windows-nt/Source/XPSP1/NT/base/ntos/ex/intrloc2.c
2020-09-26 16:20:57 +08:00

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/*++
Copyright (c) 1989 Microsoft Corporation
Module Name:
intrloc2.c
Abstract:
This module implements the *portable* (i.e. SLOW) versions of
the executive's simple atomic increment/decrement procedures.
Real implementation should be in assembler.
Author:
Bryan Willman (bryanwi) 2-Aug-90
Environment:
Kernel mode only.
Revision History:
--*/
#include "exp.h"
INTERLOCKED_RESULT
ExInterlockedIncrementLong (
IN PLONG Addend,
IN PKSPIN_LOCK Lock
)
/*++
Routine Description:
This function atomically increments Addend, returning an ennumerated
type which indicates what interesting transitions in the value of
Addend occurred due the operation.
Arguments:
Addend - Pointer to variable to increment.
Lock - Spinlock used to implement atomicity.
Return Value:
An ennumerated type:
ResultNegative if Addend is < 0 after increment.
ResultZero if Addend is = 0 after increment.
ResultPositive if Addend is > 0 after increment.
--*/
{
LONG OldValue;
OldValue = (LONG)ExInterlockedAddUlong((PULONG)Addend, 1, Lock);
if (OldValue < -1)
return ResultNegative;
if (OldValue == -1)
return ResultZero;
if (OldValue > -1)
return ResultPositive;
}
INTERLOCKED_RESULT
ExInterlockedDecrementLong (
IN PLONG Addend,
IN PKSPIN_LOCK Lock
)
/*++
Routine Description:
This function atomically decrements Addend, returning an ennumerated
type which indicates what interesting transitions in the value of
Addend occurred due the operation.
Arguments:
Addend - Pointer to variable to decrement.
Lock - Spinlock used to implement atomicity.
Return Value:
An ennumerated type:
ResultNegative if Addend is < 0 after decrement.
ResultZero if Addend is = 0 after decrement.
ResultPositive if Addend is > 0 after decrement.
--*/
{
LONG OldValue;
OldValue = (LONG)ExInterlockedAddUlong((PULONG)Addend, -1, Lock);
if (OldValue > 1)
return ResultPositive;
if (OldValue == 1)
return ResultZero;
if (OldValue < 1)
return ResultNegative;
}