gistfile1.txt

#include <windows.h>
#include <vector>
#include <iostream>
#include <winternl.h>

#pragma comment(lib, "Ntdll.lib")

typedef struct
_SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION_R {
    LARGE_INTEGER IdleTime;
    LARGE_INTEGER KernelTime;
    LARGE_INTEGER UserTime;
    LARGE_INTEGER DpcTime;
    LARGE_INTEGER InterruptTime;
    ULONG InterruptCount;
} SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION_R;

class CPU
{
public:
    uint64_t prev_idle = 0;
    uint64_t prev_ker = 0;
    uint64_t prev_user = 0;
    uint64_t cur_idle = 0;
    uint64_t cur_ker = 0;
    uint64_t cur_user = 0;

    double get()
    {
        SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION_R *a = new SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION_R[4];
        // 4 is the total of proc
        NtQuerySystemInformation(SystemProcessorPerformanceInformation, a, sizeof(SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION_R) * 4, NULL);

        prev_idle = cur_idle;
        prev_ker = cur_ker;
        prev_user = cur_user;

        cur_idle = 0;
        cur_ker = 0;
        cur_user = 0;

        for (int i = 0; i < 4; ++i)
        {
            SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION_R b = a[i];
            cur_idle += b.IdleTime.QuadPart;
            cur_ker += b.KernelTime.QuadPart;
            cur_user += b.UserTime.QuadPart;
        }

        uint64_t delta_idle = cur_idle - prev_idle;
        uint64_t delta_kernel = cur_ker - prev_ker;
        uint64_t delta_user = cur_user - prev_user;

        uint64_t delta_sys = delta_kernel + delta_user;

        delete[] a;
        return (delta_sys - delta_idle) * 100.0 / delta_sys;
    }
};

int main()
{
    CPU a;
    std::cout << "starting" << '\n';
    while(1)
    {
        std::cout << a.get() << '\n';
        Sleep(1000);
    }
    return 0;
}