1 /* $Id$ */

     2 

     3 #ifndef CMD_HELPER_H

     4 #define CMD_HELPER_H

     5 

     6 #include "direction.h"

     7 #include "macros.h"

     8 #include "road.h"

     9 

    10 

    11 template<uint N> static inline void ExtractValid();

    12 template<> static inline void ExtractValid<1>() {}

    13 

    14 

    15 template<typename T> struct ExtractBits;

    16 template<> struct ExtractBits<Axis>          { static const uint Count =  1; };

    17 template<> struct ExtractBits<DiagDirection> { static const uint Count =  2; };

    18 template<> struct ExtractBits<RoadBits>      { static const uint Count =  4; };

    19 

    20 

    21 template<typename T, uint N, typename U> static inline T Extract(U v)

    22 {

    23 	// Check if there are enough bits in v

    24 	ExtractValid<N + ExtractBits<T>::Count <= sizeof(U) * 8>();

    25 	return (T)GB(v, N, ExtractBits<T>::Count);

    26 }

    27 

    28 #endif