update speed based on refresh rate

src/main.rs

@@ -20,6 +20,8 @@ const RNG_MEMORY_LOCATION: usize = 0xff;
 
 use clap::Parser;
 
+const DEFAULT_INSTRUCTIONS_PER_FRAME: u32 = 100;
+
 /// A simple 6502 emulator
 #[derive(Parser, Debug)]
 struct Args {
@@ -33,9 +35,8 @@ struct Args {
 	#[arg(short, long, default_value_t = false)]
 	start_debug: bool,
 	/// Number of CPU instructions to execute per frame
-	// TODO: Change default value depending on screen's refresh rate
-	#[arg(short, long, default_value_t = 100)]
-	instructions_per_framce: u32,
+	#[arg(short, long, default_value_t = DEFAULT_INSTRUCTIONS_PER_FRAME)]
+	instructions_per_frame: u32,
 	/// Debug symbols generated by the provided assembler
 	#[arg(short, long, default_value_t = String::from("symbols.dbg"))]
 	debug_symbols: String,
@@ -95,7 +96,12 @@ async fn main() {
 	let mut app = App::new(debug_symbols, source_file);
 
 	app.paused = args.start_debug;
-	app.instructions_per_frame = args.instructions_per_framce;
+	// TODO: Handle the case when the user explicity sets the value to be the default
+	app.instructions_per_frame = if args.instructions_per_frame != DEFAULT_INSTRUCTIONS_PER_FRAME {
+		args.instructions_per_frame
+	} else {
+		args.instructions_per_frame * 60 / macroquad::time::get_fps() as u32
+	};
 	loop {
 		if app.reset {
 			cpu = Cpu::new();