165 lines
3.4 KiB
C
165 lines
3.4 KiB
C
/*++
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Copyright (C) Microsoft Corporation, 1993 - 1998
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Module Name:
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queue.c
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Abstract:
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Creates a simple Queue that works in Kernel Mode.
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Author:
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Robbie Harris (Hewlett-Packard) 22-May-1998
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Environment:
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Kernel mode
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Revision History :
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--*/
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#include "pch.h"
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void Queue_Create(Queue *pQueue, int size)
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{
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if( !pQueue ) {
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DD(NULL,DDE,"Queue_Create: Queue is Bad");
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return;
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}
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if (pQueue->theArray) {
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Queue_Delete(pQueue);
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}
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pQueue->theArray = (UCHAR *)ExAllocatePool(NonPagedPool, size);
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pQueue->max = size;
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pQueue->head = pQueue->tail = 0;
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}
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BOOLEAN Queue_Delete(Queue *pQueue)
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{
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if( !pQueue ) {
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return FALSE;
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}
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if( pQueue->theArray ) {
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ExFreePool(pQueue->theArray);
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pQueue->theArray = NULL;
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}
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pQueue->head = 0;
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pQueue->tail = 0;
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pQueue->max = 0;
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return TRUE;
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}
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BOOLEAN Queue_Dequeue(Queue *pQueue, PUCHAR data)
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{
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// Validity of pQueue is checked in Queue_IsEmpty proc.
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if( Queue_IsEmpty( pQueue ) ) {
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DD(NULL,DDE,"Queue_Dequeue: Queue is Empty");
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return FALSE;
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}
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*data = pQueue->theArray[pQueue->head++];
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return TRUE;
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}
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BOOLEAN Queue_Enqueue(Queue *pQueue, UCHAR data)
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{
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// Validity of pQueue is checked in Queue_IsFull proc.
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if( Queue_IsFull( pQueue ) ) {
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DD(NULL,DDE,"Queue_Enqueue: Queue is full. Data is lost");
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return FALSE;
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} else {
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pQueue->theArray[pQueue->tail++] = data;
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}
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return TRUE;
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}
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// Return TRUE if we were able to free some space in the Queue
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BOOLEAN Queue_GarbageCollect(Queue *pQueue)
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{
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int iListSize;
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int i;
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if (!pQueue)
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{
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DD(NULL,DDE,"Queue_GarbageCollect: Queue is Bad");
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return FALSE;
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}
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iListSize = pQueue->tail - pQueue->head;
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// Check to see if there is any free entries
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if (pQueue->head == 0 && pQueue->tail == pQueue->max)
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return FALSE;
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for (i = 0; i < iListSize; i++) {
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pQueue->theArray[i] = pQueue->theArray[pQueue->head+i];
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}
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pQueue->head = 0;
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pQueue->tail = iListSize;
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return TRUE;
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}
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//============================================================================
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// NAME: HPKQueue::IsEmpty()
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//
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// PARAMETERS: None
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//
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// RETURNS: True is Queue is empty or doesn't exist. Otherwise False.
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//
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//============================================================================
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BOOLEAN Queue_IsEmpty(Queue *pQueue)
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{
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if (!pQueue)
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{
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DD(NULL,DDE,"Queue_IsEmpty: Queue is Bad");
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return TRUE;
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}
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if (pQueue->theArray) {
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return (BOOLEAN)(pQueue->head == pQueue->tail);
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}
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DD(NULL,DDE,"Queue_IsEmpty: Queue->theArray is Bad");
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return TRUE;
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}
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//============================================================================
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// NAME: HPKQueue::IsFull()
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//
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// PARAMETERS: None
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//
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// RETURNS: True is Queue is full or doesn't exist. Otherwise False.
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//
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//============================================================================
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BOOLEAN Queue_IsFull(Queue *pQueue)
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{
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if( !pQueue ) {
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DD(NULL,DDE,"Queue_IsFull: Queue is Bad");
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return TRUE;
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}
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if( pQueue->theArray ) {
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if( pQueue->tail == pQueue->max ) {
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return !Queue_GarbageCollect(pQueue);
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} else {
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return FALSE;
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}
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}
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DD(NULL,DDE,"Queue_IsFull: Queue->theArray is Bad");
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return TRUE;
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}
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