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/* $Id$ */

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/** @file helpers.hpp */

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#ifndef HELPERS_HPP

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#define HELPERS_HPP

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#include "macros.h"

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/** When allocating using malloc/calloc in C++ it is usually needed to cast the return value

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*  from void* to the proper pointer type. Another alternative would be MallocT<> as follows */

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template <typename T> FORCEINLINE T* MallocT(size_t num_elements)

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{

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	T *t_ptr = (T*)malloc(num_elements * sizeof(T));

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	return t_ptr;

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}

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/** When allocating using malloc/calloc in C++ it is usually needed to cast the return value

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*  from void* to the proper pointer type. Another alternative would be MallocT<> as follows */

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template <typename T> FORCEINLINE T* CallocT(size_t num_elements)

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{

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	T *t_ptr = (T*)calloc(num_elements, sizeof(T));

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	return t_ptr;

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}

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/** When allocating using malloc/calloc in C++ it is usually needed to cast the return value

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*  from void* to the proper pointer type. Another alternative would be MallocT<> as follows */

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template <typename T> FORCEINLINE T* ReallocT(T* t_ptr, size_t num_elements)

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{

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	t_ptr = (T*)realloc(t_ptr, num_elements * sizeof(T));

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	return t_ptr;

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}

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/** type safe swap operation */

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template<typename T> void Swap(T& a, T& b)

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{

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	T t = a;

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	a = b;

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	b = t;

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}

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/** returns the absolute value of (scalar) variable. @note assumes variable to be signed */

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template <typename T> static inline T myabs(T a) { return a < (T)0 ? -a : a; }

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/** returns the (absolute) difference between two (scalar) variables */

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template <typename T> static inline T delta(T a, T b) { return a < b ? b - a : a - b; }

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/** Some enums need to have allowed incrementing (i.e. StationClassID) */

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#define DECLARE_POSTFIX_INCREMENT(type) \

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	FORCEINLINE type operator ++(type& e, int) \

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	{ \

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		type e_org = e; \

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		e = (type)((int)e + 1); \

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		return e_org; \

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	} \

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	FORCEINLINE type operator --(type& e, int) \

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	{ \

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		type e_org = e; \

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		e = (type)((int)e - 1); \

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		return e_org; \

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	}

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/** Operators to allow to work with enum as with type safe bit set in C++ */

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# define DECLARE_ENUM_AS_BIT_SET(mask_t) \

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	FORCEINLINE mask_t operator | (mask_t m1, mask_t m2) {return (mask_t)((int)m1 | m2);} \

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	FORCEINLINE mask_t operator & (mask_t m1, mask_t m2) {return (mask_t)((int)m1 & m2);} \

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	FORCEINLINE mask_t operator ^ (mask_t m1, mask_t m2) {return (mask_t)((int)m1 ^ m2);} \

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	FORCEINLINE mask_t& operator |= (mask_t& m1, mask_t m2) {m1 = m1 | m2; return m1;} \

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	FORCEINLINE mask_t& operator &= (mask_t& m1, mask_t m2) {m1 = m1 & m2; return m1;} \

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	FORCEINLINE mask_t& operator ^= (mask_t& m1, mask_t m2) {m1 = m1 ^ m2; return m1;} \

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	FORCEINLINE mask_t operator ~(mask_t m) {return (mask_t)(~(int)m);}

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/** Informative template class exposing basic enumeration properties used by several

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 *  other templates below. Here we have only forward declaration. For each enum type

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 *  we will create specialization derived from MakeEnumPropsT<>.

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 *  i.e.:

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 *    template <> struct EnumPropsT<Track> : MakeEnumPropsT<Track, byte, TRACK_BEGIN, TRACK_END, INVALID_TRACK> {};

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 *  followed by:

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 *    typedef TinyEnumT<Track> TrackByte;

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 */

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template <typename Tenum_t> struct EnumPropsT;

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/** Helper template class that makes basic properties of given enumeration type visible

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 *  from outsize. It is used as base class of several EnumPropsT specializations each

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 *  dedicated to one of commonly used enumeration types.

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 *  @param Tenum_t enumeration type that you want to describe

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 *  @param Tstorage_t what storage type would be sufficient (i.e. byte)

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 *  @param Tbegin first valid value from the contiguous range (i.e. TRACK_BEGIN)

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 *  @param Tend one past the last valid value from the contiguous range (i.e. TRACK_END)

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 *  @param Tinvalid value used as invalid value marker (i.e. INVALID_TRACK)

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 */

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template <typename Tenum_t, typename Tstorage_t, Tenum_t Tbegin, Tenum_t Tend, Tenum_t Tinvalid>

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struct MakeEnumPropsT {

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	typedef Tenum_t type;                     ///< enum type (i.e. Trackdir)

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	typedef Tstorage_t storage;               ///< storage type (i.e. byte)

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	static const Tenum_t begin = Tbegin;      ///< lowest valid value (i.e. TRACKDIR_BEGIN)

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	static const Tenum_t end = Tend;          ///< one after the last valid value (i.e. TRACKDIR_END)

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	static const Tenum_t invalid = Tinvalid;  ///< what value is used as invalid value (i.e. INVALID_TRACKDIR)

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};

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/** In some cases we use byte or uint16 to store values that are defined as enum. It is

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	*  necessary in order to control the sizeof() such values. Some compilers make enum

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	*  the same size as int (4 or 8 bytes instead of 1 or 2). As a consequence the strict

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	*  compiler type-checking causes errors like:

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	*     'HasPowerOnRail' : cannot convert parameter 1 from 'byte' to 'RailType' when

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	*  u->u.rail.railtype is passed as argument or type RailType. In such cases it is better

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	*  to teach the compiler that u->u.rail.railtype is to be treated as RailType. */

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template <typename Tenum_t> struct TinyEnumT;

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/** The general declaration of TinyEnumT<> (above) */

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template <typename Tenum_t> struct TinyEnumT

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{

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	typedef Tenum_t enum_type;                      ///< expose our enumeration type (i.e. Trackdir) to outside

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	typedef EnumPropsT<Tenum_t> Props;              ///< make easier access to our enumeration propeties

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	typedef typename Props::storage storage_type;   ///< small storage type

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	static const enum_type begin = Props::begin;    ///< enum beginning (i.e. TRACKDIR_BEGIN)

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	static const enum_type end = Props::end;        ///< enum end (i.e. TRACKDIR_END)

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	static const enum_type invalid = Props::invalid;///< invalid value (i.e. INVALID_TRACKDIR)

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	storage_type m_val;  ///< here we hold the actual value in small (i.e. byte) form

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	/** Cast operator - invoked then the value is assigned to the Tenum_t type */

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	FORCEINLINE operator enum_type () const

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	{

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		return (enum_type)m_val;

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	}

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	/** Assignment operator (from Tenum_t type) */

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	FORCEINLINE TinyEnumT& operator = (enum_type e)

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	{

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		m_val = (storage_type)e; return *this;

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	}

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	/** postfix ++ operator on tiny type */

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	FORCEINLINE TinyEnumT& operator ++ (int)

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	{

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		if (++m_val >= end) m_val -= (storage_type)(end - begin);

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		return *this;

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	}

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};

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template <typename T> void ClrBitT(T &t, int bit_index)

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{

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	t = (T)(t & ~((T)1 << bit_index));

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}

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template <typename T> void SetBitT(T &t, int bit_index)

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{

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	t = (T)(t | ((T)1 << bit_index));

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}

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template <typename T> void ToggleBitT(T &t, int bit_index)

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{

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	t = (T)(t ^ ((T)1 << bit_index));

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}

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/**

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* Zero initialization end marker.

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* @see ZeroInitBegin for usage.

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*/

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struct ZeroInitEnd {

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};

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/**

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 * Zero initialization begin marker. When you need to initialize struct/class members by

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 * memset(&m_first_member, 0, ((byte*)&m_last_member) - ((byte*)&m_first_member + sizeof(m_last_member));

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 * place ZeroInitBegin before m_first_member, place ZeroInitEnd after m_last_member, call ZeroInitBegin

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 * constructor give him ZeroInitEnd& as parameter. This will clear whole area between them using memset.

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 * @see ZeroInitEnd

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 */

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struct ZeroInitBegin {

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	ZeroInitBegin(const ZeroInitEnd &end)

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	{

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		memset(this, 0, ((byte*)&end) - ((byte*)this));

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	}

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};

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#endif /* HELPERS_HPP */