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/*
* Copyright (C) Simon Werner, 2019
*
* A Rust port of the original C++ code by Christian Briones, 2013.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
use std::f32;
use std::f32::consts::PI;
pub type WindowFn = fn(usize, usize) -> f32;
pub fn rectangular(_n: usize, _samples: usize) -> f32 {
1.0
}
pub fn hann_function(n: usize, samples: usize) -> f32 {
0.5 * (1.0 - f32::cos((2.0 * PI * n as f32) / (samples as f32 - 1.0)))
}
pub fn blackman_harris(n: usize, samples: usize) -> f32 {
const A0: f32 = 0.35875;
const A1: f32 = 0.48829;
const A2: f32 = 0.14128;
const A3: f32 = 0.01168;
let arg = 2.0 * PI * n as f32 / (samples as f32 - 1.0);
A0 - A1 * f32::cos(arg) + A2 * f32::cos(2.0 * arg) - A3 * f32::cos(3.0 * arg)
}