From 8dddb865cc4fc3e90259f671cb4739f0e4b585c3 Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Tue, 17 May 2022 12:16:03 -0300
Subject: [PATCH] fix: resolve out-of-bounds error with 8bpp tall / horizontal
 sprites

Boot ROM is now enabled by default as well
---
 src/main.zig |  2 +-
 src/ppu.zig  | 11 ++++-------
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/src/main.zig b/src/main.zig
index 1102d92..bc5aaac 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -84,7 +84,7 @@ pub fn main() anyerror!void {
     defer cpu.deinit();
 
     cpu.bus.attach(&cpu);
-    cpu.fastBoot();
+    // cpu.fastBoot();
 
     // Initialize SDL Audio
     const audio_dev = initAudio(&cpu.bus.apu);
diff --git a/src/ppu.zig b/src/ppu.zig
index 96cca86..1238dd9 100644
--- a/src/ppu.zig
+++ b/src/ppu.zig
@@ -187,14 +187,11 @@ pub const Ppu = struct {
         // When calcualting the inital address, the first entry is always 0x20 * tile_id, even if it is 8bpp
         const tile_base = char_base + (0x20 * @as(u32, tile_id)) + (tile_row_offset * row) + if (is_8bpp) col else col / 2;
 
-        // TODO: Understand more
-        var tile_offset = (tile_x / 8) * tile_len;
-        if (self.dispcnt.obj_mapping.read()) {
-            tile_offset += (tile_y / 8) * tile_len * (sprite.width / 8); // 1D Mapping
-        } else {
-            tile_offset += (tile_y / 8) * tile_len * 0x20; // 2D Mapping
-        }
+        // TODO: Finish that 2D Sprites Test ROM
+        const offset_base = (tile_x / 8) * tile_len;
+        const offset_offset = (tile_y / 8) * tile_len * if (self.dispcnt.obj_mapping.read()) sprite.width / 8 else if (is_8bpp) @as(u32, 0x10) else 0x20;
 
+        const tile_offset = offset_base + offset_offset;
         const tile = self.vram.buf[tile_base + tile_offset];
 
         const pal_id: u16 = if (!is_8bpp) blk: {