From e71dd2d9fe1cc3a6d074f9c1894e2c5200cecdb1 Mon Sep 17 00:00:00 2001
From: Kimplul <kimi.h.kuparinen@gmail.com>
Date: Sat, 16 Apr 2022 19:25:05 +0300
Subject: create more general node structure

+ Allow for easier handling of other subsystems that want to use nodes,
  mainly tcb and possibly dev_mem
---
 common/nodes.c | 148 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 148 insertions(+)
 create mode 100644 common/nodes.c

(limited to 'common/nodes.c')

diff --git a/common/nodes.c b/common/nodes.c
new file mode 100644
index 0000000..e264529
--- /dev/null
+++ b/common/nodes.c
@@ -0,0 +1,148 @@
+#include <apos/mem.h>
+#include <apos/pmem.h>
+#include <apos/nodes.h>
+#include <apos/string.h>
+
+#define MAX_NODES(node_size)\
+	((BASE_PAGE_SIZE - sizeof(struct node_region)) / (sizeof(enum node_status) + node_size))
+
+#define region_to_nodes(r)\
+	((enum node_status *)((char *)(r) + sizeof(struct node_region)))
+
+#define node_status(r)\
+	((enum node_status *)((char *)(r) - sizeof(enum node_status)))
+
+#define node_region(r)\
+	((struct node_region *)((uintptr_t)(r) & ~(BASE_PAGE_SIZE - 1)))
+
+static struct node_region *__create_region()
+{
+	struct node_region *r = (struct node_region *)alloc_page(BASE_PAGE, 0);
+	memset(r, FREE, BASE_PAGE_SIZE);
+	return r;
+}
+
+void init_nodes(struct node_root *r, size_t node_size)
+{
+	r->head = __create_region();
+	r->av_head = r->head;
+	r->node_size = node_size;
+}
+
+void destroy_nodes(struct node_root *r)
+{
+	struct node_region *nr = r->head;
+	while (nr) {
+		struct node_region *d = nr;
+		nr = nr->prev;
+		free_page(BASE_PAGE, (pm_t)d);
+	}
+}
+
+static void *__find_free_node(struct node_root *r, struct node_region *nr)
+{
+	enum node_status *w = region_to_nodes(nr);
+	for (size_t i = 0; i < MAX_NODES(r->node_size); ++i) {
+		if (*w != FREE) {
+			w = (enum node_status *)(r->node_size + (uint8_t *)(w + 1));
+			continue;
+		}
+
+		*w = USED;
+		return (void *)(w + 1);
+	}
+
+	return 0;
+}
+
+static void __pop_av_head(struct node_root *r)
+{
+	struct node_region *t = r->av_head;
+	r->av_head = r->av_head->next;
+	if (r->av_head)
+		r->av_head->av_prev = 0;
+
+	t->av_next = 0;
+	t->av_prev = 0;
+}
+
+void *get_node(struct node_root *r)
+{
+	if (!r)
+		return 0;
+
+	if (!r->av_head) {
+		r->av_head = __create_region();
+
+		r->av_head->prev = r->head;
+		r->head->next = r->av_head;
+
+		r->head = r->av_head;
+	}
+
+	void *p = __find_free_node(r, r->av_head);
+	if (++r->av_head->used_nodes == MAX_NODES(r->node_size))
+		__pop_av_head(r);
+
+	return p;
+}
+
+static void __push_av_head(struct node_root *r, struct node_region *nr)
+{
+	nr->av_prev = 0;
+	nr->av_next = r->av_head;
+	if (r->av_head)
+		r->av_head->av_prev = nr;
+
+	r->av_head = nr;
+}
+
+static void __free_region(struct node_root *r, struct node_region *nr)
+{
+	struct node_region *av_n = nr->av_next;
+	struct node_region *av_p = nr->av_prev;
+
+	if (av_n)
+		av_n->av_prev = av_p;
+
+	if (av_p)
+		av_p->av_next = av_n;
+
+	if (nr == r->av_head)
+		__pop_av_head(r);
+
+	struct node_region *n = nr->next;
+	struct node_region *p = nr->prev;
+
+	if (n)
+		n->prev = p;
+
+	if (p)
+		p->next = n;
+
+	if (nr == r->head) {
+		if (r->head->prev) {
+			r->head->next = 0;
+			r->head = r->head->prev;
+		} else
+			return;
+	}
+
+	free_page(BASE_PAGE, (pm_t)nr);
+}
+
+void free_node(struct node_root *r, void *p)
+{
+	enum node_status *w = node_status(p);
+	*w = FREE;
+
+	struct node_region *nr = node_region(w);
+
+	if (--nr->used_nodes == 0) {
+		__free_region(r, nr);
+		return;
+	}
+
+	else if (!nr->av_next && !nr->av_prev)
+		__push_av_head(r, nr);
+}
-- 
cgit v1.3