windows-server-2003/base/ntos/inc/intrlk.h

/*++ BUILD Version: 0001    // Increment this if a change has global effects

Copyright (c) 2001  Microsoft Corporation

Module Name:

    intrlk.h

Abstract:

    This module contains platform independent interlocked functions.

Author:

    David N. Cutler (davec) 15-Feb-2001

Revision History:

--*/

#ifndef _INTRLK_
#define _INTRLK_

//
// The following functions implement interlocked singly linked lists.
//
// WARNING: These lists can only be used when it is known that the ABA
//          removal problem cannot occur. If the ABA problem can occur,
//          then SLIST's should be used.
//

FORCEINLINE
PSINGLE_LIST_ENTRY
InterlockedPopEntrySingleList (
    IN PSINGLE_LIST_ENTRY ListHead
    )

/*

Routine Description:

    This function pops an entry from the front of a singly linked list.

Arguments:

    ListHead - Supplies a pointer to the listhead of a singly linked list.

Return Value:

    If the list is empty, then NULL is returned. Otherwise, the address of the
    first entry removed from the list is returned as the function
    value.

*/

{

    PSINGLE_LIST_ENTRY FirstEntry;
    PSINGLE_LIST_ENTRY NextEntry;

    FirstEntry = ListHead->Next;
    do {
        if (FirstEntry == NULL) {
            return NULL;
        }

        NextEntry = FirstEntry;
        FirstEntry =
            (PSINGLE_LIST_ENTRY)InterlockedCompareExchangePointer((PVOID *)ListHead,
                                                                  FirstEntry->Next,
                                                                  FirstEntry);

    } while (FirstEntry != NextEntry);
    return FirstEntry;
}

FORCEINLINE
PSINGLE_LIST_ENTRY
InterlockedPushEntrySingleList (
    IN PSINGLE_LIST_ENTRY ListHead,
    IN PSINGLE_LIST_ENTRY Entry
    )

/*

Routine Description:

    This function pushes an entry onto the front of a singly linked list.

Arguments:

    ListHead - Supplies a pointer to the listhead of a singly linked list.

    Entry - Supplies a pointer to a single list entry.

Return Value:

    The previous contents of the listhead are returned as the function value.
    If NULL is returned, then the list transitioned for an empty to a non
    empty state.

*/

{

    PSINGLE_LIST_ENTRY FirstEntry;
    PSINGLE_LIST_ENTRY NextEntry;

    FirstEntry = ListHead->Next;
    do {
        Entry->Next = FirstEntry;
        NextEntry = FirstEntry;
        FirstEntry =
            (PSINGLE_LIST_ENTRY)InterlockedCompareExchangePointer((PVOID *)ListHead,
                                                                  Entry,
                                                                  FirstEntry);

    } while (FirstEntry != NextEntry);
    return FirstEntry;
}

FORCEINLINE
PSINGLE_LIST_ENTRY
InterlockedFlushSingleList (
    IN PSINGLE_LIST_ENTRY ListHead
    )

/*

Routine Description:

    This function pops the entire list from the front of a singly linked list.

Arguments:

    ListHead - Supplies a pointer to the listhead of a singly linked list.

Return Value:

    If the list is empty, then NULL is returned. Otherwise, the address of the
    first entry removed from the list is returned as the function
    value.

*/

{

    return (PSINGLE_LIST_ENTRY)InterlockedExchangePointer((PVOID *)ListHead,
                                                          NULL);
}

#endif // _INTRLK_