# cmd_helper.h

    00001 /* $Id: cmd_helper.h 11689 2007-12-23 21:02:40Z smatz $ */
    00002
    00003 #ifndef CMD_HELPER_H
    00004 #define CMD_HELPER_H
    00005
    00006 #include "direction_type.h"
    00007 #include "road_type.h"
    00008
    00009
    00010 template<uint N> static inline void ExtractValid();
    00011 template<> inline void ExtractValid<1>() {}
    00012
    00013
    00014 template<typename T> struct ExtractBits;
    00015 template<> struct ExtractBits<Axis>          { static const uint Count =  1; };
    00016 template<> struct ExtractBits<DiagDirection> { static const uint Count =  2; };
    00017 template<> struct ExtractBits<RoadBits>      { static const uint Count =  4; };
    00018
    00019
    00020 template<typename T, uint N, typename U> static inline T Extract(U v)
    00021 {
    00022   // Check if there are enough bits in v
    00023   ExtractValid<N + ExtractBits<T>::Count <= sizeof(U) * 8>();
    00024   return (T)GB(v, N, ExtractBits<T>::Count);
    00025 }
    00026
    00027 #endif