Add testing code

Adapted from
github.com/sawickiap/MISC/blob/master/QueryPerformanceCounterTest.cpp

src/i_main.c

@@ -27,6 +27,116 @@
 #include "i_system.h"
 #include "m_argv.h"
 #include "version.h"
+#include "i_timer.h"
+
+#define WIN32_LEAN_AND_MEAN
+#include <Windows.h>
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+
+static uint64_t count = 1000000000;
+
+void PrintResult(const wchar_t* name, uint32_t milliseconds)
+{
+    double nsPerCall = (double)milliseconds * 1e6 / (double)count;
+    uint32_t seconds = milliseconds / 1000; milliseconds %= 1000;
+    uint32_t minutes = seconds / 60; seconds %= 60;
+    uint32_t hours = minutes / 60; minutes %= 60;
+    wprintf(L"According to %s it took %u:%02u:%02u.%03u (%g ns per call)\n", name, hours, minutes, seconds, milliseconds, nsPerCall);
+}
+
+int qpctest()
+{
+    LARGE_INTEGER freq;
+    QueryPerformanceFrequency(&freq);
+
+    //if( argc == 2 )
+    //    swscanf_s(argv[1], L"%zu", &count);
+    {
+        wprintf(L"Executing QueryPerformanceCounter x %zu...\n", count);
+
+        LARGE_INTEGER begPerfCount;
+        LARGE_INTEGER lastPerfCount;
+        //LARGE_INTEGER sumPerfCount{}; // Unused.
+
+        uint64_t begTickCount = GetTickCount64();
+        for( size_t i = 0; i < count; ++i )
+        {
+            QueryPerformanceCounter(&lastPerfCount);
+            //sumPerfCount.QuadPart += lastPerfCount.QuadPart;
+            if( i == 0 )
+                begPerfCount.QuadPart = lastPerfCount.QuadPart;
+        }
+        uint64_t endTickCount = GetTickCount64();
+
+        PrintResult(L"GetTickCount64", (uint32_t)(endTickCount - begTickCount));
+
+        uint32_t qpcMilliseconds = (uint32_t)(uint64_t)(((lastPerfCount.QuadPart - begPerfCount.QuadPart) * 1000. / freq.QuadPart) + 0.5);
+        PrintResult(L"QueryPerformanceCounter", qpcMilliseconds);
+    }
+
+    {
+        wprintf(L"\nExecuting SDL_GetPerformanceCounter x %zu...\n", count);
+        uint64_t first_time = 0;
+        uint64_t last_time = 0;
+
+        uint64_t begTickCount = GetTickCount64();
+        for( size_t i = 0; i < count; ++i )
+        {
+            last_time = SDL_GetPerformanceCounter();
+            if( i == 0 )
+                first_time = last_time;
+        }
+        uint64_t endTickCount = GetTickCount64();
+
+        PrintResult(L"GetTickCount64", (uint32_t)(endTickCount - begTickCount));
+
+        PrintResult(L"SDL_GetPerformanceCounter", (last_time - first_time) * 1000 / SDL_GetPerformanceFrequency());
+    }
+
+    {
+        wprintf(L"\nExecuting (double) I_GetTimeUS x %zu...\n", count);
+        double first_time = 0.;
+        double last_time = 0.;
+
+        uint64_t begTickCount = GetTickCount64();
+        for( size_t i = 0; i < count; ++i )
+        {
+            last_time = I_GetTimeUS();
+            if( i == 0 )
+                first_time = last_time;
+        }
+        uint64_t endTickCount = GetTickCount64();
+
+        PrintResult(L"GetTickCount64", (uint32_t)(endTickCount - begTickCount));
+
+        PrintResult(L"(double) I_GetTimeUS", (last_time - first_time) * 1e-3);
+    }
+
+    {
+        wprintf(L"\nExecuting (uint64) I_GetTimeUS x %zu...\n", count);
+        uint64_t first_time = 0;
+        uint64_t last_time = 0;
+
+        uint64_t begTickCount = GetTickCount64();
+        for( size_t i = 0; i < count; ++i )
+        {
+            last_time = I_GetTimeUSold();
+            if( i == 0 )
+                first_time = last_time;
+        }
+        uint64_t endTickCount = GetTickCount64();
+
+        PrintResult(L"GetTickCount64", (uint32_t)(endTickCount - begTickCount));
+
+        PrintResult(L"(uint64) I_GetTimeUS", (last_time - first_time) / 1000);
+    }
+
+    return 0;
+}
+
 
 //
 // D_DoomMain()
@@ -67,7 +177,11 @@ int main(int argc, char **argv)
       exit(0);
    }
 
-   D_DoomMain();
+   I_InitTimer();
+
+   qpctest();
+
+   //D_DoomMain();
 
    return 0;
 }

src/i_timer.c

@@ -65,6 +65,18 @@ double I_GetTimeUS(void)
     return (int64_t)SDL_GetPerformanceCounter() * baseperiod_us;
 }
 
+uint64_t I_GetTimeUSold(void)
+{
+    uint64_t counter = SDL_GetPerformanceCounter();
+
+    if( basecounter == 0 )
+    {
+        basecounter = counter;
+    }
+
+    return ((counter - basecounter) * 1000000ull) / basefreq;
+}
+
 int time_scale = 100;
 
 static uint64_t GetPerfCounter_Scaled(void)

src/i_timer.h

@@ -34,6 +34,8 @@ int I_GetTimeMS(void);
 
 double I_GetTimeUS(void);
 
+uint64_t I_GetTimeUSold(void);
+
 void I_SetTimeScale(int scale);
 
 void I_SetFastdemoTimer(boolean on);