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/*
* Copyright 2004-2007 Freescale Semiconductor, Inc. All Rights Reserved.
*/
/*
* The code contained herein is licensed under the GNU General Public
* License. You may obtain a copy of the GNU General Public License
* Version 2 or later at the following locations:
*
* http://www.opensource.org/licenses/gpl-license.html
* http://www.gnu.org/copyleft/gpl.html
*/
/*!
* @file sah_queue.c
*
* @brief This file provides a FIFO Queue implementation.
*
*/
/******************************************************************************
*
* CAUTION:
*******************************************************************
*/
/* SAHARA Includes */
#include <sah_queue_manager.h>
#ifdef DIAG_DRV_QUEUE
#include <diagnostic.h>
#endif
/******************************************************************************
* Queue Functions
******************************************************************************/
/*!
*******************************************************************************
* This function constructs a new sah_Queue.
*
* @brief sah_Queue Constructor
*
* @return A pointer to a newly allocated sah_Queue.
* @return NULL if allocation of memory failed.
*/
/******************************************************************************
*
* CAUTION: This function may sleep in low-memory situations, as it uses
* kmalloc ( ..., GFP_KERNEL).
******************************************************************************/
sah_Queue *sah_Queue_Construct(void)
{
sah_Queue *q = (sah_Queue *) os_alloc_memory(sizeof(sah_Queue),
GFP_KERNEL);
if (q != NULL) {
/* Initialise the queue to an empty state. */
q->head = NULL;
q->tail = NULL;
q->count = 0;
}
#ifdef DIAG_DRV_QUEUE
else {
LOG_KDIAG("kmalloc() failed.");
}
#endif
return q;
}
/*!
*******************************************************************************
* This function destroys a sah_Queue.
*
* @brief sah_Queue Destructor
*
* @param q A pointer to a sah_Queue.
*
* @return void
*/
/******************************************************************************
*
* CAUTION: This function does not free any queue entries.
*
******************************************************************************/
void sah_Queue_Destroy(sah_Queue * q)
{
#ifdef DIAG_DRV_QUEUE
if (q == NULL) {
LOG_KDIAG("Trying to kfree() a NULL pointer.");
} else {
if (q->count != 0) {
LOG_KDIAG
("Trying to destroy a queue that is not empty.");
}
}
#endif
if (q != NULL) {
os_free_memory(q);
q = NULL;
}
}
/*!
*******************************************************************************
* This function appends a sah_Head_Desc to the tail of a sah_Queue.
*
* @brief Appends a sah_Head_Desc to a sah_Queue.
*
* @param q A pointer to a sah_Queue to append to.
* @param entry A pointer to a sah_Head_Desc to append.
*
* @pre The #desc_queue_lock must be held before calling this function.
*
* @return void
*/
/******************************************************************************
*
* CAUTION: NONE
******************************************************************************/
void sah_Queue_Append_Entry(sah_Queue * q, sah_Head_Desc * entry)
{
sah_Head_Desc *tail_entry = NULL;
if ((q == NULL) || (entry == NULL)) {
#ifdef DIAG_DRV_QUEUE
LOG_KDIAG("Null pointer input.");
#endif
return;
}
if (q->count == 0) {
/* The queue is empty */
q->head = entry;
q->tail = entry;
entry->next = NULL;
entry->prev = NULL;
} else {
/* The queue is not empty */
tail_entry = q->tail;
tail_entry->next = entry;
entry->next = NULL;
entry->prev = tail_entry;
q->tail = entry;
}
q->count++;
}
/*!
*******************************************************************************
* This function a removes a sah_Head_Desc from the head of a sah_Queue.
*
* @brief Removes a sah_Head_Desc from a the head of a sah_Queue.
*
* @param q A pointer to a sah_Queue to remove from.
*
* @pre The #desc_queue_lock must be held before calling this function.
*
* @return void
*/
/******************************************************************************
*
* CAUTION: This does not kfree() the entry.
******************************************************************************/
void sah_Queue_Remove_Entry(sah_Queue * q)
{
sah_Queue_Remove_Any_Entry(q, q->head);
}
/*!
*******************************************************************************
* This function a removes a sah_Head_Desc from anywhere in a sah_Queue.
*
* @brief Removes a sah_Head_Desc from anywhere in a sah_Queue.
*
* @param qq A pointer to a sah_Queue to remove from.
* @param entry A pointer to a sah_Head_Desc to remove.
*
* @pre The #desc_queue_lock must be held before calling this function.
*
* @return void
*/
/******************************************************************************
*
* CAUTION: This does not kfree() the entry. Does not check to see if the entry
* actually belongs to the queue.
******************************************************************************/
void sah_Queue_Remove_Any_Entry(sah_Queue * q, sah_Head_Desc * entry)
{
sah_Head_Desc *prev_entry = NULL;
sah_Head_Desc *next_entry = NULL;
if ((q == NULL) || (entry == NULL)) {
#if defined DIAG_DRV_QUEUE && defined DIAG_DURING_INTERRUPT
LOG_KDIAG("Null pointer input.");
#endif
return;
}
if (q->count == 1) {
/* If q is the only entry in the queue. */
q->tail = NULL;
q->head = NULL;
q->count = 0;
} else if (q->count > 1) {
/* There are 2 or more entries in the queue. */
#if defined DIAG_DRV_QUEUE && defined DIAG_DURING_INTERRUPT
if ((entry->next == NULL) && (entry->prev == NULL)) {
LOG_KDIAG
("Queue is not empty yet both next and prev pointers"
" are NULL");
}
#endif
if (entry->next == NULL) {
/* If this is the end of the queue */
prev_entry = entry->prev;
prev_entry->next = NULL;
q->tail = prev_entry;
} else if (entry->prev == NULL) {
/* If this is the head of the queue */
next_entry = entry->next;
next_entry->prev = NULL;
q->head = next_entry;
} else {
/* If this is somewhere in the middle of the queue */
prev_entry = entry->prev;
next_entry = entry->next;
prev_entry->next = next_entry;
next_entry->prev = prev_entry;
}
q->count--;
}
/*
* Otherwise we are removing an entry from an empty queue.
* Don't do anything in the product code
*/
#if defined DIAG_DRV_QUEUE && defined DIAG_DURING_INTERRUPT
else {
LOG_KDIAG("Trying to remove an entry from an empty queue.");
}
#endif
entry->next = NULL;
entry->prev = NULL;
}
/* End of sah_queue.c */
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