xref: /original-bsd/sys/vax/if/if_en.c (revision e61fc7ea)
1 /*
2  * Copyright (c) 1982, 1986 Regents of the University of California.
3  * All rights reserved.
4  *
5  * %sccs.include.redist.c%
6  *
7  *	@(#)if_en.c	7.6 (Berkeley) 06/28/90
8  */
9 
10 #include "en.h"
11 #if NEN > 0
12 
13 /*
14  * Xerox prototype (3 Mb) Ethernet interface driver.
15  */
16 #include "machine/pte.h"
17 
18 #include "param.h"
19 #include "systm.h"
20 #include "mbuf.h"
21 #include "buf.h"
22 #include "protosw.h"
23 #include "socket.h"
24 #include "vmmac.h"
25 #include "errno.h"
26 #include "ioctl.h"
27 
28 #include "../net/if.h"
29 #include "../net/netisr.h"
30 #include "../net/route.h"
31 
32 #ifdef	INET
33 #include "../netinet/in.h"
34 #include "../netinet/in_systm.h"
35 #include "../netinet/in_var.h"
36 #include "../netinet/ip.h"
37 #endif
38 
39 #ifdef PUP
40 #include "../netpup/pup.h"
41 #include "../netpup/ether.h"
42 #endif
43 
44 #ifdef NS
45 #include "../netns/ns.h"
46 #include "../netns/ns_if.h"
47 #endif
48 
49 #include "../vax/cpu.h"
50 #include "../vax/mtpr.h"
51 #include "if_en.h"
52 #include "if_enreg.h"
53 #include "if_uba.h"
54 #include "../vaxuba/ubareg.h"
55 #include "../vaxuba/ubavar.h"
56 
57 #define	ENMTU	(1024+512)
58 #define	ENMRU	(1024+512+16)		/* 16 is enough to receive trailer */
59 
60 int	enprobe(), enattach(), enrint(), enxint(), encollide();
61 struct	uba_device *eninfo[NEN];
62 u_short enstd[] = { 0 };
63 struct	uba_driver endriver =
64 	{ enprobe, 0, enattach, 0, enstd, "en", eninfo };
65 #define	ENUNIT(x)	minor(x)
66 
67 int	eninit(),oldenoutput(),enreset(),enioctl(), enstart();
68 
69 #ifdef notdef
70 /*
71  * If you need to byte swap IP's in the system, define
72  * this and do a SIOCSIFFLAGS at boot time.
73  */
74 #define	ENF_SWABIPS	0x1000
75 #endif
76 
77 /*
78  * Ethernet software status per interface.
79  *
80  * Each interface is referenced by a network interface structure,
81  * es_if, which the routing code uses to locate the interface.
82  * This structure contains the output queue for the interface, its address, ...
83  * We also have, for each interface, a UBA interface structure, which
84  * contains information about the UNIBUS resources held by the interface:
85  * map registers, buffered data paths, etc.  Information is cached in this
86  * structure for use by the if_uba.c routines in running the interface
87  * efficiently.
88  */
89 struct	en_softc {
90 	struct	ifnet es_if;		/* network-visible interface */
91 	struct	ifuba es_ifuba;		/* UNIBUS resources */
92 	short	es_host;		/* hardware host number */
93 	short	es_delay;		/* current output delay */
94 	short	es_mask;		/* mask for current output delay */
95 	short	es_lastx;		/* host last transmitted to */
96 	short	es_oactive;		/* is output active? */
97 	short	es_olen;		/* length of last output */
98 	short	es_nsactive;		/* is interface enabled for ns? */
99 } en_softc[NEN];
100 
101 /*
102  * Do output DMA to determine interface presence and
103  * interrupt vector.  DMA is too short to disturb other hosts.
104  */
105 enprobe(reg)
106 	caddr_t reg;
107 {
108 	register int br, cvec;		/* r11, r10 value-result */
109 	register struct endevice *addr = (struct endevice *)reg;
110 
111 #ifdef lint
112 	br = 0; cvec = br; br = cvec;
113 	enrint(0); enxint(0); encollide(0);
114 #endif
115 	addr->en_istat = 0;
116 	addr->en_owc = -1;
117 	addr->en_oba = 0;
118 	addr->en_ostat = EN_IEN|EN_GO;
119 	DELAY(100000);
120 	addr->en_ostat = 0;
121 	return (1);
122 }
123 
124 /*
125  * Interface exists: make available by filling in network interface
126  * record.  System will initialize the interface when it is ready
127  * to accept packets.
128  */
129 enattach(ui)
130 	struct uba_device *ui;
131 {
132 	register struct en_softc *es = &en_softc[ui->ui_unit];
133 
134 	es->es_if.if_unit = ui->ui_unit;
135 	es->es_if.if_name = "en";
136 	es->es_if.if_mtu = ENMTU;
137 	es->es_if.if_flags = IFF_BROADCAST;
138 	es->es_if.if_init = eninit;
139 	es->es_if.if_output = oldenoutput;
140 	es->es_if.if_start = enstart;
141 	es->es_if.if_ioctl = enioctl;
142 	es->es_if.if_reset = enreset;
143 	es->es_ifuba.ifu_flags = UBA_NEEDBDP | UBA_NEED16 | UBA_CANTWAIT;
144 #if defined(VAX750)
145 	/* don't chew up 750 bdp's */
146 	if (cpu == VAX_750 && ui->ui_unit > 0)
147 		es->es_ifuba.ifu_flags &= ~UBA_NEEDBDP;
148 #endif
149 	if_attach(&es->es_if);
150 }
151 
152 /*
153  * Reset of interface after UNIBUS reset.
154  * If interface is on specified uba, reset its state.
155  */
156 enreset(unit, uban)
157 	int unit, uban;
158 {
159 	register struct uba_device *ui;
160 
161 	if (unit >= NEN || (ui = eninfo[unit]) == 0 || ui->ui_alive == 0 ||
162 	    ui->ui_ubanum != uban)
163 		return;
164 	printf(" en%d", unit);
165 	eninit(unit);
166 }
167 
168 /*
169  * Initialization of interface; clear recorded pending
170  * operations, and reinitialize UNIBUS usage.
171  */
172 eninit(unit)
173 	int unit;
174 {
175 	register struct en_softc *es = &en_softc[unit];
176 	register struct uba_device *ui = eninfo[unit];
177 	register struct endevice *addr;
178 	int s;
179 
180 	if (es->es_if.if_addrlist == (struct ifaddr *)0)
181 		return;
182 	if (if_ubainit(&es->es_ifuba, ui->ui_ubanum,
183 	    sizeof (struct en_header), (int)btoc(ENMRU)) == 0) {
184 		printf("en%d: can't initialize\n", unit);
185 		es->es_if.if_flags &= ~IFF_UP;
186 		return;
187 	}
188 	addr = (struct endevice *)ui->ui_addr;
189 	addr->en_istat = addr->en_ostat = 0;
190 
191 	/*
192 	 * Hang a receive and start any
193 	 * pending writes by faking a transmit complete.
194 	 */
195 	s = splimp();
196 	addr->en_iba = es->es_ifuba.ifu_r.ifrw_info;
197 	addr->en_iwc = -(sizeof (struct en_header) + ENMRU) >> 1;
198 	addr->en_istat = EN_IEN|EN_GO;
199 	es->es_oactive = 1;
200 	es->es_if.if_flags |= IFF_RUNNING;
201 	enxint(unit);
202 	splx(s);
203 }
204 
205 int	enalldelay = 0;
206 int	enlastdel = 50;
207 int	enlastmask = (~0) << 5;
208 
209 /*
210  * Start or restart output on interface.
211  * If interface is already active, then this is a retransmit
212  * after a collision, and just restuff registers and delay.
213  * If interface is not already active, get another datagram
214  * to send off of the interface queue, and map it to the interface
215  * before starting the output.
216  */
217 enstart(dev)
218 	dev_t dev;
219 {
220         int unit = ENUNIT(dev);
221 	struct uba_device *ui = eninfo[unit];
222 	register struct en_softc *es = &en_softc[unit];
223 	register struct endevice *addr;
224 	register struct en_header *en;
225 	struct mbuf *m;
226 	int dest;
227 
228 	if (es->es_oactive)
229 		goto restart;
230 
231 	/*
232 	 * Not already active: dequeue another request
233 	 * and map it to the UNIBUS.  If no more requests,
234 	 * just return.
235 	 */
236 	IF_DEQUEUE(&es->es_if.if_snd, m);
237 	if (m == 0) {
238 		es->es_oactive = 0;
239 		return;
240 	}
241 	en = mtod(m, struct en_header *);
242 	dest = en->en_dhost;
243 	en->en_shost = es->es_host;
244 	es->es_olen = if_wubaput(&es->es_ifuba, m);
245 #ifdef ENF_SWABIPS
246 	/*
247 	 * The Xerox interface does word at a time DMA, so
248 	 * someone must do byte swapping of user data if high
249 	 * and low ender machines are to communicate.  It doesn't
250 	 * belong here, but certain people depend on it, so...
251 	 *
252 	 * Should swab everybody, but this is a kludge anyway.
253 	 */
254 	if (es->es_if.if_flags & ENF_SWABIPS) {
255 		en = (struct en_header *)es->es_ifuba.ifu_w.ifrw_addr;
256 		if (en->en_type == ENTYPE_IP)
257 			enswab((caddr_t)(en + 1), (caddr_t)(en + 1),
258 			    es->es_olen - sizeof (struct en_header) + 1);
259 	}
260 #endif
261 
262 	/*
263 	 * Ethernet cannot take back-to-back packets (no
264 	 * buffering in interface.  To help avoid overrunning
265 	 * receivers, enforce a small delay (about 1ms) in interface:
266 	 *	* between all packets when enalldelay
267 	 *	* whenever last packet was broadcast
268 	 *	* whenever this packet is to same host as last packet
269 	 */
270 	if (enalldelay || es->es_lastx == 0 || es->es_lastx == dest) {
271 		es->es_delay = enlastdel;
272 		es->es_mask = enlastmask;
273 	}
274 	es->es_lastx = dest;
275 
276 restart:
277 	/*
278 	 * Have request mapped to UNIBUS for transmission.
279 	 * Purge any stale data from this BDP, and start the otput.
280 	 */
281 	if (es->es_ifuba.ifu_flags & UBA_NEEDBDP)
282 		UBAPURGE(es->es_ifuba.ifu_uba, es->es_ifuba.ifu_w.ifrw_bdp);
283 	addr = (struct endevice *)ui->ui_addr;
284 	addr->en_oba = (int)es->es_ifuba.ifu_w.ifrw_info;
285 	addr->en_odelay = es->es_delay;
286 	addr->en_owc = -((es->es_olen + 1) >> 1);
287 	addr->en_ostat = EN_IEN|EN_GO;
288 	es->es_oactive = 1;
289 }
290 
291 /*
292  * Ethernet interface transmitter interrupt.
293  * Start another output if more data to send.
294  */
295 enxint(unit)
296 	int unit;
297 {
298 	register struct uba_device *ui = eninfo[unit];
299 	register struct en_softc *es = &en_softc[unit];
300 	register struct endevice *addr = (struct endevice *)ui->ui_addr;
301 
302 	if (es->es_oactive == 0)
303 		return;
304 	if (es->es_mask && (addr->en_ostat&EN_OERROR)) {
305 		es->es_if.if_oerrors++;
306 		endocoll(unit);
307 		return;
308 	}
309 	es->es_if.if_opackets++;
310 	es->es_oactive = 0;
311 	es->es_delay = 0;
312 	es->es_mask = ~0;
313 	if (es->es_ifuba.ifu_xtofree) {
314 		m_freem(es->es_ifuba.ifu_xtofree);
315 		es->es_ifuba.ifu_xtofree = 0;
316 	}
317 	if (es->es_if.if_snd.ifq_head == 0) {
318 		es->es_lastx = 256;		/* putatively illegal */
319 		return;
320 	}
321 	enstart(unit);
322 }
323 
324 /*
325  * Collision on ethernet interface.  Do exponential
326  * backoff, and retransmit.  If have backed off all
327  * the way print warning diagnostic, and drop packet.
328  */
329 encollide(unit)
330 	int unit;
331 {
332 	struct en_softc *es = &en_softc[unit];
333 
334 	es->es_if.if_collisions++;
335 	if (es->es_oactive == 0)
336 		return;
337 	endocoll(unit);
338 }
339 
340 endocoll(unit)
341 	int unit;
342 {
343 	register struct en_softc *es = &en_softc[unit];
344 
345 	/*
346 	 * Es_mask is a 16 bit number with n low zero bits, with
347 	 * n the number of backoffs.  When es_mask is 0 we have
348 	 * backed off 16 times, and give up.
349 	 */
350 	if (es->es_mask == 0) {
351 		printf("en%d: send error\n", unit);
352 		enxint(unit);
353 		return;
354 	}
355 	/*
356 	 * Another backoff.  Restart with delay based on n low bits
357 	 * of the interval timer.
358 	 */
359 	es->es_mask <<= 1;
360 	es->es_delay = mfpr(ICR) &~ es->es_mask;
361 	enstart(unit);
362 }
363 
364 #ifdef notdef
365 struct	sockproto enproto = { AF_ETHERLINK };
366 struct	sockaddr_en endst = { sizeof(endst), AF_ETHERLINK };
367 struct	sockaddr_en ensrc = { sizeof(ensrc), AF_ETHERLINK };
368 #endif
369 /*
370  * Ethernet interface receiver interrupt.
371  * If input error just drop packet.
372  * Otherwise purge input buffered data path and examine
373  * packet to determine type.  If can't determine length
374  * from type, then have to drop packet.  Othewise decapsulate
375  * packet based on type and pass to type specific higher-level
376  * input routine.
377  */
378 enrint(unit)
379 	int unit;
380 {
381 	register struct en_softc *es = &en_softc[unit];
382 	struct endevice *addr = (struct endevice *)eninfo[unit]->ui_addr;
383 	register struct en_header *en;
384     	struct mbuf *m;
385 	int len; short resid;
386 	register struct ifqueue *inq;
387 	int off, s;
388 
389 	es->es_if.if_ipackets++;
390 
391 	/*
392 	 * Purge BDP; drop if input error indicated.
393 	 */
394 	if (es->es_ifuba.ifu_flags & UBA_NEEDBDP)
395 		UBAPURGE(es->es_ifuba.ifu_uba, es->es_ifuba.ifu_r.ifrw_bdp);
396 	if (addr->en_istat&EN_IERROR) {
397 		es->es_if.if_ierrors++;
398 		goto setup;
399 	}
400 
401 	/*
402 	 * Calculate input data length.
403 	 * Get pointer to ethernet header (in input buffer).
404 	 * Deal with trailer protocol: if type is PUP trailer
405 	 * get true type from first 16-bit word past data.
406 	 * Remember that type was trailer by setting off.
407 	 */
408 	resid = addr->en_iwc;
409 	if (resid)
410 		resid |= 0176000;
411 	len = (((sizeof (struct en_header) + ENMRU) >> 1) + resid) << 1;
412 	len -= sizeof (struct en_header);
413 	if (len > ENMRU)
414 		goto setup;			/* sanity */
415 	en = (struct en_header *)(es->es_ifuba.ifu_r.ifrw_addr);
416 	en->en_type = ntohs(en->en_type);
417 #define	endataaddr(en, off, type)	((type)(((caddr_t)((en)+1)+(off))))
418 	if (en->en_type >= ENTYPE_TRAIL &&
419 	    en->en_type < ENTYPE_TRAIL+ENTYPE_NTRAILER) {
420 		off = (en->en_type - ENTYPE_TRAIL) * 512;
421 		if (off > ENMTU)
422 			goto setup;		/* sanity */
423 		en->en_type = ntohs(*endataaddr(en, off, u_short *));
424 		resid = ntohs(*(endataaddr(en, off+2, u_short *)));
425 		if (off + resid > len)
426 			goto setup;		/* sanity */
427 		len = off + resid;
428 	} else
429 		off = 0;
430 	if (len == 0)
431 		goto setup;
432 #ifdef ENF_SWABIPS
433 	if (es->es_if.if_flags & ENF_SWABIPS && en->en_type == ENTYPE_IP)
434 		enswab((caddr_t)(en + 1), (caddr_t)(en + 1), len);
435 #endif
436 	/*
437 	 * Pull packet off interface.  Off is nonzero if packet
438 	 * has trailing header; if_rubaget will then force this header
439 	 * information to be at the front, but we still have to drop
440 	 * the type and length which are at the front of any trailer data.
441 	 */
442 	m = if_rubaget(&es->es_ifuba, len, off, &es->es_if);
443 	if (m == 0)
444 		goto setup;
445 	switch (en->en_type) {
446 
447 #ifdef INET
448 	case ENTYPE_IP:
449 		schednetisr(NETISR_IP);
450 		inq = &ipintrq;
451 		break;
452 #endif
453 #ifdef PUP
454 	case ENTYPE_PUP:
455 		rpup_input(m);
456 		goto setup;
457 #endif
458 #ifdef NS
459 	case ETHERTYPE_NS:
460 		if (es->es_nsactive) {
461 			schednetisr(NETISR_NS);
462 			inq = &nsintrq;
463 		} else {
464 			m_freem(m);
465 			goto setup;
466 		}
467 		break;
468 #endif
469 
470 	default:
471 #ifdef notdef
472 		enproto.sp_protocol = en->en_type;
473 		endst.sen_host = en->en_dhost;
474 		endst.sen_net = ensrc.sen_net = es->es_if.if_net;
475 		ensrc.sen_host = en->en_shost;
476 		raw_input(m, &enproto,
477 		    (struct sockaddr *)&ensrc, (struct sockaddr *)&endst);
478 #else
479 		m_freem(m);
480 #endif
481 		goto setup;
482 	}
483 
484 	s = splimp();
485 	if (IF_QFULL(inq)) {
486 		IF_DROP(inq);
487 		m_freem(m);
488 	} else
489 		IF_ENQUEUE(inq, m);
490 	splx(s);
491 
492 setup:
493 	/*
494 	 * Reset for next packet.
495 	 */
496 	addr->en_iba = es->es_ifuba.ifu_r.ifrw_info;
497 	addr->en_iwc = -(sizeof (struct en_header) + ENMRU) >> 1;
498 	addr->en_istat = EN_IEN|EN_GO;
499 }
500 
501 /*
502  * Ethernet output routine.
503  * Encapsulate a packet of type family for the local net.
504  * Use trailer local net encapsulation if enough data in first
505  * packet leaves a multiple of 512 bytes of data in remainder.
506  */
507 oldenoutput(ifp, m0, dst)
508 	struct ifnet *ifp;
509 	struct mbuf *m0;
510 	struct sockaddr *dst;
511 {
512 	int type, dest, s, error;
513 	register struct mbuf *m = m0;
514 	register struct en_header *en;
515 	register int off;
516 
517 	if ((ifp->if_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING)) {
518 		error = ENETDOWN;
519 		goto bad;
520 	}
521 	switch (dst->sa_family) {
522 
523 #ifdef INET
524 	case AF_INET:
525 		{
526 		struct in_addr in;
527 
528 		in = ((struct sockaddr_in *)dst)->sin_addr;
529 		if (in_broadcast(in))
530 			dest = EN_BROADCAST;
531 		else
532 			dest = in_lnaof(in);
533 		}
534 		if (dest >= 0x100) {
535 			error = EPERM;		/* ??? */
536 			goto bad;
537 		}
538 		off = m->m_pkthdr.len - m->m_len;
539 		/* need per host negotiation */
540 		if ((ifp->if_flags & IFF_NOTRAILERS) == 0)
541 		if (off > 0 && (off & 0x1ff) == 0 &&
542 		    (m->m_flags & M_EXT) == 0 &&
543 		    m->m_data >= m->m_pktdat + 2 * sizeof (u_short)) {
544 			type = ENTYPE_TRAIL + (off>>9);
545 			m->m_data -= 2 * sizeof (u_short);
546 			m->m_len += 2 * sizeof (u_short);
547 			*mtod(m, u_short *) = htons((u_short)ENTYPE_IP);
548 			*(mtod(m, u_short *) + 1) = ntohs((u_short)m->m_len);
549 			goto gottrailertype;
550 		}
551 		type = ENTYPE_IP;
552 		off = 0;
553 		goto gottype;
554 #endif
555 #ifdef NS
556 	case AF_NS:
557 	{
558 		u_char *up;
559 
560 		type = ETHERTYPE_NS;
561 		up = ((struct sockaddr_ns *)dst)->sns_addr.x_host.c_host;
562 		if (*up & 1)
563 			dest = EN_BROADCAST;
564 		else
565 			dest = up[5];
566 
567 		off = 0;
568 		goto gottype;
569 	}
570 #endif
571 #ifdef PUP
572 	case AF_PUP:
573 		dest = ((struct sockaddr_pup *)dst)->spup_host;
574 		type = ENTYPE_PUP;
575 		off = 0;
576 		goto gottype;
577 #endif
578 
579 #ifdef notdef
580 	case AF_ETHERLINK:
581 		goto gotheader;
582 #endif
583 
584 	default:
585 		printf("en%d: can't handle af%d\n", ifp->if_unit,
586 			dst->sa_family);
587 		error = EAFNOSUPPORT;
588 		goto bad;
589 	}
590 
591 gottrailertype:
592 	/*
593 	 * Packet to be sent as trailer: move first packet
594 	 * (control information) to end of chain.
595 	 */
596 	while (m->m_next)
597 		m = m->m_next;
598 	m->m_next = m0;
599 	m = m0->m_next;
600 	m0->m_next = 0;
601 	m0 = m;
602 
603 gottype:
604 	/*
605 	 * Add local net header.  If no space in first mbuf,
606 	 * allocate another.
607 	 */
608 	M_PREPEND(m, sizeof (struct en_header), M_DONTWAIT);
609 	if (m == NULL)
610 		return (ENOBUFS);
611 	en = mtod(m, struct en_header *);
612 	/* add en_shost later */
613 	en->en_dhost = dest;
614 	en->en_type = htons((u_short)type);
615 
616 #ifdef notdef
617 gotheader:
618 #endif
619 	/*
620 	 * Queue message on interface, and start output if interface
621 	 * not yet active.
622 	 */
623 	s = splimp();
624 	if (IF_QFULL(&ifp->if_snd)) {
625 		IF_DROP(&ifp->if_snd);
626 		error = ENOBUFS;
627 		goto qfull;
628 	}
629 	IF_ENQUEUE(&ifp->if_snd, m);
630 	if (en_softc[ifp->if_unit].es_oactive == 0)
631 		enstart(ifp->if_unit);
632 	splx(s);
633 	return (0);
634 qfull:
635 	m0 = m;
636 	splx(s);
637 bad:
638 	m_freem(m0);
639 	return (error);
640 }
641 
642 /*
643  * Process an ioctl request.
644  */
645 enioctl(ifp, cmd, data)
646 	register struct ifnet *ifp;
647 	int cmd;
648 	caddr_t data;
649 {
650 	register struct en_softc *es = ((struct en_softc *)ifp);
651 	struct ifaddr *ifa = (struct ifaddr *) data;
652 	int s = splimp(), error = 0;
653 	struct endevice *enaddr;
654 
655 	switch (cmd) {
656 
657 	case SIOCSIFADDR:
658 		enaddr = (struct endevice *)eninfo[ifp->if_unit]->ui_addr;
659 		es->es_host = (~enaddr->en_addr) & 0xff;
660 		/*
661 		 * Attempt to check agreement of protocol address
662 		 * and board address.
663 		 */
664 		switch (ifa->ifa_addr->sa_family) {
665 		case AF_INET:
666 			if (in_lnaof(IA_SIN(ifa)->sin_addr) != es->es_host)
667 				return (EADDRNOTAVAIL);
668 			break;
669 #ifdef NS
670 		case AF_NS:
671 			if (IA_SNS(ifa)->sns_addr.x_host.c_host[5]
672 							!= es->es_host)
673 				return (EADDRNOTAVAIL);
674 			es->es_nsactive = 1;
675 			break;
676 #endif
677 		}
678 		ifp->if_flags |= IFF_UP;
679 		if ((ifp->if_flags & IFF_RUNNING) == 0)
680 			eninit(ifp->if_unit);
681 		break;
682 
683 	default:
684 		error = EINVAL;
685 		break;
686 	}
687 	splx(s);
688 	return (error);
689 }
690 
691 #ifdef ENF_SWABIPS
692 /*
693  * Swab bytes
694  * Jeffrey Mogul, Stanford
695  */
696 enswab(from, to, n)
697 	register unsigned char *from, *to;
698 	register int n;
699 {
700 	register unsigned long temp;
701 
702 	if ((n <= 0) || (n > 0xFFFF)) {
703 		printf("enswab: bad len %d\n", n);
704 		return;
705 	}
706 
707 	n >>= 1; n++;
708 #define	STEP	{temp = *from++;*to++ = *from++;*to++ = temp;}
709 	/* round to multiple of 8 */
710 	while ((--n) & 07)
711 		STEP;
712 	n >>= 3;
713 	while (--n >= 0) {
714 		STEP; STEP; STEP; STEP;
715 		STEP; STEP; STEP; STEP;
716 	}
717 }
718 #endif
719 #endif
720