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/**
* @brief simple circular buffer
*/
#ifndef _RING_BUFFER_H_
#define _RING_BUFFER_H_
#ifdef __cplusplus
extern "C"{
#endif
/* The buffer is empty when head == tail.
* The buffer is full when the head is one byte in front of the tail
* The total buffer size must be a power of two
* 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;
} 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
*/
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;
}
/** 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->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->head == rb->size) ? 0 : rb->head + 1;
return ch;
}
static inline uint32 rb_full_count(ring_buffer *rb) {
/* PENDING: Broken */
volatile ring_buffer *arb = rb;
return arb->tail - arb->head;
}
/** Discard all items from the buffer */
static inline void rb_reset(ring_buffer *rb) {
rb->tail = rb->head;
}
#ifdef __cplusplus
} // extern "C"
#endif
#endif
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