mirror of
https://github.com/CloverHackyColor/CloverBootloader.git
synced 2024-11-30 12:43:41 +01:00
108 lines
2.9 KiB
C
108 lines
2.9 KiB
C
/** @file
|
|
UEFI Miscellaneous boot Services Stall service implementation
|
|
|
|
Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
|
|
SPDX-License-Identifier: BSD-2-Clause-Patent
|
|
|
|
**/
|
|
|
|
//
|
|
// Include statements
|
|
//
|
|
|
|
#include "DxeMain.h"
|
|
|
|
/**
|
|
Internal worker function to call the Metronome Architectural Protocol for
|
|
the number of ticks specified by the UINT64 Counter value. WaitForTick()
|
|
service of the Metronome Architectural Protocol uses a UINT32 for the number
|
|
of ticks to wait, so this function loops when Counter is larger than 0xffffffff.
|
|
|
|
@param Counter Number of ticks to wait.
|
|
|
|
**/
|
|
VOID
|
|
CoreInternalWaitForTick (
|
|
IN UINT64 Counter
|
|
)
|
|
{
|
|
while (RShiftU64 (Counter, 32) > 0) {
|
|
gMetronome->WaitForTick (gMetronome, 0xffffffff);
|
|
Counter -= 0xffffffff;
|
|
}
|
|
gMetronome->WaitForTick (gMetronome, (UINT32)Counter);
|
|
}
|
|
|
|
/**
|
|
Introduces a fine-grained stall.
|
|
|
|
@param Microseconds The number of microseconds to stall execution.
|
|
|
|
@retval EFI_SUCCESS Execution was stalled for at least the requested
|
|
amount of microseconds.
|
|
@retval EFI_NOT_AVAILABLE_YET gMetronome is not available yet
|
|
|
|
**/
|
|
EFI_STATUS
|
|
EFIAPI
|
|
CoreStall (
|
|
IN UINTN Microseconds
|
|
)
|
|
{
|
|
UINT64 Counter;
|
|
UINT32 Remainder;
|
|
UINTN Index;
|
|
|
|
if (gMetronome == NULL) {
|
|
return EFI_NOT_AVAILABLE_YET;
|
|
}
|
|
|
|
//
|
|
// Counter = Microseconds * 10 / gMetronome->TickPeriod
|
|
// 0x1999999999999999 = (2^64 - 1) / 10
|
|
//
|
|
if ((UINT64) Microseconds > 0x1999999999999999ULL) {
|
|
//
|
|
// Microseconds is too large to multiple by 10 first. Perform the divide
|
|
// operation first and loop 10 times to avoid 64-bit math overflow.
|
|
//
|
|
Counter = DivU64x32Remainder (
|
|
Microseconds,
|
|
gMetronome->TickPeriod,
|
|
&Remainder
|
|
);
|
|
for (Index = 0; Index < 10; Index++) {
|
|
CoreInternalWaitForTick (Counter);
|
|
}
|
|
|
|
if (Remainder != 0) {
|
|
//
|
|
// If Remainder was not zero, then normally, Counter would be rounded
|
|
// up by 1 tick. In this case, since a loop for 10 counts was used
|
|
// to emulate the multiply by 10 operation, Counter needs to be rounded
|
|
// up by 10 counts.
|
|
//
|
|
CoreInternalWaitForTick (10);
|
|
}
|
|
} else {
|
|
//
|
|
// Calculate the number of ticks by dividing the number of microseconds by
|
|
// the TickPeriod. Calculation is based on 100ns unit.
|
|
//
|
|
Counter = DivU64x32Remainder (
|
|
MultU64x32 (Microseconds, 10),
|
|
gMetronome->TickPeriod,
|
|
&Remainder
|
|
);
|
|
if (Remainder != 0) {
|
|
//
|
|
// If Remainder is not zero, then round Counter up by one tick.
|
|
//
|
|
Counter++;
|
|
}
|
|
CoreInternalWaitForTick (Counter);
|
|
}
|
|
|
|
return EFI_SUCCESS;
|
|
}
|