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diff --git a/libmaple/include/libmaple/ring_buffer.h b/libmaple/include/libmaple/ring_buffer.h
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+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2011 LeafLabs, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *****************************************************************************/
+
+/**
+ * @file ring_buffer.h
+ * @brief Simple circular buffer
+ *
+ * This implementation is not thread-safe.  In particular, none of
+ * these functions is guaranteed re-entrant.
+ */
+
+#ifndef _LIBMAPLE_RING_BUFFER_H_
+#define _LIBMAPLE_RING_BUFFER_H_
+
+#ifdef __cplusplus
+extern "C"{
+#endif
+
+#include <libmaple/libmaple_types.h>
+
+/**
+ * Ring buffer type.
+ *
+ * The buffer is empty when head == tail.
+ *
+ * The buffer is full when the head is one byte in front of the tail,
+ * modulo buffer length.
+ *
+ * One byte is left free to distinguish empty from full. */
+typedef struct ring_buffer {
+    volatile uint8 *buf; /**< Buffer items are stored into */
+    uint16 head;         /**< Index of the next item to remove */
+    uint16 tail;         /**< Index where the next item will get inserted */
+    uint16 size;         /**< Buffer capacity minus one */
+} ring_buffer;
+
+/**
+ * Initialise a ring buffer.
+ *
+ *  @param rb   Instance to initialise
+ *
+ *  @param size Number of items in buf.  The ring buffer will always
+ *              leave one element unoccupied, so the maximum number of
+ *              elements it can store will be size - 1.  Thus, size
+ *              must be at least 2.
+ *
+ *  @param buf  Buffer to store items into
+ */
+static inline void rb_init(ring_buffer *rb, uint16 size, uint8 *buf) {
+    rb->head = 0;
+    rb->tail = 0;
+    rb->size = size - 1;
+    rb->buf = buf;
+}
+
+/**
+ * @brief Return the number of elements stored in the ring buffer.
+ * @param rb Buffer whose elements to count.
+ */
+static inline uint16 rb_full_count(ring_buffer *rb) {
+    __io ring_buffer *arb = rb;
+    int32 size = arb->tail - arb->head;
+    if (arb->tail < arb->head) {
+        size += arb->size + 1;
+    }
+    return (uint16)size;
+}
+
+/**
+ * @brief Returns true if and only if the ring buffer is full.
+ * @param rb Buffer to test.
+ */
+static inline int rb_is_full(ring_buffer *rb) {
+    return (rb->tail + 1 == rb->head) ||
+        (rb->tail == rb->size && rb->head == 0);
+}
+
+/**
+ * @brief Returns true if and only if the ring buffer is empty.
+ * @param rb Buffer to test.
+ */
+static inline int rb_is_empty(ring_buffer *rb) {
+    return rb->head == rb->tail;
+}
+
+/**
+ * Append element onto the end of a ring buffer.
+ * @param rb Buffer to append onto.
+ * @param element Value to append.
+ */
+static inline void rb_insert(ring_buffer *rb, uint8 element) {
+    rb->buf[rb->tail] = element;
+    rb->tail = (rb->tail == rb->size) ? 0 : rb->tail + 1;
+}
+
+/**
+ * @brief Remove and return the first item from a ring buffer.
+ * @param rb Buffer to remove from, must contain at least one element.
+ */
+static inline uint8 rb_remove(ring_buffer *rb) {
+    uint8 ch = rb->buf[rb->head];
+    rb->head = (rb->head == rb->size) ? 0 : rb->head + 1;
+    return ch;
+}
+
+/**
+ * @brief Attempt to remove the first item from a ring buffer.
+ *
+ * If the ring buffer is nonempty, removes and returns its first item.
+ * If it is empty, does nothing and returns a negative value.
+ *
+ * @param rb Buffer to attempt to remove from.
+ */
+static inline int16 rb_safe_remove(ring_buffer *rb) {
+    return rb_is_empty(rb) ? -1 : rb_remove(rb);
+}
+
+/**
+ * @brief Attempt to insert an element into a ring buffer.
+ *
+ * @param rb Buffer to insert into.
+ * @param element Value to insert into rb.
+ * @sideeffect If rb is not full, appends element onto buffer.
+ * @return If element was appended, then true; otherwise, false. */
+static inline int rb_safe_insert(ring_buffer *rb, uint8 element) {
+    if (rb_is_full(rb)) {
+        return 0;
+    }
+    rb_insert(rb, element);
+    return 1;
+}
+
+/**
+ * @brief Append an item onto the end of a non-full ring buffer.
+ *
+ * If the buffer is full, removes its first item, then inserts the new
+ * element at the end.
+ *
+ * @param rb Ring buffer to insert into.
+ * @param element Value to insert into ring buffer.
+ * @return On success, returns -1.  If an element was popped, returns
+ *         the popped value.
+ */
+static inline int rb_push_insert(ring_buffer *rb, uint8 element) {
+    int ret = -1;
+    if (rb_is_full(rb)) {
+        ret = rb_remove(rb);
+    }
+    rb_insert(rb, element);
+    return ret;
+}
+
+/**
+ * @brief Discard all items from a ring buffer.
+ * @param rb Ring buffer to discard all items from.
+ */
+static inline void rb_reset(ring_buffer *rb) {
+    rb->tail = rb->head;
+}
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif