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-rw-r--r--lfq.c113
1 files changed, 0 insertions, 113 deletions
diff --git a/lfq.c b/lfq.c
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-/*
- * File : lfq.c
- * Author : Jérémy Zurcher <jeremy@asynk.ch>
- * Date : 01/11/09
- * License :
- *
- * Permission is hereby granted, free of charge, to any person obtaining
- * a copy of this software and associated documentation files (the
- * "Software"), to deal in the Software without restriction, including
- * without limitation the rights to use, copy, modify, merge, publish,
- * distribute, sublicense, and/or sell copies of the Software, and to
- * permit persons to whom the Software is furnished to do so, subject to
- * the following conditions:
- *
- * The above copyright notice and this permission notice shall be
- * included in all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
- * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
- * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
- * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
- * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
- * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
- * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- *
- */
-
-#include "lfq.h"
-#include "lfq_cas.h"
-#include "stdlib.h"
-
-/* initialize an empty lfq structure */
-void lfq_init( lfq_t *q ) {
- q->head.split.next = q->tail.split.next = NULL;
- q->head.split.count = q->tail.split.count = 0;
-}
-
-/* push a node at the tail of q */
-void lfq_push_tail( lfq_t *q, pointer_t *node ) {
- pointer_t tail;
- pointer_t last;
- pointer_t tmp;
-
- /* init node */
- node->split.next = NULL;
- node->split.count = 0;
-
- /* set tmp to point to node */
- tmp.split.next = node;
- tmp.split.count = 1;
-
- for(;;) {
- /* snapshot tail */
- tail.concat = q->tail.concat;
- /* nothing in tail link as first node */
- if ( tail.split.next==NULL && cas( &q->tail.split, tail.split, tmp.split ) ) { /* TODO right place ?? */
- q->head.split.next = node;
- /* q->head.split.count = 1; ??? */
- return;
- } else {
- /* snapshot last through tail */
- last.concat = (*tail.split.next).concat;
- /* if tail is still consistant */
- if (tail.concat == q->tail.concat) {
- /* if last is the last node */
- if (last.split.next == NULL) {
- tmp.split.count = last.split.count+1;
- if ( cas( &tail.split.next->split, last.split, tmp.split ) ) break;
- } else {
- /* try to swing tail to the next node */
- last.split.count = tail.split.count+1;
- cas( &q->tail.split, tail.split, last.split );
- }
- }
- }
- }
- /* try to swing tail to the next node */
- tmp.split.count = tail.split.count+1;
- cas( &q->tail.split, tail.split, tmp.split );
-}
-
-/* pop a node from the head of q */
-pointer_t* pop_head( lfq_t *q ) {
- pointer_t head;
- pointer_t tail;
- pointer_t tmp;
- pointer_t *node;
-
- for(;;) {
- /* snapshot head */
- head.concat = q->head.concat;
- /* return NULL if queue is empty */
- if (head.split.next == NULL) { return NULL; } /* TODO before snapshot using q-> ?? */
- /* snapshot tail */
- tail.concat = q->tail.concat;
- /* if there is only one node in the queue */
- if ( tail.split.next == head.split.next ) {
- /* tail points to NULL */
- tmp.split.next = NULL;
- tmp.split.count = tail.split.count+1;
- cas( &q->tail.split, tail.split, tmp.split );
- } else {
- /* get the node ptr */
- node = (pointer_t *)head.split.next;
- /* get the next head ready */
- tmp.split.next = node->split.next;
- tmp.split.count = head.split.count+1;
- if ( cas( &q->head.split, head.split, tmp.split ) ) break;
- }
- }
- return node;
-}
-