diff --git a/source/lib/sysdep/win/wcpu.cpp b/source/lib/sysdep/win/wcpu.cpp
new file mode 100755
index 0000000000..84d7e65395
--- /dev/null
+++ b/source/lib/sysdep/win/wcpu.cpp
@@ -0,0 +1,131 @@
+#include "precompiled.h"
+
+#include "lib.h"
+#include "win_internal.h"
+
+#include "cpu.h"
+
+
+int on_each_cpu(void(*cb)())
+{
+	const HANDLE hProcess = GetCurrentProcess();
+
+	DWORD process_affinity, system_affinity;
+	if(!GetProcessAffinityMask(hProcess, &process_affinity, &system_affinity))
+		return -1;
+
+	// our affinity != system affinity: OS is limiting the CPUs that
+	// this process can run on. fail (cannot call back for each CPU).
+	if(process_affinity != system_affinity)
+		return -1;
+
+	for(DWORD cpu_bit = 1; cpu_bit != 0 && cpu_bit <= process_affinity; cpu_bit *= 2)
+	{
+		// switch to target CPU (if present in affinity bitmap)
+		if(!(process_affinity & cpu_bit))
+			continue;
+		if(!SetProcessAffinityMask(hProcess, process_affinity))
+		{
+			debug_warn("SetProcessAffinityMask failed");
+			continue;
+		}
+		// .. reschedule, to make sure we switch CPUs
+		Sleep(0);
+
+		cb();
+	}
+
+	// restore to original value
+	SetProcessAffinityMask(hProcess, process_affinity);
+
+	return 0;
+}
+
+
+static void check_speedstep()
+{
+	// CallNtPowerInformation
+	// (manual import because it's not supported on Win95)
+	NTSTATUS (WINAPI *pCNPI)(POWER_INFORMATION_LEVEL, PVOID, ULONG, PVOID, ULONG) = 0;
+	HMODULE hPowrprofDll = LoadLibrary("powrprof.dll");
+	*(void**)&pCNPI = GetProcAddress(hPowrprofDll, "CallNtPowerInformation");
+	if(pCNPI)
+	{
+		// most likely not speedstep-capable if these aren't supported
+		SYSTEM_POWER_CAPABILITIES spc;
+		if(pCNPI(SystemPowerCapabilities, 0, 0, &spc, sizeof(spc)) == STATUS_SUCCESS)
+			if(!spc.ProcessorThrottle || !spc.ThermalControl)
+				cpu_speedstep = 0;
+
+		// probably speedstep if cooling mode active.
+		// the documentation of PO_TZ_* is unclear, so we can't be sure.
+		SYSTEM_POWER_INFORMATION spi;
+		if(pCNPI(SystemPowerInformation, 0, 0, &spi, sizeof(spi)) == STATUS_SUCCESS)
+			if(spi.CoolingMode != PO_TZ_INVALID_MODE)
+				cpu_speedstep = 1;
+
+		// definitely speedstep if a CPU has thermal throttling active.
+		// note that we don't care about user-defined throttles
+		// (see ppi.CurrentMhz) - they don't change often.
+		ULONG ppi_buf_size = cpus * sizeof(PROCESSOR_POWER_INFORMATION);
+		void* ppi_buf = malloc(ppi_buf_size);
+		if(pCNPI(ProcessorInformation, 0, 0, ppi_buf, ppi_buf_size) == STATUS_SUCCESS)
+		{
+			PROCESSOR_POWER_INFORMATION* ppi = (PROCESSOR_POWER_INFORMATION*)ppi_buf;
+			for(int i = 0; i < cpus; i++)
+				// thermal throttling currently active
+				if(ppi[i].MaxMhz != ppi[i].MhzLimit)
+				{
+					cpu_speedstep = 1;
+					break;
+				}
+		}
+		free(ppi_buf);
+	}
+	FreeLibrary(hPowrprofDll);
+		// this is most likely the only reference,
+		// so don't free it (=> unload) until done with the DLL.
+
+	// CallNtPowerInformation not available, or none of the above apply:
+	// don't know yet (for certain, at least).
+	if(cpu_speedstep == -1)
+	{
+		// check if running on a laptop
+		HW_PROFILE_INFO hi;
+		GetCurrentHwProfile(&hi);
+		bool is_laptop = !(hi.dwDockInfo & DOCKINFO_DOCKED) ^ !(hi.dwDockInfo & DOCKINFO_UNDOCKED);
+			// both flags set <==> this is a desktop machine.
+			// both clear is unspecified; we assume it's not a laptop.
+			// NOTE: ! is necessary (converts expression to bool)
+
+		// we'll guess SpeedStep is active if on a laptop.
+		// ia32 code will get a second crack at it.
+		cpu_speedstep = (is_laptop)? 1 : 0;
+	}
+}
+
+
+int win_get_cpu_info()
+{
+	// get number of CPUs (can't fail)
+	SYSTEM_INFO si;
+	GetSystemInfo(&si);
+	cpus = si.dwNumberOfProcessors;
+
+	// read CPU frequency from registry
+	HKEY hKey;
+	const char* key = "HARDWARE\\DESCRIPTION\\System\\CentralProcessor\\0";
+	if(RegOpenKeyEx(HKEY_LOCAL_MACHINE, key, 0, KEY_QUERY_VALUE, &hKey) == 0)
+	{
+		DWORD freq_mhz;
+		DWORD size = sizeof(freq_mhz);
+		if(RegQueryValueEx(hKey, "~MHz", 0, 0, (LPBYTE)&freq_mhz, &size) == 0)
+			cpu_freq = freq_mhz * 1e6;
+
+		RegCloseKey(hKey);
+	}
+
+	check_speedstep();
+
+	return 0;
+}