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-rw-r--r--libmaple/ring_buffer.h30
1 files changed, 15 insertions, 15 deletions
diff --git a/libmaple/ring_buffer.h b/libmaple/ring_buffer.h
index b4c136f..43e0b28 100644
--- a/libmaple/ring_buffer.h
+++ b/libmaple/ring_buffer.h
@@ -17,43 +17,43 @@ typedef struct ring_buffer {
/** Buffer items are stored into */
volatile uint8 *buf;
/** Index of the next item to remove */
- volatile uint16 head;
+ uint16 head;
/** Index where the next item will get inserted */
- volatile uint16 tail;
- /** Buffer capacity */
+ uint16 tail;
+ /** Buffer capacity minus one */
uint16 size;
} ring_buffer;
/** Initialise a ring buffer.
-
- @param rb instance to initialise
- @param size number of items in the buffer
- @param buf buffer to store items into
+ *
+ * @param rb instance to initialise
+ * @param size number of items in the buffer
+ * @param buf buffer to store items into
*/
-static inline void rb_init(ring_buffer *rb, uint8 size, uint8 *buf) {
- ASSERT(IS_POWER_OF_TWO(size));
+static inline void rb_init(ring_buffer *rb, uint16 size, uint8 *buf) {
rb->head = 0;
rb->tail = 0;
- rb->size = size;
+ rb->size = size - 1;
rb->buf = buf;
}
/** Append an item onto the end of the ring buffer */
static inline void rb_insert(ring_buffer *rb, uint8 element) {
- rb->buf[(rb->tail)++] = element;
- rb->tail &= (rb->size - 1);
+ 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 */
static inline uint8 rb_remove(ring_buffer *rb) {
- uint8 ch = rb->buf[rb->head++];
- rb->head &= (rb->size - 1);
+ uint8 ch = rb->buf[rb->head];
+ rb->head = (rb->head == rb->size) ? 0 : rb->head + 1;
return ch;
}
static inline uint32 rb_full_count(ring_buffer *rb) {
/* PENDING: Broken */
- return rb->tail - rb->head;
+ volatile ring_buffer *arb = rb;
+ return arb->tail - arb->head;
}
/** Discard all items from the buffer */