Add initial nistec project files

extra_noasm.go

@@ -0,0 +1,35 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build purego || (!amd64 && !arm64 && !ppc64le && !s390x)
+
+package nistec
+
+import "sources.truenas.cloud/code/nistec/internal/fiat"
+
+// Negate sets p = -q and returns p.
+func (p *P256Point) Negate(q *P256Point) *P256Point {
+	p.x.Set(&q.x)
+	p.y.Sub(new(fiat.P256Element), &q.y)
+	p.z.Set(&q.z)
+	return p
+}
+
+// IsInfinity returns 1 if p is the point-at-infinity, 0 otherwise.
+func (p *P256Point) IsInfinity() int {
+	return p.z.IsZero()
+}
+
+// Equal returns 1 if p and q represent the same point, 0 otherwise.
+func (p *P256Point) Equal(q *P256Point) int {
+	pinf := p.z.IsZero()
+	qinf := q.z.IsZero()
+	bothinf := pinf & qinf
+	noneinf := (1 - pinf) & (1 - qinf)
+	px := new(fiat.P256Element).Mul(&p.x, &q.z)
+	qx := new(fiat.P256Element).Mul(&q.x, &p.z)
+	py := new(fiat.P256Element).Mul(&p.y, &q.z)
+	qy := new(fiat.P256Element).Mul(&q.y, &p.z)
+	return bothinf | (noneinf & px.Equal(qx) & py.Equal(qy))
+}