1 files changed, 75 insertions, 0 deletions
diff --git a/reset-controller/fw/src/dsss_demod.h b/reset-controller/fw/src/dsss_demod.h
new file mode 100644
index 0000000..b865d83
--- /dev/null
+++ b/reset-controller/fw/src/dsss_demod.h
@@ -0,0 +1,75 @@
+#ifndef __DSSS_DEMOD_H__
+#define __DSSS_DEMOD_H__
+
+#include <stdint.h>
+#include <unistd.h>
+
+#define DSSS_GOLD_CODE_LENGTH   ((1<<DSSS_GOLD_CODE_NBITS) - 1)
+#define DSSS_GOLD_CODE_COUNT    ((1<<DSSS_GOLD_CODE_NBITS) + 1)
+#define DSSS_CORRELATION_LENGTH (DSSS_GOLD_CODE_LENGTH * DSSS_DECIMATION)
+
+/* FIXME: move to makefile */
+#define DSSS_MATCHER_CACHE_SIZE 8
+
+#if DSSS_GOLD_CODE_NBITS < 8
+typedef uint8_t symbol_t;
+#else
+typedef uint16_t symbol_t;
+#endif
+
+struct iir_biquad {
+    float a[2];
+    float b[3];
+};
+
+struct iir_biquad_state {
+    float reg[2];
+};
+
+struct cwt_iir_filter_state {
+    struct iir_biquad_state st[3];
+};
+
+struct group {
+    int len; /* length of group in samples */
+    float max; /* signed value of largest peak in group on any channel */
+    uint64_t max_ts; /* absolute position of above peak */
+    int max_ch; /* channel (gold sequence index) of above peak */
+};
+
+struct matcher_state {
+    int last_phase; /* 0 .. DSSS_CORRELATION_LENGTH */
+    int candidate_phase;
+
+    float last_score;
+    float candidate_score;
+
+    int last_skips;
+    int candidate_skips;
+
+    symbol_t data[TRANSMISSION_SYMBOLS]; 
+    int data_pos;
+    symbol_t candidate_data;
+};
+
+struct dsss_demod_state {
+    float signal[DSSS_CORRELATION_LENGTH];
+    size_t signal_wpos;
+
+    float correlation[DSSS_GOLD_CODE_COUNT][DSSS_WAVELET_LUT_SIZE];
+    size_t correlation_wpos;
+
+    struct cwt_iir_filter_state cwt_filter;
+
+    struct group group;
+
+    struct matcher_state matcher_cache[DSSS_MATCHER_CACHE_SIZE];
+};
+
+
+extern void handle_dsss_received(symbol_t data[static TRANSMISSION_SYMBOLS]);
+
+void dsss_demod_init(struct dsss_demod_state *st);
+void dsss_demod_step(struct dsss_demod_state *st, float new_value, uint64_t ts);
+
+#endif /* __DSSS_DEMOD_H__ */