1 files changed, 123 insertions, 0 deletions
diff --git a/os/boot/pc/alarm.c b/os/boot/pc/alarm.c
new file mode 100644
index 00000000..2aa4431a
--- /dev/null
+++ b/os/boot/pc/alarm.c
@@ -0,0 +1,123 @@
+#include	"u.h"
+#include	"lib.h"
+#include	"mem.h"
+#include	"dat.h"
+#include	"fns.h"
+#include	"io.h"
+#define	MAXALARM	10
+
+Alarm	alarmtab[MAXALARM];
+
+/*
+ * Insert new into list after where
+ */
+void
+insert(List **head, List *where, List *new)
+{
+	if(where == 0){
+		new->next = *head;
+		*head = new;
+	}else{
+		new->next = where->next;
+		where->next = new;
+	}
+		
+}
+
+/*
+ * Delete old from list.  where->next is known to be old.
+ */
+void
+delete(List **head, List *where, List *old)
+{
+	if(where == 0){
+		*head = old->next;
+		return;
+	}
+	where->next = old->next;
+}
+
+Alarm*
+newalarm(void)
+{
+	int i;
+	Alarm *a;
+
+	for(i=0,a=alarmtab; i < nelem(alarmtab); i++,a++)
+		if(a->busy==0 && a->f==0){
+			a->f = 0;
+			a->arg = 0;
+			a->busy = 1;
+			return a;
+		}
+	panic("newalarm");
+	return 0;	/* not reached */
+}
+
+Alarm*
+alarm(int ms, void (*f)(Alarm*), void *arg)
+{
+	Alarm *a, *w, *pw;
+	ulong s;
+
+	if(ms < 0)
+		ms = 0;
+	s = splhi();
+	a = newalarm();
+	a->dt = MS2TK(ms);
+	a->f = f;
+	a->arg = arg;
+	pw = 0;
+	for(w=m->alarm; w; pw=w, w=w->next){
+		if(w->dt <= a->dt){
+			a->dt -= w->dt;
+			continue;
+		}
+		w->dt -= a->dt;
+		break;
+	}
+	insert(&m->alarm, pw, a);
+	splx(s);
+	return a;
+}
+
+void
+cancel(Alarm *a)
+{
+	a->f = 0;
+}
+
+void
+alarminit(void)
+{
+}
+
+#define NA 10		/* alarms per clock tick */
+void
+checkalarms(void)
+{
+	int i, n, s;
+	Alarm *a;
+	void (*f)(Alarm*);
+	Alarm *alist[NA];
+
+	s = splhi();
+	a = m->alarm;
+	if(a){
+		for(n=0; a && a->dt<=0 && n<NA; n++){
+			alist[n] = a;
+			delete(&m->alarm, 0, a);
+			a = m->alarm;
+		}
+		if(a)
+			a->dt--;
+
+		for(i = 0; i < n; i++){
+			f = alist[i]->f;	/* avoid race with cancel */
+			if(f)
+				(*f)(alist[i]);
+			alist[i]->busy = 0;
+		}
+	}
+	splx(s);
+}