MdePkg: Add missing implementation of GetTimeInNanoSecond() to TimerLib library insta...

Signed-off-by: xdu2
Reviewed-by: mdkinney
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12297 6f19259b-4bc3-4df7-8a09-765794883524

diff --git a/MdePkg/Library/DxeTimerLibEsal/DxeTimerLibEsal.c b/MdePkg/Library/DxeTimerLibEsal/DxeTimerLibEsal.c
index 964f814bb22fbba30e009742c6229d19c6a7ceed..8ca3ec6f8b360c1d3671bee6f23aff877bd741c0 100644 (file)
--- a/MdePkg/Library/DxeTimerLibEsal/DxeTimerLibEsal.c
+++ b/MdePkg/Library/DxeTimerLibEsal/DxeTimerLibEsal.c
@@ -177,3 +177,47 @@ GetPerformanceCounterProperties (
 \r
   return BaseFrequence * (PalRet.r11 >> 32) / (UINT32)PalRet.r11;\r
 }\r
+\r
+/**\r
+  Converts elapsed ticks of performance counter to time in nanoseconds.\r
+\r
+  This function converts the elapsed ticks of running performance counter to\r
+  time value in unit of nanoseconds.\r
+\r
+  @param  Ticks     The number of elapsed ticks of running performance counter.\r
+\r
+  @return The elapsed time in nanoseconds.\r
+\r
+**/\r
+UINT64\r
+EFIAPI\r
+GetTimeInNanoSecond (\r
+  IN      UINT64                     Ticks\r
+  )\r
+{\r
+  UINT64  Frequency;\r
+  UINT64  NanoSeconds;\r
+  UINT64  Remainder;\r
+  INTN    Shift;\r
+\r
+  Frequency = GetPerformanceCounterProperties (NULL, NULL);\r
+\r
+  //\r
+  //          Ticks\r
+  // Time = --------- x 1,000,000,000\r
+  //        Frequency\r
+  //\r
+  NanoSeconds = MultU64x32 (DivU64x64Remainder (Ticks, Frequency, &Remainder), 1000000000u);\r
+\r
+  //\r
+  // Ensure (Remainder * 1,000,000,000) will not overflow 64-bit.\r
+  // Since 2^29 < 1,000,000,000 = 0x3B9ACA00 < 2^30, Remainder should < 2^(64-30) = 2^34,\r
+  // i.e. highest bit set in Remainder should <= 33.\r
+  //\r
+  Shift = MAX (0, HighBitSet64 (Remainder) - 33);\r
+  Remainder = RShiftU64 (Remainder, (UINTN) Shift);\r
+  Frequency = RShiftU64 (Frequency, (UINTN) Shift);\r
+  NanoSeconds += DivU64x64Remainder (MultU64x32 (Remainder, 1000000000u), Frequency, NULL);\r
+\r
+  return NanoSeconds;\r
+}\r