libmemif: set next free buffer

Adds memif_set_next_free_buffer - set internal pointer
to next free descriptor for any tx queue.

Type: feature

Signed-off-by: Jakub Grajciar <jgrajcia@cisco.com>
Change-Id: Ia24345a886a52c25c1723c6dbce023f2aed4a42c

2 files changed, 41 insertions, 0 deletions

diff --git a/extras/libmemif/src/libmemif.h b/extras/libmemif/src/libmemif.h
index 379ccd1e260..0146bb78dff 100644
--- a/extras/libmemif/src/libmemif.h
+++ b/extras/libmemif/src/libmemif.h
@@ -648,6 +648,17 @@ int memif_buffer_alloc (memif_conn_handle_t conn, uint16_t qid,
 			memif_buffer_t * bufs, uint16_t count,
 			uint16_t * count_out, uint16_t size);
 
+/** \brief Memif set next free buffer
+    @param conn - memif connection handle
+    @param qid - number identifying queue
+    @param buf - next free buffer
+
+    Sets next free descriptor pointer for specified tx queue.
+    The next allocation will happen at this buffer.
+*/
+int memif_set_next_free_buffer (memif_conn_handle_t conn, uint16_t qid,
+				memif_buffer_t *buf);
+
 /** \brief Memif refill queue
     @param conn - memif connection handle
     @param qid - number identifying queue
diff --git a/extras/libmemif/src/main.c b/extras/libmemif/src/main.c
index f5b1b5d257a..0644f948c31 100644
--- a/extras/libmemif/src/main.c
+++ b/extras/libmemif/src/main.c
@@ -2151,6 +2151,36 @@ memif_init_regions_and_queues (memif_connection_t * conn)
   return 0;
 }
 
+int
+memif_set_next_free_buffer (memif_conn_handle_t conn, uint16_t qid,
+			    memif_buffer_t *buf)
+{
+  memif_connection_t *c = (memif_connection_t *) conn;
+  if (EXPECT_FALSE (c == NULL))
+    return MEMIF_ERR_NOCONN;
+  if (EXPECT_FALSE (qid >= c->tx_queues_num))
+    return MEMIF_ERR_QID;
+  if (EXPECT_FALSE (buf == NULL))
+    return MEMIF_ERR_INVAL_ARG;
+
+  uint16_t ring_size, ns;
+  memif_queue_t *mq = &c->tx_queues[qid];
+  memif_ring_t *ring = mq->ring;
+
+  ring_size = (1 << mq->log2_ring_size);
+  if (c->args.is_master)
+    ns = ring->head - mq->next_buf;
+  else
+    ns = ring_size - mq->next_buf + ring->tail;
+
+  if ((mq->next_buf - buf->desc_index) > ns)
+    return MEMIF_ERR_INVAL_ARG;
+
+  mq->next_buf = buf->desc_index;
+
+  return MEMIF_ERR_SUCCESS;
+}
+
 static void
 memif_buffer_enq_at_idx_internal (memif_queue_t *from_q, memif_queue_t *to_q,
 				  memif_buffer_t *buf, uint16_t slot)