NFC Parser for Tianjin Railway Transit (#3954)

applications/main/nfc/application.fam

@@ -209,6 +209,15 @@ App(
     sources=["plugins/supported_cards/hworld.c"],
 )
 
+App(
+    appid="trt_parser",
+    apptype=FlipperAppType.PLUGIN,
+    entry_point="trt_plugin_ep",
+    targets=["f7"],
+    requires=["nfc"],
+    sources=["plugins/supported_cards/trt.c"],
+)
+
 App(
     appid="nfc_start",
     targets=["f7"],

applications/main/nfc/plugins/supported_cards/trt.c

@@ -0,0 +1,94 @@
+// Flipper Zero parser for for Tianjin Railway Transit (TRT)
+// https://en.wikipedia.org/wiki/Tianjin_Metro
+// Reverse engineering and parser development by @Torron (Github: @zinongli)
+
+#include "nfc_supported_card_plugin.h"
+#include <flipper_application.h>
+#include <nfc/protocols/mf_ultralight/mf_ultralight.h>
+#include <bit_lib.h>
+
+#define TAG                       "TrtParser"
+#define LATEST_SALE_MARKER        0x02
+#define FULL_SALE_TIME_STAMP_PAGE 0x09
+#define BALANCE_PAGE              0x08
+#define SALE_RECORD_TIME_STAMP_A  0x0C
+#define SALE_RECORD_TIME_STAMP_B  0x0E
+#define SALE_YEAR_OFFSET          2000
+
+static bool trt_parse(const NfcDevice* device, FuriString* parsed_data) {
+    furi_assert(device);
+    furi_assert(parsed_data);
+
+    const MfUltralightData* data = nfc_device_get_data(device, NfcProtocolMfUltralight);
+
+    bool parsed = false;
+
+    do {
+        uint8_t latest_sale_page = 0;
+
+        // Look for sale record signature
+        if(data->page[SALE_RECORD_TIME_STAMP_A].data[0] == LATEST_SALE_MARKER) {
+            latest_sale_page = SALE_RECORD_TIME_STAMP_A;
+        } else if(data->page[SALE_RECORD_TIME_STAMP_B].data[0] == LATEST_SALE_MARKER) {
+            latest_sale_page = SALE_RECORD_TIME_STAMP_B;
+        } else {
+            break;
+        }
+
+        // Check if the sale record was backed up
+        const uint8_t* partial_record_pointer = &data->page[latest_sale_page - 1].data[0];
+        const uint8_t* full_record_pointer = &data->page[FULL_SALE_TIME_STAMP_PAGE].data[0];
+        uint32_t latest_sale_record = bit_lib_get_bits_32(partial_record_pointer, 3, 20);
+        uint32_t latest_sale_full_record = bit_lib_get_bits_32(full_record_pointer, 0, 27);
+        if(latest_sale_record != (latest_sale_full_record & 0xFFFFF)) break;
+
+        // Parse date
+        // yyy yyyymmmm dddddhhh hhnnnnnn
+        uint16_t sale_year = ((latest_sale_full_record & 0x7F00000) >> 20) + SALE_YEAR_OFFSET;
+        uint8_t sale_month = (latest_sale_full_record & 0xF0000) >> 16;
+        uint8_t sale_day = (latest_sale_full_record & 0xF800) >> 11;
+        uint8_t sale_hour = (latest_sale_full_record & 0x7C0) >> 6;
+        uint8_t sale_minute = latest_sale_full_record & 0x3F;
+
+        // Parse balance
+        uint16_t balance = bit_lib_get_bits_16(&data->page[BALANCE_PAGE].data[2], 0, 16);
+        uint16_t balance_yuan = balance / 100;
+        uint8_t balance_cent = balance % 100;
+
+        // Format string for rendering
+        furi_string_cat_printf(parsed_data, "\e#TRT Tianjin Metro\n");
+        furi_string_cat_printf(parsed_data, "Single-Use Ticket\n");
+        furi_string_cat_printf(parsed_data, "Balance: %u.%02u RMB\n", balance_yuan, balance_cent);
+        furi_string_cat_printf(
+            parsed_data,
+            "Sale Date: \n%04u-%02d-%02d %02d:%02d",
+            sale_year,
+            sale_month,
+            sale_day,
+            sale_hour,
+            sale_minute);
+        parsed = true;
+    } while(false);
+
+    return parsed;
+}
+
+/* Actual implementation of app<>plugin interface */
+static const NfcSupportedCardsPlugin trt_plugin = {
+    .protocol = NfcProtocolMfUltralight,
+    .verify = NULL,
+    .read = NULL,
+    .parse = trt_parse,
+};
+
+/* Plugin descriptor to comply with basic plugin specification */
+static const FlipperAppPluginDescriptor trt_plugin_descriptor = {
+    .appid = NFC_SUPPORTED_CARD_PLUGIN_APP_ID,
+    .ep_api_version = NFC_SUPPORTED_CARD_PLUGIN_API_VERSION,
+    .entry_point = &trt_plugin,
+};
+
+/* Plugin entry point - must return a pointer to const descriptor  */
+const FlipperAppPluginDescriptor* trt_plugin_ep(void) {
+    return &trt_plugin_descriptor;
+}