Fix overflow error in line drawing function

Drawing a line with length of 0x4000 or greater was never terminating.

1 files changed, 5 insertions, 5 deletions

diff --git a/arm9/source/devices/screen.c b/arm9/source/devices/screen.c
index f1aa7f9..e394b55 100644
--- a/arm9/source/devices/screen.c
+++ b/arm9/source/devices/screen.c
@@ -244,11 +244,11 @@ void scr_draw_line(ScreenDevice *scr, u16 *layer, u8 draw) {
     s16 x_end = (s16) scr->px;
     s16 y_end = (s16) scr->py;
 
-    s16 dx =  abs(x_end - x);
-    s16 dy = -abs(y_end - y);
+    s32 dx =  abs(x_end - x);
+    s32 dy = -abs(y_end - y);
     s16 sx = x < x_end ? 1 : -1;
     s16 sy = y < y_end ? 1 : -1;
-    s16 e1 = dx + dy;
+    s32 e1 = dx + dy;
 
     if (draw & 0x10) {
     // Draw 1-bit textured line.
@@ -260,7 +260,7 @@ void scr_draw_line(ScreenDevice *scr, u16 *layer, u8 draw) {
             if (scr->sprite.sprite[y%8][x%8]) { draw_pixel(layer, x, y, c1); }
             else if (opaque)                  { draw_pixel(layer, x, y, c0); }
             if (x == x_end && y == y_end) return;
-            s16 e2 = e1 << 1;
+            s32 e2 = e1 << 1;
             if (e2 >= dy) { e1 += dy; x += sx; }
             if (e2 <= dx) { e1 += dx; y += sy; }
         }
@@ -270,7 +270,7 @@ void scr_draw_line(ScreenDevice *scr, u16 *layer, u8 draw) {
         while (1) {
             draw_pixel(layer, x, y, colour);
             if (x == x_end && y == y_end) return;
-            s16 e2 = e1 << 1;
+            s32 e2 = e1 << 1;
             if (e2 >= dy) { e1 += dy; x += sx; }
             if (e2 <= dx) { e1 += dx; y += sy; }
         }