From dbe8171815ea3b51c3ac87dae1996ae0d8f6eb04 Mon Sep 17 00:00:00 2001
From: Ben Bridle <ben@derelict.engineering>
Date: Mon, 16 Dec 2024 14:51:00 +1300
Subject: Fix overflow error in line drawing function
Drawing a line with length of 0x4000 or greater was never terminating.
---
arm9/source/devices/screen.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
(limited to 'arm9')
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; }
}
--
cgit v1.2.3-70-g09d2