From 0b50e4eae932acf1b94567a1b5a65971e81868c9 Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Thu, 17 Jun 2021 18:29:22 -0500
Subject: [PATCH] fix(ppu): implement slightly better SCX discarding

---
 src/ppu.rs | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/src/ppu.rs b/src/ppu.rs
index 0332bd5..afb8af4 100644
--- a/src/ppu.rs
+++ b/src/ppu.rs
@@ -381,12 +381,11 @@ impl Ppu {
         if self.fifo.is_enabled() {
             use RenderPriority::*;
 
-            if self.x_pos == 0 {
-                // Start of a Scanline
-                let discarded_count = self.pos.scroll_x % 8;
+            if self.x_pos == 0 && !self.fifo.back.is_empty() {
+                let to_discard = self.pos.scroll_x % 8;
 
-                for _ in 0..discarded_count {
-                    let _ = self.fifo.back.pop_back();
+                for _ in 0..to_discard {
+                    let _ = self.fifo.back.pop_front();
                 }
             }