From abe2fc431e3f8115287b99ab444e1d82bc947d52 Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Fri, 21 Oct 2022 05:11:48 -0300
Subject: [PATCH] fix(bus): restrict Game ROM and VRAM to a 16-bit bus

---
 src/bus.zig     | 1 -
 src/bus/pak.zig | 2 +-
 src/ppu.zig     | 8 +++-----
 3 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/src/bus.zig b/src/bus.zig
index 3f73f54..ba0acd0 100644
--- a/src/bus.zig
+++ b/src/bus.zig
@@ -98,7 +98,6 @@ pub const Bus = struct {
 
     pub fn write16(self: *@This(), addr: u32, halfword: u16) void {
         // TODO: write16 can write to GamePak Flash
-
         switch (addr) {
             // General Internal Memory
             0x0200_0000...0x0203_FFFF => std.debug.panic("[Bus:16] write 0x{X:} to 0x{X:} in IWRAM", .{ halfword, addr }),
diff --git a/src/bus/pak.zig b/src/bus/pak.zig
index c9ab442..d622e5e 100644
--- a/src/bus/pak.zig
+++ b/src/bus/pak.zig
@@ -23,7 +23,7 @@ pub const GamePak = struct {
     }
 
     pub inline fn get32(self: *const @This(), idx: usize) u32 {
-        return (@as(u32, self.buf[idx + 3]) << 24) | (@as(u32, self.buf[idx + 2]) << 16) | (@as(u32, self.buf[idx + 1]) << 8) | (@as(u32, self.buf[idx]));
+        return (@as(u32, self.get16(idx + 2)) << 16) | @as(u32, self.get16(idx));
     }
 
     pub inline fn get16(self: *const @This(), idx: usize) u16 {
diff --git a/src/ppu.zig b/src/ppu.zig
index 783ab1f..e149c0b 100644
--- a/src/ppu.zig
+++ b/src/ppu.zig
@@ -32,14 +32,12 @@ const Vram = struct {
     }
 
     pub inline fn get32(self: *const @This(), idx: usize) u32 {
-        return (@as(u32, self.buf[idx + 3]) << 24) | (@as(u32, self.buf[idx + 2]) << 16) | (@as(u32, self.buf[idx + 1]) << 8) | (@as(u32, self.buf[idx]));
+        return (@as(u32, self.get16(idx + 2)) << 16) | @as(u32, self.get16(idx));
     }
 
     pub inline fn set32(self: *@This(), idx: usize, word: u32) void {
-        self.buf[idx + 3] = @truncate(u8, word >> 24);
-        self.buf[idx + 2] = @truncate(u8, word >> 16);
-        self.buf[idx + 1] = @truncate(u8, word >> 8);
-        self.buf[idx] = @truncate(u8, word);
+        self.set16(idx + 2, @truncate(u16, word >> 16));
+        self.set16(idx, @truncate(u16, word));
     }
 
     pub inline fn get16(self: *const @This(), idx: usize) u16 {