私はそれをループに入れて、CPUがそれぞれの異なる操作を実行するのにかかるリアルタイムを取得する方法に興味があります
#include<iostream>
#include<cstdlib>
#include<time.h>
using namespace std;
typedef unsigned __int64 uint64;
const uint64 m1=0x5555555555555555;
const uint64 m2=0x3333333333333333;
const uint64 m4=0x0f0f0f0f0f0f0f0f;
const uint64 m8=0x00ff00ff00ff00ff;
const uint64 m16=0x0000ffff0000ffff;
const uint64 m32=0x00000000ffffffff;
const uint64 hff=0xffffffffffffffff;
const uint64 h01=0x0101010101010101;
uint64 popcount_1(uint64 x)
{
x=(x&m1)+((x>>1)&m1);
x=(x&m2)+((x>>2)&m2);
x=(x&m4)+((x>>4)&m4);
x=(x&m8)+((x>>8)&m8);
x=(x&m16)+((x>>16)&m16);
x=(x&m32)+((x>>32)&m32);
return (uint64)x;
}
//This uses fewer arithmetic operations than any other known
//implementation on machines with slow multiplication.
//It uses 17 arithmetic operations.
int popcount_2(uint64 x)
{
x-=(x>>1)&m1;//put count of each 2 bits into those 2 bits
x=(x&m2)+((x>>2)&m2);//put count of each 4 bits into those 4 bits
x=(x+(x>>4))&m4; //put count of each 8 bits into those 8 bits
x+=x>>8;//put count of each 16 bits into their lowest 8 bits
x+=x>>16;
x+=x>>32;
return x&0x7f;
}
////This uses fewer arithmetic operations than any other known
//implementation on machines with fast multiplication.
//It uses 12 arithmetic operations, one of which is a multiply.
int popcount_3(uint64 x)
{
x-=(x>>1)&m1;
x=(x&m2)+((x>>2)&m2);
x=(x+(x>>4))&m4;
return (x*h01)>>56;
}
uint64 popcount_4(uint64 x)
{
uint64 count;
for(count=0; x; count++)
{
x&=x-1;
}
return count;
}
uint64 random()
{
uint64 r30=RAND_MAX*rand()+rand();
uint64 s30=RAND_MAX*rand()+rand();
uint64 t4=rand()&0xf;
uint64 res=(r30<<34 )+(s30<<4)+t4;
return res;
}
int main()
{
int testnum;
while (true)
{
cout<<"enter number of test "<<endl;
cin>>testnum;
uint64 x= random();
switch(testnum)
{
case 1: {
clock_t start=clock();
popcount_1(x);
clock_t end=clock();
cout<<"execution time of first method"<<start-end<<" "<<endl;
}
break;
case 2: {
clock_t start=clock();
popcount_2(x);
clock_t end=clock();
cout<<"execution time of first method"<<start-end<<" "<<endl;
}
break;
case 3: {
clock_t start=clock();
popcount_3(x);
clock_t end=clock();
cout<<"execution time of first method"<<start-end<<" "<<endl;
}
break;
case 4: {
clock_t start=clock();
popcount_4(x);
clock_t end=clock();
cout<<"execution time of first method"<<start-end<<" "<<endl;
}
break;
default:
cout<<"it is not correct number "<<endl;
break;
}
}
return 0;
}
どの番号のテストを入力しても、端末には常にゼロが書き込まれます。10または20と100の操作は現代のコンピューターでは何もないため、その理由は明らかですが、正確な答えではないにしても、近似値少なくとも？どうもありがとう