diff options
Diffstat (limited to 'source/components/hardware/hwtimer.c')
| -rw-r--r-- | source/components/hardware/hwtimer.c | 27 |
1 files changed, 13 insertions, 14 deletions
diff --git a/source/components/hardware/hwtimer.c b/source/components/hardware/hwtimer.c index 358164ee8a31..0fc33e8acc06 100644 --- a/source/components/hardware/hwtimer.c +++ b/source/components/hardware/hwtimer.c @@ -283,7 +283,7 @@ AcpiGetTimerDuration ( UINT32 *TimeElapsed) { ACPI_STATUS Status; - UINT32 DeltaTicks; + UINT64 DeltaTicks; UINT64 Quotient; @@ -302,34 +302,33 @@ AcpiGetTimerDuration ( return_ACPI_STATUS (AE_SUPPORT); } + if (StartTicks == EndTicks) + { + *TimeElapsed = 0; + return_ACPI_STATUS (AE_OK); + } + /* * Compute Tick Delta: * Handle (max one) timer rollovers on 24-bit versus 32-bit timers. */ - if (StartTicks < EndTicks) - { - DeltaTicks = EndTicks - StartTicks; - } - else if (StartTicks > EndTicks) + DeltaTicks = EndTicks; + if (StartTicks > EndTicks) { if ((AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) == 0) { /* 24-bit Timer */ - DeltaTicks = (((0x00FFFFFF - StartTicks) + EndTicks) & 0x00FFFFFF); + DeltaTicks |= (UINT64) 1 << 24; } else { /* 32-bit Timer */ - DeltaTicks = (0xFFFFFFFF - StartTicks) + EndTicks; + DeltaTicks |= (UINT64) 1 << 32; } } - else /* StartTicks == EndTicks */ - { - *TimeElapsed = 0; - return_ACPI_STATUS (AE_OK); - } + DeltaTicks -= StartTicks; /* * Compute Duration (Requires a 64-bit multiply and divide): @@ -337,7 +336,7 @@ AcpiGetTimerDuration ( * TimeElapsed (microseconds) = * (DeltaTicks * ACPI_USEC_PER_SEC) / ACPI_PM_TIMER_FREQUENCY; */ - Status = AcpiUtShortDivide (((UINT64) DeltaTicks) * ACPI_USEC_PER_SEC, + Status = AcpiUtShortDivide (DeltaTicks * ACPI_USEC_PER_SEC, ACPI_PM_TIMER_FREQUENCY, &Quotient, NULL); *TimeElapsed = (UINT32) Quotient; |