chore: reorganize select parts of codebase

src/emu.rs

@@ -0,0 +1,48 @@
+use crate::cpu::Cpu as SM83;
+use crate::instruction::Cycle;
+use crate::joypad;
+use crate::ppu::Ppu;
+use anyhow::Result;
+use gilrs::Gilrs;
+use std::time::Duration;
+
+pub const SM83_CYCLE_TIME: Duration = Duration::from_nanos(1_000_000_000 / SM83_CLOCK_SPEED);
+pub const CYCLES_IN_FRAME: Cycle = Cycle::new(456 * 154); // 456 Cycles times 154 scanlines
+const SM83_CLOCK_SPEED: u64 = 0x400_000; // Hz which is 4.194304Mhz
+const DEFAULT_TITLE: &'static str = "DMG-01 Emulator";
+
+pub fn init(boot_path: Option<&str>, rom_path: &str) -> Result<SM83> {
+    let mut cpu = match boot_path {
+        Some(path) => SM83::boot_new(path)?,
+        None => SM83::new(),
+    };
+
+    cpu.load_cartridge(rom_path)?;
+    Ok(cpu)
+}
+
+pub fn rom_title(game_boy: &SM83) -> &str {
+    game_boy.rom_title().unwrap_or(DEFAULT_TITLE)
+}
+
+pub fn run(game_boy: &mut SM83, gamepad: &mut Gilrs, pending: Cycle) -> Cycle {
+    let mut elapsed = Cycle::new(0);
+
+    while elapsed < pending {
+        elapsed += run_unsynced(game_boy, gamepad);
+    }
+
+    elapsed
+}
+
+pub fn run_unsynced(game_boy: &mut SM83, gamepad: &mut Gilrs) -> Cycle {
+    if let Some(event) = gamepad.next_event() {
+        joypad::handle_gamepad_input(&mut game_boy.joypad_mut(), event);
+    }
+
+    game_boy.step()
+}
+
+pub fn draw(ppu: &Ppu, frame: &mut [u8]) {
+    ppu.copy_to_gui(frame);
+}