Indoor/sensors/MACAddress.h

/*
 * © Copyright 2014 – Urheberrechtshinweis
 * Alle Rechte vorbehalten / All Rights Reserved
 *
 * Programmcode ist urheberrechtlich geschuetzt.
 * Das Urheberrecht liegt, soweit nicht ausdruecklich anders gekennzeichnet, bei Frank Ebner.
 * Keine Verwendung ohne explizite Genehmigung.
 * (vgl. § 106 ff UrhG / § 97 UrhG)
 */

#ifndef MACADDRESS_H
#define MACADDRESS_H

#include <cstdint>
#include <string>
#include "../Exception.h"

/**
 * describes a MAC-Address as 64-bit integer.
 * provides 8-bit access to all 6 values
 */
union MACAddress {

private:

	/** fieldwise access */
	struct {
		uint8_t h5;
		uint8_t h4;
		uint8_t h3;
		uint8_t h2;
		uint8_t h1;
		uint8_t h0;
	} fields;

	/** store as 64-bit integer */
	uint64_t mac = 0;

public:

	/** empty ctor */
	MACAddress() {
		;
	}

	/** copy ctor */
	MACAddress(const MACAddress& o) : mac(o.mac) {
		;
	}

	/** ctor form long */
	MACAddress(const uint64_t mac) : mac(mac) {
		;
	}

	/** ctor form string (e.g. "xx:xx:xx:xx:xx:xx") */
	MACAddress(const std::string& str) {

		// sanity check
		if (str.size() == 17 ){
			mac = 0;	// all zeros
			fields.h5 = hexWordToInt(str[ 0], str[ 1]);
			fields.h4 = hexWordToInt(str[ 3], str[ 4]);
			fields.h3 = hexWordToInt(str[ 6], str[ 7]);
			fields.h2 = hexWordToInt(str[ 9], str[10]);
			fields.h1 = hexWordToInt(str[12], str[13]);
			fields.h0 = hexWordToInt(str[15], str[16]);
		}
		else if (str.size() == 12){
			mac = 0;	// all zeros
			fields.h5 = hexWordToInt(str[ 0], str[ 1]);
			fields.h4 = hexWordToInt(str[ 2], str[ 3]);
			fields.h3 = hexWordToInt(str[ 4], str[ 5]);
			fields.h2 = hexWordToInt(str[ 6], str[ 7]);
			fields.h1 = hexWordToInt(str[ 8], str[ 9]);
			fields.h0 = hexWordToInt(str[10], str[11]);
		}
		else{
			throw Exception("invalid hex string length. must be 17 or 12 (without :)");
		}

	}

	uint8_t getField(const int idx) const {
		switch(idx) {
			case 0: return fields.h0;
			case 1: return fields.h1;
			case 2: return fields.h2;
			case 3: return fields.h3;
			case 4: return fields.h4;
			case 5: return fields.h5;
		}
		throw Exception("field-idx out of bounds");
	}

	/** convert to lower-case hex-string ("xx:xx:xx:xx:xx:xx") */
	std::string asString() const {

		std::string str = ":::::::::::::::::";

		intToHexStr(fields.h5, &str[ 0]);
		intToHexStr(fields.h4, &str[ 3]);
		intToHexStr(fields.h3, &str[ 6]);
		intToHexStr(fields.h2, &str[ 9]);
		intToHexStr(fields.h1, &str[12]);
		intToHexStr(fields.h0, &str[15]);

		return str;

	}

	/** get the mac address as a long-int value */
	uint64_t asLong() const {
		// even if we initialized all 8 bytes with zero
		// we mask the 2 unsued bytes to be absolutely safe
		return mac & 0x0000FFFFFFFFFFFF;
	}

	/** equal? */
	bool operator == (const MACAddress& o) const {
		return o.asLong() == asLong();
	}

	/** not equal? */
	bool operator != (const MACAddress& o) const {
		return o.asLong() != asLong();
	}

private:

	/** convert the given hex char [0-F] to an integer [0-15] */
	static uint8_t hexCharToInt(const char hex) {

		// convert
		if (hex >= '0' && hex <= '9') {			// digits
			return (hex - '0');
		} else if (hex >= 'a' && hex <= 'f') {	// lower case
			return (hex - 'a' + 10);
		} else if (hex >= 'A' && hex <= 'F') {	// upper case
			return (hex - 'A' + 10);
		}

		// found an invalid character
		throw Exception("invalid character within MAC address");

	}

	/** convert the given hex-word to an integer */
	static uint8_t hexWordToInt(const char hi, const char lo) {
		return hexCharToInt(hi) << 4 | hexCharToInt(lo);
	}

	/** conver the given integer [0-15] to a hex char [0-F] */
	static char intToHexChar(const uint8_t val) {
		return (val < 10) ? ('0' + val) : ('A' - 10 + val);
	}

	/** insert two hex chars into the provided string buffer */
	static void intToHexStr(const uint8_t val, char* dst) {
		dst[0] = intToHexChar((val >> 4) & 0xF);
		dst[1] = intToHexChar((val >> 0) & 0xF);
	}

};


/** hash-method for MAC-Addresses */
namespace std {
	template <> struct hash<MACAddress> {
		std::size_t operator() (const MACAddress& mac) const {
			return std::hash<uint64_t>()(mac.asLong());
		}
	};
}

#endif // MACADDRESS_H