winapi: Move to assembly

XboxDev · Oct 24, 2023 · eb4385b · eb4385b
1 parent 8ea50ce
commit eb4385b
Showing 1 changed file with 76 additions and 13 deletions.
diff --git a/lib/winapi/profiling.c b/lib/winapi/profiling.c
@@ -14,29 +14,92 @@
 static LARGE_INTEGER frequency = {{0, 0}};
 static void __attribute__((constructor)) PrimeQueryPerformanceFrequency ()
 {
-    ULARGE_INTEGER start_rdtsc = {{0, 0}}, end_rdtsc = {{0, 0}};
-    ULONG start_ticks = 0, end_ticks = 0;
+    #define BASE_CLOCK_FLOAT 16.666667f
+    #define NV_PRAMDAC_PLL_COEFF *(volatile ULONG *)0xFD680500
+    #define NV_PTIMER_NUM *(volatile ULONG *)0xFD009200
+    #define NV_PTIMER_DEN *(volatile ULONG *)0xFD009210
+    #define NV_PTIMER_COUNT 0xFD009400
+    #define ASM_LOOPS 1024 * 4
+
+    ULARGE_INTEGER rdtsc_count_1 = {{0, 0}}, rdtsc_count_2 = {{0, 0}};
+    DWORD ptimer_count_1 = 0, ptimer_count_2 = 0;
+
+    // Precalcuate NVCLK & PTIMER freq
+    double nv_clock = BASE_CLOCK_FLOAT * ((NV_PRAMDAC_PLL_COEFF & 0xFF00) >> 8);
+    nv_clock /= 1 << ((NV_PRAMDAC_PLL_COEFF & 0x70000) >> 16);
+    nv_clock /= NV_PRAMDAC_PLL_COEFF & 0xFF;
+
+    double ptimer_frequency = (nv_clock / NV_PTIMER_NUM) * NV_PTIMER_DEN;
 
     KeEnterCriticalRegion();
 
-    // The values generated after launching aren't accurate, give it time to increment...
-    Sleep(700);
+    __asm
+    {
+        push eax
+        push edx
+        push ecx
+
+        cli
+        sfence
+
+        // Turn off caches
+        mov eax, cr0
+        or eax, 1 << 30 // Set CD bit
+        mov cr0, eax
+        wbinvd
 
-    start_rdtsc.QuadPart = __rdtsc();
-    start_ticks = KeTickCount;
+        // Reset PTIMER
+        mov eax, [NV_PTIMER_COUNT]
+        and eax, ~(0xFFFFFFE0) // First 5 bits are not used
+        mov [NV_PTIMER_COUNT], eax
 
-    Sleep(200);
+        rdtsc
+        mov rdtsc_count_1.LowPart, eax
+        mov rdtsc_count_1.HighPart, edx
+
+        mov eax, [NV_PTIMER_COUNT]
+        mov ptimer_count_1, eax
 
-    end_rdtsc.QuadPart = __rdtsc();
-    end_ticks = KeTickCount;
+        // Spin for a bit
+        mov eax, ASM_LOOPS
+        loop_1:
+        dec eax
+        jnz loop_1
 
-    end_rdtsc.QuadPart -= start_rdtsc.QuadPart;
-    end_rdtsc.QuadPart /= end_ticks - start_ticks;
+        rdtsc
+        mov rdtsc_count_2.LowPart, eax
+        mov rdtsc_count_2.HighPart, edx
+
+        mov eax, [NV_PTIMER_COUNT]
+        mov ptimer_count_2, eax
 
-    frequency.QuadPart = end_rdtsc.QuadPart;
-    frequency.QuadPart *= 1000LL;
+        // Without this, invaldidating the cache below will crash the system
+        sfence
 
+        mov eax, cr0
+        and eax, ~(1 << 30) // Clear CD bit
+        mov cr0, eax
+        wbinvd
+
+        sti
+
+        pop ecx
+        pop edx
+        pop eax
+    }
     KeLeaveCriticalRegion();
+
+    double ptimer_diff = (ptimer_count_2 >> 5) - (ptimer_count_1 >> 5);
+    double rdtsc_diff = rdtsc_count_2.QuadPart - rdtsc_count_1.QuadPart;
+
+    double ptimer_scale = ptimer_diff / ptimer_frequency;
+    double cpu_freq_float = rdtsc_diff / ptimer_scale;
+
+    if (!cpu_freq_float) {
+        frequency.QuadPart = 733333333;
+    } else {
+        frequency.QuadPart = (ULONG)(cpu_freq_float * 1000 * 1000);
+    }
 }
 #endif