Instead of multiplication arithmetic, the C + + shift calculation

Test shift and multiplication comparison, found that the shift is faster than the multiplication operation of a bit speed, but the difficulty is to determine whether it is 2 of the power of the second number, if not also through the code to split to 2 Power + on the molecular fatigue and then through the shift to get 2 of the power of the number of such;

The following code is simply the judgment that the power series is the shift operation, not the normal calculation, not exactly the shift calculation, (after finding a method to judge faster in the update)

C + +:

1#include <iostream>2 3 4 5uint64_t multiply_dived (uint64_t member, uint64_t denominator,Charstyle)6 {7     //determines whether the denominator is a power of 28     if(Denominator & (Denominator-1))9     {Ten         if(style = ='*') One         { A              while((Denominator >>=1) !=1) -             { -Member <<=1; the             } -  -}Else -         { +              while((Denominator >>=1) !=1) -             { +Member >>=1; A             } at  -         } -         returnmember; -     } -  -     if(style = ='*') in     { -         returnMember *denominator; to}Else +     { -         returnMember/denominator; the     } * } $ Panax Notoginsenguint64_t Nomorl (uint64_t member, uint64_t denominator,Charstyle) - { the     if(style = ='*') +     { A         returnMember *denominator; the}Else +     { -         returnMember/denominator; $     } $ } -  -  the intMain () - {Wuyistd::clock_t start =0, stop =0; theStart =clock (); -      for(Uint64_t i =0; I <100000000; i++) Wu     { -Multiply_dived (1, -,'/'); About     } $Stop =clock (); -Std::cout <<"In addition to shift run time:"<< (Double) (Stop-start)/clocks_per_sec) <<Std::endl; -  -  A  +  theStart =clock (); -      for(Uint64_t i =0; I <100000000; i++) $     { theNomorl (1, -,'/'); the     } theStop =clock (); theStd::cout <<"Normal except run time:"<< (Double) (Stop-start)/clocks_per_sec) <<Std::endl; -  in     return 0; the}

C + + shift calculation instead of multiplication operation