[dpdk-dev] [PATCH v4 03/20] net/virtio: add packed virtqueue helpers

[Jens Freimann]

Add helper functions to set/clear and check descriptor flags.

Signed-off-by: Jens Freimann <jfreimann at redhat.com>
---
 drivers/net/virtio/virtio_ring.h | 38 ++++++++++++++++++++++++++++++++++++++
 drivers/net/virtio/virtqueue.h   | 19 +++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/drivers/net/virtio/virtio_ring.h b/drivers/net/virtio/virtio_ring.h
index 76168eed7..4eed023cc 100644
--- a/drivers/net/virtio/virtio_ring.h
+++ b/drivers/net/virtio/virtio_ring.h
@@ -78,6 +78,7 @@ struct vring_packed_desc_event {
 
 struct vring {
 	unsigned int num;
+	unsigned int avail_wrap_counter;
 	union {
 		struct vring_desc_packed *desc_packed;
 		struct vring_desc *desc;
@@ -92,6 +93,43 @@ struct vring {
 	};
 };
 
+static inline void
+toggle_wrap_counter(struct vring *vr)
+{
+	vr->avail_wrap_counter ^= 1;
+}
+
+static inline void
+_set_desc_avail(struct vring_desc_packed *desc,
+				   int wrap_counter)
+{
+	uint16_t flags = desc->flags;
+
+	if (wrap_counter) {
+		flags |= VRING_DESC_F_AVAIL;
+		flags &= ~VRING_DESC_F_USED;
+	} else {
+		flags &= ~VRING_DESC_F_AVAIL;
+		flags |= VRING_DESC_F_USED;
+	}
+
+	desc->flags = flags;
+}
+
+static inline void
+set_desc_avail(struct vring *vr,
+				  struct vring_desc_packed *desc)
+{
+	_set_desc_avail(desc, vr->avail_wrap_counter);
+}
+
+static inline int
+desc_is_used(struct vring_desc_packed *desc)
+{
+	return !(desc->flags & VRING_DESC_F_AVAIL) ==
+		!(desc->flags & VRING_DESC_F_USED);
+}
+
 /* The standard layout for the ring is a continuous chunk of memory which
  * looks like this.  We assume num is a power of 2.
  *
diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
index cc2e7c0f6..081b27a52 100644
--- a/drivers/net/virtio/virtqueue.h
+++ b/drivers/net/virtio/virtqueue.h
@@ -245,6 +245,25 @@ struct virtio_tx_region {
 			   __attribute__((__aligned__(16)));
 };
 
+static inline uint16_t
+increment_pq_index(uint16_t idx, size_t ring_size)
+{
+	return ++idx >= ring_size ? 0 : idx;
+}
+
+static inline uint16_t
+update_pq_avail_index(struct virtqueue *vq)
+{
+	uint16_t idx;
+
+	idx = increment_pq_index(vq->vq_avail_idx, vq->vq_nentries);
+	if (idx == 0)
+		toggle_wrap_counter(&vq->vq_ring);
+	vq->vq_avail_idx = idx;
+
+	return vq->vq_avail_idx;
+}
+
 static inline void
 vring_desc_init_packed(struct vring *vr, int n)
 {
-- 
2.14.3