Add example

Author: thomasarmel

examples/highly_nonlinear_balanced_finder/.cargo/config.toml

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+[build]
+rustflags = ["-C", "target-cpu=native"]

examples/highly_nonlinear_balanced_finder/.gitignore

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+Cargo.lock
+target

examples/highly_nonlinear_balanced_finder/Cargo.toml

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+[package]
+name = "highly_nonlinear_balanced_finder"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+rayon = "1.10.0"
+boolean_function = {path = "../..", features = ["unsafe_disable_safety_checks"]}
+num-bigint = "0.4.6"

examples/highly_nonlinear_balanced_finder/data/bent-1.zip

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+use std::fs::File;
+use std::io::Read;
+use num_bigint::BigUint;
+use rayon::iter::ParallelBridge;
+use rayon::iter::ParallelIterator;
+use boolean_function::{BigBooleanFunction, BooleanFunctionImpl};
+
+// Thanks https://langevin.univ-tln.fr/project/genbent/genbent.html
+const FILENAME: &'static str = "data/bent-1.zip";
+
+fn main() {
+    let mut bent_file = File::open(FILENAME).unwrap();
+    let mut bent_function_buffer = [0u8; 32];
+
+    loop {
+        if bent_file.read(&mut bent_function_buffer).unwrap() == 0 {
+            println!("EOF");
+            break;
+        }
+        let bent_function_tt = BigUint::from_bytes_le(&bent_function_buffer);
+        let bent_function = BigBooleanFunction::from_truth_table(bent_function_tt.clone(), 8);
+
+        let close_balanced_iterator = bent_function.close_balanced_functions_iterator().unwrap();
+        close_balanced_iterator.par_bridge()
+            .filter(|balanced_function| balanced_function.nonlinearity() > 116)
+            .for_each(|balanced_function| {
+                println!("{}: {}", balanced_function.printable_hex_truth_table(), balanced_function.nonlinearity());
+            });
+    }
+}