Current Total CPU Usage in Dev-C++

#include <windows.h>
#include <stdio.h>

//------------------------------------------------------------------------------------------------------------------
// Prototype(s)...
//------------------------------------------------------------------------------------------------------------------
CHAR cpuusage(void);

//-----------------------------------------------------
typedef BOOL ( __stdcall * pfnGetSystemTimes)( LPFILETIME lpIdleTime, LPFILETIME lpKernelTime, LPFILETIME lpUserTime );
static pfnGetSystemTimes s_pfnGetSystemTimes = NULL;

static HMODULE s_hKernel = NULL;
//-----------------------------------------------------
void GetSystemTimesAddress() {
    if( s_hKernel == NULL ) {
        s_hKernel = LoadLibrary( "Kernel32.dll" );
        if( s_hKernel != NULL ) {
            s_pfnGetSystemTimes = (pfnGetSystemTimes)GetProcAddress( s_hKernel, "GetSystemTimes" );
            if( s_pfnGetSystemTimes == NULL ) {
                FreeLibrary( s_hKernel );
                s_hKernel = NULL;
            }
        }
    }
}
//----------------------------------------------------------------------------------------------------------------


//----------------------------------------------------------------------------------------------------------------
// cpuusage(void)
// ==============
// Return a CHAR value in the range 0 - 100 representing actual CPU usage in percent.
//----------------------------------------------------------------------------------------------------------------
CHAR cpuusage() {
    FILETIME               ft_sys_idle;
    FILETIME               ft_sys_kernel;
    FILETIME               ft_sys_user;

    ULARGE_INTEGER         ul_sys_idle;
    ULARGE_INTEGER         ul_sys_kernel;
    ULARGE_INTEGER         ul_sys_user;

    static ULARGE_INTEGER    ul_sys_idle_old;
    static ULARGE_INTEGER  ul_sys_kernel_old;
    static ULARGE_INTEGER  ul_sys_user_old;

    CHAR  usage = 0;

    // we cannot directly use GetSystemTimes on C language
    /* add this line :: pfnGetSystemTimes */
    s_pfnGetSystemTimes(&ft_sys_idle,    /* System idle time */
                        &ft_sys_kernel,  /* system kernel time */
                        &ft_sys_user);   /* System user time */

    CopyMemory(&ul_sys_idle  , &ft_sys_idle  , sizeof(FILETIME)); // Could been optimized away...
    CopyMemory(&ul_sys_kernel, &ft_sys_kernel, sizeof(FILETIME)); // Could been optimized away...
    CopyMemory(&ul_sys_user  , &ft_sys_user  , sizeof(FILETIME)); // Could been optimized away...

    usage  =
        (
            (
                (
                    (
                        (ul_sys_kernel.QuadPart - ul_sys_kernel_old.QuadPart)+
                        (ul_sys_user.QuadPart   - ul_sys_user_old.QuadPart)
                    )
                    -
                    (ul_sys_idle.QuadPart-ul_sys_idle_old.QuadPart)
                )
                *
                (100)
            )
            /
            (
                (ul_sys_kernel.QuadPart - ul_sys_kernel_old.QuadPart)+
                (ul_sys_user.QuadPart   - ul_sys_user_old.QuadPart)
            )
        );

    ul_sys_idle_old.QuadPart   = ul_sys_idle.QuadPart;
    ul_sys_user_old.QuadPart   = ul_sys_user.QuadPart;
    ul_sys_kernel_old.QuadPart = ul_sys_kernel.QuadPart;

    return usage;
}
//------------------------------------------------------------------------------------------------------------------
// Entry point
//------------------------------------------------------------------------------------------------------------------
int main(void) {
    GetSystemTimesAddress();
    for(int n=0; n<30; n++) {
        printf("CPU Usage: %3d%%\n",cpuusage());
        Sleep(1000);
    }
    return 0;
}