mirror of https://github.com/merbanan/rtl_433.git
200 lines
7.3 KiB
C
200 lines
7.3 KiB
C
/** @file
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Various utility functions for use by device drivers.
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Copyright (C) 2015 Tommy Vestermark
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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*/
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#ifndef INCLUDE_BIT_UTIL_H_
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#define INCLUDE_BIT_UTIL_H_
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#include <stdint.h>
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/// Reverse (reflect) the bits in an 32 bit byte.
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///
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/// @param x input byte
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/// @return bit reversed byte
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uint32_t reverse32(uint32_t x);
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/// Reverse (reflect) the bits in an 8 bit byte.
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///
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/// @param x input byte
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/// @return bit reversed byte
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uint8_t reverse8(uint8_t x);
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/// Reflect (reverse LSB to MSB) each byte of a number of bytes.
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///
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/// @param message bytes of message data
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/// @param num_bytes number of bytes to reflect
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void reflect_bytes(uint8_t message[], unsigned num_bytes);
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/// Reflect (reverse LSB to MSB) each nibble in an 8 bit byte, preserves nibble order.
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///
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/// @param x input byte
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/// @return reflected nibbles
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uint8_t reflect4(uint8_t x);
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/// Reflect (reverse LSB to MSB) each nibble in a number of bytes.
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///
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/// @param message bytes of nibble message data
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/// @param num_bytes number of bytes to reflect
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void reflect_nibbles(uint8_t message[], unsigned num_bytes);
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/// Unstuff nibbles with 1-bit separator (4B1S) to bytes, returns number of successfully unstuffed nibbles.
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///
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/// @param message bytes of message data
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/// @param offset_bits start offset of message in bits
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/// @param num_bits message length in bits
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/// @param dst target buffer for extracted nibbles, at least num_bits/5 size
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/// @return number of successfully unstuffed nibbles.
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unsigned extract_nibbles_4b1s(uint8_t *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst);
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/// UART "8n1" (10-to-8) decoder with 1 start bit (0), no parity, 1 stop bit (1), LSB-first bit-order.
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///
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/// @param message bytes of message data
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/// @param offset_bits start offset of message in bits
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/// @param num_bits message length in bits
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/// @param dst target buffer for extracted bytes, at least num_bits/10 size
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/// @return number of successful decoded bytes
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unsigned extract_bytes_uart(uint8_t *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst);
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/// Decode symbols to bits.
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///
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/// @param message bytes of message data
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/// @param offset_bits start offset of message in bits
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/// @param num_bits message length in bits
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/// @param zero symbol for zero bit, bits MSB aligned, count in LSB
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/// @param one symbol for one bit, bits MSB aligned, count in LSB
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/// @param sync symbol for sync bit, ignored at start, terminates at end
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/// @param dst target buffer for extracted bits, at least num_bits/symbol_x_len size
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/// @return number of successful decoded bits
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unsigned extract_bits_symbols(uint8_t *message, unsigned offset_bits, unsigned num_bits, uint32_t zero, uint32_t one, uint32_t sync, uint8_t *dst);
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/// CRC-4.
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///
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/// @param message array of bytes to check
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/// @param nBytes number of bytes in message
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/// @param polynomial CRC polynomial
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/// @param init starting crc value
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/// @return CRC value
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uint8_t crc4(uint8_t const message[], unsigned nBytes, uint8_t polynomial, uint8_t init);
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/// CRC-7.
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///
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/// @param message array of bytes to check
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/// @param nBytes number of bytes in message
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/// @param polynomial CRC polynomial
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/// @param init starting crc value
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/// @return CRC value
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uint8_t crc7(uint8_t const message[], unsigned nBytes, uint8_t polynomial, uint8_t init);
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/// Generic Cyclic Redundancy Check CRC-8.
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///
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/// Example polynomial: 0x31 = x8 + x5 + x4 + 1 (x8 is implicit)
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/// Example polynomial: 0x80 = x8 + x7 (a normal bit-by-bit parity XOR)
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///
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/// @param message array of bytes to check
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/// @param nBytes number of bytes in message
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/// @param polynomial byte is from x^7 to x^0 (x^8 is implicitly one)
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/// @param init starting crc value
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/// @return CRC value
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uint8_t crc8(uint8_t const message[], unsigned nBytes, uint8_t polynomial, uint8_t init);
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/// "Little-endian" Cyclic Redundancy Check CRC-8 LE
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/// Input and output are reflected, i.e. least significant bit is shifted in first.
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///
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/// @param message array of bytes to check
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/// @param nBytes number of bytes in message
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/// @param polynomial CRC polynomial
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/// @param init starting crc value
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/// @return CRC value
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uint8_t crc8le(uint8_t const message[], unsigned nBytes, uint8_t polynomial, uint8_t init);
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/// CRC-16 LSB.
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/// Input and output are reflected, i.e. least significant bit is shifted in first.
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/// Note that poly and init already need to be reflected.
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///
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/// @param message array of bytes to check
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/// @param nBytes number of bytes in message
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/// @param polynomial CRC polynomial
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/// @param init starting crc value
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/// @return CRC value
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uint16_t crc16lsb(uint8_t const message[], unsigned nBytes, uint16_t polynomial, uint16_t init);
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/// CRC-16.
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///
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/// @param message array of bytes to check
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/// @param nBytes number of bytes in message
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/// @param polynomial CRC polynomial
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/// @param init starting crc value
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/// @return CRC value
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uint16_t crc16(uint8_t const message[], unsigned nBytes, uint16_t polynomial, uint16_t init);
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/// Digest-8 by "LFSR-based Toeplitz hash".
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///
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/// @param message bytes of message data
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/// @param bytes number of bytes to digest
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/// @param gen key stream generator, needs to includes the MSB if the LFSR is rolling
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/// @param key initial key
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/// @return digest value
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uint8_t lfsr_digest8(uint8_t const message[], unsigned bytes, uint8_t gen, uint8_t key);
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/// Digest-8 by "LFSR-based Toeplitz hash", byte reflect, bit reflect.
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///
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/// @param message bytes of message data
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/// @param bytes number of bytes to digest
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/// @param gen key stream generator, needs to includes the MSB if the LFSR is rolling
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/// @param key initial key
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/// @return digest value
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uint8_t lfsr_digest8_reflect(uint8_t const message[], int bytes, uint8_t gen, uint8_t key);
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/// Digest-16 by "LFSR-based Toeplitz hash".
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///
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/// @param message bytes of message data
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/// @param bytes number of bytes to digest
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/// @param gen key stream generator, needs to includes the MSB if the LFSR is rolling
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/// @param key initial key
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/// @return digest value
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uint16_t lfsr_digest16(uint8_t const message[], unsigned bytes, uint16_t gen, uint16_t key);
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/// Compute bit parity of a single byte (8 bits).
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///
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/// @param byte single byte to check
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/// @return 1 odd parity, 0 even parity
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int parity8(uint8_t byte);
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/// Compute bit parity of a number of bytes.
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///
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/// @param message bytes of message data
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/// @param num_bytes number of bytes to sum
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/// @return 1 odd parity, 0 even parity
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int parity_bytes(uint8_t const message[], unsigned num_bytes);
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/// Compute XOR (byte-wide parity) of a number of bytes.
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///
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/// @param message bytes of message data
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/// @param num_bytes number of bytes to sum
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/// @return summation value, per bit-position 1 odd parity, 0 even parity
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uint8_t xor_bytes(uint8_t const message[], unsigned num_bytes);
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/// Compute Addition of a number of bytes.
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///
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/// @param message bytes of message data
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/// @param num_bytes number of bytes to sum
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/// @return summation value
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int add_bytes(uint8_t const message[], unsigned num_bytes);
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/// Compute Addition of a number of nibbles (byte wise).
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///
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/// @param message bytes (of two nibbles) of message data
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/// @param num_bytes number of bytes to sum
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/// @return summation value
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int add_nibbles(uint8_t const message[], unsigned num_bytes);
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#endif /* INCLUDE_BIT_UTIL_H_ */
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