RFID: add support for Kantech IOProx cards (#1261)

applications/lfrfid/helpers/decoder_ioprox.cpp

@@ -0,0 +1,107 @@
+#include "decoder_ioprox.h"
+#include <furi_hal.h>
+#include <cli/cli.h>
+#include <utility>
+
+constexpr uint32_t clocks_in_us = 64;
+
+constexpr uint32_t jitter_time_us = 20;
+constexpr uint32_t min_time_us = 64;
+constexpr uint32_t max_time_us = 80;
+constexpr uint32_t baud_time_us = 500;
+
+constexpr uint32_t min_time = (min_time_us - jitter_time_us) * clocks_in_us;
+constexpr uint32_t mid_time = ((max_time_us - min_time_us) / 2 + min_time_us) * clocks_in_us;
+constexpr uint32_t max_time = (max_time_us + jitter_time_us) * clocks_in_us;
+constexpr uint32_t baud_time = baud_time_us * clocks_in_us;
+
+bool DecoderIoProx::read(uint8_t* data, uint8_t data_size) {
+    bool result = false;
+    furi_assert(data_size >= 4);
+
+    if(ready) {
+        result = true;
+        ioprox.decode(raw_data, sizeof(raw_data), data, data_size);
+        ready = false;
+    }
+
+    return result;
+}
+
+void DecoderIoProx::process_front(bool is_rising_edge, uint32_t time) {
+    if(ready) {
+        return;
+    }
+
+    // Always track the time that's gone by.
+    current_period_duration += time;
+    demodulation_sample_duration += time;
+
+    // If a baud time has elapsed, we're at a sample point.
+    if(demodulation_sample_duration >= baud_time) {
+        // Start a new baud period...
+        demodulation_sample_duration = 0;
+        demodulated_value_invalid = false;
+
+        // ... and if we didn't have any baud errors, capture a sample.
+        if(!demodulated_value_invalid) {
+            store_data(current_demodulated_value);
+        }
+    }
+
+    //
+    // FSK demodulator.
+    //
+
+    // If this isn't a rising edge, this isn't a pulse of interest.
+    // We're done.
+    if(!is_rising_edge) {
+        return;
+    }
+
+    bool is_valid_low = (current_period_duration > min_time) &&
+                        (current_period_duration <= mid_time);
+    bool is_valid_high = (current_period_duration > mid_time) &&
+                         (current_period_duration < max_time);
+
+    // If this is between the minimum and our threshold, this is a logical 0.
+    if(is_valid_low) {
+        current_demodulated_value = false;
+    }
+    // Otherwise, if between our threshold and the max time, it's a logical 1.
+    else if(is_valid_high) {
+        current_demodulated_value = true;
+    }
+    // Otherwise, invalidate this sample.
+    else {
+        demodulated_value_invalid = true;
+    }
+
+    // We're starting a new period; track that.
+    current_period_duration = 0;
+}
+
+DecoderIoProx::DecoderIoProx() {
+    reset_state();
+}
+
+void DecoderIoProx::store_data(bool data) {
+    for(int i = 0; i < 7; ++i) {
+        raw_data[i] = (raw_data[i] << 1) | ((raw_data[i + 1] >> 7) & 1);
+    }
+    raw_data[7] = (raw_data[7] << 1) | data;
+
+    if(ioprox.can_be_decoded(raw_data, sizeof(raw_data))) {
+        ready = true;
+    }
+}
+
+void DecoderIoProx::reset_state() {
+    current_demodulated_value = false;
+    demodulated_value_invalid = false;
+
+    current_period_duration = 0;
+    demodulation_sample_duration = 0;
+
+    ready = false;
+}