initial commit

components/fastcon/protocol.cpp

@@ -0,0 +1,60 @@
+#include <algorithm>
+#include "protocol.h"
+
+namespace esphome
+{
+    namespace fastcon
+    {
+        std::vector<uint8_t> get_rf_payload(const std::vector<uint8_t> &addr, const std::vector<uint8_t> &data)
+        {
+            const size_t data_offset = 0x12;
+            const size_t inverse_offset = 0x0f;
+            const size_t result_data_size = data_offset + addr.size() + data.size();
+
+            // Create result buffer including space for checksum
+            std::vector<uint8_t> resultbuf(result_data_size + 2, 0);
+
+            // Set hardcoded values
+            resultbuf[0x0f] = 0x71;
+            resultbuf[0x10] = 0x0f;
+            resultbuf[0x11] = 0x55;
+
+            // Copy address in reverse
+            for (size_t i = 0; i < addr.size(); i++)
+            {
+                resultbuf[data_offset + addr.size() - i - 1] = addr[i];
+            }
+
+            // Copy data
+            std::copy(data.begin(), data.end(), resultbuf.begin() + data_offset + addr.size());
+
+            // Reverse bytes in specified range
+            for (size_t i = inverse_offset; i < inverse_offset + addr.size() + 3; i++)
+            {
+                resultbuf[i] = reverse_8(resultbuf[i]);
+            }
+
+            // Add CRC
+            uint16_t crc = crc16(addr, data);
+            resultbuf[result_data_size] = crc & 0xFF;
+            resultbuf[result_data_size + 1] = (crc >> 8) & 0xFF;
+
+            return resultbuf;
+        }
+
+        std::vector<uint8_t> prepare_payload(const std::vector<uint8_t> &addr, const std::vector<uint8_t> &data)
+        {
+            auto payload = get_rf_payload(addr, data);
+
+            // Initialize whitening
+            WhiteningContext context;
+            whitening_init(0x25, context);
+
+            // Apply whitening to the payload
+            whitening_encode(payload, context);
+
+            // Return only the portion after 0xf bytes
+            return std::vector<uint8_t>(payload.begin() + 0xf, payload.end());
+        }
+    } // namespace fastcon
+} // namespace esphome