CpuUsage: make the result more accurate

src/detection/cpuUsage/cpuUsage_windows.c

@@ -1,6 +1,45 @@
 #include "fastfetch.h"
 #include "cpuUsage.h"
 
+#ifdef FF_USE_WIN_NTAPI
+
+#include "util/mallocHelper.h"
+
+#include <ntstatus.h>
+#include <winternl.h>
+
+const char* ffGetCpuUsageInfo(uint64_t* inUseAll, uint64_t* totalAll)
+{
+    ULONG size = 0;
+    if(NtQuerySystemInformation(SystemProcessorPerformanceInformation, NULL, 0, &size) != STATUS_INFO_LENGTH_MISMATCH)
+        return "NtQuerySystemInformation(SystemProcessorPerformanceInformation, NULL) failed";
+
+    SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION* FF_AUTO_FREE pinfo = (SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION*)malloc(size);
+    if(!NT_SUCCESS(NtQuerySystemInformation(SystemProcessorPerformanceInformation, pinfo, size, &size)))
+        return "NtQuerySystemInformation(SystemProcessorPerformanceInformation, size) failed";
+
+    *inUseAll = *totalAll = 0;
+
+    for (uint32_t i = 0; i < size / sizeof(SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION); ++i)
+    {
+        SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION* coreInfo = pinfo + i;
+
+        // KernelTime includes idle time.
+        LONGLONG dpcTime = coreInfo->Reserved1[0].QuadPart;
+        LONGLONG interruptTime = coreInfo->Reserved1[1].QuadPart;
+        coreInfo->KernelTime.QuadPart -= coreInfo->IdleTime.QuadPart;
+        coreInfo->KernelTime.QuadPart += dpcTime + interruptTime;
+
+        LONGLONG inUse = coreInfo->UserTime.QuadPart + coreInfo->KernelTime.QuadPart;
+        *inUseAll += (uint64_t)inUse;
+        *totalAll += (uint64_t)(inUse + coreInfo->IdleTime.QuadPart);
+    }
+
+    return NULL;
+}
+
+#else
+
 #include <processthreadsapi.h>
 
 static inline uint64_t fileTimeToUint64(const FILETIME* ft) {
@@ -19,3 +58,5 @@ const char* ffGetCpuUsageInfo(uint64_t* inUseAll, uint64_t* totalAll)
     *inUseAll = *totalAll - fileTimeToUint64(&idleTime);
     return NULL;
 }
+
+#endif