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Struct&var refactor for clarity
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@zacharyweiss
zacharyweiss committed Apr 10, 2024
1 parent 33cfd63 commit 2150f18
Showing 1 changed file with 61 additions and 55 deletions.
116 changes: 61 additions & 55 deletions applications/main/nfc/plugins/supported_cards/charliecard.c
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Original file line number Diff line number Diff line change
Expand Up @@ -94,7 +94,7 @@
// timestep is one minute
#define CHARLIE_TIME_DELTA_SECS 60
#define CHARLIE_END_VALID_DELTA_SECS 60 * 8
#define CHARLIE_N_TRIP_HISTORY 10
#define CHARLIE_N_TRANSACTION_HISTORY 10
#define CHARLIE_N_PASSES 4

typedef struct {
Expand Down Expand Up @@ -147,7 +147,7 @@ typedef struct {
uint8_t g_flag;
Money fare;
uint16_t f_flag;
} Trip;
} Transaction;

typedef struct {
bool valid;
Expand Down Expand Up @@ -206,7 +206,7 @@ static const IdMapping charliecard_types[] = {
{.id = 166, .name = "30 Day Commuter Rail Zone 1A Pass"},
{.id = 167, .name = "30 Day Commuter Rail Zone 1 Pass"},
{.id = 168, .name = "30 Day Commuter Rail Zone 2 Pass"},
{.id = 169, .name = "30 Day Commuter Rail Zone 3 Pass"},
{.id = 169, .name = "30 Day ComZmuter Rail Zone 3 Pass"},
{.id = 170, .name = "30 Day Commuter Rail Zone 4 Pass"},
{.id = 171, .name = "30 Day Commuter Rail Zone 5 Pass"},
{.id = 172, .name = "30 Day Commuter Rail Zone 6 Pass"},
Expand Down Expand Up @@ -717,7 +717,11 @@ static Pass
// the uk1 and date fields, and is always set to 1 regardless
// same is true of type & end-validity split found in balance sector
//
//
// likely fields incl
// — type #,
// — a secondary date field (eg start/end, end validity or normal format)
// — ID of FVM from which the pass was loaded

// check for empty, if so, return struct filled w/ 0s
// (incl "valid" field: hence, "valid" is false-y)
if(pos_to_num(data, sector_num, block_num, byte_num, 6) == 0x002000000000) {
Expand All @@ -727,7 +731,7 @@ static Pass
// const DateTime start = date_parse(data, sector_num, block_num, byte_num + 1);

const uint16_t pre = pos_to_num(data, sector_num, block_num, byte_num, 2) >> 6;
const uint16_t post = pos_to_num(data, sector_num, block_num, byte_num + 4, 2);
const uint16_t post = (pos_to_num(data, sector_num, block_num, byte_num + 4, 2) >> 2) & 0x3ff;

// these values make sense for a date, but implied position of type
// before end validity, as seen in balance sector, doesn't seem
Expand All @@ -740,8 +744,9 @@ static Pass
return (Pass){true, pre, post, date};
}

static Trip trip_parse(const MfClassicData* data, uint8_t sector, uint8_t block, uint8_t byte) {
/* This function parses individual trips. Each trip packs 7 bytes, stored as follows:
static Transaction
transaction_parse(const MfClassicData* data, uint8_t sector, uint8_t block, uint8_t byte) {
/* This function parses individual transactions. Each transaction packs 7 bytes, stored as follows:
0 1 2 3 4 5 6
+----.----.----+----.--+-+----.----+
Expand All @@ -753,23 +758,23 @@ static Trip trip_parse(const MfClassicData* data, uint8_t sector, uint8_t block,
Gate ID ("loc") is only the first 13 bits of 0x3:0x5, the final three bits appear to be flags ("f").
Least significant flag bit seems to indicate:
— When f & 1 == 0, fare (the amount by which balance is decremented)
— When f & 1 == 1, refill (the amount by which balance is incremented)
— When f & 1 == 1, fare (the amount by which balance is decremented)
— When f & 1 == 0, refill (the amount by which balance is incremented)
MSB (sign bit) of amt seems to serve the same role, just inverted, ie
— When amt & 0x8000 == 0x8000, fare
— When amt & 0x8000 == 0, refill
— When amt & 0x8000 == 0, fare
— When amt & 0x8000 == 0x8000, refill
Remaining unknown bits:
— f & 0b100
— f & 0b010
— amt & 1; does not seem to correspond with card type, last trip, first trip, refill v. fare, etc
— amt & 1; does not seem to correspond with card type, last transaction, first transaction, refill v. fare, etc
*/
const DateTime date = date_parse(data, sector, block, byte);
const uint16_t gate = pos_to_num(data, sector, block, byte + 3, 2) >> 3;
const uint8_t g_flag = pos_to_num(data, sector, block, byte + 3, 2) & 0b111;
const Money fare = money_parse(data, sector, block, byte + 5);
const uint16_t f_flag = pos_to_num(data, sector, block, byte + 5, 2) & 0x8001;
return (Trip){date, gate, g_flag, fare, f_flag};
return (Transaction){date, gate, g_flag, fare, f_flag};
}

// **********************************************************
Expand Down Expand Up @@ -810,10 +815,10 @@ static CounterSector counter_sector_parse(const MfClassicData* data) {
// 0x060 | uses2 | uk | ... 00 00 ... |
// +----.----+----+----.----.----.----.----.----.----.----.----.----.----.----.----+
//
// uk := "unknown"; if nonzero, seems to only occupy the first 4 bits (ie, mask w/ 0xF0),
// uk := "unknown"; if nonzero, seems to only occupy the first 4 bits (ie, uk & 0xF0 == uk),
// with the remaining 4 zero

// Card has two transaction sectors (2 & 3) containing balance data, with two
// Card has two sectors (2 & 3) containing balance data, with two
// corresponding trip counters in 0x50:0x51 & 0x60:0x61 (sector 1, byte 0:1 of blocks 1 & 2).

// The *lower* of the two values *minus one* is the true use count,
Expand Down Expand Up @@ -866,7 +871,7 @@ static Pass* passes_parse(const MfClassicData* data) {
//
// 0 1 2 3 4 5 6 7 8 9 A B C D E F
// +----.----.----.----.----.----+----+----.----.----.----.----.----+----+----.----+
// 0x100 | pass0? | 00 | pass1? | 00 | crc | 0x140
// 0x100 | pass0/2? | 00 | pass1/3? | 00 | crc | 0x140
// +----.----.----.----.----.----+----+----.----.----.----.----.----+----+----.----+
// 0x110 | ... 00 00 ... | crc | 0x150
// +----.----.----.----.----.----.----.----.----.----.----.----.----.----+----.----+
Expand All @@ -886,62 +891,62 @@ static Pass* passes_parse(const MfClassicData* data) {
return passes;
}

static Trip* trips_parse(const MfClassicData* data) {
static Transaction* transactions_parse(const MfClassicData* data) {
// Transaction history (Sectors 6–7)
//
// 0 1 2 3 4 5 6 7 8 9 A B C D E F
// +----.----.----.----.----.----.----+----.----.----.----.----.----.----+----.----+
// 0x180 | trip0 | trip1 | crc |
// 0x180 | transaction0 | transaction1 | crc |
// +----.----.----.----.----.----.----+----.----.----.----.----.----.----+----.----+
// ... ... ... ...
// +----.----.----.----.----.----.----+----.----.----.----.----.----.----+----.----+
// 0x1D0 | trip8 | trip9 | crc |
// 0x1D0 | transaction8 | transaction9 | crc |
// +----.----.----.----.----.----.----+----.----.----.----.----.----.----+----.----+
// 0x1E0 | ... 00 00 ... | crc |
// +----.----.----.----.----.----.----.----.----.----.----.----.----.----+----.----+
//
// Transactions are not sorted, rather, appear to get overwritten
// sequentially. (eg, sorted modulo array rotation)

Trip* trips = malloc(sizeof(Trip) * CHARLIE_N_TRIP_HISTORY);
Transaction* transactions = malloc(sizeof(Transaction) * CHARLIE_N_TRANSACTION_HISTORY);

// Parse each trip field using some modular math magic to get the offsets:
// move from sector 6 -> 7 after the first 6 trips
// move a block within a given sector every 2 trips, reset every 3 blocks (as sector has changed)
// Parse each transaction field using some modular math magic to get the offsets:
// move from sector 6 -> 7 after the first 6 transactions
// move a block within a given sector every 2 transactions, reset every 3 blocks (as sector has changed)
// alternate between a start byte of 0 and 7 with every iteration
for(size_t i = 0; i < CHARLIE_N_TRIP_HISTORY; i++) {
trips[i] = trip_parse(data, 6 + (i / 6), (i / 2) % 3, (i % 2) * 7);
for(size_t i = 0; i < CHARLIE_N_TRANSACTION_HISTORY; i++) {
transactions[i] = transaction_parse(data, 6 + (i / 6), (i / 2) % 3, (i % 2) * 7);
}

// Iterate through the array to find the maximum (newest) date value
int max_idx = 0;
for(int i = 1; i < CHARLIE_N_TRIP_HISTORY; i++) {
if(dt_ge(trips[i].date, trips[max_idx].date)) {
for(int i = 1; i < CHARLIE_N_TRANSACTION_HISTORY; i++) {
if(dt_ge(transactions[i].date, transactions[max_idx].date)) {
max_idx = i;
}
}

// Sort by rotating
for(int r = 0; r < (max_idx + 1); r++) {
// Store the first element
Trip temp = trips[0];
Transaction temp = transactions[0];
// Shift elements to the left
for(int i = 0; i < CHARLIE_N_TRIP_HISTORY - 1; i++) {
trips[i] = trips[i + 1];
for(int i = 0; i < CHARLIE_N_TRANSACTION_HISTORY - 1; i++) {
transactions[i] = transactions[i + 1];
}
// Move the first element to the last
trips[CHARLIE_N_TRIP_HISTORY - 1] = temp;
transactions[CHARLIE_N_TRANSACTION_HISTORY - 1] = temp;
}

// Reverse order, such that newest is first, oldest last
for(int i = 0; i < CHARLIE_N_TRIP_HISTORY / 2; i++) {
for(int i = 0; i < CHARLIE_N_TRANSACTION_HISTORY / 2; i++) {
// Swap elements at index i and size - i - 1
Trip temp = trips[i];
trips[i] = trips[CHARLIE_N_TRIP_HISTORY - i - 1];
trips[CHARLIE_N_TRIP_HISTORY - i - 1] = temp;
Transaction temp = transactions[i];
transactions[i] = transactions[CHARLIE_N_TRANSACTION_HISTORY - i - 1];
transactions[CHARLIE_N_TRANSACTION_HISTORY - i - 1] = temp;
}

return trips;
return transactions;
}

/*
Expand Down Expand Up @@ -976,12 +981,12 @@ static DateTime expiry(DateTime iss) {
return exp;
}
static bool expired(DateTime expiry, DateTime last_trip) {
static bool expired(DateTime expiry, DateTime last_transaction) {
// if a card has sat unused for >2 years, expired (verify this claim?)
// else expired if current date > expiry date
uint32_t ts_exp = datetime_datetime_to_timestamp(&expiry);
uint32_t ts_last = datetime_datetime_to_timestamp(&last_trip);
uint32_t ts_last = datetime_datetime_to_timestamp(&last_transaction);
uint32_t ts_now = time_now();
return (ts_exp <= ts_now) | ((ts_now - ts_last) >= (2 * 365 * 24 * 60 * 60));
Expand Down Expand Up @@ -1020,7 +1025,8 @@ void type_format_cat(FuriString* out, uint16_t type) {
void pass_format_cat(FuriString* out, Pass pass) {
furi_string_cat_printf(out, "\n-Pre: %b", pass.pre);
// type_format_cat(out, pass.type);
furi_string_cat_printf(out, "\n-Post: %b", pass.post);
furi_string_cat_printf(out, "\n-Post: ");
type_format_cat(out, pass.post);
// locale_format_dt_cat(out, &pass.start);
furi_string_cat_printf(out, "\n-Date: ");
locale_format_dt_cat(out, &pass.date);
Expand Down Expand Up @@ -1055,37 +1061,37 @@ void money_format_cat(FuriString* out, Money money) {
furi_string_cat_printf(out, "$%u.%02u", money.dollars, money.cents);
}

void trip_format_cat(FuriString* out, Trip trip) {
void transaction_format_cat(FuriString* out, Transaction transaction) {
const char* sep = " ";
const char* sta;

locale_format_dt_cat(out, &trip.date);
furi_string_cat_printf(out, "\n%s", !!(trip.g_flag & 0x1) ? "-" : "+");
money_format_cat(out, trip.fare);
if(!!(trip.g_flag & 0x1) && (trip.fare.dollars == FARE_BUS.dollars) &&
(trip.fare.cents == FARE_BUS.cents)) {
locale_format_dt_cat(out, &transaction.date);
furi_string_cat_printf(out, "\n%s", !!(transaction.g_flag & 0x1) ? "-" : "+");
money_format_cat(out, transaction.fare);
if(!!(transaction.g_flag & 0x1) && (transaction.fare.dollars == FARE_BUS.dollars) &&
(transaction.fare.cents == FARE_BUS.cents)) {
// if not a refill, and the fare amount is equal to bus fare (any better approach? flag bits for modality?)
// format for bus — supposedly some correlation between gate ID & bus #, haven't investigated
furi_string_cat_printf(out, "%s#%u", sep, trip.gate);
} else if(get_map_item(trip.gate, charliecard_fare_gate_ids, kNumFareGateIds, &sta)) {
furi_string_cat_printf(out, "%s#%u", sep, transaction.gate);
} else if(get_map_item(transaction.gate, charliecard_fare_gate_ids, kNumFareGateIds, &sta)) {
// station found in fare gate ID map, append station name
furi_string_cat_str(out, sep);
furi_string_cat_str(out, sta);
} else {
// no found station in fare gate ID map & not a bus, just print ID w/o add'l info
furi_string_cat_printf(out, "%s#%u", sep, trip.gate);
furi_string_cat_printf(out, "%s#%u", sep, transaction.gate);
}
// print flags for debugging purposes
if(is_debug()) {
furi_string_cat_printf(out, "%s%x%s%x", sep, trip.g_flag, sep, trip.f_flag);
furi_string_cat_printf(out, "%s%x%s%x", sep, transaction.g_flag, sep, transaction.f_flag);
}
}

void trips_format_cat(FuriString* out, Trip* trips) {
void transactions_format_cat(FuriString* out, Transaction* transactions) {
furi_string_cat_printf(out, "\nTransactions:");
for(size_t i = 0; i < CHARLIE_N_TRIP_HISTORY; i++) {
for(size_t i = 0; i < CHARLIE_N_TRANSACTION_HISTORY; i++) {
furi_string_cat_printf(out, "\n");
trip_format_cat(out, trips[i]);
transaction_format_cat(out, transactions[i]);
furi_string_cat_printf(out, "\n");
}
}
Expand Down Expand Up @@ -1126,7 +1132,7 @@ static bool charliecard_parse(const NfcDevice* device, FuriString* parsed_data)
const BalanceSector balance_sector =
balance_sector_parse(data, counter_sector.active_balance_sector);
Pass* passes = passes_parse(data);
Trip* trips = trips_parse(data);
Transaction* transactions = transactions_parse(data);

// print/append card data
furi_string_cat_printf(parsed_data, "\e#CharlieCard");
Expand All @@ -1152,8 +1158,8 @@ static bool charliecard_parse(const NfcDevice* device, FuriString* parsed_data)
passes_format_cat(parsed_data, passes);
free(passes);

trips_format_cat(parsed_data, trips);
free(trips);
transactions_format_cat(parsed_data, transactions);
free(transactions);

parsed = true;
} while(false);
Expand Down

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