Share PM67 upload protocol through C core

c/set-protocol/include/set_crc.h

@@ -0,0 +1,19 @@
+/** @file set_crc.h @brief Shared checksums used by legacy SET controllers. */
+#ifndef SET_CRC_H
+#define SET_CRC_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** CRC-16/Modbus: reflected polynomial 0xA001, initial value 0xFFFF. */
+uint16_t set_crc16_modbus(const uint8_t *data, size_t size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* SET_CRC_H */