radix.c

很好的一个嵌入式linux平台下的bootloader

	cplim = netmask + mlen;
	for (cp = netmask + skip; cp < cplim; cp++)
		if (*(u_char *)cp != 0xff)
			break;
	b = (cp - netmask) << 3;
	if (cp != cplim) {
		if (*cp != 0) {
			gotOddMasks = 1;
			for (j = 0x80; j; b++, j >>= 1)  
				if ((j & *cp) == 0)
					break;
		}
	}
	x->rn_b = -1 - b;
	return (x);
}

struct radix_node *
rn_addroute(v, netmask, head, treenodes)
struct radix_node *head;
	caddr_t netmask, v;
	struct radix_node treenodes[2];
{
	register int j;
	register caddr_t cp;
	register struct radix_node *t, *x, *tt;
	short b = 0, b_leaf;
	int vlen = *(u_char *)v, mlen, keyduplicated;
	caddr_t cplim; unsigned char *maskp;
	struct radix_mask *m, **mp;
	struct radix_node *saved_tt;

	/*
	 * In dealing with non-contiguous masks, there may be
	 * many different routes which have the same mask.
	 * We will find it useful to have a unique pointer to
	 * the mask to speed avoiding duplicate references at
	 * nodes and possibly save time in calculating indices.
	 */
	if (netmask)  {
		x = rn_search(netmask, rn_maskhead);
		mlen = *(u_char *)netmask;
		if (Bcmp(netmask, x->rn_key, mlen) != 0) {
			x = rn_addmask(netmask, 0, head->rn_off);
			if (x == 0)
				return (0);
		}
		netmask = x->rn_key;
		b = -1 - x->rn_b;
	}
	/*
	 * Deal with duplicated keys: attach node to previous instance
	 */
	saved_tt = tt = rn_insert(v, head, &keyduplicated, treenodes);
	if (keyduplicated) {
		do {
			if (tt->rn_mask == netmask)
				return (0);
			t = tt;
		} while (tt = tt->rn_dupedkey);
		/*
		 * If the mask is not duplicated, we wouldn't
		 * find it among possible duplicate key entries
		 * anyway, so the above test doesn't hurt.
		 *
		 * XXX: we really ought to sort the masks
		 * for a duplicated key the same way as in a masklist.
		 * It is an unfortunate pain having to relocate
		 * the head of the list.
		 */
		t->rn_dupedkey = tt = treenodes;
#ifdef RN_DEBUG
		t=tt+1; tt->rn_info = rn_nodenum++; t->rn_info = rn_nodenum++;
		tt->rn_twin = t; tt->rn_ybro = rn_clist; rn_clist = tt;
#endif
		t = saved_tt;
		tt->rn_key = (caddr_t) v;
		tt->rn_b = -1;
		tt->rn_flags = t->rn_flags & ~RNF_ROOT;
	}
	/*
	 * Put mask in tree.
	 */
	if (netmask) {
		tt->rn_mask = netmask;
		tt->rn_b = x->rn_b;
	}
	t = saved_tt->rn_p;
	b_leaf = -1 - t->rn_b;
	if (t->rn_r == saved_tt) x = t->rn_l; else x = t->rn_r;
	/* Promote general routes from below */
	if (x->rn_b < 0) { 
		if (x->rn_mask && (x->rn_b >= b_leaf) && x->rn_mklist == 0) {
			MKGet(m);
			if (m) {
				Bzero(m, sizeof *m);
				m->rm_b = x->rn_b;
				m->rm_mask = x->rn_mask;
				x->rn_mklist = t->rn_mklist = m;
			}
		}
	} else if (x->rn_mklist) {
		/*
		 * Skip over masks whose index is > that of new node
		 */
		for (mp = &x->rn_mklist; m = *mp; mp = &m->rm_mklist)
			if (m->rm_b >= b_leaf)
				break;
		t->rn_mklist = m; *mp = 0;
	}
	/* Add new route to highest possible ancestor's list */
	if ((netmask == 0) || (b > t->rn_b ))
		return tt; /* can't lift at all */
	b_leaf = tt->rn_b;
	do {
		x = t;
		t = t->rn_p;
	} while (b <= t->rn_b && x != head);
	/*
	 * Search through routes associated with node to
	 * insert new route according to index.
	 * For nodes of equal index, place more specific
	 * masks first.
	 */
	cplim = netmask + mlen;
	for (mp = &x->rn_mklist; m = *mp; mp = &m->rm_mklist) {
		if (m->rm_b < b_leaf)
			continue;
		if (m->rm_b > b_leaf)
			break;
		if (m->rm_mask == netmask) {
			m->rm_refs++;
			tt->rn_mklist = m;
			return tt;
		}
		maskp = (u_char *)m->rm_mask;
		for (cp = netmask; cp < cplim; cp++)
			if (*(u_char *)cp > *maskp++)
				goto on2;
	}
on2:
	MKGet(m);
	if (m == 0) {
		printf("Mask for route not entered\n");
		return (tt);
	}
	Bzero(m, sizeof *m);
	m->rm_b = b_leaf;
	m->rm_mask = netmask;
	m->rm_mklist = *mp;
	*mp = m;
	tt->rn_mklist = m;
	return tt;
}

struct radix_node *
rn_delete(v, netmask, head)
	caddr_t v, netmask;
	struct radix_node *head;
{
	register struct radix_node *t, *p, *x = head;
	register struct radix_node *tt = rn_search(v, x);
	int b, head_off = x->rn_off, vlen =  * (u_char *) v;
	struct radix_mask *m, *saved_m, **mp;
	struct radix_node *dupedkey, *saved_tt = tt;

	if (tt == 0 ||
	    Bcmp(v + head_off, tt->rn_key + head_off, vlen - head_off))
		return (0);
	/*
	 * Delete our route from mask lists.
	 */
	if (dupedkey = tt->rn_dupedkey) {
		if (netmask) 
			netmask = rn_search(netmask, rn_maskhead)->rn_key;
		while (tt->rn_mask != netmask)
			if ((tt = tt->rn_dupedkey) == 0)
				return (0);
	}
	if (tt->rn_mask == 0 || (saved_m = m = tt->rn_mklist) == 0)
		goto on1;
	if (m->rm_mask != tt->rn_mask) {
		printf("rn_delete: inconsistent annotation\n");
		goto on1;
	}
	if (--m->rm_refs >= 0)
		goto on1;
	b = -1 - tt->rn_b;
	t = saved_tt->rn_p;
	if (b > t->rn_b)
		goto on1; /* Wasn't lifted at all */
	do {
		x = t;
		t = t->rn_p;
	} while (b <= t->rn_b && x != head);
	for (mp = &x->rn_mklist; m = *mp; mp = &m->rm_mklist)
		if (m == saved_m) {
			*mp = m->rm_mklist;
			MKFree(m);
			break;
		}
	if (m == 0)
		printf("rn_delete: couldn't find our annotation\n");
on1:
	/*
	 * Eliminate us from tree
	 */
	if (tt->rn_flags & RNF_ROOT)
		return (0);
#ifdef RN_DEBUG
	/* Get us out of the creation list */
	for (t = rn_clist; t && t->rn_ybro != tt; t = t->rn_ybro) {}
	if (t) t->rn_ybro = tt->rn_ybro;
#endif RN_DEBUG
	t = tt->rn_p;
	if (dupedkey) {
		if (tt == saved_tt) {
			x = dupedkey; x->rn_p = t;
			if (t->rn_l == tt) t->rn_l = x; else t->rn_r = x;
#ifndef RN_DEBUG
			x++; t = tt + 1; *x = *t; p = t->rn_p;
#else
			x++; b = x->rn_info; t = tt + 1; *x = *t; p = t->rn_p;
			x->rn_info = b;
#endif
			if (p->rn_l == t) p->rn_l = x; else p->rn_r = x;
			x->rn_l->rn_p = x; x->rn_r->rn_p = x;
		} else {
			for (p = saved_tt; p && p->rn_dupedkey != tt;)
				p = p->rn_dupedkey;
			if (p) p->rn_dupedkey = tt->rn_dupedkey;
			else printf("rn_delete: couldn't find us\n");
		}
		goto out;
	}
	if (t->rn_l == tt) x = t->rn_r; else x = t->rn_l;
	p = t->rn_p;
	if (p->rn_r == t) p->rn_r = x; else p->rn_l = x;
	x->rn_p = p;
	/*
	 * Demote routes attached to us.
	 */
	if (t->rn_mklist) {
		if (x->rn_b >= 0) {
			for (mp = &x->rn_mklist; m = *mp;)
				mp = &m->rm_mklist;
			*mp = t->rn_mklist;
		} else {
			for (m = t->rn_mklist; m;) {
				struct radix_mask *mm = m->rm_mklist;
				if (m == x->rn_mklist && (--(m->rm_refs) < 0)) {
					x->rn_mklist = 0;
					MKFree(m);
				} else 
					printf("%s %x at %x\n",
					    "rn_delete: Orphaned Mask", m, x);
				m = mm;
			}
		}
	}
	/*
	 * We may be holding an active internal node in the tree.
	 */
	x = tt + 1;
	if (t != x) {
#ifndef RN_DEBUG
		*t = *x;
#else
		b = t->rn_info; *t = *x; t->rn_info = b;
#endif
		t->rn_l->rn_p = t; t->rn_r->rn_p = t;
		p = x->rn_p;
		if (p->rn_l == x) p->rn_l = t; else p->rn_r = t;
	}
out:
	tt->rn_flags &= ~RNF_ACTIVE;
	tt[1].rn_flags &= ~RNF_ACTIVE;
	return (tt);
}
char rn_zeros[MAXKEYLEN], rn_ones[MAXKEYLEN];

rn_inithead(head, off, af)
struct radix_node_head **head;
int off;
{
	register struct radix_node_head *rnh;
	register struct radix_node *t, *tt, *ttt;
	if (*head)
		return (1);
	R_Malloc(rnh, struct radix_node_head *, sizeof (*rnh));
	if (rnh == 0)
		return (0);
	Bzero(rnh, sizeof (*rnh));
	*head = rnh;
	t = rn_newpair(rn_zeros, off, rnh->rnh_nodes);
	ttt = rnh->rnh_nodes + 2;
	t->rn_r = ttt;
	t->rn_p = t;
	tt = t->rn_l;
	tt->rn_flags = t->rn_flags = RNF_ROOT | RNF_ACTIVE;
	tt->rn_b = -1 - off;
	*ttt = *tt;
	ttt->rn_key = rn_ones;
	rnh->rnh_af = af;
	rnh->rnh_treetop = t;
	if (radix_node_head == 0) {
		caddr_t cp = rn_ones, cplim = rn_ones + MAXKEYLEN;
		while (cp < cplim)
			*cp++ = -1;
		if (rn_inithead(&radix_node_head, 0, 0) == 0) {
			Free(rnh);
			*head = 0;
			return (0);
		}
		mask_rnhead = radix_node_head;
	}
	rnh->rnh_next = radix_node_head->rnh_next;
	if (radix_node_head != rnh)
		radix_node_head->rnh_next = rnh;
	return (1);
}