1 files changed, 110 insertions, 0 deletions
diff --git a/src/pool.c b/src/pool.c
new file mode 100644
index 0000000..1417a02
--- /dev/null
+++ b/src/pool.c
@@ -0,0 +1,110 @@
+#include <atari.h>
+#include "pool.h"
+#include "addrs.h"
+#include "memclear.h"
+
+screen_t screens[MAX_SCREENS];
+pool_t pools[MAX_POOLS];
+
+void init_pools(void) {
+	char p;
+
+	pools[0].screen_count = 0;
+	pools[0].free_list = (line_t *)END_MARKER;
+
+	for(p = 1; p < MAX_POOLS; p++)
+		pools[p].screen_count = POOL_UNUSED;
+
+	add_to_pool(0, SCR_MAIN_MEM, SCR_MAIN_END);
+
+	if((u16)OS.memlo < SCR_LOW_END - sizeof(pool_t))
+		add_to_pool(0, (u16)OS.memlo, SCR_LOW_END);
+}
+
+void add_to_pool(char p, u16 start, u16 end) {
+	line_t *l;
+
+	end -= sizeof(line_t);
+
+	l = (line_t *)start;
+
+	while(l <= (line_t *)end) {
+		memclear(l, sizeof(line_t));
+		l->next = pools[p].free_list;
+		pools[p].free_list = l;
+		l++;
+	}
+}
+
+char get_smallest_pool(void) {
+	char p, r;
+	u16 min;
+
+	min = 0xffff;
+	r = 0;
+
+	for(p = 0; p < MAX_POOLS; p++) {
+		if(pools[p].screen_count = POOL_UNUSED)
+			continue; /* maybe break here instead */
+		if(pools[p].screen_count < min) {
+			min = pools[p].screen_count;
+			r = p;
+		}
+	}
+	return r;
+}
+
+line_t *steal_line(char s) {
+	line_t *l;
+	char candidate, victim;
+	u16 maxheight;
+
+	victim = s;
+	maxheight = 0;
+
+	for(candidate = 0; candidate < MAX_SCREENS; candidate++) {
+		/* only steal from the same pool */
+		if(screens[candidate].pool != screens[s].pool)
+			continue;
+		/* steal from the screen with the most lines */
+		if(screens[candidate].line_count > maxheight) {
+			maxheight = screens[candidate].line_count;
+			victim = candidate;
+		}
+	}
+
+	/* find 2nd to last line of the victim screen */
+	for(l = screens[victim].line_list; l->next->next != (line_t *)END_MARKER; l = l->next)
+		;
+
+	/* prepend last line to screen s */
+	l->next->next = screens[s].line_list;
+	screens[s].line_list = l->next;
+	memclear(screens[s].line_list->data, LINE_LEN);
+
+	l->next = (line_t *)END_MARKER;
+
+	return l;
+}
+
+line_t *find_line(char s) {
+	line_t *p;
+
+	p = pools[screens[s].pool].free_list;
+	if(p != (line_t *)END_MARKER) {
+		pools[screens[s].pool].free_list = p->next;
+		return p;
+	}
+
+	/* free_list was null, pool is full */
+	return steal_line(s);
+}
+
+void add_line(char s) {
+	line_t *p;
+
+	p = find_line(s);
+	p->next = screens[s].line_list;
+	screens[s].line_list = p;
+	screens[s].line_count++;
+}