mirror of https://github.com/OpenTTD/OpenTTD.git
162 lines
6.2 KiB
C++
162 lines
6.2 KiB
C++
/* $Id$ */
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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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#endif /* HELPERS_HPP */
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