test ssb

lib/hilbert.c

@@ -0,0 +1,24 @@
+#include "hilbert.h"
+
+void init_hilbert(HilbertTransformer *hilbert) {
+    hilbert->delay = calloc(D_SIZE, sizeof(float));
+    hilbert->dptr = 0;
+}
+
+void apply_hilbert(HilbertTransformer *hilbert, float sample, float *output_0deg, float *output_90deg) {
+    float hilb;
+
+    hilbert->delay[hilbert->dptr] = sample;
+    hilb = 0.0f;
+    for(int i = 0; i < NZEROS/2; i++) {
+        hilb += (xcoeffs[i] * hilbert->delay[(hilbert->dptr - i*2) & (D_SIZE - 1)]);
+    }
+
+    *output_0deg = hilbert->delay[(hilbert->dptr - 99) & (D_SIZE - 1)];
+    *output_90deg = hilb;
+    hilbert->dptr = (hilbert->dptr + 1) & (D_SIZE - 1);
+}
+
+void exit_hilbert(HilbertTransformer *hilbert) {
+    free(hilbert->delay);
+}

lib/hilbert.h

@@ -0,0 +1,42 @@
+#include <stdlib.h>
+
+#define D_SIZE 256
+#define NZEROS 200
+
+/* The non-zero taps of the Hilbert transformer */
+static float xcoeffs[] = {
+     +0.0008103736f, +0.0008457886f, +0.0009017196f, +0.0009793364f,
+     +0.0010798341f, +0.0012044365f, +0.0013544008f, +0.0015310235f,
+     +0.0017356466f, +0.0019696659f, +0.0022345404f, +0.0025318040f,
+     +0.0028630784f, +0.0032300896f, +0.0036346867f, +0.0040788644f,
+     +0.0045647903f, +0.0050948365f, +0.0056716186f, +0.0062980419f,
+     +0.0069773575f, +0.0077132300f, +0.0085098208f, +0.0093718901f,
+     +0.0103049226f, +0.0113152847f, +0.0124104218f, +0.0135991079f,
+     +0.0148917649f, +0.0163008758f, +0.0178415242f, +0.0195321089f,
+     +0.0213953037f, +0.0234593652f, +0.0257599469f, +0.0283426636f,
+     +0.0312667947f, +0.0346107648f, +0.0384804823f, +0.0430224431f,
+     +0.0484451086f, +0.0550553725f, +0.0633242001f, +0.0740128560f,
+     +0.0884368322f, +0.1090816773f, +0.1412745301f, +0.1988673273f,
+     +0.3326528346f, +0.9997730178f, -0.9997730178f, -0.3326528346f,
+     -0.1988673273f, -0.1412745301f, -0.1090816773f, -0.0884368322f,
+     -0.0740128560f, -0.0633242001f, -0.0550553725f, -0.0484451086f,
+     -0.0430224431f, -0.0384804823f, -0.0346107648f, -0.0312667947f,
+     -0.0283426636f, -0.0257599469f, -0.0234593652f, -0.0213953037f,
+     -0.0195321089f, -0.0178415242f, -0.0163008758f, -0.0148917649f,
+     -0.0135991079f, -0.0124104218f, -0.0113152847f, -0.0103049226f,
+     -0.0093718901f, -0.0085098208f, -0.0077132300f, -0.0069773575f,
+     -0.0062980419f, -0.0056716186f, -0.0050948365f, -0.0045647903f,
+     -0.0040788644f, -0.0036346867f, -0.0032300896f, -0.0028630784f,
+     -0.0025318040f, -0.0022345404f, -0.0019696659f, -0.0017356466f,
+     -0.0015310235f, -0.0013544008f, -0.0012044365f, -0.0010798341f,
+     -0.0009793364f, -0.0009017196f, -0.0008457886f, -0.0008103736f,
+};
+
+typedef struct {
+    float* delay;
+    int dptr;
+} HilbertTransformer;
+
+void init_hilbert(HilbertTransformer *hilbert);
+void apply_hilbert(HilbertTransformer *hilbert, float sample, float *output_0deg, float *output_90deg);
+void exit_hilbert(HilbertTransformer *hilbert);