flipperzero-firmware/lib/subghz/blocks/math.c

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#include "math.h"
uint64_t subghz_protocol_blocks_reverse_key(uint64_t key, uint8_t bit_count) {
uint64_t reverse_key = 0;
for(uint8_t i = 0; i < bit_count; i++) {
reverse_key = reverse_key << 1 | bit_read(key, i);
}
return reverse_key;
}
uint8_t subghz_protocol_blocks_get_parity(uint64_t key, uint8_t bit_count) {
uint8_t parity = 0;
for(uint8_t i = 0; i < bit_count; i++) {
parity += bit_read(key, i);
}
return parity & 0x01;
}
uint8_t subghz_protocol_blocks_crc4(
uint8_t const message[],
size_t size,
uint8_t polynomial,
uint8_t init) {
uint8_t remainder = init << 4; // LSBs are unused
uint8_t poly = polynomial << 4;
uint8_t bit;
while(size--) {
remainder ^= *message++;
for(bit = 0; bit < 8; bit++) {
if(remainder & 0x80) {
remainder = (remainder << 1) ^ poly;
} else {
remainder = (remainder << 1);
}
}
}
return remainder >> 4 & 0x0f; // discard the LSBs
}
uint8_t subghz_protocol_blocks_crc7(
uint8_t const message[],
size_t size,
uint8_t polynomial,
uint8_t init) {
uint8_t remainder = init << 1; // LSB is unused
uint8_t poly = polynomial << 1;
for(size_t byte = 0; byte < size; ++byte) {
remainder ^= message[byte];
for(uint8_t bit = 0; bit < 8; ++bit) {
if(remainder & 0x80) {
remainder = (remainder << 1) ^ poly;
} else {
remainder = (remainder << 1);
}
}
}
return remainder >> 1 & 0x7f; // discard the LSB
}
uint8_t subghz_protocol_blocks_crc8(
uint8_t const message[],
size_t size,
uint8_t polynomial,
uint8_t init) {
uint8_t remainder = init;
for(size_t byte = 0; byte < size; ++byte) {
remainder ^= message[byte];
for(uint8_t bit = 0; bit < 8; ++bit) {
if(remainder & 0x80) {
remainder = (remainder << 1) ^ polynomial;
} else {
remainder = (remainder << 1);
}
}
}
return remainder;
}
uint8_t subghz_protocol_blocks_crc8le(
uint8_t const message[],
size_t size,
uint8_t polynomial,
uint8_t init) {
uint8_t remainder = subghz_protocol_blocks_reverse_key(init, 8);
polynomial = subghz_protocol_blocks_reverse_key(polynomial, 8);
for(size_t byte = 0; byte < size; ++byte) {
remainder ^= message[byte];
for(uint8_t bit = 0; bit < 8; ++bit) {
if(remainder & 1) {
remainder = (remainder >> 1) ^ polynomial;
} else {
remainder = (remainder >> 1);
}
}
}
return remainder;
}
uint16_t subghz_protocol_blocks_crc16lsb(
uint8_t const message[],
size_t size,
uint16_t polynomial,
uint16_t init) {
uint16_t remainder = init;
for(size_t byte = 0; byte < size; ++byte) {
remainder ^= message[byte];
for(uint8_t bit = 0; bit < 8; ++bit) {
if(remainder & 1) {
remainder = (remainder >> 1) ^ polynomial;
} else {
remainder = (remainder >> 1);
}
}
}
return remainder;
}
uint16_t subghz_protocol_blocks_crc16(
uint8_t const message[],
size_t size,
uint16_t polynomial,
uint16_t init) {
uint16_t remainder = init;
for(size_t byte = 0; byte < size; ++byte) {
remainder ^= message[byte] << 8;
for(uint8_t bit = 0; bit < 8; ++bit) {
if(remainder & 0x8000) {
remainder = (remainder << 1) ^ polynomial;
} else {
remainder = (remainder << 1);
}
}
}
return remainder;
}
uint8_t subghz_protocol_blocks_lfsr_digest8(
uint8_t const message[],
size_t size,
uint8_t gen,
uint8_t key) {
uint8_t sum = 0;
for(size_t byte = 0; byte < size; ++byte) {
uint8_t data = message[byte];
for(int i = 7; i >= 0; --i) {
// XOR key into sum if data bit is set
if((data >> i) & 1) sum ^= key;
// roll the key right (actually the LSB is dropped here)
// and apply the gen (needs to include the dropped LSB as MSB)
if(key & 1)
key = (key >> 1) ^ gen;
else
key = (key >> 1);
}
}
return sum;
}
uint8_t subghz_protocol_blocks_lfsr_digest8_reflect(
uint8_t const message[],
size_t size,
uint8_t gen,
uint8_t key) {
uint8_t sum = 0;
// Process message from last byte to first byte (reflected)
for(int byte = size - 1; byte >= 0; --byte) {
uint8_t data = message[byte];
// Process individual bits of each byte (reflected)
for(uint8_t i = 0; i < 8; ++i) {
// XOR key into sum if data bit is set
if((data >> i) & 1) {
sum ^= key;
}
// roll the key left (actually the LSB is dropped here)
// and apply the gen (needs to include the dropped lsb as MSB)
if(key & 0x80)
key = (key << 1) ^ gen;
else
key = (key << 1);
}
}
return sum;
}
uint16_t subghz_protocol_blocks_lfsr_digest16(
uint8_t const message[],
size_t size,
uint16_t gen,
uint16_t key) {
uint16_t sum = 0;
for(size_t byte = 0; byte < size; ++byte) {
uint8_t data = message[byte];
for(int8_t i = 7; i >= 0; --i) {
// if data bit is set then xor with key
if((data >> i) & 1) sum ^= key;
// roll the key right (actually the LSB is dropped here)
// and apply the gen (needs to include the dropped LSB as MSB)
if(key & 1)
key = (key >> 1) ^ gen;
else
key = (key >> 1);
}
}
return sum;
}
uint8_t subghz_protocol_blocks_add_bytes(uint8_t const message[], size_t size) {
uint32_t result = 0;
for(size_t i = 0; i < size; ++i) {
result += message[i];
}
return (uint8_t)result;
}
uint8_t subghz_protocol_blocks_parity8(uint8_t byte) {
byte ^= byte >> 4;
byte &= 0xf;
return (0x6996 >> byte) & 1;
}
uint8_t subghz_protocol_blocks_parity_bytes(uint8_t const message[], size_t size) {
uint8_t result = 0;
for(size_t i = 0; i < size; ++i) {
result ^= subghz_protocol_blocks_parity8(message[i]);
}
return result;
}
uint8_t subghz_protocol_blocks_xor_bytes(uint8_t const message[], size_t size) {
uint8_t result = 0;
for(size_t i = 0; i < size; ++i) {
result ^= message[i];
}
return result;
}