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/*
* Copyright (c) 1998, 1999 The University of Utah and the Flux Group.
* All rights reserved.
*
* This file is part of the Flux OSKit. The OSKit is free software, also known
* as "open source;" you can redistribute it and/or modify it under the terms
* of the GNU General Public License (GPL), version 2, as published by the Free
* Software Foundation (FSF). To explore alternate licensing terms, contact
* the University of Utah at csl-dist@cs.utah.edu or +1-801-585-3271.
*
* The OSKit is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GPL for more details. You should have
* received a copy of the GPL along with the OSKit; see the file COPYING. If
* not, write to the FSF, 59 Temple Place #330, Boston, MA 02111-1307, USA.
*/
/*
* A queue of pointers to COM objects.
* Reference counts are handled via oskit_iunknown_addref, etc.
*
* NOTE: this doesn't use the notion of size as specified in the queue
* interface.
* This is because it isn't needed for allocating and managing the queue.
* This means that `enqueue' ignores the `size' argument and `dequeue',
* and `front' do not return it.
*/
#include <oskit/com/queue.h>
#include <oskit/c/assert.h>
#include <oskit/c/stdlib.h>
struct queue {
oskit_queue_t q_ioi;
oskit_u32_t q_count;
oskit_size_t q_curlength;
oskit_size_t q_maxlength;
oskit_size_t q_head;
oskit_size_t q_tail;
oskit_iunknown_t *q_array[1];
};
#define increment(q,c) (q->c = (q->c + 1) % q->q_maxlength)
static OSKIT_COMDECL
queue_query(oskit_queue_t *_, const oskit_iid_t *iid, void **out_ihandle)
{
struct queue *q = (void *)_;
assert(q && q->q_count);
if (memcmp(iid, &oskit_iunknown_iid, sizeof(*iid)) == 0 ||
memcmp(iid, &oskit_queue_iid, sizeof(*iid)) == 0) {
*out_ihandle = &q->q_ioi;
++q->q_count;
return 0;
}
*out_ihandle = NULL;
return OSKIT_E_NOINTERFACE;
}
static OSKIT_COMDECL_U
queue_addref(oskit_queue_t *_)
{
struct queue *q = (void *)_;
assert(q && q->q_count);
if (q == NULL || q->q_count == 0)
return OSKIT_E_INVALIDARG;
return ++q->q_count;
}
static OSKIT_COMDECL_U
queue_release(oskit_queue_t *_)
{
struct queue *q = (void *)_;
oskit_size_t i;
assert(q && q->q_count);
if (--q->q_count)
return q->q_count;
for (i = 0; i < q->q_maxlength; i++)
if (q->q_array[i])
oskit_iunknown_release(q->q_array[i]);
free(q);
return 0;
}
static OSKIT_COMDECL
queue_enqueue(oskit_queue_t *_, const void *item, oskit_size_t ignored_size)
{
struct queue *q = (void *)_;
oskit_iunknown_t *obj = (void *)item;
assert(q && q->q_count);
/* If the queue is full, drop it. */
if (q->q_array[q->q_tail] != NULL) {
return OSKIT_E_FAIL;
}
/* Otherwise we have space. */
q->q_array[q->q_tail] = obj;
oskit_iunknown_addref(obj);
increment(q,q_tail);
q->q_curlength++;
return 0;
}
static OSKIT_COMDECL_U
queue_dequeue(oskit_queue_t *_, void *item)
{
struct queue *q = (void *)_;
oskit_iunknown_t **obj = item;
assert(q && q->q_count);
/* Nothing to dequeue? */
assert(q->q_curlength != 0);
/* Head shouldn't be NULL if q_curlength is non-zero. */
assert(q->q_array[q->q_head] != NULL);
/* Otherwise, take the head elem. */
*obj = q->q_array[q->q_head]; /* they get our ref */
q->q_array[q->q_head] = NULL;
increment(q,q_head);
q->q_curlength--;
return 0;
}
static OSKIT_COMDECL_U
queue_size(oskit_queue_t *_)
{
struct queue *q = (void *)_;
assert(q && q->q_count);
return q->q_curlength;
}
static OSKIT_COMDECL_U
queue_front(oskit_queue_t *_, void *item)
{
struct queue *q = (void *)_;
oskit_iunknown_t **obj = item;
assert(q && q->q_count);
/* Empty queue? */
assert(q->q_curlength != 0);
/* Head shouldn't be NULL if q_curlength is non-zero. */
assert(q->q_array[q->q_head] != NULL);
/* Give them a pointer to the head. */
*obj = q->q_array[q->q_head];
oskit_iunknown_addref(*obj);
return 0;
}
static struct oskit_queue_ops queue_ops = {
queue_query,
queue_addref,
queue_release,
queue_enqueue,
queue_dequeue,
queue_size,
queue_front
};
oskit_error_t
oskit_bounded_com_queue_create(oskit_size_t length, oskit_queue_t **out_q)
{
struct queue *q;
if (length == 0)
return OSKIT_E_INVALIDARG;
q = calloc(sizeof(struct queue) + (length-1)*sizeof(oskit_iunknown_t), 1);
if (q == NULL)
return OSKIT_E_OUTOFMEMORY;
q->q_ioi.ops = &queue_ops;
q->q_count = 1;
q->q_curlength = 0;
q->q_maxlength = length;
q->q_head = 0;
q->q_tail = 0;
/* q_array is already zeroed */
*out_q = &q->q_ioi;
return 0;
}
#if 0
#include <oskit/c/stdio.h>
void
oskit_bounded_com_queue_dump(oskit_queue_t *_)
{
struct queue *q = (void *)_;
oskit_size_t i;
assert(q && q->q_count);
printf("%d (%d,%d): [ ", q->q_curlength, q->q_head, q->q_tail);
for (i = 0; i < q->q_maxlength; i++)
printf("%p ", q->q_array[i]);
printf("]\n");
}
#endif
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