From da7f21f47e613b2ec841c83e6e1e8d863a9a291b Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Fri, 7 Jan 2022 22:46:17 -0400
Subject: [PATCH] feat: draw white texture using SDL2

---
 .gitmodules  |  3 +++
 build.zig    |  9 ++++++++-
 lib/SDL.zig  |  1 +
 src/main.zig | 50 +++++++++++++++++++++++++++++++++++++++++++++-----
 4 files changed, 57 insertions(+), 6 deletions(-)
 create mode 100644 .gitmodules
 create mode 160000 lib/SDL.zig

diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..4470c92
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "lib/SDL.zig"]
+	path = lib/SDL.zig
+	url = https://github.com/MasterQ32/SDL.zig
diff --git a/build.zig b/build.zig
index dc9af7d..cec93c3 100644
--- a/build.zig
+++ b/build.zig
@@ -1,4 +1,5 @@
 const std = @import("std");
+const Sdk = @import("lib/SDL.zig/Sdk.zig");
 
 pub fn build(b: *std.build.Builder) void {
     // Standard target options allows the person running `zig build` to choose
@@ -14,7 +15,13 @@ pub fn build(b: *std.build.Builder) void {
     const exe = b.addExecutable("zba", "src/main.zig");
 
     // Bitfield type from FlorenceOS: https://github.com/FlorenceOS/
-    exe.addPackage(.{ .name = "bitfield", .path = .{ .path = "./lib/util/bitfield.zig" } });
+    exe.addPackage(.{ .name = "bitfield", .path = .{ .path = "lib/util/bitfield.zig" } });
+
+    // Zig SDL Bindings: https://github.com/MasterQ32/SDL.zig
+    const sdk = Sdk.init(b);
+    sdk.link(exe, .dynamic);
+
+    exe.addPackage(sdk.getNativePackage("sdl2"));
 
     exe.setTarget(target);
     exe.setBuildMode(mode);
diff --git a/lib/SDL.zig b/lib/SDL.zig
new file mode 160000
index 0000000..d3a7648
--- /dev/null
+++ b/lib/SDL.zig
@@ -0,0 +1 @@
+Subproject commit d3a764869b31575d3d73cc874b1ff27879407b5a
diff --git a/src/main.zig b/src/main.zig
index f7b2b67..fd40574 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -1,15 +1,18 @@
 const std = @import("std");
-const emu = @import("emu.zig");
+const SDL = @import("sdl2");
 
+const emu = @import("emu.zig");
 const Bus = @import("Bus.zig");
 const Arm7tdmi = @import("cpu.zig").Arm7tdmi;
 const Scheduler = @import("scheduler.zig").Scheduler;
 
 pub fn main() anyerror!void {
+    // Allocator for Emulator + CLI Aruments
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
     const alloc = gpa.allocator();
     defer std.debug.assert(!gpa.deinit());
 
+    // Handle CLI Arguments
     const args = try std.process.argsAlloc(alloc);
     defer std.process.argsFree(alloc, args);
 
@@ -23,6 +26,7 @@ pub fn main() anyerror!void {
         return;
     }
 
+    // Initialize Emulator
     var scheduler = Scheduler.init(alloc);
     defer scheduler.deinit();
 
@@ -30,14 +34,50 @@ pub fn main() anyerror!void {
     defer bus.deinit();
 
     var cpu = Arm7tdmi.init(&scheduler, &bus);
-
     cpu.skipBios();
 
-    while (true) {
+    // Initialize SDL
+    const status = SDL.SDL_Init(SDL.SDL_INIT_VIDEO | SDL.SDL_INIT_EVENTS | SDL.SDL_INIT_AUDIO);
+    if (status < 0) sdlPanic();
+    defer SDL.SDL_Quit();
+
+    var window = SDL.SDL_CreateWindow(
+        "Gameboy Advance Emulator",
+        SDL.SDL_WINDOWPOS_CENTERED,
+        SDL.SDL_WINDOWPOS_CENTERED,
+        240 * 3,
+        160 * 3,
+        SDL.SDL_WINDOW_SHOWN,
+    ) orelse sdlPanic();
+    defer _ = SDL.SDL_DestroyWindow(window);
+
+    var renderer = SDL.SDL_CreateRenderer(window, -1, SDL.SDL_RENDERER_ACCELERATED) orelse sdlPanic();
+    defer _ = SDL.SDL_DestroyRenderer(renderer);
+
+    const texture = SDL.SDL_CreateTexture(renderer, SDL.SDL_PIXELFORMAT_RGBA8888, SDL.SDL_TEXTUREACCESS_STREAMING, 240, 160);
+    defer SDL.SDL_DestroyTexture(texture);
+
+    const buf_len = (240 * 4) * 160;
+    var white: [buf_len]u8 = [_]u8{0xFF} ** buf_len;
+
+    emu_loop: while (true) {
         emu.runFrame(&scheduler, &cpu, &bus);
+
+        var event: SDL.SDL_Event = undefined;
+        _ = SDL.SDL_PollEvent(&event);
+
+        switch (event.type) {
+            SDL.SDL_QUIT => break :emu_loop,
+            else => {},
+        }
+
+        _ = SDL.SDL_UpdateTexture(texture, null, &white, 240 * 4);
+        _ = SDL.SDL_RenderCopy(renderer, texture, null, null);
+        SDL.SDL_RenderPresent(renderer);
     }
 }
 
-test "basic test" {
-    try std.testing.expectEqual(10, 3 + 7);
+fn sdlPanic() noreturn {
+    const str = @as(?[*:0]const u8, SDL.SDL_GetError()) orelse "unknown error";
+    @panic(std.mem.sliceTo(str, 0));
 }