[PATCH 1/2] MdePkg/TimerLib: Add a function to calculate elapsed time

[Pankaj Bansal <pankaj.bansal@nxp.com>]

This function calculates the time elaped in Naoseconds between call to
this function and BaseTime, which is passed as argument.

This is particularly useful in detecting timeout conditions.

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Pankaj Bansal <pankaj.bansal@nxp.com>

diff --git a/MdePkg/Include/Library/TimerLib.h b/MdePkg/Include/Library/TimerLib.h
index ecc3ad3..82a5c5c 100644
--- a/MdePkg/Include/Library/TimerLib.h
+++ b/MdePkg/Include/Library/TimerLib.h
@@ -111,4 +111,20 @@ GetTimeInNanoSecond (
   IN      UINT64                     Ticks
   );
 
+/**
+  Get Elapsed time in Nanoseonds w.r.t BaseTime
+
+  This function calculates the time elaped in Naoseconds between call to this
+  function and BaseTime, which is passed as argument.
+
+  @param  BaseTime     BaseTime in NanoSeconds.
+
+  @return The elapsed time in nanoseconds.
+
+**/
+UINT64
+EFIAPI
+GetElapsedTime (
+  IN      UINT64                     BaseTime
+  );
 #endif
-- 
2.7.4