1 files changed, 93 insertions, 25 deletions

diff --git a/libmaple/ring_buffer.h b/libmaple/ring_buffer.h
index a44088e..2536617 100644
--- a/libmaple/ring_buffer.h
+++ b/libmaple/ring_buffer.h
@@ -1,3 +1,29 @@
+/******************************************************************************
+ * 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
@@ -9,25 +35,26 @@
 #ifndef _RING_BUFFER_H_
 #define _RING_BUFFER_H_
 
+#include "libmaple_types.h"
+
 #ifdef __cplusplus
 extern "C"{
 #endif
 
-/* The buffer is empty when head == tail.
+/**
+ * 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 {
-    /** Buffer items are stored into */
-    volatile uint8 *buf;
-    /** Index of the next item to remove */
-    uint16 head;
-    /** Index where the next item will get inserted */
-    uint16 tail;
-    /** Buffer capacity minus one */
-    uint16 size;
+    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;
 
 /**
@@ -42,17 +69,19 @@ typedef struct ring_buffer {
  *
  *  @param buf  Buffer to store items into
  */
-__attribute__((unused))
-static void rb_init(ring_buffer *rb, uint16 size, uint8 *buf) {
+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;
 }
 
-/** Return the number of elements stored in the ring buffer. */
+/**
+ * @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) {
-    volatile ring_buffer *arb = rb;
+    __io ring_buffer *arb = rb;
     int32 size = arb->tail - arb->head;
     if (arb->tail < arb->head) {
         size += arb->size + 1;
@@ -60,19 +89,37 @@ static inline uint16 rb_full_count(ring_buffer *rb) {
     return (uint16)size;
 }
 
-/** Return true if and only if the ring buffer is full. */
+/**
+ * @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);
 }
 
-/** Append element onto the end of the ring buffer. */
+/**
+ * @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;
 }
 
-/** Remove and return the first item from the ring buffer. */
+/**
+ * @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;
@@ -80,8 +127,24 @@ static inline uint8 rb_remove(ring_buffer *rb) {
 }
 
 /**
- * If rb is not full, appends element and returns true; otherwise,
- * does nothing and returns false. */
+ * @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;
@@ -91,12 +154,16 @@ static inline int rb_safe_insert(ring_buffer *rb, uint8 element) {
 }
 
 /**
- * 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
+ * @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.
  *
- * On success, returns -1.  If an element was popped, returns the
- * popped value. */
+ * @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)) {
@@ -106,7 +173,10 @@ static inline int rb_push_insert(ring_buffer *rb, uint8 element) {
     return ret;
 }
 
-/** Discard all items from the buffer */
+/**
+ * @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;
 }
@@ -115,7 +185,5 @@ static inline void rb_reset(ring_buffer *rb) {
 } // extern "C"
 #endif
 
-
-
 #endif