From 1973eaf67ca7f01b92e1c4528413970a9d0fb969 Mon Sep 17 00:00:00 2001
From: Max Paperno <mpaperno@users.noreply.github.com>
Date: Sun, 19 Mar 2017 15:07:30 -0400
Subject: [PATCH] [Simulator] Improve CoGetOSTime() for MSVC. (#4635)

* [Simulator] Increase resolution of CoGetOSTime() on Windows MSVC (possible fix for #4529, ref. #4342).

* Return total time, not delta time.

* Improve efficiency.
---
 radio/src/targets/simu/simpgmspace.cpp | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/radio/src/targets/simu/simpgmspace.cpp b/radio/src/targets/simu/simpgmspace.cpp
index c737df300..1353043c6 100644
--- a/radio/src/targets/simu/simpgmspace.cpp
+++ b/radio/src/targets/simu/simpgmspace.cpp
@@ -96,10 +96,29 @@ uint16_t getTmr2MHz()
 #endif
 }
 
+// return 2ms resolution to match CoOS settings
 U64 CoGetOSTime(void)
 {
 #if defined(_MSC_VER)
-  return GetTickCount()/2;
+  static double freqScale = 0.0;
+  static LARGE_INTEGER firstTick;
+  LARGE_INTEGER newTick;
+
+  if (!freqScale) {
+    LARGE_INTEGER frequency;
+    // get ticks per second
+    QueryPerformanceFrequency(&frequency);
+    // 2ms resolution
+    freqScale = 500.0 / frequency.QuadPart;
+    // init timer
+    QueryPerformanceCounter(&firstTick);
+    TRACE_SIMPGMSPACE("CoGetOSTime() init: first tick = %llu @ %llu Hz", firstTick.QuadPart, frequency.QuadPart);
+  }
+  // read the timer
+  QueryPerformanceCounter(&newTick);
+  // compute the elapsed time
+  return U64((newTick.QuadPart - firstTick.QuadPart) * freqScale);
+  //return GetTickCount64() / 2;  // only 10-16ms typical resolution
 #else
   auto now = std::chrono::steady_clock::now();
   return (U64) std::chrono::duration_cast<std::chrono::milliseconds>(now.time_since_epoch()).count() / 2;