1 files changed, 11 insertions, 7 deletions

diff --git a/src/listnav.c b/src/listnav.c
index 707a973..28db2d3 100644
--- a/src/listnav.c
+++ b/src/listnav.c
@@ -12,26 +12,30 @@ listnav_init(struct listnav *nav)
 void
 listnav_update_bounds(struct listnav *nav, int min, int max)
 {
+	ASSERT(max >= min);
 	nav->min = min;
 	nav->max = max;
-	nav->wmin = MAX(nav->wmin, nav->min);
-	nav->wmax = MIN(nav->wmin + nav->wlen, nav->max);
-	nav->sel = MIN(MAX(nav->sel, nav->wmin), nav->wmax - 1);
+	listnav_update_wlen(nav, MIN(nav->wlen, nav->max - nav->min));
 }
 
 void
 listnav_update_wlen(struct listnav *nav, int wlen)
 {
-	nav->wlen = wlen;
-	nav->wmax = MIN(nav->wmin + nav->wlen, nav->max);
-	nav->sel = MIN(MAX(nav->sel, nav->wmin), nav->wmax - 1);
+	ASSERT(wlen >= 0);
+
+	nav->wlen = MIN(wlen, nav->max - nav->min);
+	if (nav->wmin < nav->min)
+		nav->wmin = nav->min;
+	if (nav->wmin + nav->wlen > nav->max)
+		nav->wmin = nav->max - nav->wlen;
+	nav->wmax = nav->wmin + nav->wlen;
+	nav->sel = MAX(MIN(nav->sel, nav->wmax - 1), nav->wmin);
 }
 
 void
 listnav_update_sel(struct listnav *nav, int sel)
 {
 	nav->sel = MAX(MIN(sel, nav->max - 1), nav->min);
-
 	if (nav->sel >= nav->wmax) {
 		nav->wmax = nav->sel + 1;
 		nav->wmin = MAX(nav->min, nav->wmax - nav->wlen);