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

Revision:

0:119624335925

--- /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.h	Sat Jun 30 01:40:30 2018 +0000
@@ -0,0 +1,70 @@
+// ----------------------------------------------------------------------------
+// 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.
+// ----------------------------------------------------------------------------
+
+#ifndef ATOMIC_QUEUE_ATOMIC_H
+#define ATOMIC_QUEUE_ATOMIC_H
+#include <stdint.h>
+
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+enum {
+   AQ_ATOMIC_CAS_DEREF_SUCCESS = 0,
+   AQ_ATOMIC_CAS_DEREF_NULLPTR,
+   AQ_ATOMIC_CAS_DEREF_VALUE,
+   AQ_ATOMIC_CAS_DEREF_INTERUPTED,
+};
+
+int aq_atomic_cas_uintptr(uintptr_t *ptr, uintptr_t oldval, uintptr_t newval);
+
+/**
+ * @brief Atomically compares the value of a dereferenced pointer, replacing the pointer on success.
+ * @detail aq_atomic_cas_deref_uintptr provides a mechanism to atomically change a pointer based on a value contained
+ *     in the structure referenced by the pointer. This is done in the following sequence of operations:
+ *
+ *     1. Load the value of `*ptrAddr`
+ *     2. Optionally store the current value of `*ptrAddr`
+ *     3. Check that the pointer is valid: `*ptrAddr != NULL`
+ *     4. Check the value of the referenced location: `*(*ptrAddr + valueOffset) == expectedDerefValue` (casts omitted)
+ *     5. If 3 and 4 succeeded, store newPtrValue: `*ptrAddr = newPtrValue` (NOTE: in non-blocking implementations, this step can fail)
+ *     6. Return a status code based on the results of 3, 4, 5.
+ *
+ * @param[in,out] ptrAddr            The address of the pointer to manipulate
+ * @param[out]    currentPtrValue    A pointer to a container for the current value of *ptrAddr
+ * @param[in]     expectedDerefValue This is the value that is expected at *(uintptr_t *)((uintptr_t)*ptrAddr + valueOffset)
+ * @param[in]     newPtrValue        The value to store to *ptrAddr if the comparison is successful
+ * @param[in]     valueOffset        The offset of the target value from *ptrAddr
+ *
+ * @retval AQ_ATOMIC_CAS_DEREF_SUCCESS    The compare and set has succeeded
+ * @retval AQ_ATOMIC_CAS_DEREF_NULLPTR    `*ptrAddr` was `NULL`
+ * @retval AQ_ATOMIC_CAS_DEREF_VALUE      The value test failed (*(*ptrAddr + valueOffset) != expectedDerefValue`)
+ * @retval AQ_ATOMIC_CAS_DEREF_INTERUPTED Another context modified `*ptrAddr`
+ */
+int aq_atomic_cas_deref_uintptr(uintptr_t* volatile * ptrAddr,
+                            uintptr_t** currentPtrValue,
+                            uintptr_t expectedDerefValue,
+                            uintptr_t* newPtrValue,
+                            uintptr_t valueOffset);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+#endif // ATOMIC_QUEUE_ATOMIC_H