static int vcon_can_read(void *opaque) { VirtIOConsole *s = (VirtIOConsole *) opaque; if (!virtio_queue_ready(s->ivq) || !(s->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK) || virtio_queue_empty(s->ivq)) return 0; /* current implementations have a page sized buffer. * We fall back to a one byte per read if there is not enough room. * It would be cool to have a function that returns the available byte * instead of checking for a limit */ if (virtqueue_avail_bytes(s->ivq, TARGET_PAGE_SIZE, 0)) return TARGET_PAGE_SIZE; if (virtqueue_avail_bytes(s->ivq, 1, 0)) return 1; return 0; }
static int do_virtio_net_can_receive(VirtIONet *n, int bufsize) { if (!virtio_queue_ready(n->rx_vq) || !(n->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK)) return 0; if (virtio_queue_empty(n->rx_vq) || (n->mergeable_rx_bufs && !virtqueue_avail_bytes(n->rx_vq, bufsize, 0))) { virtio_queue_set_notification(n->rx_vq, 1); return 0; } virtio_queue_set_notification(n->rx_vq, 0); return 1; }