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/**************************************************************************
*
* Copyright 2009 VMware, Inc.
* All Rights Reserved.
*
* 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, sub license, 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 (including the
* next paragraph) 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 NON-INFRINGEMENT.
* IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS 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.
*
**************************************************************************/
/**
* Scene queue. We'll use two queues. One contains "full" scenes which
* are produced by the "setup" code. The other contains "empty" scenes
* which are produced by the "rast" code when it finishes rendering a scene.
*/
#include "os/os_thread.h"
#include "util/u_memory.h"
#include "lp_scene_queue.h"
#include "util/u_math.h"
#define SCENE_QUEUE_SIZE 4
/**
* A queue of scenes
*/
struct lp_scene_queue
{
struct lp_scene *scenes[SCENE_QUEUE_SIZE];
mtx_t mutex;
cnd_t change;
/* These values wrap around, so that head == tail means empty. When used
* to index the array, we use them modulo the queue size. This scheme
* works because the queue size is a power of two.
*/
unsigned head;
unsigned tail;
};
/** Allocate a new scene queue */
struct lp_scene_queue *
lp_scene_queue_create(void)
{
/* Circular queue behavior depends on size being a power of two. */
STATIC_ASSERT(SCENE_QUEUE_SIZE > 0);
STATIC_ASSERT((SCENE_QUEUE_SIZE & (SCENE_QUEUE_SIZE - 1)) == 0);
struct lp_scene_queue *queue = CALLOC_STRUCT(lp_scene_queue);
if (!queue)
return NULL;
(void) mtx_init(&queue->mutex, mtx_plain);
cnd_init(&queue->change);
return queue;
}
/** Delete a scene queue */
void
lp_scene_queue_destroy(struct lp_scene_queue *queue)
{
cnd_destroy(&queue->change);
mtx_destroy(&queue->mutex);
FREE(queue);
}
/** Remove first lp_scene from head of queue */
struct lp_scene *
lp_scene_dequeue(struct lp_scene_queue *queue, boolean wait)
{
mtx_lock(&queue->mutex);
if (wait) {
/* Wait for queue to be not empty. */
while (queue->head == queue->tail)
cnd_wait(&queue->change, &queue->mutex);
} else {
if (queue->head == queue->tail) {
mtx_unlock(&queue->mutex);
return NULL;
}
}
struct lp_scene *scene = queue->scenes[queue->head++ % SCENE_QUEUE_SIZE];
cnd_signal(&queue->change);
mtx_unlock(&queue->mutex);
return scene;
}
/** Add an lp_scene to tail of queue */
void
lp_scene_enqueue(struct lp_scene_queue *queue, struct lp_scene *scene)
{
mtx_lock(&queue->mutex);
/* Wait for free space. */
while (queue->tail - queue->head >= SCENE_QUEUE_SIZE)
cnd_wait(&queue->change, &queue->mutex);
queue->scenes[queue->tail++ % SCENE_QUEUE_SIZE] = scene;
cnd_signal(&queue->change);
mtx_unlock(&queue->mutex);
}
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