From cb0bc911a4cffdd6b4af35e64a6e6f6d93e53625 Mon Sep 17 00:00:00 2001
From: PlexSheep <PlexSheep@protonmail.com>
Date: Sun, 28 May 2023 00:09:46 +0200
Subject: [PATCH] gyllois python interface

---
 src/lib.rs          |  1 +
 src/math/gallois.rs |  5 +++++
 src/math/gcd.rs     | 26 ++++++++++++++++++++++++++
 3 files changed, 32 insertions(+)

diff --git a/src/lib.rs b/src/lib.rs
index 79112f5..0b2fc5b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -54,6 +54,7 @@ fn register_math_module(py: Python, parent_module: &PyModule) -> PyResult<()> {
     math_module.add_function(wrap_pyfunction!(math::pm1::py_p_minus_one, math_module)?)?;
     math_module.add_function(wrap_pyfunction!(math::gcd::gcd, math_module)?)?;
     math_module.add_function(wrap_pyfunction!(math::gcd::egcd, math_module)?)?;
+    math_module.add_function(wrap_pyfunction!(math::gcd::alt_egcd, math_module)?)?;
     math_module.add_function(wrap_pyfunction!(math::factorise::prime_factors , math_module)?)?;
     math_module.add_class::<math::gallois::GalloisFiled>()?;
     parent_module.add_submodule(math_module)?;
diff --git a/src/math/gallois.rs b/src/math/gallois.rs
index 374894d..4539866 100644
--- a/src/math/gallois.rs
+++ b/src/math/gallois.rs
@@ -375,5 +375,10 @@ fn test_gallois_inverse() {
     assert_eq!(field.inverse(54).unwrap(), 20);
     assert!(field.inverse(0).is_err());
 
+    let field = GalloisFiled::new(1151, true);
+    assert_eq!(field.inverse(6).unwrap(), 14);
+    assert_eq!(field.inverse(54).unwrap(), 20);
+    assert!(field.inverse(0).is_err());
+
     // TODO add a test for a field that has a non prime base
 }
diff --git a/src/math/gcd.rs b/src/math/gcd.rs
index 54d203c..ffc9f91 100644
--- a/src/math/gcd.rs
+++ b/src/math/gcd.rs
@@ -23,6 +23,32 @@ pub fn egcd(mut a: u128, mut b: u128) -> Vec<i128> {
         return vec![egcd.gcd, egcd.x, egcd.y]
 }
 
+#[pyfunction]
+/// own implementation of egcd
+pub fn alt_egcd(mut a: i128, mut b: i128, recursion: bool) -> Vec<i128> {
+    if recursion && a > b {
+        let tmp = a;
+        a = b;
+        b = tmp;
+    }
+    if a == 0 {
+        return vec![b, 0, 1]
+    }
+    let v = alt_egcd(b % a, a, true);
+    let mut result =  vec![
+        v[0], 
+        v[2] - (b.checked_div(a).unwrap()) * v[1], 
+        v[1],
+    ];
+    return result;
+}
+
+#[test]
+fn test_alt_gcd() {
+    assert_eq!(egcd(12193, 123213), alt_egcd(12193, 123213, false));
+    assert_eq!(egcd(52193, 123212), alt_egcd(52193, 123212, false));
+}
+
 #[pyfunction]
 /// euclidian algorithm
 pub fn gcd(a: u128, b: u128) -> u128 {