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[rtl-433.git] / include / util.h

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+/**
+ * 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 <stdint.h>
+#include <time.h>
+
+// 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 the bits in an 8 bit byte
+/// @param x: input byte
+/// @return bit reversed byte
+uint8_t reverse8(uint8_t x);
+
+/// 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
+///
+/// Based on code generated from PyCyc, (pycrc.org)
+///
+/// @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
+///
+/// @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);
+
+/// CRC-16 CCITT
+///
+/// @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_ccitt(uint8_t const message[], unsigned nBytes, uint16_t polynomial, uint16_t init);
+
+/// compute bit parity of a single byte
+///
+/// @param inByte: single byte to check
+/// @return 1 odd parity, 0 even parity
+int byteParity(uint8_t inByte);
+
+// buffer to hold localized timestamp YYYY-MM-DD HH:MM:SS
+#define LOCAL_TIME_BUFLEN      32
+
+/// 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);
+
+/// 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);
+
+
+#endif /* INCLUDE_UTIL_H_ */