kernel: new queue abstraction

The postqueue functions remain as-is, as that's a more "specialized" interface.
They're mostly wrappers around queue.h, though.

1 files changed, 37 insertions, 0 deletions

diff --git a/src/kernel/queue.h b/src/kernel/queue.h
new file mode 100644
index 0000000..896824f
--- /dev/null
+++ b/src/kernel/queue.h
@@ -0,0 +1,37 @@
+/* documented in queue(9) */
+#include <kernel/panic.h>
+
+/* struct QueueNode {
+ *   ...
+ *   struct QueueNode *name_next;
+ *   ...
+ * }
+ * struct QueueHead {
+ *   struct QueueNode *head, **slot;
+ * }
+ */
+
+#define QUEUE_INIT(q) do { \
+	(q)->head = NULL; \
+	(q)->slot = &(q)->head; \
+} while(0)
+
+#define QUEUE_APPEND(q, name, el) do { \
+	assert((el)->name##_next == NULL); \
+	assert((q)->slot != NULL); \
+	assert(*(q)->slot == NULL); \
+	*(q)->slot = (el); \
+	(q)->slot = &(el)->name##_next; \
+} while(0)
+
+#define QUEUE_POP(q, name) ({ \
+	typeof((q)->head) __q_el = (q)->head; \
+	if (__q_el) { \
+		(q)->head = __q_el->name##_next; \
+		__q_el->name##_next = NULL; \
+		if ((q)->slot == &__q_el->name##_next) { \
+			(q)->slot = &(q)->head; \
+		} \
+	} \
+	__q_el; \
+})