func (p *point) Neg(ca abstract.Point) abstract.Point {
if ca != p {
a := ca.(*point)
if C.EC_POINT_copy(p.p, a.p) == 0 {
panic("EC_POINT_copy: " + getErrString())
}
}
if C.EC_POINT_invert(p.c.g, p.p, p.c.ctx) == 0 {
panic("EC_POINT_invert: " + getErrString())
}
return p
}
func (p *point) Sub(ca, cb abstract.Point) abstract.Point {
a := ca.(*point)
b := cb.(*point)
// Add the point inverse. Must use temporary if p == a.
t := p
if p == a {
t = newPoint(p.c)
}
if C.EC_POINT_copy(t.p, b.p) == 0 {
panic("EC_POINT_copy: " + getErrString())
}
if C.EC_POINT_invert(p.c.g, t.p, p.c.ctx) == 0 {
panic("EC_POINT_invert: " + getErrString())
}
if C.EC_POINT_add(p.c.g, p.p, a.p, t.p, p.c.ctx) == 0 {
panic("EC_POINT_add: " + getErrString())
}
return p
}