feat: add refcount type (wip)

include/zenoh-pico/collections/refcount.h

@@ -0,0 +1,67 @@
+//
+// Copyright (c) 2023 ZettaScale Technology
+//
+// This program and the accompanying materials are made available under the
+// terms of the Eclipse Public License 2.0 which is available at
+// http://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+// which is available at https://www.apache.org/licenses/LICENSE-2.0.
+//
+// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+//
+// Contributors:
+//   ZettaScale Zenoh Team, <[email protected]>
+//
+
+#ifndef ZENOH_PICO_COLLECTIONS_REFCOUNT_H
+#define ZENOH_PICO_COLLECTIONS_REFCOUNT_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "zenoh-pico/collections/pointer.h"
+
+typedef struct ref {
+    void (*free)(const struct ref *);
+    int count;
+} _z_rc_t;
+
+#if Z_FEATURE_MULTI_THREAD == 1
+#if ZENOH_C_STANDARD != 99
+#if !defined(ZENOH_NO_STDATOMIC)
+
+#else
+#error "Implement Windows atomics"
+#endif  // !defined(ZENOH_NO_STDATOMIC)
+
+static inline void ref_inc(const struct ref *ref) {
+    _z_atomic_fetch_add_explicit((int *)&ref->count, 1, _z_memory_order_relaxed);
+}
+
+static inline void ref_dec(const struct ref *ref) {
+    if (_z_atomic_fetch_sub_explicit((int *)&ref->count, 1, _z_memory_order_relaxed) == 1) {
+        ref->free(ref);
+    }
+}
+
+#else
+// FIXME Check for Windows
+static inline void ref_inc(const struct ref *ref) { __sync_add_and_fetch((int *)&ref->count, 1); }
+
+static inline void ref_dec(const struct ref *ref) {
+    if (__sync_sub_and_fetch((int *)&ref->count, 1) == 0) {
+        ref->free(ref);
+    }
+}
+#endif  // ZENOH_C_STANDARD != 99
+
+#else
+static inline void ref_inc(const struct ref *ref) { ((struct ref *)ref)->count++; }
+
+static inline void ref_dec(const struct ref *ref) {
+    if (--((struct ref *)ref)->count == 0) {
+        ref->free(ref);
+    }
+}
+#endif  // Z_FEATURE_MULTI_THREAD == 1
+
+#endif  // ZENOH_PICO_COLLECTIONS_REFCOUNT_H