From 6ebd66eb3bb753f7d09c0e32e87ed4c03b0fd65e Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Thu, 23 Feb 2023 22:12:06 -0600
Subject: [PATCH] tmp: implement mechanisms for a emu reset fn (currently
 crashes)

---
 src/core/cpu.zig       |  8 ++++++++
 src/core/emu.zig       |  7 +++++++
 src/core/scheduler.zig | 15 +++++++++++++--
 src/imgui.zig          |  7 +++++--
 4 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/src/core/cpu.zig b/src/core/cpu.zig
index 669d195..e005c9e 100644
--- a/src/core/cpu.zig
+++ b/src/core/cpu.zig
@@ -314,6 +314,14 @@ pub const Arm7tdmi = struct {
         };
     }
 
+    // FIXME: Resetting disables logging (if enabled)
+    pub fn reset(self: *Self) void {
+        const bus_ptr = self.bus;
+        const scheduler_ptr = self.sched;
+
+        self.* = Self.init(scheduler_ptr, bus_ptr, null);
+    }
+
     pub inline fn hasSPSR(self: *const Self) bool {
         const mode = getModeChecked(self, self.cpsr.mode.read());
         return switch (mode) {
diff --git a/src/core/emu.zig b/src/core/emu.zig
index 11931d7..fe6dc9d 100644
--- a/src/core/emu.zig
+++ b/src/core/emu.zig
@@ -222,3 +222,10 @@ pub const EmuThing = struct {
         }
     }
 };
+
+pub fn reset(cpu: *Arm7tdmi) void {
+    @breakpoint();
+    cpu.sched.reset(); // Yes this is order sensitive, see the PPU reset for why
+    // cpu.bus.reset();
+    cpu.reset();
+}
diff --git a/src/core/scheduler.zig b/src/core/scheduler.zig
index 8a57183..86ebab1 100644
--- a/src/core/scheduler.zig
+++ b/src/core/scheduler.zig
@@ -11,11 +11,11 @@ const log = std.log.scoped(.Scheduler);
 pub const Scheduler = struct {
     const Self = @This();
 
-    tick: u64,
+    tick: u64 = 0,
     queue: PriorityQueue(Event, void, lessThan),
 
     pub fn init(allocator: Allocator) Self {
-        var sched = Self{ .tick = 0, .queue = PriorityQueue(Event, void, lessThan).init(allocator, {}) };
+        var sched = Self{ .queue = PriorityQueue(Event, void, lessThan).init(allocator, {}) };
         sched.queue.add(.{ .kind = .HeatDeath, .tick = std.math.maxInt(u64) }) catch unreachable;
 
         return sched;
@@ -26,6 +26,17 @@ pub const Scheduler = struct {
         self.* = undefined;
     }
 
+    pub fn reset(self: *Self) void {
+        // `std.PriorityQueue` provides no reset function, so we will just create a new one
+        const allocator = self.queue.allocator;
+        self.queue.deinit();
+
+        var new_queue = PriorityQueue(Event, void, lessThan).init(allocator, {});
+        new_queue.add(.{ .kind = .HeatDeath, .tick = std.math.maxInt(u64) }) catch unreachable;
+
+        self.* = .{ .queue = new_queue };
+    }
+
     pub inline fn now(self: *const Self) u64 {
         return self.tick;
     }
diff --git a/src/imgui.zig b/src/imgui.zig
index 2dcf60f..5651d5d 100644
--- a/src/imgui.zig
+++ b/src/imgui.zig
@@ -48,7 +48,7 @@ pub const State = struct {
     }
 };
 
-pub fn draw(state: *State, tex_id: GLuint, cpu: *const Arm7tdmi) void {
+pub fn draw(state: *State, tex_id: GLuint, cpu: *Arm7tdmi) void {
     const win_scale = config.config().host.win_scale;
 
     {
@@ -77,7 +77,10 @@ pub fn draw(state: *State, tex_id: GLuint, cpu: *const Arm7tdmi) void {
         if (zgui.beginMenu("Emulation", true)) {
             defer zgui.endMenu();
 
-            if (zgui.menuItem("Restart", .{})) log.warn("TODO: Restart Emulator", .{});
+            if (zgui.menuItem("Restart", .{})) {
+                @breakpoint();
+                emu.reset(cpu);
+            }
         }
     }