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Internal code cleanup.

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Reduce ambiguity in function and parameter names.
This commit is contained in:
Henry Gabryjelski 2024-05-14 19:16:05 -07:00
commit d27c084819
1 changed files with 31 additions and 24 deletions
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53
armsrc/em4x70.c
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@ -80,9 +80,9 @@ static bool command_parity = true;
#define IS_TIMEOUT(timeout_ticks) (GetTicks() > timeout_ticks)
#define TICKS_ELAPSED(start_ticks) (GetTicks() - start_ticks)
static uint8_t bits2byte(const uint8_t *bits, int length);
static void bits2bytes(const uint8_t *bits, int length, uint8_t *out);
static int em4x70_receive(uint8_t *bits, size_t length);
static uint8_t encoded_bit_array_to_byte(const uint8_t *bits, int count_of_bits);
static void encoded_bit_array_to_bytes(const uint8_t *bits, int count_of_bits, uint8_t *out);
static int em4x70_receive(uint8_t *bits, size_t maximum_bits_to_read);
static bool find_listen_window(bool command);
static void init_tag(void) {
@ -207,9 +207,10 @@ static uint32_t get_pulse_length(edge_detection_t edge) {
return 0;
}
static bool check_pulse_length(uint32_t pl, uint32_t length) {
// check if pulse length <pl> corresponds to given length <length>
return ((pl >= (length - EM4X70_T_TAG_TOLERANCE)) && (pl <= (length + EM4X70_T_TAG_TOLERANCE)));
static bool check_pulse_length(uint32_t pulse_tick_length, uint32_t target_tick_length) {
// check if pulse tick length corresponds to target length (+/- tolerance)
return ((pulse_tick_length >= (target_tick_length - EM4X70_T_TAG_TOLERANCE)) &&
(pulse_tick_length <= (target_tick_length + EM4X70_T_TAG_TOLERANCE)));
}
static void em4x70_send_bit(bool bit) {
@ -344,7 +345,11 @@ static int authenticate(const uint8_t *rnd, const uint8_t *frnd, uint8_t *respon
if (g_dbglevel >= DBG_EXTENDED) Dbprintf("Auth failed");
return PM3_ESOFT;
}
bits2bytes(grnd, 24, response);
// although only received 20 bits
// ask for 24 bits converted because
// this utility function requires
// decoding in multiples of 8 bits
encoded_bit_array_to_bytes(grnd, 24, response);
return PM3_SUCCESS;
}
@ -455,12 +460,12 @@ static int send_pin(const uint32_t pin) {
WaitTicks(EM4X70_T_TAG_WEE);
// <-- Receive header + ID
uint8_t tag_id[EM4X70_MAX_RECEIVE_LENGTH];
int num = em4x70_receive(tag_id, 32);
if (num < 32) {
int count_of_bits_received = em4x70_receive(tag_id, 32);
if (count_of_bits_received < 32) {
Dbprintf("Invalid ID Received");
return PM3_ESOFT;
}
bits2bytes(tag_id, num, &tag.data[4]);
encoded_bit_array_to_bytes(tag_id, count_of_bits_received, &tag.data[4]);
return PM3_SUCCESS;
}
}
@ -537,30 +542,32 @@ static bool find_listen_window(bool command) {
return false;
}
static void bits2bytes(const uint8_t *bits, int length, uint8_t *out) {
// *bits == array of bytes, each byte storing a single bit.
// *out == array of bytes, storing converted bits --> bytes.
//
// [in, bcount(count_of_bits) ] const uint8_t *bits
// [out, bcount(count_of_bits/8)] uint8_t *out
static void encoded_bit_array_to_bytes(const uint8_t *bits, int count_of_bits, uint8_t *out) {
if (length % 8 != 0) {
Dbprintf("Should have a multiple of 8 bits, was sent %d", length);
if (count_of_bits % 8 != 0) {
Dbprintf("Should have a multiple of 8 bits, was sent %d", count_of_bits);
}
int num_bytes = length / 8; // We should have a multiple of 8 here
int num_bytes = count_of_bits / 8; // We should have a multiple of 8 here
for (int i = 1; i <= num_bytes; i++) {
out[num_bytes - i] = bits2byte(bits, 8);
out[num_bytes - i] = encoded_bit_array_to_byte(bits, 8);
bits += 8;
}
}
static uint8_t bits2byte(const uint8_t *bits, int length) {
static uint8_t encoded_bit_array_to_byte(const uint8_t *bits, int count_of_bits) {
// converts <length> separate bits into a single "byte"
// converts <count_of_bits> separate bits into a single "byte"
uint8_t byte = 0;
for (int i = 0; i < length; i++) {
byte |= bits[i];
if (i != length - 1)
for (int i = 0; i < count_of_bits; i++) {
byte <<= 1;
byte |= bits[i];
}
return byte;
@ -581,7 +588,7 @@ static bool send_command_and_read(uint8_t command, uint8_t *bytes, size_t expect
Dbprintf("Invalid data received length: %d, expected %d", len, out_length_bits);
return false;
}
bits2bytes(bits, len, bytes);
encoded_bit_array_to_bytes(bits, len, bytes);
return true;
}
}