25 #define INIT_LIST(list) \  argument
26 	do { (list).head = NULL; (list).tail = NULL; } while (/*CONSTCOND*/0)
38 #define HEAD(list) ((list).head)  argument
39 #define TAIL(list) ((list).tail)  argument
40 #define EMPTY(list) ((list).head == NULL)  argument
42 #define PREPEND(list, elt, link) \  argument
45 		if ((list).head != NULL) \
46 			(list).head->link.prev = (elt); \
48 			(list).tail = (elt); \
50 		(elt)->link.next = (list).head; \
51 		(list).head = (elt); \
54 #define APPEND(list, elt, link) \  argument
57 		if ((list).tail != NULL) \
58 			(list).tail->link.next = (elt); \
60 			(list).head = (elt); \
61 		(elt)->link.prev = (list).tail; \
63 		(list).tail = (elt); \
66 #define UNLINK_TYPE(list, elt, link, type) \  argument
72 			(list).tail = (elt)->link.prev; \
76 			(list).head = (elt)->link.next; \
79 #define UNLINK(list, elt, link) \  argument
80 	UNLINK_TYPE(list, elt, link, void)
85 #define INSERT_BEFORE(list, before, elt, link) \  argument
89 			PREPEND(list, elt, link); \
98 #define INSERT_AFTER(list, after, elt, link) \  argument
102 			APPEND(list, elt, link); \
111 #define ENQUEUE(list, elt, link) APPEND(list, elt, link)  argument
112 #define DEQUEUE(list, elt, link) UNLINK(list, elt, link)  argument