From f474245e874f386b279899afbee762290f91b49b Mon Sep 17 00:00:00 2001
From: MITSUNARI Shigeo <herumi@nifty.com>
Date: Mon, 10 May 2021 12:24:45 +0900
Subject: [PATCH] avoid cast in Fp2::inv

---
 include/mcl/fp_tower.hpp | 39 ++++++++++++++++++---------------------
 include/mcl/op.hpp       |  2 --
 2 files changed, 18 insertions(+), 23 deletions(-)

diff --git a/include/mcl/fp_tower.hpp b/include/mcl/fp_tower.hpp
index f75b4c2..247f7e9 100644
--- a/include/mcl/fp_tower.hpp
+++ b/include/mcl/fp_tower.hpp
@@ -275,8 +275,25 @@ public:
 	{
 		Fp::op_.fp2_mul_xiA_(y.a.v_, x.a.v_);
 	}
+	/*
+		x = a + bi
+		1 / x = (a - bi) / (a^2 + b^2)
+	*/
+	static void inv(Fp2T& y, const Fp2T& x)
+	{
+		assert(!x.isZero());
+		const Fp& a = x.a;
+		const Fp& b = x.b;
+		Fp aa, bb;
+		Fp::sqr(aa, a);
+		Fp::sqr(bb, b);
+		aa += bb;
+		Fp::inv(aa, aa); // aa = 1 / (a^2 + b^2)
+		Fp::mul(y.a, a, aa);
+		Fp::mul(y.b, b, aa);
+		Fp::neg(y.b, y.b);
+	}
 	static void addPre(Fp2T& z, const Fp2T& x, const Fp2T& y) { Fp::addPre(z.a, x.a, y.a); Fp::addPre(z.b, x.b, y.b); }
-	static void inv(Fp2T& y, const Fp2T& x) { Fp::op_.fp2_inv(y.a.v_, x.a.v_); }
 	static void divBy2(Fp2T& y, const Fp2T& x)
 	{
 		Fp::divBy2(y.a, x.a);
@@ -446,7 +463,6 @@ public:
 				op.fp2_mul_xiA_ = fp2_mul_xiA;
 			}
 		}
-		op.fp2_inv = fp2_invW;
 		FpDblT<Fp>::init();
 		Fp2DblT<Fp>::init();
 		// call init before Fp2::pow because FpDbl is used in Fp2T
@@ -630,25 +646,6 @@ private:
 		Fp::sub(y.a, a, b);
 		y.b = t;
 	}
-	/*
-		x = a + bi
-		1 / x = (a - bi) / (a^2 + b^2)
-	*/
-	static void fp2_invW(Unit *y, const Unit *x)
-	{
-		const Fp *px = reinterpret_cast<const Fp*>(x);
-		Fp *py = reinterpret_cast<Fp*>(y);
-		const Fp& a = px[0];
-		const Fp& b = px[1];
-		Fp aa, bb;
-		Fp::sqr(aa, a);
-		Fp::sqr(bb, b);
-		aa += bb;
-		Fp::inv(aa, aa); // aa = 1 / (a^2 + b^2)
-		Fp::mul(py[0], a, aa);
-		Fp::mul(py[1], b, aa);
-		Fp::neg(py[1], py[1]);
-	}
 };
 
 template<class Fp>
diff --git a/include/mcl/op.hpp b/include/mcl/op.hpp
index b1085da..25d6bce 100644
--- a/include/mcl/op.hpp
+++ b/include/mcl/op.hpp
@@ -258,7 +258,6 @@ struct Op {
 	*/
 	int xi_a; // xi = xi_a + u
 	void4u fp2_mulNF;
-	void2u fp2_inv;
 	void2u fp2_mul_xiA_;
 	uint32_t (*hash)(void *out, uint32_t maxOutSize, const void *msg, uint32_t msgSize);
 
@@ -345,7 +344,6 @@ struct Op {
 
 		xi_a = 0;
 		fp2_mulNF = 0;
-		fp2_inv = 0;
 		fp2_mul_xiA_ = 0;
 		hash = 0;