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#![feature(use_extern_macros)]

//! rust-rfcalcs Radio Frequency (RF) Calculations in Rustlang
//!
//! Copyright 2017 Ryan Kurte
//!

pub mod types;
pub mod consts;

pub mod fresnel;

use types::*;
use consts::*;

/// Calculates the Free Space Path Loss (FSPL) in Decibels for a given frequency and distance
/// https://en.wikipedia.org/wiki/Free-space_path_loss#Free-space_path_loss_formula
pub fn free_space_path_loss(freq: Frequency, dist: Distance) -> Attenuation {
    let fading = 20.0 * (4.0 * PI * dist.0 * freq.0 / C).log10();
    return Attenuation(fading);
}

#[cfg(test)]
mod tests {

    extern crate assert_approx_eq;
    use super::*;

    #[test]
    fn fspl() {
        let mut path_loss: Attenuation;

        /// Test against precalculated results
        path_loss = free_space_path_loss(ghz(2.4), m(1e0));
        assert_approx_eq::assert_approx_eq!(40.05, path_loss.0, 0.01);

        path_loss = free_space_path_loss(ghz(2.4), m(1e3));
        assert_approx_eq::assert_approx_eq!(100.05, path_loss.0, 0.01);

        path_loss = free_space_path_loss(ghz(2.4), m(1e6));
        assert_approx_eq::assert_approx_eq!(160.05, path_loss.0, 0.01);

        path_loss = free_space_path_loss(mhz(433.0), m(1e3));
        assert_approx_eq::assert_approx_eq!(85.178, path_loss.0, 0.01);

        path_loss = free_space_path_loss(mhz(433.0), m(1e6));
        assert_approx_eq::assert_approx_eq!(145.178, path_loss.0, 0.01);
    }


}