Diff: mbed-os/platform/CircularBuffer.h

Revision:

0:fbdae7e6d805

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-os/platform/CircularBuffer.h	Mon May 14 11:29:06 2018 +0000
@@ -0,0 +1,187 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2015 ARM Limited
+ *
+ * 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 MBED_CIRCULARBUFFER_H
+#define MBED_CIRCULARBUFFER_H
+
+#include "platform/mbed_critical.h"
+#include "platform/mbed_assert.h"
+
+namespace mbed {
+
+namespace internal {
+/* Detect if CounterType of the Circular buffer is of unsigned type. */
+template<typename T>
+struct is_unsigned { static const bool value = false; };
+template<>
+struct is_unsigned<unsigned char> { static const bool value = true; };
+template<>
+struct is_unsigned<unsigned short> { static const bool value = true; };
+template<>
+struct is_unsigned<unsigned int> { static const bool value = true; };
+template<>
+struct is_unsigned<unsigned long> { static const bool value = true; };
+template<>
+struct is_unsigned<unsigned long long> { static const bool value = true; };
+};
+
+/** \addtogroup platform */
+/** @{*/
+/**
+ * \defgroup platform_CircularBuffer CircularBuffer functions
+ * @{
+ */
+
+/** Templated Circular buffer class
+ *
+ *  @note Synchronization level: Interrupt safe
+ *  @note CounterType must be unsigned and consistent with BufferSize
+ */
+template<typename T, uint32_t BufferSize, typename CounterType = uint32_t>
+class CircularBuffer {
+public:
+    CircularBuffer() : _head(0), _tail(0), _full(false) {
+        MBED_STATIC_ASSERT(
+            internal::is_unsigned<CounterType>::value,
+            "CounterType must be unsigned"
+        );
+
+        MBED_STATIC_ASSERT(
+            (sizeof(CounterType) >= sizeof(uint32_t)) ||
+            (BufferSize < (((uint64_t) 1) << (sizeof(CounterType) * 8))),
+            "Invalid BufferSize for the CounterType"
+        );
+    }
+
+    ~CircularBuffer() {
+    }
+
+    /** Push the transaction to the buffer. This overwrites the buffer if it's
+     *  full
+     *
+     * @param data Data to be pushed to the buffer
+     */
+    void push(const T& data) {
+        core_util_critical_section_enter();
+        if (full()) {
+            _tail++;
+            _tail %= BufferSize;
+        }
+        _pool[_head++] = data;
+        _head %= BufferSize;
+        if (_head == _tail) {
+            _full = true;
+        }
+        core_util_critical_section_exit();
+    }
+
+    /** Pop the transaction from the buffer
+     *
+     * @param data Data to be popped from the buffer
+     * @return True if the buffer is not empty and data contains a transaction, false otherwise
+     */
+    bool pop(T& data) {
+        bool data_popped = false;
+        core_util_critical_section_enter();
+        if (!empty()) {
+            data = _pool[_tail++];
+            _tail %= BufferSize;
+            _full = false;
+            data_popped = true;
+        }
+        core_util_critical_section_exit();
+        return data_popped;
+    }
+
+    /** Check if the buffer is empty
+     *
+     * @return True if the buffer is empty, false if not
+     */
+    bool empty() const {
+        core_util_critical_section_enter();
+        bool is_empty = (_head == _tail) && !_full;
+        core_util_critical_section_exit();
+        return is_empty;
+    }
+
+    /** Check if the buffer is full
+     *
+     * @return True if the buffer is full, false if not
+     */
+    bool full() const {
+        core_util_critical_section_enter();
+        bool full = _full;
+        core_util_critical_section_exit();
+        return full;
+    }
+
+    /** Reset the buffer
+     *
+     */
+    void reset() {
+        core_util_critical_section_enter();
+        _head = 0;
+        _tail = 0;
+        _full = false;
+        core_util_critical_section_exit();
+    }
+
+    /** Get the number of elements currently stored in the circular_buffer */
+    CounterType size() const {
+        core_util_critical_section_enter();
+        CounterType elements;
+        if (!_full) {
+            if (_head < _tail) {
+                elements = BufferSize + _head - _tail;
+            } else {
+                elements = _head - _tail;
+            }
+        } else {
+            elements = BufferSize;
+        }
+        core_util_critical_section_exit();
+        return elements;
+    }
+
+    /** Peek into circular buffer without popping
+     *
+     * @param data Data to be peeked from the buffer
+     * @return True if the buffer is not empty and data contains a transaction, false otherwise
+     */
+    bool peek(T& data) const {
+        bool data_updated = false;
+        core_util_critical_section_enter();
+        if (!empty()) {
+            data = _pool[_tail];
+            data_updated = true;
+        }
+        core_util_critical_section_exit();
+        return data_updated;
+    }
+    
+private:
+    T _pool[BufferSize];
+    volatile CounterType _head;
+    volatile CounterType _tail;
+    volatile bool _full;
+};
+
+/**@}*/
+
+/**@}*/
+
+}
+
+#endif