bjarni@6268: /* $Id$ */
bjarni@6268: 
bjarni@6268: #ifndef CMD_HELPER_H
bjarni@6268: #define CMD_HELPER_H
bjarni@6268: 
bjarni@6268: #include "direction.h"
bjarni@6268: #include "macros.h"
bjarni@6268: #include "road.h"
bjarni@6268: 
bjarni@6268: 
bjarni@6268: template<uint N> static inline void ExtractValid();
bjarni@6268: template<> static inline void ExtractValid<1>() {}
bjarni@6268: 
bjarni@6268: 
bjarni@6268: template<typename T> struct ExtractBits;
bjarni@6268: template<> struct ExtractBits<Axis>          { static const uint Count =  1; };
bjarni@6268: template<> struct ExtractBits<DiagDirection> { static const uint Count =  2; };
bjarni@6268: template<> struct ExtractBits<RoadBits>      { static const uint Count =  4; };
bjarni@6268: 
bjarni@6268: 
bjarni@6268: template<typename T, uint N, typename U> static inline T Extract(U v)
bjarni@6268: {
bjarni@6268: 	// Check if there are enough bits in v
bjarni@6268: 	ExtractValid<N + ExtractBits<T>::Count <= sizeof(U) * 8>();
bjarni@6268: 	return (T)GB(v, N, ExtractBits<T>::Count);
bjarni@6268: }
bjarni@6268: 
bjarni@6268: #endif