1 files changed, 95 insertions, 0 deletions
diff --git a/src/VBox/Runtime/nt/RTSemEventGetResolution-nt.cpp b/src/VBox/Runtime/nt/RTSemEventGetResolution-nt.cpp
new file mode 100644
index 00000000..b7fe22aa
--- /dev/null
+++ b/src/VBox/Runtime/nt/RTSemEventGetResolution-nt.cpp
@@ -0,0 +1,95 @@
+/* $Id: RTSemEventGetResolution-nt.cpp $ */
+/** @file
+ * IPRT -  Single Release Event Semaphores, RTSemEventGetResolution.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMEVENT_WITHOUT_REMAPPING
+#ifdef IN_RING0
+# include "../r0drv/nt/the-nt-kernel.h"
+#else
+# include <iprt/nt/nt.h>
+#endif
+#include <iprt/semaphore.h>
+
+#include <iprt/assert.h>
+#include <iprt/timer.h>
+#ifdef IN_RING3
+# include <iprt/system.h>
+#endif
+
+
+RTDECL(uint32_t) RTSemEventGetResolution(void)
+{
+    /*
+     * We need to figure the KeWaitForSingleObject / NtWaitForSingleObject timeout
+     * resolution, i.e. if we wish to wait for 1000ns how long are we likely to
+     * actually wait before woken up.
+     *
+     * In older versions of NT, these timeout were implemented using KTIMERs and
+     * have the same resolution as what them.  This should be found using
+     * ExSetTimerResolution or NtQueryTimerResolution.
+     *
+     * Probably since windows 8.1 the value returned by NtQueryTimerResolution (and
+     * set NtSetTimerResolution) have been virtualized and no longer reflects the
+     * timer wheel resolution, at least from what I can tell. ExSetTimerResolution
+     * still works as before, but it accesses variable that I cannot find out how
+     * to access from user land.  So, kernel will get (and be able to set) the right
+     * granularity, while in user land we'll be forced to reporting the max value.
+     *
+     * (The reason why I suspect it's since 8.1 is because the high resolution
+     * ExSetTimer APIs were introduced back then.)
+     */
+#ifdef IN_RING0
+    return RTTimerGetSystemGranularity();
+#else
+    ULONG cNtTicksMin = 0;
+    ULONG cNtTicksMax = 0;
+    ULONG cNtTicksCur = 0;
+    NTSTATUS rcNt = NtQueryTimerResolution(&cNtTicksMin, &cNtTicksMax, &cNtTicksCur);
+    if (NT_SUCCESS(rcNt))
+    {
+        Assert(cNtTicksMin >= cNtTicksMax);
+        if (RTSystemGetNtVersion() >= RTSYSTEM_MAKE_NT_VERSION(6,3,9600)) /** @todo check when the switch happened, might be much later... */
+            return cNtTicksMin * 100;
+        return cNtTicksCur * 100;
+    }
+    AssertFailed();
+    return 16 * RT_NS_1MS; /* the default on 64-bit windows 10 */
+#endif
+}
+