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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 <olivier.martin@arm.com>



git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16329 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
Olivier Martin 2014-11-11 00:52:46 +00:00 committed by oliviermartin
parent 284fb5c811
commit 4a2928934b
1 changed files with 1 additions and 1 deletions
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ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c
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@ -85,7 +85,7 @@ MicroSecondDelay (
// 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 ();