From 3e41ebdfe931d12c0a3aa7833b66820cf283a2bd Mon Sep 17 00:00:00 2001
From: Mirek Kratochvil <exa.exa@gmail.com>
Date: Thu, 8 Nov 2012 12:52:07 +0100
Subject: [PATCH] mod_to_fractor replaced by more general ext_euclid

---
 include/codecrypt.h |  1 -
 lib/decoding.cpp    |  2 +-
 lib/polynomial.cpp  | 29 -----------------------------
 3 files changed, 1 insertion(+), 31 deletions(-)

diff --git a/include/codecrypt.h b/include/codecrypt.h
index 1c58b39..ebb02b7 100644
--- a/include/codecrypt.h
+++ b/include/codecrypt.h
@@ -253,7 +253,6 @@ public:
 
 	void sqrt (vector<polynomial>&, gf2m&);
 	polynomial gcd (polynomial, gf2m&);
-	void mod_to_fracton (polynomial&, polynomial&, polynomial&, gf2m&);
 	void ext_euclid (polynomial&, polynomial&, polynomial&, gf2m&, int);
 
 	bool is_irreducible (gf2m&) const;
diff --git a/lib/decoding.cpp b/lib/decoding.cpp
index 3957332..cd04824 100644
--- a/lib/decoding.cpp
+++ b/lib/decoding.cpp
@@ -38,7 +38,7 @@ void compute_goppa_error_locator (polynomial&syndrome, gf2m&fld,
 	v.sqrt (sqInv, fld); //v = sqrt((1/s)+x) mod goppa
 
 	polynomial a, b;
-	v.mod_to_fracton (a, b, goppa, fld);
+	v.ext_euclid (a, b, goppa, fld, goppa.degree()/2);
 
 	a.square (fld);
 	b.square (fld);
diff --git a/lib/polynomial.cpp b/lib/polynomial.cpp
index f7a97c1..19070b0 100644
--- a/lib/polynomial.cpp
+++ b/lib/polynomial.cpp
@@ -391,32 +391,3 @@ void polynomial::ext_euclid (polynomial&a_out, polynomial&b_out,
 	b.swap (b_out);
 }
 
-void polynomial::mod_to_fracton (polynomial&a, polynomial&b,
-                                 polynomial&m, gf2m&fld)
-{
-	//TODO: replace with ext_euclid
-	int deg = m.degree() / 2;
-	polynomial a0, a1, b0, b1, q, r;
-	a0 = m;
-	a1 = *this;
-	a1.mod (m, fld);
-
-	b0.clear();
-	b1.clear();
-	b1.resize (1, 1);
-
-	while (a1.degree() > deg) {
-
-		a0.divmod (a1, q, r, fld);
-		a0.swap (a1);
-		a1.swap (r);
-
-		q.mult (b1, fld);
-		q.mod (m, fld);
-		q.add (b0, fld);
-		b0.swap (b1);
-		b1.swap (q);
-	}
-	a.swap (a1);
-	b.swap (b1);
-}