#include <iostream>
#include <alsa/asoundlib.h>
#include <cmath>
#include <random>

constexpr int rate = 44100;

int main()
{
    int err;
    snd_pcm_t *handle;
    snd_pcm_sframes_t frames;

     if ((err = snd_pcm_open(&handle, "default", SND_PCM_STREAM_PLAYBACK, SND_PCM_ASYNC)) < 0) {
        printf("Playback open error: %s\n", snd_strerror(err));
        exit(EXIT_FAILURE);
    }

     if ((err = snd_pcm_set_params(handle,
                      SND_PCM_FORMAT_FLOAT,
                      SND_PCM_ACCESS_RW_INTERLEAVED,
                      1,
                      rate,
                      0,
                      50000)) < 0) {
        printf("Playback open error: %s\n", snd_strerror(err));
        exit(EXIT_FAILURE);
    }

    std::random_device rd;
    std::mt19937 gen(rd());
    std::uniform_real_distribution<float> distrib(-1.0f, 1.0f);

    constexpr int buf_len = rate * 3;
    float* in = new float[buf_len];
    float* out = new float[buf_len]();

    constexpr int M = 200;
    float fc = 2100.0f / rate;
    double h[M + 1]{0.0f};

    for (int i = 0; i < buf_len; i++)
    {
        in[i] = distrib(gen);
    }

    for (int i = 0; i <= M; i++)
    {
        if ((i - M/2) == 0)
        {
            h[i] = 2*M_PI*fc;
        }
        else
        {
            h[i] = std::sin(2.0*M_PI*fc*(i - M/2)) / (i - M/2);
        }
        h[i] *= 0.42 - 0.5 * std::cos((2.0*M_PI*i)/M) + 0.08 * std::cos((4.0*M_PI*i)/M);
    }

    double sum = 0;
    for (int i = 0; i <= M; i++)
    {
        sum += h[i];
    }
    for (int i = 0; i <= M; i++)
    {
        h[i] /= sum;
    }

    //change to high pass
    for (int i = 0; i <= M; i++)
    {
        h[i] *= -1.0;
    }
    h[M/2] += 1.0f;

    // Convolve
    for (int i = M; i < buf_len; i++)
    {
        for (int j = 0; j <= M; j++)
        {
            out[i] += in[i - j] * h[j];
        }
    }

    frames = snd_pcm_writei(handle, out, buf_len);
    if (frames < 0)
    {
        frames = snd_pcm_recover(handle, frames, 0);
    }

    snd_pcm_drain(handle);
}