gistfile1.txt

extern crate threadpool;
struct Rng {
    state: (u32, u32)
}
impl Rng {
    fn random(&mut self) -> f64 {
        let r0 = (18273 * (self.state.0 & 0xFFFF)) + (self.state.0 >> 16);
        self.state.0 = r0;
        let r1 = (36969 * (self.state.1 & 0xFFFF)) + (self.state.1 >> 16);
        self.state.1 = r1;
        let x = (r0 << 16) + (r1 & 0xFFFF); 
        let x = x as f64;
        let imm = if x < 0.0 {
            x + 4294967296.0f64 
        } else {
            x
        };

        imm * 2.3283064365386962890625e-10
    }
}

fn main() {
    let count = 4u32;
    let tp = threadpool::ThreadPool::new(count as usize);
    let (tx, rx) = std::sync::mpsc::channel();
    let outputs = vec![0.23127878946252167, 0.3485930557362735];
    for i in 0..count {
        let tx = tx.clone();
        let outputs = outputs.clone();
        tp.execute(move || {
            bf_range(std::u32::MAX/count*i, std::u32::MAX/count*(i+1), outputs);
            tx.send(()).unwrap();
        });
    }
    rx.iter().take(count as usize).collect::<Vec<_>>();
}

fn bf_range(start: u32, end: u32, outputs: Vec<f64>) {
    println!("Bruteforcing from {} to {}...", start, end);
    let mut rng = Rng { state: (0, 0) }; 
    // need inclusive range syntax :|
    let statesample = (outputs[0] / 2.3283064365386962890625e-10) as u32;
    let first_lower = statesample >> 16;
    let last_lower = statesample & 0xFFFF;
    'o: for guess in start..end {
        let first = first_lower + ((guess & 0xFFFF) << 16);
        let last = last_lower + (guess & 0xFFFF0000);
        // spread it out among the two parts
                rng.state = (first, last);
                for &output in &outputs[1..] {
                    let r = rng.random();
                    if r != output {
                        continue 'o;
                    }
                }
                println!("Got it! {:?}", rng.state);
                for _ in 0..20 {
                    println!("Predicted output: {}", rng.random());
                }
    }
    println!("Done.")
}