rtl_433/include/util.h

/**
 * Various utility functions for use by device drivers
 *
 * Copyright (C) 2015 Tommy Vestermark
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#ifndef INCLUDE_UTIL_H_
#define INCLUDE_UTIL_H_

#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
#include <time.h>
#include "compat_time.h"

#if defined _MSC_VER // Microsoft Visual Studio
    // MSC has something like C99 restrict as __restrict
    #ifndef restrict
	#define restrict  __restrict
    #endif
#endif

// Helper macros
#ifndef max
#define max(a,b) ((a) > (b) ? (a) : (b))
#endif
#ifndef min
#define min(a,b) ((a) < (b) ? (a) : (b))
#endif

/// Reverse (reflect) the bits in an 8 bit byte.
///
/// @param x: input byte
/// @return bit reversed byte
uint8_t reverse8(uint8_t x);

/// Reflect (reverse LSB to MSB) each byte of a number of bytes.
///
/// @param message bytes of message data
/// @param num_bytes number of bytes to reflect
void reflect_bytes(uint8_t message[], unsigned num_bytes);

/// CRC-4
///
/// @param message[]: array of bytes to check
/// @param nBytes: number of bytes in message
/// @param polynomial: CRC polynomial
/// @param init: starting crc value
/// @return CRC value
uint8_t crc4(uint8_t const message[], unsigned nBytes, uint8_t polynomial, uint8_t init);

/// CRC-7
///
/// @param message[]: array of bytes to check
/// @param nBytes: number of bytes in message
/// @param polynomial: CRC polynomial
/// @param init: starting crc value
/// @return CRC value
uint8_t crc7(uint8_t const message[], unsigned nBytes, uint8_t polynomial, uint8_t init);

/// Generic Cyclic Redundancy Check CRC-8
///
/// Example polynomial: 0x31 = x8 + x5 + x4 + 1	(x8 is implicit)
/// Example polynomial: 0x80 = x8 + x7			(a normal bit-by-bit parity XOR)
///
/// @param message[]: array of bytes to check
/// @param nBytes: number of bytes in message
/// @param polynomial: byte is from x^7 to x^0 (x^8 is implicitly one)
/// @param init: starting crc value
/// @return CRC value
uint8_t crc8(uint8_t const message[], unsigned nBytes, uint8_t polynomial, uint8_t init);

/// "Little-endian" Cyclic Redundancy Check CRC-8 LE
/// Input and output are reflected, i.e. least significant bit is shifted in first.
///
/// @param message[]: array of bytes to check
/// @param nBytes: number of bytes in message
/// @param polynomial: CRC polynomial
/// @param init: starting crc value
/// @return CRC value
uint8_t crc8le(uint8_t const message[], unsigned nBytes, uint8_t polynomial, uint8_t init);

/// CRC-16 LSB
/// Input and output are reflected, i.e. least significant bit is shifted in first.
/// Note that poly and init already need to be reflected.
///
/// @param message[]: array of bytes to check
/// @param nBytes: number of bytes in message
/// @param polynomial: CRC polynomial
/// @param init: starting crc value
/// @return CRC value
uint16_t crc16lsb(uint8_t const message[], unsigned nBytes, uint16_t polynomial, uint16_t init);

/// CRC-16
///
/// @param message[]: array of bytes to check
/// @param nBytes: number of bytes in message
/// @param polynomial: CRC polynomial
/// @param init: starting crc value
/// @return CRC value
uint16_t crc16(uint8_t const message[], unsigned nBytes, uint16_t polynomial, uint16_t init);

/// Digest-8 by "LFSR-based Toeplitz hash".
///
/// @param message bytes of message data
/// @param bytes number of bytes to digest
/// @param gen key stream generator, needs to includes the MSB if the LFSR is rolling
/// @param key initial key
/// @return digest value
uint8_t lfsr_digest8(uint8_t const message[], unsigned bytes, uint8_t gen, uint8_t key);

/// Digest-16 by "LFSR-based Toeplitz hash".
///
/// @param data up to 32 bits data, LSB aligned
/// @param bits number of bits to digest
/// @param gen key stream generator, needs to includes the MSB if the LFSR is rolling
/// @param key initial key
/// @return digest value
uint16_t lfsr_digest16(uint32_t data, int bits, uint16_t gen, uint16_t key);

/// Compute bit parity of a single byte (8 bits).
///
/// @param byte: single byte to check
/// @return 1 odd parity, 0 even parity
int parity8(uint8_t byte);

/// Compute bit parity of a number of bytes.
///
/// @param message bytes of message data
/// @param num_bytes number of bytes to sum
/// @return 1 odd parity, 0 even parity
int parity_bytes(uint8_t const message[], unsigned num_bytes);

/// Compute XOR (byte-wide parity) of a number of bytes.
///
/// @param message bytes of message data
/// @param num_bytes number of bytes to sum
/// @return summation value, per bit-position 1 odd parity, 0 even parity
uint8_t xor_bytes(uint8_t const message[], unsigned num_bytes);

/// Compute Addition of a number of bytes.
///
/// @param message bytes of message data
/// @param num_bytes number of bytes to sum
/// @return summation value
int add_bytes(uint8_t const message[], unsigned num_bytes);

// buffer to hold localized timestamp "YYYY-MM-DD HH:MM:SS.000000"
#define LOCAL_TIME_BUFLEN	32

/// Get current time with usec precision.
///
/// @param tv: output for current time
void get_time_now(struct timeval *tv);

/// Printable timestamp in local time
///
/// @param time_secs: 0 for now, or seconds since the epoch
/// @param buf: output buffer, long enough for "YYYY-MM-DD HH:MM:SS"
/// @return buf pointer (for short hand use as operator)
char* local_time_str(time_t time_secs, char *buf);

/// Printable timestamp in local time with microseconds.
///
/// @param tv: NULL for now, or seconds and microseconds since the epoch
/// @param buf: output buffer, long enough for "YYYY-MM-DD HH:MM:SS"
/// @return buf pointer (for short hand use as operator)
char *usecs_time_str(struct timeval *tv, char *buf);

/// Printable sample position
///
/// @param sample_pos sample position
/// @param buf: output buffer, long enough for "@0.000000s"
/// @return buf pointer (for short hand use as operator)
char *sample_pos_str(float sample_file_pos, char *buf);

/// Convert Celsius to Fahrenheit
///
/// @param celsius: temperature in Celsius
/// @return temperature value in Fahrenheit
float celsius2fahrenheit(float celsius);


/// Convert Fahrenheit to Celsius
///
/// @param celsius: temperature in Fahrenheit
/// @return temperature value in Celsius
float fahrenheit2celsius(float fahrenheit);


/// Convert Kilometers per hour (kph) to Miles per hour (mph)
///
/// @param kph: speed in Kilometers per hour
/// @return speed in miles per hour
float kmph2mph(float kph);

/// Convert Miles per hour (mph) to Kilometers per hour (kmph)
///
/// @param mph: speed in Kilometers per hour
/// @return speed in kilometers per hour
float mph2kmph(float kph);


/// Convert millimeters (mm) to inches (inch)
///
/// @param mm: measurement in millimeters
/// @return measurement in inches
float mm2inch(float mm);

/// Convert inches (inch) to millimeters (mm)
///
/// @param inch: measurement in inches
/// @return measurement in millimeters
float inch2mm(float inch);


/// Convert kilo Pascal (kPa) to pounds per square inch (PSI)
///
/// @param kpa: pressure in kPa
/// @return pressure in PSI
float kpa2psi(float kpa);

/// Convert pounds per square inch (PSI) to kilo Pascal (kPa)
///
/// @param psi: pressure in PSI
/// @return pressure in kPa
float psi2kpa(float psi);


/// Convert hecto Pascal (hPa) to inches of mercury (inHg)
///
/// @param kpa: pressure in kPa
/// @return pressure in inHg
float hpa2inhg(float hpa);

/// Convert inches of mercury (inHg) to hecto Pascal (hPa)
///
/// @param kpa: pressure in inHg
/// @return pressure in hPa
float inhg2hpa(float inhg);


/// Return true if the string ends with the specified suffix, otherwise return false.
///
/// @param str: string to search for patterns
/// @param suffix: the pattern to search
/// @return true if the string ends with the specified suffix, false otherwise.
bool str_endswith(const char *restrict str, const char *restrict suffix);

/// Replace a pattern in a string. This utility function is
/// useful when converting native units to si or customary.
///
/// @param orig: string to search for patterns
/// @param rep: the pattern to replace
/// @param with: the replacement pattern
/// @return a new string that has rep replaced with with
char *str_replace(char *orig, char *rep, char *with);

/// Make a nice printable string for a frequency.
///
/// @param freq: the frequency to convert to a string.
const char *nice_freq (double freq);

#endif /* INCLUDE_UTIL_H_ */