===================================================================
RCS file: /home/cvs/OpenXM_contrib2/asir2000/engine/Hgfs.c,v
retrieving revision 1.1
retrieving revision 1.29
diff -u -p -r1.1 -r1.29
--- OpenXM_contrib2/asir2000/engine/Hgfs.c	2001/06/20 09:32:13	1.1
+++ OpenXM_contrib2/asir2000/engine/Hgfs.c	2002/11/22 08:44:57	1.29
@@ -1,34 +1,36 @@
-/* $OpenXM$ */
+/* $OpenXM: OpenXM_contrib2/asir2000/engine/Hgfs.c,v 1.28 2002/11/22 07:32:10 noro Exp $ */
 
 #include "ca.h"
+#include "inline.h"
 
-struct p_pair {
-	UM p0;
-	UM p1;
-	struct p_pair *next;
-};
+void lnfsf(int n,UM p0,UM p1,struct p_pair *list,UM np0,UM np1);
+void extractcoefbm(BM f,int dx,UM r);
 
-void canzassf(UM,int,UM *);
-void lnfsf(int,UM,UM,struct p_pair *,UM,UM);
-void minipolysf(UM,UM,UM);
-void czsfum(UM,UM *);
-void gensqfrsfum(UM,DUM);
+int comp_dum(DUM a,DUM b)
+{
+	if ( DEG(a->f) > DEG(b->f) )
+		return -1;
+	else if ( DEG(a->f) < DEG(b->f) )
+		return 1;
+	else
+		return 0;
+}
 
-void fctrsf(p,dcp)
-P p;
-DCP *dcp;
+void ufctrsf(P p,DCP *dcp)
 {
 	int n,i,j,k;
 	DCP dc,dc0;
 	P lc;
-	P zp;
 	UM mp;
 	UM *tl;
+	Obj obj;
 	struct oDUM *udc,*udc1;
 
-	simp_ff(p,&zp); p = zp;
+	simp_ff((Obj)p,&obj); p = (P)obj;
 	if ( !p ) {
-		*dcp = 0; return;
+		NEWDC(dc); COEF(dc) = 0; DEG(dc) = ONE; 
+		NEXT(dc) = 0; *dcp = dc;
+		return;
 	}
 	mp = W_UMALLOC(UDEG(p));
 	ptosfum(p,mp);
@@ -61,6 +63,10 @@ DCP *dcp;
 			}
 		}
 	udc = udc1;
+	for ( i = 0; udc[i].f; i++ );
+	qsort(udc,i,sizeof(struct oDUM),
+		(int (*)(const void *,const void *))comp_dum);
+
 	NEWDC(dc0); COEF(dc0) = lc; DEG(dc0) = ONE; dc = dc0;
 	for ( n = 0; udc[n].f; n++ ) {
 		NEWDC(NEXT(dc)); dc = NEXT(dc);
@@ -69,12 +75,11 @@ DCP *dcp;
 	NEXT(dc) = 0; *dcp = dc0;
 }
 
-void gensqfrsfum(p,dc)
-UM p;
-struct oDUM *dc;
+void gensqfrsfum(UM p,struct oDUM *dc)
 {
 	int n,i,j,d,mod;
 	UM t,s,g,f,f1,b;
+	GFS u,v;
 
 	if ( (n = DEG(p)) == 1 ) {
 		dc[0].f = UMALLOC(DEG(p)); cpyum(p,dc[0].f); dc[0].n = 1;
@@ -113,8 +118,11 @@ struct oDUM *dc;
 				break;
 			else {
 				DEG(s) = DEG(t)/mod;
-				for ( j = 0; j <= DEG(t); j++ )
-					COEF(s)[j] = COEF(t)[j*mod];	
+				for ( j = 0; j <= DEG(t); j++ ) {
+					iftogfs(COEF(t)[j*mod],&u);
+					pthrootgfs(u,&v);
+					COEF(s)[j] = v?FTOIF(CONT(v)):0;
+				}
 				cpyum(s,b); d *= mod;
 			}
 		}
@@ -124,21 +132,17 @@ struct oDUM *dc;
 	}
 }
 
-void randsfum(d,p)
-int d;
-UM p;
+void randsfum(int d,UM p)
 {
-	unsigned int n;
 	int i;
 
-	n = ((unsigned int)random()) % d; DEG(p) = n; COEF(p)[n] = _onesf();
-	for ( i = 0; i < (int)n; i++ )
+	for ( i = 0; i < d; i++ )
 		COEF(p)[i] = _randomsf();
+	for ( i = d-1; i >= 0 && !COEF(p)[i]; i-- );
+	p->d = i;
 }
 
-void pwrmodsfum(p,e,f,pr)
-int e;
-UM p,f,pr;
+void pwrmodsfum(UM p,int e,UM f,UM pr)
 {
 	UM wt,ws,q;
 
@@ -166,9 +170,7 @@ UM p,f,pr;
 	}
 }
 
-void spwrum0sf(m,f,e,r)
-UM f,m,r;
-N e;
+void spwrsfum(UM m,UM f,N e,UM r)
 {
 	UM t,s,q;
 	N e1;
@@ -180,7 +182,7 @@ N e;
 		cpyum(f,r);
 	else {
 		a = divin(e,2,&e1);
-		t = W_UMALLOC(2*DEG(m)); spwrum0sf(m,f,e1,t);
+		t = W_UMALLOC(2*DEG(m)); spwrsfum(m,f,e1,t);
 		s = W_UMALLOC(2*DEG(m)); q = W_UMALLOC(2*DEG(m));
 		mulsfum(t,t,s); DEG(s) = divsfum(s,m,q);
 		if ( a ) {
@@ -190,11 +192,28 @@ N e;
 	}
 }
 
-void make_qmatsf(p,tab,mp)
-UM p;
-UM *tab;
-int ***mp;
+void tracemodsfum(UM m,UM f,int e,UM r)
 {
+	UM t,s,q,u;
+	int i;
+
+	q = W_UMALLOC(2*DEG(m)+DEG(f)); /* XXX */
+	t = W_UMALLOC(2*DEG(m));
+	s = W_UMALLOC(2*DEG(m));
+	u = W_UMALLOC(2*DEG(m));
+	DEG(f) = divsfum(f,m,q);
+	cpyum(f,s);
+	cpyum(f,t);
+	for ( i = 1; i < e; i++ ) {
+		mulsfum(t,t,u);
+		DEG(u) = divsfum(u,m,q); cpyum(u,t);
+		addsfum(t,s,u); cpyum(u,s);
+	}
+	cpyum(s,r);
+}
+
+void make_qmatsf(UM p,UM *tab,int ***mp)
+{
 	int n,i,j;
 	int *c;
 	UM q,r;
@@ -214,10 +233,7 @@ int ***mp;
 		mat[i][i] = _subsf(mat[i][i],one);
 }
 
-void nullsf(mat,n,ind)
-int **mat;
-int *ind;
-int n;
+void nullsf(int **mat,int n,int *ind)
 {
 	int i,j,l,s,h,inv;
 	int *t,*u;
@@ -249,11 +265,7 @@ int n;
 	}
 }
 
-void null_to_solsf(mat,ind,n,r)
-int **mat;
-int *ind;
-int n;
-UM *r;
+void null_to_solsf(int **mat,int *ind,int n,UM *r)
 {
 	int i,j,k,l;
 	int *c;
@@ -282,8 +294,7 @@ nullsf(mat,n,ind)
 null_to_solsf(ind,n,r)
 */
 
-void czsfum(f,r)
-UM f,*r;
+void czsfum(UM f,UM *r)
 {
 	int i,j;
 	int d,n,ord;
@@ -337,10 +348,7 @@ UM f,*r;
 	r[j] = 0;
 }
 
-int berlekampsf(p,df,tab,r)
-UM p;
-int df;
-UM *tab,*r;
+int berlekampsf(UM p,int df,UM *tab,UM *r)
 {
 	int n,i,j,k,nf,d,nr;
 	int **mat;
@@ -386,10 +394,12 @@ UM *tab,*r;
 			}
 		}
 	}
+	/* NOT REACHED */
+	error("berlekampsf : cannot happen");
+	return 0;
 }
 
-void minipolysf(f,p,mp)
-UM f,p,mp;
+void minipolysf(UM f,UM p,UM mp)
 {
 	struct p_pair *list,*l,*l1,*lprev;	
 	int n,d;
@@ -424,13 +434,9 @@ UM f,p,mp;
 	}
 }
 
-void lnfsf(n,p0,p1,list,np0,np1)
-int n;
-UM p0,p1;
-struct p_pair *list;
-UM np0,np1;
+void lnfsf(int n,UM p0,UM p1,struct p_pair *list,UM np0,UM np1)
 {
-	int inv,h,d1;
+	int h,d1;
 	UM t0,t1,s0,s1;
 	struct p_pair *l;
 
@@ -447,12 +453,10 @@ UM np0,np1;
 	}
 }
 
-int find_rootsf(p,root)
-UM p;
-int *root;
+int find_rootsf(UM p,int *root)
 {
 	UM *r;
-	int i,j,n;
+	int i,n;
 
 	n = DEG(p);
 	r = ALLOCA((DEG(p))*sizeof(UM));
@@ -462,14 +466,12 @@ int *root;
 	return n;
 }
 
-void canzassf(f,d,r)
-UM f,*r;
-int d;
+void canzassf(UM f,int d,UM *r)
 {
 	UM t,s,u,w,g,o;
 	N n1,n2,n3,n4,n5;
 	UM *b;
-	int n,m,i,q;
+	int n,q,ed;
 
 	if ( DEG(f) == d ) {
 		r[0] = UMALLOC(d); cpyum(f,r[0]);
@@ -483,11 +485,19 @@ int d;
 		w = W_UMALLOC(DEG(f)); g = W_UMALLOC(DEG(f));
 		o = W_UMALLOC(0); DEG(o) = 0; COEF(o)[0] = _onesf();
 		q = field_order_sf();
-		STON(q,n1); pwrn(n1,d,&n2); subn(n2,ONEN,&n3);
-		STON(2,n4); divsn(n3,n4,&n5);
+		if ( q % 2 ) {
+			STON(q,n1); pwrn(n1,d,&n2); subn(n2,ONEN,&n3);
+			STON(2,n4); divsn(n3,n4,&n5);
+		} else
+			ed = d*extdeg_sf();
 		while ( 1 ) {
-			randsfum(2*d,t); spwrum0sf(f,t,n5,s);
-			subsfum(s,o,u); cpyum(f,w); gcdsfum(w,u,g);
+			randsfum(2*d,t);
+			if ( q % 2 ) {
+				spwrsfum(f,t,n5,s); subsfum(s,o,u);
+			} else
+				tracemodsfum(f,t,ed,u);
+			cpyum(f,w);
+			gcdsfum(w,u,g);
 			if ( (DEG(g) >= 1) && (DEG(g) < DEG(f)) ) {
 				canzassf(g,d,r); 
 				cpyum(f,w); divsfum(w,g,s);
@@ -498,3 +508,1046 @@ int d;
 	}
 }
 
+/* Hensel related functions */
+
+int sfberle(V,V,P,int,GFS *,DCP *);
+void sfgcdgen(P,ML,ML *);
+void sfhenmain2(BM,UM,UM,int,BM *);
+void ptosfbm(int,P,BM);
+void sfhensel(int count,P f,V x,V y,int degbound,GFS *evp,P *sfp,ML *listp);
+
+/* f = f(x,y) */
+
+void sfhensel(int count,P f,V x,V y,int degbound,GFS *evp,P *sfp,ML *listp)
+{
+	int i;
+	int fn;
+	ML rlist;
+	BM fl;
+	VL vl,nvl;
+	int dx,dy,bound;
+	GFS ev;
+	P f1,t,c,sf;
+	DCP dc,dct,dc0;
+	UM q,fm,hm;
+	UM *gm;
+	struct oEGT tmp0,tmp1,eg_hensel,eg_hensel_t;
+
+	clctv(CO,f,&vl);
+	if ( vl->v != x ) {
+		reordvar(vl,x,&nvl); reorderp(nvl,vl,f,&f1);
+		vl = nvl; f = f1;
+	}
+	if ( vl->next )
+		y = vl->next->v;
+	dx = getdeg(x,f);
+	dy = getdeg(y,f);
+	if ( dx == 1 ) {
+		*listp = rlist = MLALLOC(1); rlist->n = 1; rlist->c[0] = 0;
+		return;
+	}
+	fn = sfberle(x,y,f,count,&ev,&dc);
+	if ( fn <= 1 ) {
+		/* fn == 0 => short of evaluation points */
+		*listp = rlist = MLALLOC(1); rlist->n = fn; rlist->c[0] = 0;
+		return;
+	}
+	if ( degbound >= 0 ) {
+		/*
+		 * reconstruct dc so that
+		 * dc[1],... : factors satisfy degree bound
+		 * dc[0]     : product of others
+		 */
+		c = dc->c; dc = NEXT(dc);
+		dc0 = 0;
+		fn = 0;
+		while ( dc ) {
+			if ( getdeg(x,COEF(dc)) <= degbound ) {
+				dct = NEXT(dc); NEXT(dc) = dc0; dc0 = dc; dc = dct;
+				fn++;
+			} else {
+				mulp(vl,COEF(dc),c,&t); c = t;
+				dc = NEXT(dc);
+			}
+		}
+		if ( OID(c) == O_P ) {
+			NEWDC(dc); COEF(dc) = c; DEG(dc) = ONE; NEXT(dc) = dc0;
+			fn++;
+		} else {
+			mulp(vl,dc0->c,c,&t); dc0->c = t; dc = dc0;
+		}
+	} else {
+		/* pass the the leading coeff. to the first element */
+		c = dc->c; dc = NEXT(dc);
+		mulp(vl,dc->c,c,&t); dc->c = t;
+	}
+
+	/* convert mod y-a factors into UM */
+	gm = (UM *)ALLOCA(fn*sizeof(UM));
+	for ( i = 0; i < fn; i++, dc = NEXT(dc) ) {
+		gm[i] = W_UMALLOC(UDEG(dc->c));
+		ptosfum(dc->c,gm[i]);
+	}
+
+	/* set bound */
+	/* g | f, lc_y(g) = lc_y(f) => deg_y(g) <= deg_y(f) */
+	/* so, bound = dy is sufficient, but we use slightly large value */
+	bound = dy+2;
+
+	/* f(x,y) -> f(x,y+ev) */
+	fl = BMALLOC(dx,bound);
+	ptosfbm(bound,f,fl);
+	if ( ev ) shiftsfbm(fl,FTOIF(CONT(ev)));
+
+	/* sf = f(x+ev) */
+	sfbmtop(fl,x,y,&sf);
+
+	/* fm = fl mod y */
+	fm = W_UMALLOC(dx);
+	cpyum(COEF(fl)[0],fm);
+	hm = W_UMALLOC(dx);
+
+	q = W_UMALLOC(dx);
+	rlist = MLALLOC(fn); rlist->n = fn; rlist->bound = bound;
+	fprintf(asir_out,"%d candidates\n",fn);
+	init_eg(&eg_hensel);
+	for ( i = 0; i < fn-1; i++ ) {
+		fprintf(asir_out,"deg(fm) = %d, deg(gm[%d]) = %d\n",
+			DEG(fm),i,DEG(gm[i]));
+		init_eg(&eg_hensel_t);
+		get_eg(&tmp0);
+		/* fl = gm[i]*hm mod y */
+		divsfum(fm,gm[i],hm);
+		/* fl is replaced by the cofactor of gk mod y^bound */
+		/* rlist->c[i] = gk */
+		sfhenmain2(fl,gm[i],hm,bound,(BM *)&rlist->c[i]);
+		cpyum(hm,fm);
+		get_eg(&tmp1); add_eg(&eg_hensel_t,&tmp0,&tmp1);
+		add_eg(&eg_hensel,&tmp0,&tmp1);
+		print_eg("Hensel",&eg_hensel_t);
+		fprintf(asir_out,"\n");
+	}
+	print_eg("Hensel total",&eg_hensel);
+	fprintf(asir_out,"\n");
+	/* finally, fl must be the lift of gm[fn-1] */
+	rlist->c[i] = fl;
+
+#if 0
+	/* y -> y-a */
+	mev = _chsgnsf(FTOIF(CONT(ev)));
+	for ( i = 0; i < fn; i++ )
+		shiftsfbm((BM)(rlist->c[i]),mev);
+#endif
+	*evp = ev;
+	*sfp = sf;
+	*listp = rlist;
+}
+
+/* main variable of f = x */
+
+int sfberle(V x,V y,P f,int count,GFS *ev,DCP *dcp)
+{
+	UM wf,wf1,wf2,wfs,gcd;
+	int fn,n;
+	GFS m,fm;
+	DCP dc,dct,dc0;
+	VL vl;
+	P lc,lc0,f0;
+	Obj obj;
+	int j,q,index,i;
+
+	NEWVL(vl); vl->v = x;
+	NEWVL(NEXT(vl)); NEXT(vl)->v = y;
+	NEXT(NEXT(vl)) =0;
+	simp_ff((Obj)f,&obj); f = (P)obj;
+	n = QTOS(DEG(DC(f)));
+	wf = W_UMALLOC(n); wf1 = W_UMALLOC(n); wf2 = W_UMALLOC(n);
+	wfs = W_UMALLOC(n); gcd = W_UMALLOC(n);
+	q = field_order_sf();
+	lc = DC(f)->c;
+	for ( j = 0, fn = n + 1, index = 0; 
+		index < q && j < count && fn > 1; index++ ) {
+		indextogfs(index,&m);
+		substp(vl,lc,y,(P)m,&lc0);
+		if ( lc0 ) {
+			substp(vl,f,y,(P)m,&f0);
+			ptosfum(f0,wf); cpyum(wf,wf1); 
+			diffsfum(wf1,wf2); gcdsfum(wf1,wf2,gcd);
+			if ( DEG(gcd) == 0 ) {
+				ufctrsf(f0,&dc);
+				for ( dct = NEXT(dc), i = 0; dct; dct = NEXT(dct), i++ );
+				if ( i < fn ) {
+					dc0 = dc; fn = i; fm = m;
+				}
+				j++;
+			}
+		}
+	}
+	if ( index == q )
+		return 0;
+	else if ( fn == 1 )
+		return 1;
+	else {
+		*dcp = dc0;
+		*ev = fm;
+		return fn;
+	}
+}
+
+void sfgcdgen(P f,ML blist,ML *clistp)
+{
+	int i;
+	int n,d,np;
+	UM wf,wm,wx,wy,wu,wv,wa,wb,wg,q,tum;
+	UM *in,*out;
+	ML clist;
+
+	n = UDEG(f); np = blist->n;
+	d = 2*n;
+	q = W_UMALLOC(d); wf = W_UMALLOC(d);
+	wm = W_UMALLOC(d); wx = W_UMALLOC(d);
+	wy = W_UMALLOC(d); wu = W_UMALLOC(d);
+	wv = W_UMALLOC(d); wg = W_UMALLOC(d);
+	wa = W_UMALLOC(d); wb = W_UMALLOC(d);
+	ptosfum(f,wf); DEG(wg) = 0; COEF(wg)[0] = _onesf();
+	*clistp = clist = MLALLOC(np); clist->n = np;
+	for ( i = 0, in = (UM *)blist->c, out = (UM *)clist->c; i < np; i++ ) {
+		divsfum(wf,in[i],q); tum = wf; wf = q; q = tum;
+		cpyum(wf,wx); cpyum(in[i],wy);
+		eucsfum(wx,wy,wa,wb); mulsfum(wa,wg,wm);
+		DEG(wm) = divsfum(wm,in[i],q); out[i] = UMALLOC(DEG(wm));
+		cpyum(wm,out[i]); mulsfum(q,wf,wu);
+		mulsfum(wg,wb,wv); addsfum(wu,wv,wg);
+	}
+}
+
+/* f = g0*h0 mod y -> f = gk*hk mod y^(dy+1), f is replaced by hk */
+
+void sfhenmain2(BM f,UM g0,UM h0,int dy,BM *gp)
+{
+	int i,k;
+	int dx;
+	UM wt,wa,wb,q,w1,w2,wh1,wg1,ws;
+	UM wc,wd,we,wz;
+	BM wb0,wb1;
+	int dg,dh;
+	BM fk,gk,hk;
+	
+	if ( DEG(f) < dy )
+		error("sfhenmain2 : invalid input");
+
+	dx = degbm(f);
+	dg = DEG(g0);
+	dh = DEG(h0);
+
+	W_BMALLOC(dx,dy,wb0); W_BMALLOC(dx,dy,wb1);
+	wt = W_UMALLOC(dx); ws = W_UMALLOC(dx); q = W_UMALLOC(2*dx);
+	wg1 = W_UMALLOC(2*dx); wh1 = W_UMALLOC(2*dx);
+
+	/* fk = gk*hk mod y^k */
+	W_BMALLOC(dx,dy,fk);
+	cpyum(COEF(f)[0],COEF(fk)[0]);
+	gk = BMALLOC(dg,dy);
+	cpyum(g0,COEF(gk)[0]);
+	W_BMALLOC(dh,dy,hk);
+	cpyum(h0,COEF(hk)[0]);
+
+	wc = W_UMALLOC(2*dx); wd = W_UMALLOC(2*dx);
+	we = W_UMALLOC(2*dx); wz = W_UMALLOC(2*dx);
+
+	/* compute wa,wb s.t. wa*g0+wb*h0 = 1 mod y */
+	w1 = W_UMALLOC(dg); cpyum(g0,w1);
+	w2 = W_UMALLOC(dh); cpyum(h0,w2);
+	wa = W_UMALLOC(2*dx); wb = W_UMALLOC(2*dx);  /* XXX */
+	eucsfum(w1,w2,wa,wb);
+
+	fprintf(stderr,"dy=%d\n",dy);
+	for ( k = 1; k <= dy; k++ ) {
+		fprintf(stderr,".");
+
+		/* at this point, f = gk*hk mod y^k */
+
+		/* clear wt */
+		clearum(wt,dx);
+
+		/* wt = (f-gk*hk)/y^k */
+		subsfum(COEF(f)[k],COEF(fk)[k],wt);
+		
+		/* compute wf1,wg1 s.t. wh1*g0+wg1*h0 = wt */
+		mulsfum(wa,wt,wh1); DEG(wh1) = divsfum(wh1,h0,q);
+		mulsfum(wh1,g0,wc); subsfum(wt,wc,wd); DEG(wd) = divsfum(wd,h0,wg1);
+
+		/* check */
+#if 0
+		if ( DEG(wd) >= 0 || DEG(wg1) > ng )
+			error("henmain2 : cannot happen(adj)");
+
+		mulsfum(wg1,h0,wc); mulsfum(wh1,g0,wd); addsfum(wc,wd,we);
+		subsfum(we,wt,wz);
+		if ( DEG(wz) >= 0 )
+			error("henmain2 : cannot happen");
+#endif
+
+		/* fk += ((wg1*hk+wh1*gk)*y^k+wg1*wh1*y^(2*k) mod y^(dy+1) */
+		/* wb0 = wh1*y^k */
+		clearbm(dx,wb0);
+		cpyum(wh1,COEF(wb0)[k]);
+
+		/* wb1 = gk*wb0 mod y^(dy+1) */
+		clearbm(dx,wb1);
+		mulsfbm(gk,wb0,wb1);
+		/* fk += wb1 */
+		addtosfbm(wb1,fk);
+
+		/* wb0 = wg1*y^k */
+		clearbm(dx,wb0);
+		cpyum(wg1,COEF(wb0)[k]);
+
+		/* wb1 = hk*wb0 mod y^(dy+1) */
+		clearbm(dx,wb1);
+		mulsfbm(hk,wb0,wb1);
+		/* fk += wb1 */
+		addtosfbm(wb1,fk);
+
+		/* fk += wg1*wh1*y^(2*k) mod y^(dy+1) */
+		if ( 2*k <= dy ) {
+			mulsfum(wg1,wh1,wt); addsfum(COEF(fk)[2*k],wt,ws);
+			cpyum(ws,COEF(fk)[2*k]);
+		}
+
+		/* gk += wg1*y^k, hk += wh1*y^k */
+		cpyum(wg1,COEF(gk)[k]);
+		cpyum(wh1,COEF(hk)[k]);
+	}
+	fprintf(stderr,"\n");
+	*gp = gk;
+	DEG(f) = dy;
+	for ( i = 0; i <= dy; i++ )
+		cpyum(COEF(hk)[i],COEF(f)[i]);
+}
+
+/* a0*g+b0*h = 1 mod y -> a*g+b*h = 1 mod y^(dy+1) */
+
+void sfexgcd_by_hensel(BM g,BM h,int dy,BM *ap,BM *bp)
+{
+	int i,k;
+	int dx;
+	UM wt,wa,wb,q,w1,w2,ws;
+	UM wc,wd,we,wz,wa1,wb1;
+	BM wz0,wz1;
+	int dg,dh;
+	BM a,b,c;
+
+	dg = degbm(g);
+	dh = degbm(h);
+	dx = dg+dh;
+
+	a = BMALLOC(dh,dy);
+	b = BMALLOC(dg,dy);
+	/* c holds a*g+b*h-1 */
+	c = BMALLOC(dg+dh,dy);
+
+	W_BMALLOC(dx,dy,wz0); W_BMALLOC(dx,dy,wz1);
+
+	wt = W_UMALLOC(dx); ws = W_UMALLOC(dx); q = W_UMALLOC(2*dx);
+	wa1 = W_UMALLOC(2*dx); wb1 = W_UMALLOC(2*dx);
+	wc = W_UMALLOC(2*dx); wd = W_UMALLOC(2*dx);
+	we = W_UMALLOC(2*dx); wz = W_UMALLOC(2*dx);
+
+	/* compute wa,wb s.t. wa*g0+wb*h0 = 1 mod y */
+	w1 = W_UMALLOC(dg); cpyum(COEF(g)[0],w1);
+	w2 = W_UMALLOC(dh); cpyum(COEF(h)[0],w2);
+	wa = W_UMALLOC(2*dx); wb = W_UMALLOC(2*dx);  /* XXX */
+	eucsfum(w1,w2,wa,wb);
+	cpyum(wa,COEF(a)[0]); cpyum(wb,COEF(b)[0]);
+	
+	/* initialize c to a*g+b*h-1 */
+	mulsfbm(a,g,c); mulsfbm(b,h,wz0); addtosfbm(wz0,c);
+	COEF(COEF(c)[0])[0] = 0;
+	
+	fprintf(stderr,"dy=%d\n",dy);
+	for ( k = 1; k <= dy; k++ ) {
+		fprintf(stderr,".");
+
+		/* at this point, a*g+b*h = 1 mod y^k, c = a*g+b*h-1 */
+
+		/* wt = -((a*g+b*h-1)/y^k) */
+		cpyum(COEF(c)[k],wt);
+		for ( i = DEG(wt); i >= 0; i-- )
+			COEF(wt)[i] = _chsgnsf(COEF(wt)[i]);
+		
+		/* compute wa1,wb1 s.t. wa1*g0+wb1*h0 = wt */
+		mulsfum(wa,wt,wa1); DEG(wa1) = divsfum(wa1,COEF(h)[0],q);
+		mulsfum(wa1,COEF(g)[0],wc); subsfum(wt,wc,wd); 
+		DEG(wd) = divsfum(wd,COEF(h)[0],wb1);
+
+		/* c += ((wa1*g+wb1*h)*y^k mod y^(dy+1) */
+		/* wz0 = wa1*y^k */
+		clearbm(dx,wz0);
+		cpyum(wa1,COEF(wz0)[k]);
+
+		/* wz1 = wz0*g mod y^(dy+1) */
+		clearbm(dx,wz1);
+		mulsfbm(g,wz0,wz1);
+		/* c += wz1 */
+		addtosfbm(wz1,c);
+
+		/* wz0 = wb1*y^k */
+		clearbm(dx,wz0);
+		cpyum(wb1,COEF(wz0)[k]);
+
+		/* wz1 = wz0*h mod y^(dy+1) */
+		clearbm(dx,wz1);
+		mulsfbm(h,wz0,wz1);
+		/* c += wz1 */
+		addtosfbm(wz1,c);
+
+		/* a += wa1*y^k, b += wb1*y^k */
+		cpyum(wa1,COEF(a)[k]);
+		cpyum(wb1,COEF(b)[k]);
+	}
+	fprintf(stderr,"\n");
+	DEG(a) = dy;
+	DEG(b) = dy;
+	*ap = a;
+	*bp = b;
+}
+
+/* fl->c[i] = coef_y(f,i) */
+
+void ptosfbm(int dy,P f,BM fl)
+{
+	DCP dc;
+	int d,i,dx;
+	UM t;
+
+	dx = QTOS(DEG(DC(f)));
+	if ( DEG(fl) < dy )
+		error("ptosfbm : invalid input");
+	DEG(fl) = dy;
+	clearbm(dx,fl);
+	t = UMALLOC(dy);
+	for ( dc = DC(f); dc; dc = NEXT(dc) ) {
+		d = QTOS(DEG(dc));
+		ptosfum(COEF(dc),t);
+		for ( i = 0; i <= DEG(t); i++ )
+			COEF(COEF(fl)[i])[d] = COEF(t)[i];
+	}
+	for ( i = 0; i <= dy; i++ )
+		degum(COEF(fl)[i],dx);
+}
+
+/* x : main variable */
+
+void sfbmtop(BM f,V x,V y,P *fp)
+{
+	UM *c;
+	int i,j,d,a,dy;
+	GFS b;
+	DCP dc0,dc,dct;
+
+	dy = DEG(f);
+	c = COEF(f);
+	d = degbm(f);
+
+	dc0 = 0;
+	for ( i = 0; i <= d; i++ ) {
+		dc = 0;
+		for ( j = 0; j <= dy; j++ ) {
+			if ( DEG(c[j]) >= i && (a = COEF(c[j])[i]) ) {
+				NEWDC(dct);
+				STOQ(j,DEG(dct));
+				iftogfs(a,&b);
+				COEF(dct) = (P)b;
+				NEXT(dct) = dc;
+				dc = dct;
+			}
+		}
+		if ( dc ) {
+			NEWDC(dct);
+			STOQ(i,DEG(dct));
+			MKP(y,dc,COEF(dct));
+			NEXT(dct) = dc0;
+			dc0 = dct;
+		}
+	}
+	if ( dc0 )
+		MKP(x,dc0,*fp);
+	else
+		*fp = 0;
+}
+
+void sfsqfr(P f,DCP *dcp)
+{
+	Obj obj;
+	DCP dc;
+	VL vl;
+
+	simp_ff((Obj)f,&obj); f = (P)obj;
+	clctv(CO,f,&vl);
+	if ( !vl ) {
+		/* f is a const */
+		NEWDC(dc); DEG(dc) = ONE; COEF(dc) = f; NEXT(dc) = 0; *dcp = dc;
+	} else if ( !NEXT(vl) )
+		sfusqfr(f,dcp);
+	else
+		sqfrsf(f,dcp);
+}
+
+void sfusqfr(P f,DCP *dcp)
+{
+	DCP dc,dct;
+	struct oDUM *udc;
+	V x;
+	P lc;
+	int n,i;
+	UM mf;
+
+	x = VR(f);
+	n = getdeg(x,f);
+	mf = W_UMALLOC(n);
+	ptosfum(f,mf);
+	lc = COEF(DC(f));
+	if ( !_isonesf(COEF(mf)[n]) ) {
+		monicsfum(mf);
+	}
+	W_CALLOC(n+1,struct oDUM,udc);
+	gensqfrsfum(mf,udc);
+	for ( i = 0, dc = 0; udc[i].f; i++ ) {
+		NEWDC(dct); STOQ(udc[i].n,DEG(dct));
+		sfumtop(x,udc[i].f,&COEF(dct));
+		NEXT(dct) = dc; dc = dct;
+	}
+	NEWDC(dct); DEG(dct) = ONE; COEF(dct) = (P)lc; NEXT(dct) = dc;
+	*dcp = dct;
+}
+
+#if 0
+void sfbsqfrmain(P f,V x,V y,DCP *dcp)
+{
+	/* XXX*/
+}
+
+/* f is bivariate */
+
+void sfbsqfr(P f,V x,V y,DCP *dcp)
+{
+	P t,rf,cx,cy;
+	VL vl,rvl;
+	DCP dcx,dcy,dct,dc;
+	struct oVL vl0,vl1;
+
+	/* cy(y) = cont(f,x), f /= cy */
+	cont_pp_sfp(vl,f,&cy,&t); f = t;
+	/* rvl = [y,x] */
+	reordvar(vl,y,&rvl); reorderp(rvl,vl,f,&rf);
+	/* cx(x) = cont(rf,y), Rf /= cy */
+	cont_pp_sfp(rvl,rf,&cx,&t); rf = t;
+	reorderp(vl,rvl,rf,&f);
+
+	/* f -> cx*cy*f */
+	sfsqfr(cx,&dcx); dcx = NEXT(dcx);
+	sfsqfr(cy,&dcy); dcy = NEXT(dcy);
+	if ( dcx ) {
+		for ( dct = dcx; NEXT(dct); dct = NEXT(dct) );
+		NEXT(dct) = dcy;
+	} else
+		dcx = dcy;
+	if ( OID(f) == O_N )
+		*dcp = dcx;
+	else {
+		/* f must be bivariate */
+		sfbsqfrmain(f,x,y,&dc);
+		if ( dcx ) {
+			for ( dct = dcx; NEXT(dct); dct = NEXT(dct) );
+			NEXT(dct) = dc;
+		} else
+			dcx = dc;
+		*dcp = dcx;
+	}
+}
+#endif
+
+void sfdtest(P,ML,V,V,DCP *);
+
+/* if degbound >= 0 find factor s.t. deg_x(factor) <= degbound */
+
+void sfbfctr(P f,V x,V y,int degbound,DCP *dcp)
+{
+	ML list;
+	P sf;
+	GFS ev;
+	DCP dc,dct;
+	BM fl;
+	int dx,dy;
+
+	/* sf(x) = f(x+ev) = list->c[0]*list->c[1]*... */
+	sfhensel(5,f,x,y,degbound,&ev,&sf,&list);
+	if ( list->n == 0 )
+		error("sfbfctr : short of evaluation points");
+	else if ( list->n == 1 ) {
+		/* f is irreducible */
+		NEWDC(dc); DEG(dc) = ONE; COEF(dc) = f; NEXT(dc) = 0;
+		*dcp = dc;
+		return;
+	}
+	sfdtest(sf,list,x,y,&dc);
+	if ( ev ) {
+		dx = getdeg(x,sf);
+		dy = getdeg(y,sf);
+		W_BMALLOC(dx,dy,fl);
+		for ( dct = dc; dct; dct = NEXT(dct) ) {
+			ptosfbm(dy,COEF(dct),fl);
+			shiftsfbm(fl,_chsgnsf(FTOIF(CONT(ev))));
+			sfbmtop(fl,x,y,&COEF(dct));
+		}
+	}
+	*dcp = dc;
+}
+
+/* returns shifted f, shifted factors and the eval pt */
+
+void sfbfctr_shift(P f,V x,V y,int degbound,GFS *evp,P *sfp,DCP *dcp)
+{
+	ML list;
+	P sf;
+	GFS ev;
+	DCP dc,dct;
+	int dx,dy;
+
+	/* sf(x) = f(x+ev) = list->c[0]*list->c[1]*... */
+	sfhensel(5,f,x,y,degbound,&ev,&sf,&list);
+	if ( list->n == 0 )
+		error("sfbfctr_shift : short of evaluation points");
+	else if ( list->n == 1 ) {
+		/* f is irreducible */
+		NEWDC(dc); DEG(dc) = ONE; COEF(dc) = f; NEXT(dc) = 0;
+		*evp = 0;
+		*sfp = f;
+		*dcp = dc;
+	} else {
+		sfdtest(sf,list,x,y,dcp);
+		*evp = ev;
+		*sfp = sf;
+	}
+}
+
+/* f = f(x,y) = list->c[0]*list->c[1]*... mod y^(list->bound+1) */
+
+void sfdtest(P f,ML list,V x,V y,DCP *dcp)
+{
+	int np,dx,dy;
+	int i,j,k,bound;
+	int *win;
+	P g,lcg,factor,cofactor,lcyx;
+	P csum;
+	DCP dcf,dcf0,dc;
+	BM *c;
+	BM lcy;
+	UM lcg0,lcy0,w;
+	UM *d1c;
+	ML wlist;
+	struct oVL vl1,vl0;
+	VL vl;
+	int z,dt,dtok;
+
+	/* vl = [x,y] */
+	vl0.v = x; vl0.next = &vl1; vl1.v = y; vl1.next = 0; vl = &vl0;
+
+	/* setup various structures and arrays */
+	dx = getdeg(x,f);
+	dy = getdeg(y,f);
+	np = list->n;
+	win = W_ALLOC(np+1);
+	wlist = W_MLALLOC(np);
+	wlist->n = list->n;
+	bound = wlist->bound = list->bound;
+	c = (BM *)COEF(wlist);
+	bcopy((char *)COEF(list),(char *)c,(int)(sizeof(BM)*np));
+
+	lcg0 = W_UMALLOC(2*dy);
+
+	/* initialize g by f */
+	g = f;
+
+	/* initialize lcg */
+	mulp(vl,g,COEF(DC(g)),&lcg);
+
+	/* initialize lcg0 */
+	const_term(lcg,lcg0);
+
+	/* initialize csum = lcg(1) */
+	sfcsump(vl,lcg,&csum);
+
+	/* initialize lcy by LC(f) */
+	W_BMALLOC(0,dy,lcy);
+	NEWDC(dc); COEF(dc) = COEF(DC(g)); DEG(dc) = 0; 
+	NEWP(lcyx); VR(lcyx) = x; DC(lcyx) = dc;
+	ptosfbm(dy,lcyx,lcy);
+
+	/* initialize lcy0 by LC(f) */
+	lcy0 = W_UMALLOC(bound);
+	ptosfum(COEF(DC(g)),lcy0);
+
+	/* ((d-1 coefs)*lcy0 */
+	d1c = (UM *)W_ALLOC(np*sizeof(UM));
+	w = W_UMALLOC(2*bound);
+	for ( i = 1; i < np; i++ ) {
+		extractcoefbm(c[i],degbm(c[i])-1,w);
+		d1c[i] = W_UMALLOC(2*bound);
+		mulsfum(w,lcy0,d1c[i]);
+		/* d1c[i] = d1c[i] mod y^(bound+1) */
+		if ( DEG(d1c[i]) > bound ) {
+			for ( j = DEG(d1c[i]); j > bound; j-- )
+				COEF(d1c[i])[j] = 0;
+			degum(d1c[i],bound);
+		}
+	}
+
+	fprintf(stderr,"np = %d\n",np);
+	dtok = 0;
+	for ( g = f, k = 1, dcf = dcf0 = 0, win[0] = 1, --np, z = 0; ; z++ ) {
+		if ( !(z % 1000) ) fprintf(stderr,".");
+		dt = sfdegtest(dy,bound,d1c,k,win);
+		if ( dt )
+			dtok++;
+		if ( dt && sfdtestmain(vl,lcg,lcg0,lcy,csum,wlist,
+				k,win,&factor,&cofactor) ) {
+			NEXTDC(dcf0,dcf); DEG(dcf) = ONE; COEF(dcf) = factor;
+			g = cofactor;
+
+			/* update lcg */
+			mulp(vl,g,COEF(DC(g)),&lcg);
+
+			/* update lcg0 */
+			const_term(lcg,lcg0);
+
+			/* update csum */
+			sfcsump(vl,lcg,&csum);
+
+			/* update dy */
+			dy = getdeg(y,g);
+
+			/* update lcy */
+			clearbm(0,lcy);
+			COEF(dc) = COEF(DC(g));
+			ptosfbm(dy,lcyx,lcy);
+
+			for ( i = 0; i < k - 1; i++ ) 
+				for ( j = win[i] + 1; j < win[i + 1]; j++ ) 
+					c[j-i-1] = c[j];
+			for ( j = win[k-1] + 1; j <= np; j++ ) 	
+					c[j-k] = c[j];
+			if ( ( np -= k ) < k ) 
+				break;
+			if ( np - win[0] + 1 < k ) 
+				if ( ++k > np )
+					break;
+				else
+					for ( i = 0; i < k; i++ ) 
+						win[i] = i + 1;
+			else 
+				for ( i = 1; i < k; i++ ) 
+					win[i] = win[0] + i;
+
+
+			/* update lcy0  */
+			ptosfum(COEF(DC(g)),lcy0);
+		
+			/* update d-1 coeffs */
+			for ( i = 1; i <= np; i++ ) {
+				extractcoefbm(c[i],degbm(c[i])-1,w);
+				mulsfum(w,lcy0,d1c[i]);
+				/* d1c[i] = d1c[1] mod y^(bound+1) */
+				if ( DEG(d1c[i]) > bound ) {
+					for ( j = DEG(d1c[i]); j > bound; j-- )
+						COEF(d1c[i])[j] = 0;
+					degum(d1c[i],bound);
+				}
+			}
+		} else if ( !ncombi(1,np,k,win) ) 
+			if ( k == np ) 
+				break;
+			else
+				for ( i = 0, ++k; i < k; i++ ) 
+					win[i] = i + 1;
+	}
+	fprintf(stderr,"total %d, omitted by degtest %d\n",z,z-dtok);
+	NEXTDC(dcf0,dcf); COEF(dcf) = g;
+	DEG(dcf) = ONE; NEXT(dcf) = 0; *dcp = dcf0;
+}
+
+void extractcoefbm(BM f,int dx,UM r)
+{
+	int j;
+	UM fj;
+
+	for ( j = DEG(f); j >= 0; j-- ) {
+		fj = COEF(f)[j];
+		if ( fj && DEG(fj) >= dx ) {
+			COEF(r)[j] = COEF(fj)[dx];
+		} else
+			COEF(r)[j] = 0;
+	}
+	degum(r,DEG(f));
+}
+
+/* deg_y(prod mod y^(bound+1)) <= dy ? */
+
+int sfdegtest(int dy,int bound,UM *d1c,int k,int *in)
+{
+	int i,j;
+	UM w,w1,wt;
+	BM t;
+
+	w = W_UMALLOC(bound);
+	w1 = W_UMALLOC(bound);
+	clearum(w,bound);
+	for ( i = 0; i < k; i++ ) {
+		addsfum(w,d1c[in[i]],w1); wt = w; w = w1; w1 = wt;
+	}
+	return DEG(w) <= dy ? 1 : 0;
+}
+
+/* lcy = LC(g), lcg = lcy*g, lcg0 = const part of lcg */
+
+int sfdtestmain(VL vl,P lcg,UM lcg0,BM lcy,P csum,ML list,
+	int k,int *in,P *fp,P *cofp)
+{
+	P fmul,csumg,q,cont;
+	V x,y;
+
+	x = vl->v;
+	y = vl->next->v;
+	if (!sfctest(lcg0,lcy,list,k,in))
+		return 0;
+	mulsfbmarray(UDEG(lcg),lcy,list,k,in,x,y,&fmul);
+	if ( csum ) {
+		sfcsump(vl,fmul,&csumg);
+		if ( csumg ) {
+			if ( !divtp(vl,csum,csumg,&q) )
+				return 0;
+		} 
+	}
+	if ( divtp_by_sfbm(vl,lcg,fmul,&q) ) {
+		cont_pp_sfp(vl,fmul,&cont,fp);
+		cont_pp_sfp(vl,q,&cont,cofp);
+		return 1;
+	} else
+		return 0;
+}
+
+void const_term(P f,UM c)
+{
+	DCP dc;
+
+	for ( dc = DC(f); dc && DEG(dc); dc = NEXT(dc) );
+	if ( dc ) 
+		ptosfum(COEF(dc),c);
+	else 
+		DEG(c) = -1;
+}
+
+void const_term_sfbm(BM f,UM c)
+{
+	int i,dy;
+
+	dy = DEG(f);
+	for ( i = 0; i <= dy; i++ )
+		if ( DEG(COEF(f)[i]) >= 0 )
+			COEF(c)[i] = COEF(COEF(f)[i])[0];
+		else
+			COEF(c)[i] = 0;
+	degum(c,dy);
+}
+
+/* lcy*(product of const part) | lcg0 ? */
+
+int sfctest(UM lcg0,BM lcy,ML list,int k,int *in)
+{
+	int dy,i,dr;
+	UM t,s,u,w;
+	BM *l;
+
+	dy = list->bound;
+	t = W_UMALLOC(2*dy);
+	s = W_UMALLOC(2*dy);
+	u = W_UMALLOC(2*dy);
+	const_term_sfbm(lcy,t);
+	if ( DEG(t) < 0 )
+		return 1;
+
+	l = (BM *)list->c;
+	for ( i = 0; i < k; i++ ) {
+		const_term_sfbm(l[in[i]],s);
+		mulsfum(t,s,u);
+		if ( DEG(u) > dy )
+			degum(u,dy);
+		w = t; t = u; u = w;
+	}
+	cpyum(lcg0,s);
+	dr = divsfum(s,t,u);
+	if ( dr >= 0 )
+		return 0;
+	else
+		return 1;
+}
+
+/* main var of f is x */
+
+void mulsfbmarray(int dx,BM lcy,ML list,int k,int *in,V x,V y,P *g)
+{
+	int dy,i;
+	BM wb0,wb1,t;
+	BM *l;
+
+	dy = list->bound;
+	W_BMALLOC(dx,dy,wb0); W_BMALLOC(dx,dy,wb1);
+	l = (BM *)list->c;
+	clearbm(dx,wb0);
+	mulsfbm(lcy,l[in[0]],wb0);
+	for ( i = 1; i < k; i++ ) {
+		clearbm(dx,wb1);
+		mulsfbm(l[in[i]],wb0,wb1);
+		t = wb0; wb0 = wb1; wb1 = t;
+	}
+	sfbmtop(wb0,x,y,g);
+}
+
+void sfcsump(VL vl,P f,P *s)
+{
+	P t,u;
+	DCP dc;
+
+	for ( dc = DC(f), t = 0; dc; dc = NEXT(dc) ) {
+		addp(vl,COEF(dc),t,&u); t = u;
+	}
+	*s = t;
+}
+
+/* *fp = primitive part of f w.r.t. x */
+
+void cont_pp_sfp(VL vl,P f,P *cp,P *fp)
+{
+	V x,y;
+	int d;
+	UM t,s,gcd;
+	DCP dc;
+	GFS g;
+
+	x = vl->v;
+	y = vl->next->v;
+	d = getdeg(y,f);
+	if ( d == 0 ) {
+		itogfs(1,&g);
+		*cp = (P)g;
+		*fp = f;  /* XXX */
+	} else {
+		t = W_UMALLOC(2*d);
+		s = W_UMALLOC(2*d);
+		gcd = W_UMALLOC(2*d);
+		dc = DC(f);
+		ptosfum(COEF(dc),gcd);
+		for ( dc = NEXT(dc); dc; dc = NEXT(dc) ) {
+			ptosfum(COEF(dc),t);
+			gcdsfum(gcd,t,s);
+			cpyum(s,gcd);
+		}
+		sfumtop(y,gcd,cp);
+		divsp(vl,f,*cp,fp);
+	}
+}
+
+int divtp_by_sfbm(VL vl,P f,P g,P *qp)
+{
+	V x,y;
+	int fx,fy,gx,gy;
+	BM fl,gl,ql;
+	UM *cf,*cg,*cq;
+	UM hg,q,t,s;
+	int i,j,dr;
+
+	x = vl->v; y = vl->next->v;
+	fx = getdeg(x,f); fy = getdeg(y,f);
+	gx = getdeg(x,g); gy = getdeg(y,g);
+
+	if ( fx < gx || fy < gy )
+		return 0;
+	W_BMALLOC(fx,fy,fl); ptosfbm(fy,f,fl); cf = COEF(fl);
+	W_BMALLOC(gx,gy,gl); ptosfbm(gy,g,gl); cg = COEF(gl);
+	W_BMALLOC(fx-gx,fy-gy,ql); cq = COEF(ql);
+
+	hg = cg[gy];
+	q = W_UMALLOC(fx); t = W_UMALLOC(fx); s = W_UMALLOC(fx);
+
+	for ( i = fy; i >= gy; i-- ) {
+		if ( DEG(cf[i]) < 0 )
+			continue;
+		dr = divsfum(cf[i],hg,q);
+		if ( dr >= 0 )
+			return 0;
+		if ( DEG(q) > fx-gx )
+			return 0;
+		cpyum(q,cq[i-gy]);
+		for ( j = 0; j <= gy; j++ ) {
+			mulsfum(cg[j],q,t);
+			subsfum(cf[j+i-gy],t,s);
+			cpyum(s,cf[j+i-gy]);
+		}
+	}
+	for ( j = gy-1; j >= 0 && DEG(cf[j]) < 0; j-- );
+	if ( j >= 0 )
+		return 0;
+	sfbmtop(ql,x,y,qp);
+	return 1;
+}
+
+/* XXX generate an irreducible poly of degree n */
+
+extern int current_gfs_q1;
+extern int *current_gfs_ntoi;
+
+void generate_defpoly_sfum(int n,UM *dp)
+{
+	UM r,dr,t,g;
+	UM *f;
+	int *c,*w;
+	int max,i,j;
+
+	*dp = r = UMALLOC(n);
+	DEG(r) = n;
+	c = COEF(r);
+	c[n] = _onesf();
+	max = current_gfs_q1;
+	w = (int *)ALLOCA(n*sizeof(int));
+	bzero(w,n*sizeof(int));
+
+	dr = W_UMALLOC(n); t = W_UMALLOC(n); g = W_UMALLOC(n);
+	f = (UM *)ALLOCA((n+1)*sizeof(UM));
+	while ( 1 ) {
+		for ( i = 0; i < n && w[i] == max; i++ );
+		if ( i == n ) {
+			/* XXX cannot happen */
+			error("generate_defpoly_sfum : cannot happen");
+		}
+		for ( j = 0; j < i; j++ )
+			w[j] = 0;
+		w[i]++;
+		if ( !current_gfs_ntoi )
+			for ( i = 0; i < n; i++ )
+				c[i] = w[i]?FTOIF(w[i]):0;
+		else
+			for ( i = 0; i < n; i++ )
+				c[i] = w[i]?FTOIF(w[i]-1):0;
+		if ( !c[0] )
+			continue;
+		diffsfum(r,dr); cpyum(r,t); gcdsfum(t,dr,g);
+		if ( DEG(g) > 0 )
+			continue;
+
+		czsfum(r,f);
+		for ( i = 0; f[i]; i++ );
+		if ( i == 1 )
+			return;
+	}
+}