Add new API GetTimeInNanoSecond() to TimerLib to convert elapsed ticks to time in unit of nanoseconds.

Signed-off-by: xdu2
Reviewed-by: mdkinney

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12206 6f19259b-4bc3-4df7-8a09-765794883524

1 files changed, 36 insertions, 0 deletions

diff --git a/OvmfPkg/Library/AcpiTimerLib/AcpiTimerLib.c b/OvmfPkg/Library/AcpiTimerLib/AcpiTimerLib.c
index 7a6745c..a2f774f 100644
--- a/OvmfPkg/Library/AcpiTimerLib/AcpiTimerLib.c
+++ b/OvmfPkg/Library/AcpiTimerLib/AcpiTimerLib.c
@@ -239,3 +239,39 @@ GetPerformanceCounterProperties (
 

   return ACPI_TIMER_FREQUENCY;

 }

+

+/**

+  Converts elapsed ticks of performance counter to time in nanoseconds.

+

+  This function converts the elapsed ticks of running performance counter to

+  time value in unit of nanoseconds.

+

+  @param  Ticks     The number of elapsed ticks of running performance counter.

+

+  @return The elapsed time in nanoseconds.

+

+**/

+UINT64

+EFIAPI

+GetTimeInNanoSecond (

+  IN      UINT64                     Ticks

+  )

+{

+  UINT64  NanoSeconds;

+  UINT32  Remainder;

+

+  //

+  //          Ticks

+  // Time = --------- x 1,000,000,000

+  //        Frequency

+  //

+  NanoSeconds = MultU64x32 (DivU64x32Remainder (Ticks, ACPI_TIMER_FREQUENCY, &Remainder), 1000000000u);

+

+  //

+  // Frequency < 0x100000000, so Remainder < 0x100000000, then (Remainder * 1,000,000,000)

+  // will not overflow 64-bit.

+  //

+  NanoSeconds += DivU64x32 (MultU64x32 ((UINT64) Remainder, 1000000000u), ACPI_TIMER_FREQUENCY);

+

+  return NanoSeconds;

+}