vppinfra: add simple ring implementation

Change-Id: I188e2dfd187d7b2ab7e0fbb11461f3db052f3224
Signed-off-by: Damjan Marion <damarion@cisco.com>

1 files changed, 134 insertions, 0 deletions

diff --git a/src/vppinfra/ring.h b/src/vppinfra/ring.h
new file mode 100644
index 00000000000..be61dc44978
--- /dev/null
+++ b/src/vppinfra/ring.h
@@ -0,0 +1,134 @@
+/*
+ * Copyright (c) 2018 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef included_ring_h
+#define included_ring_h
+
+#include <vppinfra/error.h>
+#include <vppinfra/format.h>
+#include <vppinfra/vec.h>
+#include <vppinfra/vector.h>
+
+typedef struct
+{
+  u32 next, n_enq;
+} clib_ring_header_t;
+
+always_inline clib_ring_header_t *
+clib_ring_header (void *v)
+{
+  return vec_aligned_header (v, sizeof (clib_ring_header_t), sizeof (void *));
+}
+
+always_inline void
+clib_ring_new_inline (void **p, u32 elt_bytes, u32 size, u32 align)
+{
+  void *v;
+  clib_ring_header_t *h;
+
+  v = _vec_resize ((void *) 0,
+		   /* length increment */ size,
+		   /* data bytes */ elt_bytes * size,
+		   /* header bytes */ sizeof (h[0]),
+		   /* data align */ align);
+
+  h = clib_ring_header (v);
+  h->next = 0;
+  h->n_enq = 0;
+  p[0] = v;
+}
+
+#define clib_ring_new_aligned(ring, size, align) \
+{ clib_ring_new_inline ((void **)&(ring), sizeof(ring[0]), size, align); }
+
+#define clib_ring_new(ring, size) \
+{ clib_ring_new_inline ((void **)&(ring), sizeof(ring[0]), size, 0);}
+
+#define clib_ring_free(f) vec_free_h((f), sizeof(clib_ring_header_t))
+
+always_inline u32
+clib_ring_n_enq (void *v)
+{
+  clib_ring_header_t *h = clib_ring_header (v);
+  return h->n_enq;
+}
+
+always_inline void *
+clib_ring_get_last_inline (void *v, u32 elt_bytes, int enqueue)
+{
+  clib_ring_header_t *h = clib_ring_header (v);
+  u32 slot;
+
+  if (enqueue)
+    {
+      if (h->n_enq == _vec_len (v))
+	return 0;
+      slot = h->next;
+      h->n_enq++;
+      h->next++;
+      if (h->next == _vec_len (v))
+	h->next = 0;
+    }
+  else
+    {
+      if (h->n_enq == 0)
+	return 0;
+      slot = h->next == 0 ? _vec_len (v) - 1 : h->next - 1;
+    }
+
+  return (void *) ((u8 *) v + elt_bytes * slot);
+}
+
+#define clib_ring_enq(ring) \
+clib_ring_get_last_inline (ring, sizeof(ring[0]), 1)
+
+#define clib_ring_get_last(ring) \
+clib_ring_get_last_inline (ring, sizeof(ring[0]), 0)
+
+always_inline void *
+clib_ring_get_first_inline (void *v, u32 elt_bytes, int dequeue)
+{
+  clib_ring_header_t *h = clib_ring_header (v);
+  u32 slot;
+
+  if (h->n_enq == 0)
+    return 0;
+
+  if (h->n_enq > h->next)
+    slot = _vec_len (v) + h->next - h->n_enq;
+  else
+    slot = h->next - h->n_enq;
+
+  if (dequeue)
+    h->n_enq--;
+
+  return (void *) ((u8 *) v + elt_bytes * slot);
+}
+
+#define clib_ring_deq(ring) \
+clib_ring_get_first_inline (ring, sizeof(ring[0]), 1)
+
+#define clib_ring_get_first(ring) \
+clib_ring_get_first_inline (ring, sizeof(ring[0]), 0)
+
+#endif /* included_ring_h */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */