From a156a8763dc7c1e36bd6193d2d3c7938aace9102 Mon Sep 17 00:00:00 2001
From: paoda <rekai@musuka.dev>
Date: Mon, 8 Aug 2022 14:41:48 +0200
Subject: [PATCH] fix: 8-bit writes to WIN PPU registers

Advance Wars depends on these registers similar to Mario Kart's 8-bit
writes to Affine Background registers:
---
 src/core/bus/io.zig | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/core/bus/io.zig b/src/core/bus/io.zig
index 7e9e535..4736d2f 100644
--- a/src/core/bus/io.zig
+++ b/src/core/bus/io.zig
@@ -424,8 +424,12 @@ pub const BldY = extern union {
     raw: u16,
 };
 
+const u8WriteKind = enum { Hi, Lo };
+
 /// Write-only
 pub const WinH = extern union {
+    const Self = @This();
+
     x2: Bitfield(u16, 0, 8),
     x1: Bitfield(u16, 8, 8),
     raw: u16,
@@ -433,9 +437,18 @@ pub const WinH = extern union {
 
 /// Write-only
 pub const WinV = extern union {
+    const Self = @This();
+
     y2: Bitfield(u16, 0, 8),
     y1: Bitfield(u16, 8, 8),
     raw: u16,
+
+    pub fn set(self: *Self, comptime K: u8WriteKind, value: u8) void {
+        self.raw = switch (K) {
+            .Hi => (@as(u16, value) << 8) | self.raw & 0xFF,
+            .Lo => (self.raw & 0xFF00) | value,
+        };
+    }
 };
 
 pub const WinIn = extern union {