gptboot.c revision 45309 
1/*
2 * Copyright (c) 1998 Robert Nordier
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms are freely
6 * permitted provided that the above copyright notice and this
7 * paragraph and the following disclaimer are duplicated in all
8 * such forms.
9 *
10 * This software is provided "AS IS" and without any express or
11 * implied warranties, including, without limitation, the implied
12 * warranties of merchantability and fitness for a particular
13 * purpose.
14 */
15
16/*
17 *	$Id: boot2.c,v 1.21 1999/03/31 08:28:42 joerg Exp $
18 */
19
20#include <sys/param.h>
21#include <sys/reboot.h>
22#include <sys/diskslice.h>
23#include <sys/disklabel.h>
24#include <sys/dirent.h>
25#include <machine/bootinfo.h>
26
27#include <ufs/ffs/fs.h>
28#include <ufs/ufs/dinode.h>
29
30#include <stdarg.h>
31
32#include <a.out.h>
33#include <elf.h>
34
35#include <btxv86.h>
36
37#include "lib.h"
38
39#define RBX_ASKNAME	0x0	/* -a */
40#define RBX_SINGLE	0x1	/* -s */
41#define RBX_DFLTROOT	0x5	/* -r */
42#define RBX_KDB 	0x6	/* -d */
43#define RBX_CONFIG	0xa	/* -c */
44#define RBX_VERBOSE	0xb	/* -v */
45#define RBX_SERIAL	0xc	/* -h */
46#define RBX_CDROM	0xd	/* -C */
47#define RBX_GDB 	0xf	/* -g */
48#define RBX_DUAL	0x1d	/* -D */
49#define RBX_PROBEKBD	0x1e	/* -P */
50
51#define RBX_MASK	0xffff
52
53#define PATH_CONFIG	"/boot.config"
54#define PATH_BOOT3	"/boot/loader"
55#define PATH_KERNEL	"/kernel"
56
57#define ARGS		0x900
58#define NOPT		11
59#define BSIZEMAX	8192
60#define NDEV		5
61#define MEM_BASE	0x12
62#define MEM_EXT 	0x15
63#define V86_CY(x)	((x) & 1)
64#define V86_ZR(x)	((x) & 0x40)
65
66#define DRV_HARD	0x80
67#define DRV_MASK	0x7f
68
69#define MAJ_WD		0
70#define MAJ_WFD 	1
71#define MAJ_FD		2
72#define MAJ_DA		4
73
74extern uint32_t _end;
75
76static const char optstr[NOPT] = "DhaCcdgPrsv";
77static const unsigned char flags[NOPT] = {
78    RBX_DUAL,
79    RBX_SERIAL,
80    RBX_ASKNAME,
81    RBX_CDROM,
82    RBX_CONFIG,
83    RBX_KDB,
84    RBX_GDB,
85    RBX_PROBEKBD,
86    RBX_DFLTROOT,
87    RBX_SINGLE,
88    RBX_VERBOSE
89};
90
91static const char *const dev_nm[] = {"wd", "  ", "fd", "  ", "da"};
92
93static struct dsk {
94    unsigned drive;
95    unsigned type;
96    unsigned unit;
97    unsigned slice;
98    unsigned part;
99    unsigned start;
100    int init;
101    int meta;
102} dsk;
103static char cmd[512];
104static char kname[1024];
105static uint32_t opts;
106static struct bootinfo bootinfo;
107static int ls;
108static uint32_t fs_off;
109static uint8_t ioctrl = 0x1;
110
111void exit(int);
112static void load(const char *);
113static int parse(char *);
114static void readfile(const char *, void *, size_t);
115static ino_t lookup(const char *);
116static int fsfind(const char *, ino_t *);
117static int xfsread(ino_t, void *, size_t);
118static ssize_t fsread(ino_t, void *, size_t);
119static int dskread(void *, unsigned, unsigned);
120static int printf(const char *,...);
121static void getstr(char *, int);
122static int putchar(int);
123static int getchar(void);
124static void *memcpy(void *, const void *, size_t);
125static int strcmp(const char *, const char *);
126static void *malloc(size_t);
127static uint32_t memsize(int);
128static uint32_t drvinfo(int);
129static int drvread(void *, unsigned, unsigned);
130static int keyhit(unsigned);
131static int xputc(int);
132static int xgetc(int);
133static void putc(int);
134static int getc(int);
135
136int
137main(void)
138{
139    int autoboot, i;
140
141    v86.ctl = V86_FLAGS;
142    dsk.drive = *(uint8_t *)PTOV(ARGS);
143    dsk.type = dsk.drive & DRV_HARD ? MAJ_WD : MAJ_FD;
144    dsk.unit = dsk.drive & DRV_MASK;
145    dsk.slice = *(uint8_t *)PTOV(ARGS + 1) + 1;
146    bootinfo.bi_version = BOOTINFO_VERSION;
147    bootinfo.bi_size = sizeof(bootinfo);
148    bootinfo.bi_basemem = memsize(MEM_BASE);
149    bootinfo.bi_extmem = memsize(MEM_EXT);
150    bootinfo.bi_memsizes_valid++;
151    for (i = 0; i < N_BIOS_GEOM; i++)
152	bootinfo.bi_bios_geom[i] = drvinfo(i);
153    autoboot = 2;
154    readfile(PATH_CONFIG, cmd, sizeof(cmd));
155    if (*cmd) {
156	printf("%s: %s", PATH_CONFIG, cmd);
157	if (parse(cmd))
158	    autoboot = 0;
159	*cmd = 0;
160    }
161    if (autoboot && !*kname) {
162	if (autoboot == 2) {
163	    memcpy(kname, PATH_BOOT3, sizeof(PATH_BOOT3));
164	    if (!keyhit(0x37)) {
165		load(kname);
166		autoboot = 1;
167	    }
168	}
169	if (autoboot == 1)
170	    memcpy(kname, PATH_KERNEL, sizeof(PATH_KERNEL));
171    }
172    for (;;) {
173	printf(" \n"
174	       "Default: %u:%s(%u,%c)%s\n"
175	       "boot: ",
176	       dsk.drive & DRV_MASK, dev_nm[dsk.type], dsk.unit,
177	       'a' + dsk.part, kname);
178	if (ioctrl & 0x2)
179	    sio_flush();
180	if (!autoboot || keyhit(0x5a))
181	    getstr(cmd, sizeof(cmd));
182	else
183	    putchar('\n');
184	autoboot = 0;
185	if (parse(cmd))
186	    putchar('\a');
187	else
188	    load(kname);
189    }
190}
191
192void
193exit(int x)
194{
195}
196
197static void
198load(const char *fname)
199{
200    union {
201	struct exec ex;
202	Elf32_Ehdr eh;
203    } hdr;
204    Elf32_Phdr ep[2];
205    Elf32_Shdr es[2];
206    caddr_t p;
207    ino_t ino;
208    uint32_t addr, x;
209    int fmt, i, j;
210
211    if (!(ino = lookup(fname))) {
212	if (!ls)
213	    printf("No %s\n", fname);
214	return;
215    }
216    if (xfsread(ino, &hdr, sizeof(hdr)))
217	return;
218    if (N_GETMAGIC(hdr.ex) == ZMAGIC)
219	fmt = 0;
220    else if (IS_ELF(hdr.eh))
221	fmt = 1;
222    else {
223	printf("Invalid %s\n", "format");
224	return;
225    }
226    if (fmt == 0) {
227	addr = hdr.ex.a_entry & 0xffffff;
228	p = PTOV(addr);
229	fs_off = PAGE_SIZE;
230	if (xfsread(ino, p, hdr.ex.a_text))
231	    return;
232	p += roundup2(hdr.ex.a_text, PAGE_SIZE);
233	if (xfsread(ino, p, hdr.ex.a_data))
234	    return;
235	p += hdr.ex.a_data + roundup2(hdr.ex.a_bss, PAGE_SIZE);
236	bootinfo.bi_symtab = VTOP(p);
237	memcpy(p, &hdr.ex.a_syms, sizeof(hdr.ex.a_syms));
238	p += sizeof(hdr.ex.a_syms);
239	if (hdr.ex.a_syms) {
240	    if (xfsread(ino, p, hdr.ex.a_syms))
241		return;
242	    p += hdr.ex.a_syms;
243	    if (xfsread(ino, p, sizeof(int)))
244		return;
245	    x = *(uint32_t *)p;
246	    p += sizeof(int);
247	    x -= sizeof(int);
248	    if (xfsread(ino, p, x))
249		return;
250	    p += x;
251	}
252    } else {
253	fs_off = hdr.eh.e_phoff;
254	for (j = i = 0; i < hdr.eh.e_phoff && j < 2; i++) {
255	    if (xfsread(ino, ep + j, sizeof(ep[0])))
256		return;
257	    if (ep[j].p_type == PT_LOAD)
258		j++;
259	}
260	for (i = 0; i < 2; i++) {
261	    p = PTOV(ep[i].p_paddr & 0xffffff);
262	    fs_off = ep[i].p_offset;
263	    if (xfsread(ino, p, ep[i].p_filesz))
264		return;
265	}
266	p += roundup2(ep[1].p_memsz, PAGE_SIZE);
267	bootinfo.bi_symtab = VTOP(p);
268	if (hdr.eh.e_shnum == hdr.eh.e_shstrndx + 3) {
269	    fs_off = hdr.eh.e_shoff + sizeof(es[0]) *
270		(hdr.eh.e_shstrndx + 1);
271	    if (xfsread(ino, &es, sizeof(es)))
272		return;
273	    for (i = 0; i < 2; i++) {
274		memcpy(p, &es[i].sh_size, sizeof(es[i].sh_size));
275		p += sizeof(es[i].sh_size);
276		fs_off = es[i].sh_offset;
277		if (xfsread(ino, p, es[i].sh_size))
278		    return;
279		p += es[i].sh_size;
280	    }
281	}
282	addr = hdr.eh.e_entry & 0xffffff;
283    }
284    bootinfo.bi_esymtab = VTOP(p);
285    bootinfo.bi_kernelname = VTOP(fname);
286    bootinfo.bi_bios_dev = dsk.drive;
287    __exec((caddr_t)addr, RB_BOOTINFO | (opts & RBX_MASK),
288	   MAKEBOOTDEV(dsk.type, 0, dsk.slice, dsk.unit, dsk.part),
289	   0, 0, 0, VTOP(&bootinfo));
290}
291
292static int
293parse(char *arg)
294{
295    char *p, *q;
296    int drv, c, i;
297
298    while ((c = *arg++)) {
299	if (c == ' ')
300	    continue;
301	for (p = arg; *p && *p != '\n' && *p != ' '; p++);
302	if (*p)
303	    *p++ = 0;
304	if (c == '-') {
305	    while ((c = *arg++)) {
306		for (i = 0; c != optstr[i]; i++)
307		    if (i == NOPT - 1)
308			return -1;
309		opts ^= 1 << flags[i];
310	    }
311	    if (opts & 1 << RBX_PROBEKBD) {
312		i = *(uint8_t *)PTOV(0x496) & 0x10;
313		printf("Keyboard: %s\n", i ? "yes" : "no");
314		if (!i)
315		    opts |= 1 << RBX_DUAL | 1 << RBX_SERIAL;
316		opts &= ~(1 << RBX_PROBEKBD);
317	    }
318	    ioctrl = opts & 1 << RBX_DUAL ? 0x3 :
319		     opts & 1 << RBX_SERIAL ? 0x2 : 0x1;
320	    if (ioctrl & 0x2)
321	        sio_init();
322	} else {
323	    for (q = arg--; *q && *q != '('; q++);
324	    if (*q) {
325		drv = -1;
326		if (arg[1] == ':') {
327		    if (*arg < '0' || *arg > '9')
328			return -1;
329		    drv = *arg - '0';
330		    arg += 2;
331		}
332		if (q - arg != 2)
333		    return -1;
334		for (i = 0; arg[0] != dev_nm[i][0] ||
335			    arg[1] != dev_nm[i][1]; i++)
336		    if (i == NDEV - 1)
337			return -1;
338		dsk.type = i;
339		arg += 3;
340		if (arg[1] != ',' || *arg < '0' || *arg > '9')
341		    return -1;
342		dsk.unit = *arg - '0';
343		arg += 2;
344		dsk.slice = WHOLE_DISK_SLICE;
345		if (arg[1] == ',') {
346		    if (*arg < '0' || *arg > '0' + NDOSPART)
347			return -1;
348		    if ((dsk.slice = *arg - '0'))
349			dsk.slice++;
350		    arg += 2;
351		}
352		if (arg[1] != ')' || *arg < 'a' || *arg > 'p')
353		    return -1;
354		dsk.part = *arg - 'a';
355		arg += 2;
356		if (drv == -1)
357		    drv = dsk.unit;
358		dsk.drive = (dsk.type == MAJ_WD ||
359			     dsk.type == MAJ_DA ? DRV_HARD : 0) + drv;
360		dsk.meta = 0;
361		fsread(0, NULL, 0);
362	    }
363	    if ((i = p - arg - !*(p - 1))) {
364		if (i >= sizeof(kname))
365		    return -1;
366		memcpy(kname, arg, i + 1);
367	    }
368	}
369	arg = p;
370    }
371    return 0;
372}
373
374static void
375readfile(const char *fname, void *buf, size_t size)
376{
377    ino_t ino;
378
379    if ((ino = lookup(fname)))
380	fsread(ino, buf, size);
381}
382
383static ino_t
384lookup(const char *path)
385{
386    char name[MAXNAMLEN + 1];
387    const char *s;
388    ino_t ino;
389    ssize_t n;
390    int dt;
391
392    ino = ROOTINO;
393    dt = DT_DIR;
394    for (;;) {
395	if (*path == '/')
396	    path++;
397	if (!*path)
398	    break;
399	for (s = path; *s && *s != '/'; s++);
400	if ((n = s - path) > MAXNAMLEN)
401	    return 0;
402	ls = *path == '?' && n == 1 && !*s;
403	memcpy(name, path, n);
404	name[n] = 0;
405	if ((dt = fsfind(name, &ino)) <= 0)
406	    break;
407	path = s;
408    }
409    return dt == DT_REG ? ino : 0;
410}
411
412static int
413fsfind(const char *name, ino_t * ino)
414{
415    char buf[DEV_BSIZE];
416    struct dirent *d;
417    char *s;
418    ssize_t n;
419
420    fs_off = 0;
421    while ((n = fsread(*ino, buf, DEV_BSIZE)) > 0)
422	for (s = buf; s < buf + DEV_BSIZE;) {
423	    d = (void *)s;
424	    if (ls)
425		printf("%s ", d->d_name);
426	    else if (!strcmp(name, d->d_name)) {
427		*ino = d->d_fileno;
428		return d->d_type;
429	    }
430	    s += d->d_reclen;
431	}
432    if (n != -1 && ls)
433	putchar('\n');
434    return 0;
435}
436
437static int
438xfsread(ino_t inode, void *buf, size_t nbyte)
439{
440    if (fsread(inode, buf, nbyte) != nbyte) {
441	printf("Invalid %s\n", "format");
442	return -1;
443    }
444    return 0;
445}
446
447static ssize_t
448fsread(ino_t inode, void *buf, size_t nbyte)
449{
450    static struct fs fs;
451    static struct dinode din;
452    static char *blkbuf;
453    static ufs_daddr_t *indbuf;
454    static ino_t inomap;
455    static ufs_daddr_t blkmap, indmap;
456    static unsigned fsblks;
457    char *s;
458    ufs_daddr_t lbn, addr;
459    size_t n, nb, off;
460
461    if (!dsk.meta) {
462	if (!blkbuf)
463	    blkbuf = malloc(BSIZEMAX);
464	inomap = 0;
465	if (dskread(blkbuf, SBOFF / DEV_BSIZE, SBSIZE / DEV_BSIZE))
466	    return -1;
467	memcpy(&fs, blkbuf, sizeof(fs));
468	if (fs.fs_magic != FS_MAGIC) {
469	    printf("Not ufs\n");
470	    return -1;
471	}
472	fsblks = fs.fs_bsize >> DEV_BSHIFT;
473	dsk.meta++;
474    }
475    if (!inode)
476	return 0;
477    if (inomap != inode) {
478	if (dskread(blkbuf, fsbtodb(&fs, ino_to_fsba(&fs, inode)),
479		    fsblks))
480	    return -1;
481	din = ((struct dinode *)blkbuf)[inode % INOPB(&fs)];
482	inomap = inode;
483	fs_off = 0;
484	blkmap = indmap = 0;
485    }
486    s = buf;
487    if (nbyte > (n = din.di_size - fs_off))
488	nbyte = n;
489    nb = nbyte;
490    while (nb) {
491	lbn = lblkno(&fs, fs_off);
492	if (lbn < NDADDR)
493	    addr = din.di_db[lbn];
494	else {
495	    if (indmap != din.di_ib[0]) {
496		if (!indbuf)
497		    indbuf = malloc(BSIZEMAX);
498		if (dskread(indbuf, fsbtodb(&fs, din.di_ib[0]),
499			    fsblks))
500		    return -1;
501		indmap = din.di_ib[0];
502	    }
503	    addr = indbuf[(lbn - NDADDR) % NINDIR(&fs)];
504	}
505	n = dblksize(&fs, &din, lbn);
506	if (blkmap != addr) {
507	    if (dskread(blkbuf, fsbtodb(&fs, addr), n >> DEV_BSHIFT))
508		return -1;
509	    blkmap = addr;
510	}
511	off = blkoff(&fs, fs_off);
512	n -= off;
513	if (n > nb)
514	    n = nb;
515	memcpy(s, blkbuf + off, n);
516	s += n;
517	fs_off += n;
518	nb -= n;
519    }
520    return nbyte;
521}
522
523static int
524dskread(void *buf, unsigned lba, unsigned nblk)
525{
526    static char *sec;
527    struct dos_partition *dp;
528    struct disklabel *d;
529    unsigned sl, i;
530
531    if (!dsk.meta) {
532	if (!sec)
533	    sec = malloc(DEV_BSIZE);
534	dsk.start = 0;
535	if (drvread(sec, DOSBBSECTOR, 1))
536	    return -1;
537	dp = (void *)(sec + DOSPARTOFF);
538	sl = dsk.slice;
539	if (sl < BASE_SLICE) {
540	    for (i = 0; i < NDOSPART; i++)
541		if (dp[i].dp_typ == DOSPTYP_386BSD &&
542		    (dp[i].dp_flag & 0x80 || sl < BASE_SLICE)) {
543		    sl = BASE_SLICE + i;
544		    if (dp[i].dp_flag & 0x80 ||
545			dsk.slice == COMPATIBILITY_SLICE)
546			break;
547		}
548	    if (dsk.slice == WHOLE_DISK_SLICE)
549		dsk.slice = sl;
550	}
551	if (sl != WHOLE_DISK_SLICE) {
552	    if (sl != COMPATIBILITY_SLICE)
553		dp += sl - BASE_SLICE;
554	    if (dp->dp_typ != DOSPTYP_386BSD) {
555		printf("Invalid %s\n", "slice");
556		return -1;
557	    }
558	    dsk.start = dp->dp_start;
559	}
560	if (drvread(sec, dsk.start + LABELSECTOR, 1))
561		return -1;
562	d = (void *)(sec + LABELOFFSET);
563	if (d->d_magic != DISKMAGIC || d->d_magic2 != DISKMAGIC) {
564	    if (dsk.part != RAW_PART) {
565		printf("Invalid %s\n", "label");
566		return -1;
567	    }
568	} else {
569	    if (!dsk.init) {
570		if (d->d_type == DTYPE_SCSI)
571		    dsk.type = MAJ_DA;
572		dsk.init++;
573	    }
574	    if (dsk.part >= d->d_npartitions ||
575		!d->d_partitions[dsk.part].p_size) {
576		printf("Invalid %s\n", "partition");
577		return -1;
578	    }
579	    dsk.start = d->d_partitions[dsk.part].p_offset;
580	}
581    }
582    return drvread(buf, dsk.start + lba, nblk);
583}
584
585static int
586printf(const char *fmt,...)
587{
588    static const char digits[16] = "0123456789abcdef";
589    va_list ap;
590    char buf[10];
591    char *s;
592    unsigned r, u;
593    int c;
594
595    va_start(ap, fmt);
596    while ((c = *fmt++)) {
597	if (c == '%') {
598	    c = *fmt++;
599	    switch (c) {
600	    case 'c':
601		putchar(va_arg(ap, int));
602		continue;
603	    case 's':
604		for (s = va_arg(ap, char *); *s; s++)
605		    putchar(*s);
606		continue;
607	    case 'u':
608	    case 'x':
609		r = c == 'u' ? 10U : 16U;
610		u = va_arg(ap, unsigned);
611		s = buf;
612		do
613		    *s++ = digits[u % r];
614		while (u /= r);
615		while (--s >= buf)
616		    putchar(*s);
617		continue;
618	    }
619	}
620	putchar(c);
621    }
622    va_end(ap);
623    return 0;
624}
625
626static void
627getstr(char *str, int size)
628{
629    char *s;
630    int c;
631
632    s = str;
633    do {
634	switch (c = getchar()) {
635	case 0:
636	    break;
637	case '\b':
638	case '\177':
639	    if (s > str) {
640		s--;
641		putchar('\b');
642		putchar(' ');
643	    } else
644		c = 0;
645	    break;
646	case '\n':
647	    *s = 0;
648	    break;
649	default:
650	    if (s - str < size - 1)
651		*s++ = c;
652	}
653	if (c)
654	    putchar(c);
655    } while (c != '\n');
656}
657
658static int
659putchar(int c)
660{
661    if (c == '\n')
662	xputc('\r');
663    return xputc(c);
664}
665
666static int
667getchar(void)
668{
669    int c;
670
671    c = xgetc(0);
672    if (c == '\r')
673	c = '\n';
674    return c;
675}
676
677static void *
678memcpy(void *dst, const void *src, size_t size)
679{
680    const char *s;
681    char *d;
682
683    for (d = dst, s = src; size; size--)
684	*d++ = *s++;
685    return dst;
686}
687
688static int
689strcmp(const char *s1, const char *s2)
690{
691    for (; *s1 == *s2 && *s1; s1++, s2++);
692    return (u_char)*s1 - (u_char)*s2;
693}
694
695static void *
696malloc(size_t size)
697{
698    static uint32_t next;
699    void *p;
700
701    if (!next)
702	next = roundup2(__base + _end, 0x10000) - __base;
703    p = (void *)next;
704    next += size;
705    return p;
706}
707
708static uint32_t
709memsize(int type)
710{
711    v86.addr = type;
712    v86.eax = 0x8800;
713    v86int();
714    return v86.eax;
715}
716
717static uint32_t
718drvinfo(int drive)
719{
720    v86.addr = 0x13;
721    v86.eax = 0x800;
722    v86.edx = DRV_HARD + drive;
723    v86int();
724    if (V86_CY(v86.efl))
725	return 0x4f010f;
726    return ((v86.ecx & 0xc0) << 18) | ((v86.ecx & 0xff00) << 8) |
727	   (v86.edx & 0xff00) | (v86.ecx & 0x3f);
728}
729
730static int
731drvread(void *buf, unsigned lba, unsigned nblk)
732{
733    static unsigned c = 0x2d5c7c2f;
734
735    printf("%c\b", c = c << 8 | c >> 24);
736    v86.ctl = V86_ADDR | V86_CALLF | V86_FLAGS;
737    v86.addr = 0x704;		/* call to xread in boot1 */
738    v86.es = VTOPSEG(buf);
739    v86.eax = lba;
740    v86.ebx = VTOPOFF(buf);
741    v86.ecx = lba >> 16;
742    v86.edx = nblk << 8 | dsk.drive;
743    v86int();
744    v86.ctl = V86_FLAGS;
745    if (V86_CY(v86.efl)) {
746	printf("Disk error 0x%x (lba=0x%x)\n", v86.eax >> 8 & 0xff,
747	       lba);
748	return -1;
749    }
750    return 0;
751}
752
753static int
754keyhit(unsigned ticks)
755{
756    uint32_t t0, t1;
757
758    t0 = 0;
759    for (;;) {
760	if (xgetc(1))
761	    return 1;
762	t1 = *(uint32_t *)PTOV(0x46c);
763	if (!t0)
764	    t0 = t1;
765	if (t1 < t0 || t1 >= t0 + ticks)
766	    return 0;
767    }
768}
769
770static int
771xputc(int c)
772{
773    if (ioctrl & 0x1)
774	putc(c);
775    if (ioctrl & 0x2)
776	sio_putc(c);
777    return c;
778}
779
780static int
781xgetc(int fn)
782{
783    for (;;) {
784	if (ioctrl & 0x1 && getc(1))
785	    return fn ? 1 : getc(0);
786	if (ioctrl & 0x2 && sio_ischar())
787	    return fn ? 1 : sio_getc();
788	if (fn)
789	    return 0;
790    }
791}
792
793static void
794putc(int c)
795{
796    v86.addr = 0x10;
797    v86.eax = 0xe00 | (c & 0xff);
798    v86.ebx = 0x7;
799    v86int();
800}
801
802static int
803getc(int fn)
804{
805    v86.addr = 0x16;
806    v86.eax = fn << 8;
807    v86int();
808    return fn == 0 ? v86.eax & 0xff : !V86_ZR(v86.efl);
809}
810