Changes in / [68cf1d4:36e120a]


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  • src/Common/utility.h

    r68cf1d4 r36e120a  
    111111};
    112112
    113 // -----------------------------------------------------------------------------
    114 // O(1) polymorphic integer ilog2, using clz, which returns the number of leading 0-bits, starting at the most
    115 // significant bit (single instruction on x86)
    116 
    117 template<typename T>
    118 inline
    119 #if defined(__GNUC__) && __GNUC__ > 4
    120 constexpr
    121 #endif
    122 T ilog2(const T & t) {
    123         if(std::is_integral<T>::value) {
    124                 const constexpr int r = sizeof(t) * __CHAR_BIT__ - 1;
    125                 if( sizeof(T) == sizeof(unsigned       int) ) return r - __builtin_clz  ( t );
    126                 if( sizeof(T) == sizeof(unsigned      long) ) return r - __builtin_clzl ( t );
    127                 if( sizeof(T) == sizeof(unsigned long long) ) return r - __builtin_clzll( t );
    128         }
    129         assert(false);
    130         return -1;
    131 } // ilog2
    132 
    133113// Local Variables: //
    134114// tab-width: 4 //
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