rdsp-experiments/src/main.rs

use std::{
    f32::consts::PI,
    fs::File,
    io::{Read, Write},
    ops::{Add, Div, Mul, Sub},
};

mod bfsk;
mod complex;
pub mod fft;
mod nco;

use bfsk::BFSKMod;
use complex::Complex;
use complex::Complex32;
use fft::rader;
use nco::Nco;
use plotters::prelude::*;

use crate::fft::{
    DFT, create_fft,
    dft::NaiveDFT,
    mixed_radix::MixedRadixFFT,
    prime_factors,
    rader::{RaderFFT, compute_prime_primitive_root, exp_mod},
    rader2::{Rader2FFT, next_pow2},
    radix2::Radix2FFT,
    windows,
};

// Utilities
fn map<T>(input: T, in_min: T, in_max: T, out_min: T, out_max: T) -> T
where
    T: Clone + Add<Output = T> + Mul<Output = T> + Sub<Output = T> + Div<Output = T>,
{
    ((input - in_min.clone()) / (in_max - in_min)) * (out_max - out_min.clone()) + out_min
}

fn euclid_mod(a: f32, m: f32) -> f32 {
    let r = a % m;
    if r < 0.0 { r + m } else { r }
}
fn main() {
    test();
}

fn test() {
    let freq1 = 2. * PI / 4.0;
    let freq2 = 2. * PI / 8.0;

    //let sample_count = 71*71;
    //let sample_count = 71 * 71;
    //let sample_count = 4804;
    let sample_count = 4799;

    let mut o1 = Nco::new(freq1);
    let mut o2 = Nco::new(freq2);

    let mut fft = RaderFFT::create(sample_count);
    let mut dft = RaderFFT::create(sample_count);
    for (x, y) in fft.get_input().iter_mut().zip(dft.get_input().iter_mut()) {
        *y = o1.cexp();// + o2.cexp();
        //*y = *x;

        o1.step();
        o2.step();
    }

    //fft.execute(windows::rectanguar);
    dft.execute(windows::rectanguar);

    let root = BitMapBackend::new("out.png", (640, 480)).into_drawing_area();
    root.fill(&WHITE).unwrap();
    let mut chart = ChartBuilder::on(&root)
        .caption("fft", ("sans-serif", 50).into_font())
        .margin(5)
        .x_label_area_size(30)
        .y_label_area_size(30)
        .build_cartesian_2d(0f32..(sample_count as f32), -PI..PI)
        .unwrap();

    //chart.configure_mesh().draw()?;

    chart
        .draw_series(LineSeries::new(
            (0..sample_count)
                .zip(dft.get_output().iter())
                .map(|(x, y)| (x as f32, (*y).arg() * (*y).mag())),
            &RED,
        ))
        .unwrap()
        .legend(|(x, y)| PathElement::new(vec![(x, y), (x + 20, y)], RED));

    chart
        .draw_series(LineSeries::new(
            (0..sample_count)
                .zip(dft.get_output().iter())
                .map(|(x, y)| (x as f32, (*y).mag() / sample_count as f32)),
            &BLUE,
        ))
        .unwrap()
        .legend(|(x, y)| PathElement::new(vec![(x, y), (x + 20, y)], BLUE));

    chart
        .configure_series_labels()
        .background_style(&WHITE.mix(0.8))
        .border_style(&BLACK)
        .draw()
        .unwrap();

    root.present().unwrap();
}

fn modulate() {
    let sample_rate = 44100;
    let mut frequency = 2000.0; //HZ
    let mut bandwidth = 500.0; //HZ

    let path = "a.jpg";
    let file = File::open(path).unwrap();
    let mut bit_stream = file.bytes().flat_map(|byte| {
        let byte = byte.unwrap();
        [
            byte & 1 == 1,
            (byte >> 1) & 1 == 1,
            (byte >> 2) & 1 == 1,
            (byte >> 3) & 1 == 1,
            (byte >> 4) & 1 == 1,
            (byte >> 5) & 1 == 1,
            (byte >> 6) & 1 == 1,
            (byte >> 7) & 1 == 1,
        ]
    });
    //let mut bit_stream = (0..22000).map(|_| false).chain((0..22000).map(|_| true));
    //let mut bit_stream = (0..22000).flat_map(|_| [true, false]);

    let baud_rate = 400;
    println!("{} samples/bit", sample_rate / baud_rate);
    let mut bfsk = BFSKMod::new(
        sample_rate / baud_rate,
        2. * PI * (bandwidth / sample_rate as f32),
        &mut bit_stream,
    );

    let spec = hound::WavSpec {
        channels: 1,
        sample_rate,
        bits_per_sample: 16,
        sample_format: hound::SampleFormat::Int,
    };
    let mut writer = hound::WavWriter::create("sine.wav", spec).unwrap();

    let mut lo = Nco::new(2. * PI * (frequency / sample_rate as f32));

    let prev = Complex::new(0., 0.);
    let alpha = 1.0 - (-2.0 * PI * ((1.5 * 0.5 * bandwidth) / sample_rate as f32));
    while let Some(sample) = bfsk.step_modulate() {
        let amplitude = i16::MAX as f32;
        let c_sample = lo.cexp() * sample;

        let filtered = prev + (c_sample - prev) * alpha;
        writer
            .write_sample((amplitude * c_sample.re) as i16)
            .unwrap();
        lo.step();
    }
    writer.finalize().unwrap();
}