Windows2003-3790/enduser/netmeeting/av/rrcm/rtcp/rrcmqueu.cpp

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2001-01-01 00:00:00 +01:00
/*----------------------------------------------------------------------------
* File: RRCMQUEU.C
* Product: RTP/RTCP implementation.
* Description: Provides queue management function for RRCM.
*
* INTEL Corporation Proprietary Information
* This listing is supplied under the terms of a license agreement with
* Intel Corporation and may not be copied nor disclosed except in
* accordance with the terms of that agreement.
* Copyright (c) 1995 Intel Corporation.
*--------------------------------------------------------------------------*/
#include "rrcm.h"
/*---------------------------------------------------------------------------
/ Global Variables
/--------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------
/ External Variables
/--------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------
* Function : allocateLinkedList
* Description: Allocates all the necessary memory resource and link the
* cells to the link list.
*
* Input : *listPtr : Address of head pointer.
* hHeap : Heap to allocate the data from.
* *numCells : -> to the number of cells to allocate.
* elementSize : Element size.
* pCritSect : -> to critical section
*
* Return: TRUE = Error Code, no queues allocated and linked
* FALSE = OK
--------------------------------------------------------------------------*/
DWORD allocateLinkedList (PLINK_LIST pList,
HANDLE hHeap,
DWORD *numCells,
DWORD elementSize,
CRITICAL_SECTION *pCritSect)
{
DWORD cellsAllocated = *numCells;
PLINK_LIST pHead;
PLINK_LIST pTmp;
IN_OUT_STR ("RTCP: Enter allocateLinkedList()\n");
// allocate first cell
pHead = (PLINK_LIST)HeapAlloc (hHeap, HEAP_ZERO_MEMORY, elementSize);
if (pHead == NULL)
{
RRCM_DBG_MSG ("RTCP: ERROR - Resource allocation failed", 0,
__FILE__, __LINE__, DBG_CRITICAL);
IN_OUT_STR ("RTCP: Exit allocateLinkedList()\n");
return (RRCMError_RTCPResources);
}
// protect the pointers
EnterCriticalSection (pCritSect);
// initialize list tail pointer
pList->prev = pHead;
// update number of cells allocated
cellsAllocated--;
while (cellsAllocated)
{
cellsAllocated--;
pHead->next = (PLINK_LIST)HeapAlloc (hHeap, HEAP_ZERO_MEMORY,
elementSize);
if (pHead->next == NULL)
break;
// save head pointer
pTmp = pHead;
// update head ptr
pHead = pHead->next;
pHead->prev = pTmp;
}
// set number of cells allocated
*numCells -= cellsAllocated;
// set head/tail pointers
pList->next = pHead;
// unprotect the pointers
LeaveCriticalSection (pCritSect);
IN_OUT_STR ("RTCP: Exit allocateLinkedList()\n");
return (RRCM_NoError);
}
/*--------------------------------------------------------------------------
** Function : addToHeadOfList
** Description: Add a new cell to the specified queue. The queue acts as a
** FIFO (cells enqueud on the next pointer and dequeued by the
** starting address of the queue).
**
** Input : pHead = Address of head pointer of queue.
** pNew = Cell address to be added to the linked list.
** pCritSect = -> to critical section object.
**
** Return: None.
--------------------------------------------------------------------------*/
void addToHeadOfList (PLINK_LIST pHead,
PLINK_LIST pNew,
CRITICAL_SECTION *pCritSect)
{
ASSERT (pHead);
ASSERT (pNew);
IN_OUT_STR ("RTCP: Enter addToHeadOfList()\n");
// safe access to pointers
EnterCriticalSection (pCritSect);
if (pHead->next == NULL)
{
// head is NULL for the first cell. Assign the address of
// the free cell
pHead->next = pHead->prev = pNew;
pNew->next = pNew->prev = NULL;
}
else
// head ptr points to something
{
pNew->prev = pHead->next;
(pHead->next)->next = pNew;
pNew->next = NULL;
// update the head pointer now
pHead->next = pNew;
}
// unlock pointer access
LeaveCriticalSection (pCritSect);
IN_OUT_STR ("RTCP: Exit addToHeadOfList()\n");
}
/*--------------------------------------------------------------------------
** Function : addToTailOfList
** Description: Add a new cell to the specified queue. The queue acts as a
** FIFO (cells enqueud on the next pointer and dequeued by the
** starting address of the queue).
**
** Input : pTail = Address of tail pointer to enqueue in.
** pNew = New cell address to be added to the linked list.
**
** Return: None.
--------------------------------------------------------------------------*/
void addToTailOfList (PLINK_LIST pTail,
PLINK_LIST pNew,
CRITICAL_SECTION *pCritSect)
{
ASSERT (pTail);
ASSERT (pNew);
IN_OUT_STR ("RTCP: Enter addToTailOfList()\n");
// safe access to pointers
EnterCriticalSection (pCritSect);
if (pTail->prev == NULL)
{
// head is NULL for the first cell. Assign the address of
// the free cell
pTail->next = pTail->prev = pNew;
pNew->next = pNew->prev = NULL;
}
else
// tail ptr points to something
{
pNew->next = pTail->prev;
(pTail->prev)->prev = pNew;
pNew->prev = NULL;
// update the parent tail pointer now
pTail->prev = pNew;
}
// unlock pointer access
LeaveCriticalSection (pCritSect);
IN_OUT_STR ("RTCP: Exit addToTailOfList()\n");
}
/*--------------------------------------------------------------------------
** Function : removePcktFromHead
** Description: Remove a cell from front of the specified queue.
**
** Input : pQueue: -> to the list to remove the packet from
**
** Return: NULL ==> Empty queue.
** Buffer Address ==> OK, cell removed
--------------------------------------------------------------------------*/
PLINK_LIST removePcktFromHead (PLINK_LIST pQueue,
CRITICAL_SECTION *pCritSect)
{
PLINK_LIST pReturnQ;
IN_OUT_STR ("RTCP: Enter removePcktFromHead()\n");
// safe access to pointers
EnterCriticalSection (pCritSect);
if ((pReturnQ = pQueue->next) != NULL)
{
// We have a buffer. If this is the last buffer in the queue,
// mark it empty.
if (pReturnQ->prev == NULL)
{
pQueue->prev = NULL;
pQueue->next = NULL;
}
else
{
// Have the new head buffer point to NULL
(pReturnQ->prev)->next = NULL;
// Have the queue head point to the new head buffer
pQueue->next = pReturnQ->prev;
}
}
// unlock pointer access
LeaveCriticalSection (pCritSect);
IN_OUT_STR ("RTCP: Exit removePcktFromHead()\n");
return (pReturnQ);
}
/*--------------------------------------------------------------------------
** Function : removePcktFromTail
** Description: Remove a cell from end of the specified queue.
**
** Input : pQueue: -> to the list to remove the packet from
**
** Return: NULL ==> Empty queue.
** Buffer Address ==> OK, cell removed
--------------------------------------------------------------------------*/
PLINK_LIST removePcktFromTail (PLINK_LIST pQueue,
CRITICAL_SECTION *pCritSect)
{
PLINK_LIST pReturnQ;
IN_OUT_STR ("RTCP: Enter removePcktFromTail()\n");
// safe access to pointers
EnterCriticalSection (pCritSect);
if ((pReturnQ = pQueue->prev) != NULL)
{
// We have a buffer. If this is the last buffer in the queue,
// mark it empty.
if (pReturnQ->next == NULL)
{
pQueue->prev = NULL;
pQueue->next = NULL;
}
else
{
// In any event, the new prev pointer is NULL: end of list
(pReturnQ->next)->prev = NULL;
// have the queue prev pointer point to the new 'last' element
pQueue->prev = pReturnQ->next;
}
}
// unlock pointer access
LeaveCriticalSection (pCritSect);
IN_OUT_STR ("RTCP: Enter removePcktFromTail()\n");
return (pReturnQ);
}
// [EOF]