From 8bb1e280280c2f30740defca68ea643c56a3d880 Mon Sep 17 00:00:00 2001
From: Kimplul <kimi.h.kuparinen@gmail.com>
Date: Sun, 19 Dec 2021 10:48:40 +0200
Subject: [WIP] virtual memory management

---
 common/sp_tree.c | 236 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 236 insertions(+)
 create mode 100644 common/sp_tree.c

(limited to 'common/sp_tree.c')

diff --git a/common/sp_tree.c b/common/sp_tree.c
new file mode 100644
index 0000000..abfaa4b
--- /dev/null
+++ b/common/sp_tree.c
@@ -0,0 +1,236 @@
+#include <apos/sp_tree.h>
+
+inline static void __sp_turn_left(struct sp_node *n)
+{
+	struct sp_node *l = sp_left(n);
+	struct sp_node *p = sp_paren(n);
+
+	sp_paren(l) = sp_paren(n);
+	sp_left(n) = sp_right(l);
+	sp_paren(n) = l;
+	sp_right(l) = n;
+
+	if(p && sp_left(p) == n)
+		sp_left(p) = l;
+	else if (p)
+		sp_right(p) = l;
+
+	if(sp_left(n))
+		sp_lparen(n) = n;
+}
+
+inline static void __sp_turn_right(struct sp_node *n)
+{
+	struct sp_node *r = sp_right(n);
+	struct sp_node *p = sp_paren(n);
+
+	sp_paren(r) = sp_paren(n);
+	sp_right(n) = sp_left(r);
+	sp_paren(n) = r;
+	sp_left(r) = n;
+
+	if(p && sp_left(p) == n)
+		sp_left(p) = r;
+	else if (p)
+		sp_right(p) = r;
+
+	if(sp_right(n))
+		sp_rparen(n) = n;
+}
+
+inline static int __sp_balance(struct sp_node *n)
+{
+	int l = 0;
+	int r = 0;
+
+	if(sp_left(n))
+		l = sp_left(n)->hint + 1;
+
+	if(sp_right(n))
+		r = sp_right(n)->hint + 1;
+
+	return l - r;
+}
+
+inline static int __sp_max_hint(struct sp_node *n)
+{
+	int l = 0;
+	int r = 0;
+
+	if(sp_left(n))
+		l = sp_left(n)->hint + 1;
+
+	if(sp_right(n))
+		r = sp_right(n)->hint + 1;
+
+	if(l > r)
+		return l;
+	else
+		return r;
+}
+
+inline static void sp_update(struct sp_node **root, struct sp_node *n)
+{
+	while(n){
+
+		int b = __sp_balance(n);
+		int prev_hint = n->hint;
+		struct sp_node *p = sp_paren(n);
+
+		if(b < -1) {
+			/* leaning to the right */
+			if(n == *root)
+				*root = sp_right(n);
+
+			__sp_turn_right(n);
+		}
+
+		else if(b > 1){
+			/* leaning to the left */
+			if(n == *root)
+				*root = sp_left(n);
+
+			__sp_turn_left(n);
+		}
+
+		n->hint = __sp_max_hint(n);
+		if(n->hint == 0 || n->hint != prev_hint)
+			n = p;
+		else
+			return;
+	}
+}
+
+void sp_insert(struct sp_node **root, struct sp_node *p,
+		struct sp_node *n, enum sp_dir d)
+{
+	if(!*root){
+		*root = n;
+		return;
+	}
+
+	if(d == LEFT)
+		sp_left(p) = n;
+	else
+		sp_right(p) = n;
+
+	sp_paren(n) = p;
+	sp_update(root, n);
+}
+
+inline static void __sp_replace_right(struct sp_node *n, struct sp_node *r)
+{
+	struct sp_node *p = sp_paren(n);
+	struct sp_node *rp = sp_paren(r);
+
+	if(sp_left(rp) == r){
+		sp_left(rp) = sp_right(r);
+		if(sp_right(r))
+			sp_rparen(r) = rp;
+	}
+
+	if(sp_paren(rp) == n)
+		sp_paren(rp) = r;
+
+	sp_paren(r) = p;
+	sp_left(r) = sp_left(n);
+
+	if(sp_right(n) != r){
+		sp_right(r) = sp_right(n);
+		sp_rparen(n) = r;
+	}
+
+	if(p && sp_left(p) == n)
+		sp_left(p) = r;
+	else if (p)
+		sp_right(p) = r;
+
+	if(sp_left(n))
+		sp_lparen(n) = r;
+}
+
+inline static void __sp_replace_left(struct sp_node *n, struct sp_node *l)
+{
+	struct sp_node *p = sp_paren(n);
+	struct sp_node *lp = sp_paren(l);
+
+	if(sp_right(lp) == l){
+		sp_right(lp) = sp_left(l);
+		if(sp_left(l))
+			sp_lparen(l) = lp;
+	}
+
+	if(sp_paren(lp) == n)
+		sp_paren(lp) = l;
+
+	sp_paren(l) = p;
+	sp_right(l) = sp_right(n);
+
+	if(sp_left(n) != l){
+		sp_left(l) = sp_left(n);
+		sp_lparen(n) = l;
+	}
+
+	if(p && sp_left(p) == n)
+		sp_left(p) = l;
+	else if (p)
+		sp_right(p) = l;
+
+	if(sp_right(n))
+		sp_rparen(n) = l;
+}
+
+/* TODO: handle root better */
+void sp_remove(struct sp_node **root, struct sp_node *del)
+{
+	if(sp_right(del)){
+		struct sp_node *least = sp_first(sp_right(del));
+
+		if(del == *root)
+			*root = least;
+
+		__sp_replace_right(del, least);
+		sp_update(root, sp_right(least));
+		return;
+	}
+
+	if(sp_left(del)){
+		struct sp_node *most = sp_last(sp_left(del));
+
+		if(del == *root)
+			*root = most;
+
+		__sp_replace_left(del, most);
+		sp_update(root, sp_left(most));
+		return;
+	}
+
+	if(del == *root){
+		*root = 0;
+		return;
+	}
+
+	/* empty node */
+	struct sp_node *paren = sp_paren(del);
+
+	if(sp_left(paren) == del)
+		sp_left(paren) = 0;
+	else
+		sp_right(paren) = 0;
+
+	sp_update(root, paren);
+}
+
+struct sp_node *sp_first(struct sp_node *n)
+{
+	if(!sp_left(n)) return n;
+
+	return sp_first(sp_left(n));
+}
+
+struct sp_node *sp_last(struct sp_node *n)
+{
+	if(!sp_right(n)) return n;
+
+	return sp_last(sp_right(n));
+}
-- 
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