[PATCH 11/17] vhost: add helpers for packed virtqueues

[Jens Freimann <jfreimann@redhat.com>]

Add some helper functions to set/check descriptor flags
and toggle the used wrap counter.

Signed-off-by: Jens Freimann <jfreimann@redhat.com>
---
 lib/librte_vhost/virtio-1.1.h | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/lib/librte_vhost/virtio-1.1.h b/lib/librte_vhost/virtio-1.1.h
index b37d621..7b37d26 100644
--- a/lib/librte_vhost/virtio-1.1.h
+++ b/lib/librte_vhost/virtio-1.1.h
@@ -17,4 +17,47 @@ struct vring_desc_packed {
 	uint16_t flags;
 };
 
+static inline void
+toggle_wrap_counter(struct vhost_virtqueue *vq)
+{
+	vq->used_wrap_counter ^= 1;
+}
+
+static inline int
+desc_is_avail(struct vhost_virtqueue *vq, struct vring_desc_packed *desc)
+{
+	if (unlikely(!vq))
+		return -1;
+
+	if (vq->used_wrap_counter == 1)
+		if ((desc->flags & DESC_AVAIL) && !(desc->flags & DESC_USED))
+			return 1;
+	if (vq->used_wrap_counter == 0)
+		if (!(desc->flags & DESC_AVAIL) && (desc->flags & DESC_USED))
+			return 1;
+	return 0;
+}
+
+static inline void
+_set_desc_used(struct vring_desc_packed *desc, int wrap_counter)
+{
+	uint16_t flags = desc->flags;
+
+	if (wrap_counter == 1) {
+		flags |= DESC_USED;
+		flags |= DESC_AVAIL;
+	} else {
+		flags &= ~DESC_USED;
+		flags &= ~DESC_AVAIL;
+	}
+
+	desc->flags = flags;
+}
+
+static inline void
+set_desc_used(struct vhost_virtqueue *vq, struct vring_desc_packed *desc)
+{
+	_set_desc_used(desc, vq->used_wrap_counter);
+}
+
 #endif /* __VIRTIO_PACKED_H */
-- 
1.8.3.1