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/*
* Copyright 2009, 2010 Red Hat, Inc.
*
* 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
* on 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
* THE AUTHORS 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.
*
*/
/** \file qxl_ring.c
* \author Søren Sandmann <sandmann@redhat.com>
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <sched.h>
#include "qxl.h"
struct ring
{
struct qxl_ring_header header;
uint8_t elements[0];
};
struct qxl_ring
{
volatile struct ring *ring;
int element_size;
int n_elements;
int io_port_prod_notify;
qxl_screen_t *qxl;
};
struct qxl_ring *
qxl_ring_create (struct qxl_ring_header *header,
int element_size,
int n_elements,
int io_port_prod_notify,
qxl_screen_t *qxl)
{
struct qxl_ring *ring;
ring = malloc (sizeof *ring);
if (!ring)
return NULL;
ring->ring = (volatile struct ring *)header;
ring->element_size = element_size;
ring->n_elements = n_elements;
ring->io_port_prod_notify = io_port_prod_notify;
ring->qxl = qxl;
return ring;
}
void
qxl_ring_push (struct qxl_ring *ring,
const void *new_elt)
{
volatile struct qxl_ring_header *header = &(ring->ring->header);
volatile uint8_t *elt;
int idx;
while (header->prod - header->cons == header->num_items)
{
header->notify_on_cons = header->cons + 1;
#ifdef XSPICE
/* in gtkperf, circles, this is a major bottleneck. Can't be that good in a vm either
* Adding the yield reduces cpu usage, but doesn't improve throughput. */
sched_yield();
#endif
mem_barrier();
}
idx = header->prod & (ring->n_elements - 1);
elt = ring->ring->elements + idx * ring->element_size;
memcpy((void *)elt, new_elt, ring->element_size);
header->prod++;
mem_barrier();
if (header->prod == header->notify_on_prod) {
ioport_write (ring->qxl, ring->io_port_prod_notify, 0);
}
}
Bool
qxl_ring_pop (struct qxl_ring *ring,
void *element)
{
volatile struct qxl_ring_header *header = &(ring->ring->header);
volatile uint8_t *ring_elt;
int idx;
if (header->cons == header->prod)
return FALSE;
idx = header->cons & (ring->n_elements - 1);
ring_elt = ring->ring->elements + idx * ring->element_size;
memcpy (element, (void *)ring_elt, ring->element_size);
header->cons++;
return TRUE;
}
void
qxl_ring_wait_idle (struct qxl_ring *ring)
{
while (ring->ring->header.cons != ring->ring->header.prod)
{
usleep (1000);
mem_barrier();
}
}
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