From 6d95ed53dc81a2951585c5bf94a5dba77842c8f0 Mon Sep 17 00:00:00 2001
From: Owen Rudge <owen@owenrudge.net>
Date: Fri, 11 Dec 2020 15:20:13 +0000
Subject: [PATCH] Feature: Add support for rdtsc for ARM-based Windows (MSVC)

---
 src/cpu.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/cpu.cpp b/src/cpu.cpp
index bafa0f7352..b93f0fa5ed 100644
--- a/src/cpu.cpp
+++ b/src/cpu.cpp
@@ -16,11 +16,18 @@
 
 /* rdtsc for MSC_VER, uses simple inline assembly, or _rdtsc
  * from external win64.asm because VS2005 does not support inline assembly */
-#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64)) && !defined(RDTSC_AVAILABLE)
+#if defined(_MSC_VER) && !defined(RDTSC_AVAILABLE)
 #include <intrin.h>
+#include <windows.h>
 uint64 ottd_rdtsc()
 {
+#if defined(_M_ARM)
+	return __rdpmccntr64();
+#elif defined(_M_ARM64)
+	return _ReadStatusReg(ARM64_PMCCNTR_EL0);
+#else
 	return __rdtsc();
+#endif
 }
 #define RDTSC_AVAILABLE
 #endif