1 files changed, 509 insertions, 0 deletions
diff --git a/src/drivers/device/ringbuffer.h b/src/drivers/device/ringbuffer.h
new file mode 100644
index 000000000..a9e22eaa6
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+++ b/src/drivers/device/ringbuffer.h
@@ -0,0 +1,509 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2013 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file ringbuffer.h
+ *
+ * A flexible ringbuffer class.
+ */
+
+#pragma once
+
+class RingBuffer {
+public:
+	RingBuffer(unsigned ring_size, size_t entry_size);
+	virtual ~RingBuffer();
+
+	/**
+	 * Put an item into the buffer.
+	 *
+	 * @param val		Item to put
+	 * @return		true if the item was put, false if the buffer is full
+	 */
+	bool			put(const void *val, size_t val_size = 0);
+
+	bool			put(int8_t val);
+	bool			put(uint8_t val);
+	bool			put(int16_t val);
+	bool			put(uint16_t val);
+	bool			put(int32_t val);
+	bool			put(uint32_t val);
+	bool			put(int64_t val);
+	bool			put(uint64_t val);
+	bool			put(float val);
+	bool			put(double val);
+
+	/**
+	 * Force an item into the buffer, discarding an older item if there is not space.
+	 *
+	 * @param val		Item to put
+	 * @return		true if an item was discarded to make space
+	 */
+	bool			force(const void *val, size_t val_size = 0);
+
+	bool			force(int8_t val);
+	bool			force(uint8_t val);
+	bool			force(int16_t val);
+	bool			force(uint16_t val);
+	bool			force(int32_t val);
+	bool			force(uint32_t val);
+	bool			force(int64_t val);
+	bool			force(uint64_t val);
+	bool			force(float val);
+	bool			force(double val);
+
+	/**
+	 * Get an item from the buffer.
+	 *
+	 * @param val		Item that was gotten
+	 * @return		true if an item was got, false if the buffer was empty.
+	 */
+	bool			get(void *val, size_t val_size = 0);
+
+	bool			get(int8_t &val);
+	bool			get(uint8_t &val);
+	bool			get(int16_t &val);
+	bool			get(uint16_t &val);
+	bool			get(int32_t &val);
+	bool			get(uint32_t &val);
+	bool			get(int64_t &val);
+	bool			get(uint64_t &val);
+	bool			get(float &val);
+	bool			get(double &val);
+
+	/*
+	 * Get the number of slots free in the buffer.
+	 *
+	 * @return		The number of items that can be put into the buffer before
+	 *			it becomes full.
+	 */
+	unsigned		space(void);
+
+	/*
+	 * Get the number of items in the buffer.
+	 *
+	 * @return		The number of items that can be got from the buffer before
+	 *			it becomes empty.
+	 */
+	unsigned		count(void);
+
+	/*
+	 * Returns true if the buffer is empty.
+	 */
+	bool			empty();
+
+	/*
+	 * Returns true if the buffer is full.
+	 */
+	bool			full();
+
+	/*
+	 * Returns the capacity of the buffer, or zero if the buffer could
+	 * not be allocated.
+	 */
+	unsigned		size();
+
+	/*
+	 * Empties the buffer.
+	 */
+	void			flush();
+
+	/*
+	 * resize the buffer. This is unsafe to be called while
+	 * a producer or consuming is running. Caller is responsible
+	 * for any locking needed
+	 *
+	 * @param new_size	new size for buffer
+	 * @return		true if the resize succeeds, false if
+	 * 			not (allocation error)
+	 */
+	bool			resize(unsigned new_size);
+
+	/*
+	 * printf() some info on the buffer
+	 */
+	void			print_info(const char *name);
+
+private:
+	unsigned		_num_items;
+	const size_t		_item_size;
+	char			*_buf;	
+	volatile unsigned	_head;	/**< insertion point in _item_size units */
+	volatile unsigned	_tail;	/**< removal point in _item_size units */
+
+	unsigned		_next(unsigned index);
+};
+
+RingBuffer::RingBuffer(unsigned num_items, size_t item_size) :
+	_num_items(num_items),
+	_item_size(item_size),
+	_buf(new char[(_num_items+1) * item_size]),
+ 	_head(_num_items),
+ 	_tail(_num_items)
+{}
+
+RingBuffer::~RingBuffer()
+{
+	if (_buf != nullptr)
+		delete[] _buf;
+}
+
+unsigned
+RingBuffer::_next(unsigned index)
+{
+	return (0 == index) ? _num_items : (index - 1); 
+}
+
+bool
+RingBuffer::empty()
+{
+	return _tail == _head; 
+}
+
+bool
+RingBuffer::full()
+{
+	return _next(_head) == _tail; 
+}
+
+unsigned
+RingBuffer::size()
+{
+	return (_buf != nullptr) ? _num_items : 0; 
+}
+
+void
+RingBuffer::flush()
+{
+	while (!empty())
+		get(NULL);
+}
+
+bool
+RingBuffer::put(const void *val, size_t val_size) 
+{
+	unsigned next = _next(_head);
+	if (next != _tail) {
+		if ((val_size == 0) || (val_size > _item_size))
+			val_size = _item_size;
+		memcpy(&_buf[_head * _item_size], val, val_size);
+		_head = next;
+		return true;
+	} else {
+		return false;
+	}
+}
+
+bool
+RingBuffer::put(int8_t val)
+{
+	return put(&val, sizeof(val));
+}
+
+bool
+RingBuffer::put(uint8_t val)
+{
+	return put(&val, sizeof(val));
+}
+
+bool
+RingBuffer::put(int16_t val)
+{
+	return put(&val, sizeof(val));
+}
+
+bool
+RingBuffer::put(uint16_t val)
+{
+	return put(&val, sizeof(val));
+}
+
+bool
+RingBuffer::put(int32_t val)
+{
+	return put(&val, sizeof(val));
+}
+
+bool
+RingBuffer::put(uint32_t val)
+{
+	return put(&val, sizeof(val));
+}
+
+bool
+RingBuffer::put(int64_t val)
+{
+	return put(&val, sizeof(val));
+}
+
+bool
+RingBuffer::put(uint64_t val)
+{
+	return put(&val, sizeof(val));
+}
+
+bool
+RingBuffer::put(float val)
+{
+	return put(&val, sizeof(val));
+}
+
+bool
+RingBuffer::put(double val)
+{
+	return put(&val, sizeof(val));
+}
+
+bool
+RingBuffer::force(const void *val, size_t val_size)
+{
+	bool overwrote = false;
+
+	for (;;) {
+		if (put(val, val_size))
+			break;
+		get(NULL);
+		overwrote = true;
+	}
+	return overwrote;
+}
+
+bool
+RingBuffer::force(int8_t val)
+{
+	return force(&val, sizeof(val));
+}
+
+bool
+RingBuffer::force(uint8_t val)
+{
+	return force(&val, sizeof(val));
+}
+
+bool
+RingBuffer::force(int16_t val)
+{
+	return force(&val, sizeof(val));
+}
+
+bool
+RingBuffer::force(uint16_t val)
+{
+	return force(&val, sizeof(val));
+}
+
+bool
+RingBuffer::force(int32_t val)
+{
+	return force(&val, sizeof(val));
+}
+
+bool
+RingBuffer::force(uint32_t val)
+{
+	return force(&val, sizeof(val));
+}
+
+bool
+RingBuffer::force(int64_t val)
+{
+	return force(&val, sizeof(val));
+}
+
+bool
+RingBuffer::force(uint64_t val)
+{
+	return force(&val, sizeof(val));
+}
+
+bool
+RingBuffer::force(float val)
+{
+	return force(&val, sizeof(val));
+}
+
+bool
+RingBuffer::force(double val)
+{
+	return force(&val, sizeof(val));
+}
+
+bool
+RingBuffer::get(void *val, size_t val_size) 
+{
+	if (_tail != _head) {
+		unsigned candidate;
+		unsigned next;
+
+		if ((val_size == 0) || (val_size > _item_size))
+			val_size = _item_size;
+
+		do {
+			/* decide which element we think we're going to read */
+			candidate = _tail;
+
+			/* and what the corresponding next index will be */
+			next = _next(candidate);
+
+			/* go ahead and read from this index */
+			if (val != NULL)
+				memcpy(val, &_buf[candidate * _item_size], val_size);
+
+			/* if the tail pointer didn't change, we got our item */
+		} while (!__sync_bool_compare_and_swap(&_tail, candidate, next));
+
+		return true;
+	} else {
+		return false;
+	}
+}
+
+bool
+RingBuffer::get(int8_t &val)
+{
+	return get(&val, sizeof(val));
+}
+
+bool
+RingBuffer::get(uint8_t &val)
+{
+	return get(&val, sizeof(val));
+}
+
+bool
+RingBuffer::get(int16_t &val)
+{
+	return get(&val, sizeof(val));
+}
+
+bool
+RingBuffer::get(uint16_t &val)
+{
+	return get(&val, sizeof(val));
+}
+
+bool
+RingBuffer::get(int32_t &val)
+{
+	return get(&val, sizeof(val));
+}
+
+bool
+RingBuffer::get(uint32_t &val)
+{
+	return get(&val, sizeof(val));
+}
+
+bool
+RingBuffer::get(int64_t &val)
+{
+	return get(&val, sizeof(val));
+}
+
+bool
+RingBuffer::get(uint64_t &val)
+{
+	return get(&val, sizeof(val));
+}
+
+bool
+RingBuffer::get(float &val)
+{
+	return get(&val, sizeof(val));
+}
+
+bool
+RingBuffer::get(double &val)
+{
+	return get(&val, sizeof(val));
+}
+
+unsigned
+RingBuffer::space(void) 
+{
+	unsigned tail, head;
+
+	/*
+	 * Make a copy of the head/tail pointers in a fashion that
+	 * may err on the side of under-estimating the free space
+	 * in the buffer in the case that the buffer is being updated
+	 * asynchronously with our check.
+	 * If the head pointer changes (reducing space) while copying,
+	 * re-try the copy.
+	 */
+	do {
+		head = _head;
+		tail = _tail;
+	} while (head != _head);
+
+	return (tail >= head) ? (_num_items - (tail - head)) : (head - tail - 1);
+}
+
+unsigned
+RingBuffer::count(void) 
+{
+	/*
+	 * Note that due to the conservative nature of space(), this may
+	 * over-estimate the number of items in the buffer.
+	 */
+	return _num_items - space();
+}
+
+bool
+RingBuffer::resize(unsigned new_size) 
+{
+	char *old_buffer;
+	char *new_buffer = new char [(new_size+1) * _item_size];
+	if (new_buffer == nullptr) {
+		return false;
+	}
+	old_buffer = _buf;
+	_buf = new_buffer;
+	_num_items = new_size;
+	_head = new_size;
+	_tail = new_size;
+	delete[] old_buffer;
+	return true;
+}
+
+void
+RingBuffer::print_info(const char *name) 
+{
+	printf("%s	%u/%u (%u/%u @ %p)\n",
+	       name, 
+	       _num_items, 
+	       _num_items * _item_size, 
+	       _head, 
+	       _tail, 
+	       _buf);
+}