Revision: 16329
http://sourceforge.net/p/edk2/code/16329
Author: oliviermartin
Date: 2014-11-11 00:52:46 +0000 (Tue, 11 Nov 2014)
Log Message:
-----------
ArmPkg/ArmArchTimerLib: Promotes 32bit value to prevent overflow
Both MicroSeconds and PcdArmArchTimerFreqInHz are 32-bit values on
AArch32 so their multiplication produces 32-bit result that might
cause wrong calculation.
Example: With MicroSeconds = 200 us, PcdArmArchTimerFreqInHz = 24MHz.
200*24000000 = 0x1_1E1A_3000 => So 0x1E1A_3000 when the type is UINT32.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Olivier Martin <[email protected]>
Modified Paths:
--------------
trunk/edk2/ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c
Modified: trunk/edk2/ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c
===================================================================
--- trunk/edk2/ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c 2014-11-11
00:52:11 UTC (rev 16328)
+++ trunk/edk2/ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c 2014-11-11
00:52:46 UTC (rev 16329)
@@ -85,7 +85,7 @@
// Calculate counter ticks that can represent requested delay:
// = MicroSeconds x TICKS_PER_MICRO_SEC
// = MicroSeconds x Frequency.10^-6
- TimerTicks64 = (MicroSeconds * PcdGet32 (PcdArmArchTimerFreqInHz)) /
1000000U;
+ TimerTicks64 = ((UINT64)MicroSeconds * PcdGet32 (PcdArmArchTimerFreqInHz)) /
1000000U;
// Read System Counter value
SystemCounterVal = ArmGenericTimerGetSystemCount ();
------------------------------------------------------------------------------
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