[Win32] Use nvapi on windows for gpu usage

src/gpu.cpp

@@ -6,6 +6,7 @@ struct gpuInfo gpu_info;
 amdgpu_files amdgpu {};
 
 void getNvidiaGpuInfo(){
+#ifdef __gnu_linux__
     if (nvmlSuccess){
         getNVMLInfo();
         gpu_info.load = nvidiaUtilization.gpu;
@@ -26,6 +27,10 @@ void getNvidiaGpuInfo(){
         gpu_info.powerUsage = 0;
     }
 #endif
+#endif
+#ifdef __WIN32
+    nvapi_util();
+#endif
 }
 
 void getAmdGpuInfo(){

src/meson.build

@@ -48,6 +48,7 @@ if ['windows', 'mingw'].contains(host_machine.system())
     'file_utils_win32.cpp',
     'loaders/loader_nvml_win32.cpp',
     'cpu_win32.cpp',
+    'nvapi.cpp',
 #    'MangoHud.def',
   )
 endif

src/nvapi.cpp

@@ -0,0 +1,65 @@
+#include <windows.h>
+#include <iostream>
+#include "nvidia_info.h"
+#include "gpu.h"
+
+// magic numbers, do not change them
+#define NVAPI_MAX_PHYSICAL_GPUS   64
+#define NVAPI_MAX_USAGES_PER_GPU  34
+
+// function pointer types
+typedef int *(*NvAPI_QueryInterface_t)(unsigned int offset);
+typedef int (*NvAPI_Initialize_t)();
+typedef int (*NvAPI_EnumPhysicalGPUs_t)(int **handles, int *count);
+typedef int (*NvAPI_GPU_GetUsages_t)(int *handle, unsigned int *usages);
+
+NvAPI_QueryInterface_t      NvAPI_QueryInterface     = NULL;
+NvAPI_Initialize_t          NvAPI_Initialize         = NULL;
+NvAPI_EnumPhysicalGPUs_t    NvAPI_EnumPhysicalGPUs   = NULL;
+NvAPI_GPU_GetUsages_t       NvAPI_GPU_GetUsages      = NULL;
+HMODULE hmod;
+bool init_nvapi_bool;
+int         *gpuHandles[NVAPI_MAX_PHYSICAL_GPUS] = { NULL };
+int          gpuCount = 0;
+unsigned int gpuUsages[NVAPI_MAX_USAGES_PER_GPU] = { 0 };
+
+bool checkNVAPI(){
+
+    if (MANGOHUD_ARCH == "64bit")
+        hmod = LoadLibraryA("nvapi64.dll");
+    else
+        hmod = LoadLibraryA("nvapi.dll");
+    if (hmod == NULL)
+    {
+        printf("Failed to load nvapi.dll");
+        return false;
+    }
+    NvAPI_QueryInterface = (NvAPI_QueryInterface_t) GetProcAddress(hmod, "nvapi_QueryInterface");
+    NvAPI_Initialize = (NvAPI_Initialize_t) (*NvAPI_QueryInterface)(0x0150E828);
+    NvAPI_EnumPhysicalGPUs = (NvAPI_EnumPhysicalGPUs_t) (*NvAPI_QueryInterface)(0xE5AC921F);
+    NvAPI_GPU_GetUsages = (NvAPI_GPU_GetUsages_t) (*NvAPI_QueryInterface)(0x189A1FDF);
+    if (NvAPI_Initialize == NULL || NvAPI_EnumPhysicalGPUs == NULL ||
+        NvAPI_EnumPhysicalGPUs == NULL || NvAPI_GPU_GetUsages == NULL)
+    {
+        std::cerr << "Couldn't get functions in nvapi.dll" << std::endl;
+        return 2;
+    }
+    (*NvAPI_Initialize)();
+    
+    int         *gpuHandles[NVAPI_MAX_PHYSICAL_GPUS] = { NULL };
+
+    return true;
+}
+
+void nvapi_util()
+{  
+    if (!init_nvapi_bool){
+        init_nvapi_bool = checkNVAPI();
+    }
+    
+    gpuUsages[0] = (NVAPI_MAX_USAGES_PER_GPU * 4) | 0x10000;
+    (*NvAPI_EnumPhysicalGPUs)(gpuHandles, &gpuCount);
+    (*NvAPI_GPU_GetUsages)(gpuHandles[0], gpuUsages);
+    gpu_info.load = gpuUsages[3];
+
+}

src/nvidia_info.h

@@ -8,4 +8,6 @@ extern struct nvmlMemory_st nvidiaMemory;
 extern bool nvmlSuccess;
 
 bool checkNVML(const char* pciBusId);
+bool checkNVAPI(void);
 bool getNVMLInfo(void);
+void nvapi_util(void);