 0;
+}
+
+void SampleFilter_put(SampleFilter* f, double input) {
+  f->history[f->last_index++] = input;
+  if(f->last_index == SAMPLEFILTER_TAP_NUM)
+    f->last_index = 0;
+}
+
+double SampleFilter_get(SampleFilter* f) {
+  double acc = 0;
+  int index = f->last_index, i;
+  for(i = 0; i < SAMPLEFILTER_TAP_NUM; ++i) {
+    index = index != 0 ? index-1 : SAMPLEFILTER_TAP_NUM-1;
+    acc += f->history[index] * filter_taps[i];
+  };
+  return acc;
+}
\ No newline at end of file