tron@6134: /* $Id$ */
tron@6134: 
tron@6134: #ifndef CMD_HELPER_H
tron@6134: #define CMD_HELPER_H
tron@6134: 
tron@6134: #include "direction.h"
tron@6134: #include "macros.h"
tron@6134: #include "road.h"
tron@6134: 
tron@6134: 
tron@6134: template<uint N> static inline void ExtractValid();
tron@6134: template<> static inline void ExtractValid<1>() {}
tron@6134: 
tron@6134: 
tron@6134: template<typename T> struct ExtractBits;
tron@6134: template<> struct ExtractBits<Axis>          { static const uint Count =  1; };
tron@6134: template<> struct ExtractBits<DiagDirection> { static const uint Count =  2; };
tron@6134: template<> struct ExtractBits<RoadBits>      { static const uint Count =  4; };
tron@6134: 
tron@6134: 
tron@6134: template<typename T, uint N, typename U> static inline T Extract(U v)
tron@6134: {
tron@6134: 	// Check if there are enough bits in v
tron@6134: 	ExtractValid<N + ExtractBits<T>::Count <= sizeof(U) * 8>();
tron@6134: 	return (T)GB(v, N, ExtractBits<T>::Count);
tron@6134: }
tron@6134: 
tron@6134: #endif