static mp *fneg(field *ff, mp *d, mp *x)
{ fctx *f = (fctx *)ff; return (mp_sub(d, f->r.p, x)); }
static mp *fadd(field *ff, mp *d, mp *x, mp *y) {
fctx *f = (fctx *)ff; d = mp_add(d, x, y);
static mp *fneg(field *ff, mp *d, mp *x)
{ fctx *f = (fctx *)ff; return (mp_sub(d, f->r.p, x)); }
static mp *fadd(field *ff, mp *d, mp *x, mp *y) {
fctx *f = (fctx *)ff; d = mp_add(d, x, y);