8  * Memory FIFO permitting enqueue at tail (last) and dequeue from head (first).
17  * Invariant: last-index refers to the buffer that is safe to write while in
18  * limbo-state. Outside limbo state, last-index refers one buffer ahead of what
55 			uint8_t l; /* Last. Write index */ \
60  * @details API 1 and 2. An MFIFO is empty if first == last
81 					 uint8_t last, uint8_t *idx)  in mfifo_enqueue_idx_get()  argument
84 	last = last + 1;  in mfifo_enqueue_idx_get()
85 	if (last == count) {  in mfifo_enqueue_idx_get()
86 		last = 0U;  in mfifo_enqueue_idx_get()
91 	 * first == last, but we just advanced a copy of the write-index before  in mfifo_enqueue_idx_get()
92 	 * and may have wrapped. So if first == last the queue is full and we  in mfifo_enqueue_idx_get()
95 	if (last == first) {  in mfifo_enqueue_idx_get()
99 	*idx = last; /* Emit the allocated buffer's index */  in mfifo_enqueue_idx_get()
118 					uint8_t idx, void *mem, uint8_t *last)  in mfifo_by_idx_enqueue()  argument
121 	void **p = (void **)(fifo + (*last) * size); /* buffer preceding idx */  in mfifo_by_idx_enqueue()
125 	*last = idx; /* Commit: Update write index */  in mfifo_by_idx_enqueue()
145 					uint8_t last, void **mem)  in mfifo_enqueue_get()  argument
150 	if (!mfifo_enqueue_idx_get(count, first, last, &idx)) {  in mfifo_enqueue_get()
157 	 * buffer (last). Recall that last has not been updated,  in mfifo_enqueue_get()
158 	 * so idx != last  in mfifo_enqueue_get()
160 	*mem = (void *)(fifo + last * size); /* preceding buffer */  in mfifo_enqueue_get()
188  * @param last[out] Write-index
190 static inline void mfifo_enqueue(uint8_t idx, uint8_t *last)  in mfifo_enqueue()  argument
193 	*last = idx; /* Commit: Update write index */  in mfifo_enqueue()
208  *   Empty if first == last
211 					    uint8_t last)  in mfifo_avail_count_get()  argument
213 	if (last >= first) {  in mfifo_avail_count_get()
214 		return last - first;  in mfifo_avail_count_get()
216 		return count - first + last;  in mfifo_avail_count_get()
233 				      uint8_t first, uint8_t last)  in mfifo_dequeue_get()  argument
235 	if (first == last) {  in mfifo_dequeue_get()
255 				       uint8_t first, uint8_t last)  in mfifo_dequeue_peek()  argument
257 	if (first == last) {  in mfifo_dequeue_peek()
275 					   uint8_t last, uint8_t *idx)  in mfifo_dequeue_iter_get()  argument
284 	if (*idx == last) {  in mfifo_dequeue_iter_get()
311  * @param last[in]      Tail index, Span: [0 .. count-1]
316 				  uint8_t last, uint8_t *first)  in mfifo_dequeue()  argument
321 	/* Queue is empty if first == last */  in mfifo_dequeue()
322 	if (_first == last) {  in mfifo_dequeue()