#![allow(unused_parens)]

use std::io::prelude::*;
use std::fs::File;
use std::env::args;

use std::f32::consts::PI;

fn main()
{
	let argv = args().collect::<Vec<String>>();
	if argv.len() != 6
	{
		eprintln!("no. <length> <start> <stop> <sin.dat> <cos.dat>");
		return;
	}
	let length = argv[1].parse::<usize>().unwrap();
	let start_freq = argv[2].parse::<f32>().unwrap();
	let stop_freq = argv[3].parse::<f32>().unwrap();
	let mut sin_file = File::create(&argv[4]).unwrap();
	let mut cos_file = File::create(&argv[5]).unwrap();

	let delta_freq = 
	(
		(stop_freq - start_freq) 
		/ 
		(
			2.0 
			* 
			(length as f32)
		)
	);
	let mut sin_buffer:Vec<u8> = Vec::with_capacity(length * 4);
	let mut cos_buffer:Vec<u8> = Vec::with_capacity(length * 4);
	for i in 0..length
	{
		sin_buffer.extend_from_slice(
			&(
				(i as f32) * PI
				*
				(start_freq + delta_freq * (i as f32))
				/
				(length as f32)
			)
			.sin()
			.to_be_bytes()
		);
		cos_buffer.extend_from_slice(
			&(
				(i as f32) * PI
				*
				(start_freq + delta_freq * (i as f32))
				/
				(length as f32)
			)
			.cos()
			.to_be_bytes()
		);
	}
	sin_file.write_all(&sin_buffer).unwrap();
	cos_file.write_all(&cos_buffer).unwrap();
}