Diff: simple-mbed-cloud-client/mbed-cloud-client/update-client-hub/modules/atomic-queue/source/atomic-queue.c

Revision:

0:8f0bb79ddd48

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/simple-mbed-cloud-client/mbed-cloud-client/update-client-hub/modules/atomic-queue/source/atomic-queue.c	Tue May 04 08:55:12 2021 +0000
@@ -0,0 +1,130 @@
+// ----------------------------------------------------------------------------
+// Copyright 2015-2017 ARM Ltd.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// 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.
+// ----------------------------------------------------------------------------
+
+#include "atomic-queue/atomic-queue.h"
+#include "atomic.h"
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+
+#define CORE_UTIL_ASSERT_MSG(test, msg)
+
+
+int aq_element_take(struct atomic_queue_element *e, void *ctx)
+{
+    if (!e) { return ATOMIC_QUEUE_NULL_ELEMENT;}
+    if (!ctx) { return ATOMIC_QUEUE_INVALID_CONTEXT;}
+    // Duplicate element check using lock
+    uintptr_t lock; // This is initialized in the do/while loop.
+    // Check/obtain a lock on the element.
+    do {
+        lock = e->lock;
+        if (lock) {
+            return ATOMIC_QUEUE_DUPLICATE_ELEMENT;
+        }
+    } while (!aq_atomic_cas_uintptr(&e->lock, lock, (uintptr_t)ctx));
+    return ATOMIC_QUEUE_SUCCESS;
+}
+
+int aq_element_release(struct atomic_queue_element *e, void **ctx)
+{
+    if (!e) { return ATOMIC_QUEUE_NULL_ELEMENT;}
+    if (!ctx) { return ATOMIC_QUEUE_INVALID_CONTEXT;}
+    *ctx = (void *) e->lock;
+    e->lock = 0;
+    return ATOMIC_QUEUE_SUCCESS;
+}
+
+int aq_push_tail(struct atomic_queue *q, struct atomic_queue_element *e)
+{
+    CORE_UTIL_ASSERT_MSG(q != NULL, "null queue used");
+    if (!e) { return ATOMIC_QUEUE_NULL_ELEMENT;}
+    if (q == NULL) {
+        return ATOMIC_QUEUE_NULL_QUEUE;
+    }
+
+    do {
+        e->next = q->tail;
+    } while (!aq_atomic_cas_uintptr((uintptr_t *)&q->tail, (uintptr_t)e->next, (uintptr_t)e));
+
+    return ATOMIC_QUEUE_SUCCESS;
+}
+
+struct atomic_queue_element *aq_pop_head(struct atomic_queue *q)
+{
+    CORE_UTIL_ASSERT_MSG(q != NULL, "null queue used");
+    if (q == NULL) {
+        return NULL;
+    }
+    struct atomic_queue_element *current;
+    int fail = AQ_ATOMIC_CAS_DEREF_VALUE;
+    while (fail != AQ_ATOMIC_CAS_DEREF_SUCCESS) {
+        // Set the element reference pointer to the tail pointer
+        struct atomic_queue_element *volatile *px = &q->tail;
+        if (*px == NULL) {
+            return NULL;
+        }
+        fail = AQ_ATOMIC_CAS_DEREF_VALUE;
+        while (fail == AQ_ATOMIC_CAS_DEREF_VALUE) {
+            fail = aq_atomic_cas_deref_uintptr((uintptr_t *volatile *)px,
+                                               (uintptr_t **)&current,
+                                               (uintptr_t) NULL,
+                                               NULL,
+                                               offsetof(struct atomic_queue_element, next));
+            if (fail == AQ_ATOMIC_CAS_DEREF_VALUE) {
+                // Detect a loop to the tail of the queue
+                if (current->next == q->tail) {
+                    return NULL;
+                }
+                px = &current->next;
+            }
+        }
+    }
+
+    return current;
+}
+
+
+int aq_empty(struct atomic_queue *q)
+{
+    return q->tail == NULL;
+}
+
+unsigned aq_count(struct atomic_queue *q)
+{
+    unsigned x;
+    struct atomic_queue_element *volatile e;
+    if (aq_empty(q)) {
+        return 0;
+    }
+    e = q->tail;
+    for (x = 1; e->next != NULL; x++, e = e->next) {
+        if (e->next == q->tail) {
+            return (unsigned) - 1;
+        }
+    }
+    return x;
+}
+
+void aq_initialize_element(struct atomic_queue_element *e)
+{
+    if (!e) { return;}
+    e->lock = 0;
+    e->next = NULL;
+}