1 #include <u.h> 2 #include <libc.h> 3 #include <ctype.h> 4 #include <disk.h> 5 6 /* 7 * disk types (all MFM encoding) 8 */ 9 typedef struct Type Type; 10 struct Type 11 { 12 char *name; 13 int bytes; /* bytes/sector */ 14 int sectors; /* sectors/track */ 15 int heads; /* number of heads */ 16 int tracks; /* tracks/disk */ 17 int media; /* media descriptor byte */ 18 int cluster; /* default cluster size */ 19 }; 20 Type floppytype[] = 21 { 22 { "3½HD", 512, 18, 2, 80, 0xf0, 1, }, 23 { "3½DD", 512, 9, 2, 80, 0xf9, 2, }, 24 { "3½QD", 512, 36, 2, 80, 0xf9, 2, }, /* invented */ 25 { "5¼HD", 512, 15, 2, 80, 0xf9, 1, }, 26 { "5¼DD", 512, 9, 2, 40, 0xfd, 2, }, 27 { "hard", 512, 0, 0, 0, 0xf8, 4, }, 28 }; 29 30 #define NTYPES (sizeof(floppytype)/sizeof(Type)) 31 32 typedef struct Dosboot Dosboot; 33 struct Dosboot{ 34 uchar magic[3]; /* really an x86 JMP instruction */ 35 uchar version[8]; 36 uchar sectsize[2]; 37 uchar clustsize; 38 uchar nresrv[2]; 39 uchar nfats; 40 uchar rootsize[2]; 41 uchar volsize[2]; 42 uchar mediadesc; 43 uchar fatsize[2]; 44 uchar trksize[2]; 45 uchar nheads[2]; 46 uchar nhidden[4]; 47 uchar bigvolsize[4]; 48 uchar driveno; 49 uchar reserved0; 50 uchar bootsig; 51 uchar volid[4]; 52 uchar label[11]; 53 uchar type[8]; 54 }; 55 #define PUTSHORT(p, v) { (p)[1] = (v)>>8; (p)[0] = (v); } 56 #define PUTLONG(p, v) { PUTSHORT((p), (v)); PUTSHORT((p)+2, (v)>>16); } 57 #define GETSHORT(p) (((p)[1]<<8)|(p)[0]) 58 #define GETLONG(p) (((ulong)GETSHORT(p+2)<<16)|(ulong)GETSHORT(p)) 59 60 typedef struct Dosdir Dosdir; 61 struct Dosdir 62 { 63 uchar name[8]; 64 uchar ext[3]; 65 uchar attr; 66 uchar reserved[10]; 67 uchar time[2]; 68 uchar date[2]; 69 uchar start[2]; 70 uchar length[4]; 71 }; 72 73 #define DRONLY 0x01 74 #define DHIDDEN 0x02 75 #define DSYSTEM 0x04 76 #define DVLABEL 0x08 77 #define DDIR 0x10 78 #define DARCH 0x20 79 80 /* 81 * the boot program for the boot sector. 82 */ 83 int nbootprog = 188; /* no. of bytes of boot program, including the first 0x3E */ 84 uchar bootprog[512] = 85 { 86 [0x000] 0xEB, 0x3C, 0x90, 0x00, 0x00, 0x00, 0x00, 0x00, 87 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 88 [0x03E] 0xFA, 0xFC, 0x8C, 0xC8, 0x8E, 0xD8, 0x8E, 0xD0, 89 0xBC, 0x00, 0x7C, 0xBE, 0x77, 0x7C, 0xE8, 0x19, 90 0x00, 0x33, 0xC0, 0xCD, 0x16, 0xBB, 0x40, 0x00, 91 0x8E, 0xC3, 0xBB, 0x72, 0x00, 0xB8, 0x34, 0x12, 92 0x26, 0x89, 0x07, 0xEA, 0x00, 0x00, 0xFF, 0xFF, 93 0xEB, 0xD6, 0xAC, 0x0A, 0xC0, 0x74, 0x09, 0xB4, 94 0x0E, 0xBB, 0x07, 0x00, 0xCD, 0x10, 0xEB, 0xF2, 95 0xC3, 'N', 'o', 't', ' ', 'a', ' ', 'b', 96 'o', 'o', 't', 'a', 'b', 'l', 'e', ' ', 97 'd', 'i', 's', 'c', ' ', 'o', 'r', ' ', 98 'd', 'i', 's', 'c', ' ', 'e', 'r', 'r', 99 'o', 'r', '\r', '\n', 'P', 'r', 'e', 's', 100 's', ' ', 'a', 'l', 'm', 'o', 's', 't', 101 ' ', 'a', 'n', 'y', ' ', 'k', 'e', 'y', 102 ' ', 't', 'o', ' ', 'r', 'e', 'b', 'o', 103 'o', 't', '.', '.', '.', 0x00, 0x00, 0x00, 104 [0x1F0] 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 105 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x55, 0xAA, 106 }; 107 108 char *dev; 109 int clustersize; 110 uchar *fat; /* the fat */ 111 int fatbits; 112 int fatsecs; 113 int fatlast; /* last cluster allocated */ 114 int clusters; 115 int fatsecs; 116 vlong volsecs; 117 uchar *root; /* first block of root */ 118 int rootsecs; 119 int rootfiles; 120 int rootnext; 121 int nresrv = 1; 122 int chatty; 123 vlong length; 124 Type *t; 125 int fflag; 126 int hflag; 127 int xflag; 128 char *file; 129 char *pbs; 130 char *type; 131 char *bootfile; 132 int dos; 133 134 enum 135 { 136 Sof = 1, /* start of file */ 137 Eof = 2, /* end of file */ 138 }; 139 140 void dosfs(int, int, Disk*, char*, int, char*[], int); 141 ulong clustalloc(int); 142 void addrname(uchar*, Dir*, char*, ulong); 143 void sanitycheck(Disk*); 144 145 void 146 usage(void) 147 { 148 fprint(2, "usage: disk/format [-df] [-b bootblock] [-c csize] [-l label] [-r nresrv] [-t type] disk [files ...]\n"); 149 exits("usage"); 150 } 151 152 void 153 fatal(char *fmt, ...) 154 { 155 char err[128]; 156 va_list arg; 157 158 va_start(arg, fmt); 159 vsnprint(err, sizeof(err), fmt, arg); 160 va_end(arg); 161 fprint(2, "format: %s\n", err); 162 if(fflag && file) 163 remove(file); 164 exits(err); 165 } 166 167 void 168 main(int argc, char **argv) 169 { 170 int n, writepbs; 171 int fd; 172 char buf[512]; 173 char label[11]; 174 char *a; 175 Disk *disk; 176 177 dos = 0; 178 type = nil; 179 clustersize = 0; 180 writepbs = 0; 181 memmove(label, "CYLINDRICAL", sizeof(label)); 182 ARGBEGIN { 183 case 'c': 184 clustersize = atoi(ARGF()); 185 break; 186 case 'd': 187 dos = 1; 188 writepbs = 1; 189 break; 190 case 'f': 191 fflag = 1; 192 break; 193 case 'l': 194 a = ARGF(); 195 n = strlen(a); 196 if(n > sizeof(label)) 197 n = sizeof(label); 198 memmove(label, a, n); 199 while(n < sizeof(label)) 200 label[n++] = ' '; 201 break; 202 case 'b': 203 pbs = ARGF(); 204 writepbs = 1; 205 break; 206 case 'r': 207 nresrv = atoi(ARGF()); 208 break; 209 case 't': 210 type = ARGF(); 211 break; 212 case 'v': 213 chatty++; 214 break; 215 case 'x': 216 xflag = 1; 217 break; 218 default: 219 usage(); 220 } ARGEND 221 222 if(argc < 1) 223 usage(); 224 225 disk = opendisk(argv[0], 0, 0); 226 if(disk == nil) { 227 if(fflag) { 228 if((fd = create(argv[0], ORDWR, 0666)) >= 0) { 229 file = argv[0]; 230 close(fd); 231 disk = opendisk(argv[0], 0, 0); 232 } 233 } 234 } 235 if(disk == nil) 236 fatal("opendisk: %r"); 237 238 if(disk->type == Tfile) 239 fflag = 1; 240 241 if(type == nil) { 242 switch(disk->type){ 243 case Tfile: 244 type = "3½HD"; 245 break; 246 case Tfloppy: 247 seek(disk->ctlfd, 0, 0); 248 n = read(disk->ctlfd, buf, 10); 249 if(n <= 0 || n >= 10) 250 fatal("reading floppy type"); 251 buf[n] = 0; 252 type = strdup(buf); 253 if(type == nil) 254 fatal("out of memory"); 255 break; 256 case Tsd: 257 type = "hard"; 258 break; 259 default: 260 type = "unknown"; 261 break; 262 } 263 } 264 265 if(!fflag && disk->type == Tfloppy) 266 if(fprint(disk->ctlfd, "format %s", type) < 0) 267 fatal("formatting floppy as %s: %r", type); 268 269 if(disk->type != Tfloppy) 270 sanitycheck(disk); 271 272 /* check that everything will succeed */ 273 dosfs(dos, writepbs, disk, label, argc-1, argv+1, 0); 274 275 /* commit */ 276 dosfs(dos, writepbs, disk, label, argc-1, argv+1, 1); 277 278 print("used %lld bytes\n", fatlast*clustersize*disk->secsize); 279 exits(0); 280 } 281 282 /* 283 * Look for a partition table on sector 1, as would be the 284 * case if we were erroneously formatting 9fat without -r 2. 285 * If it's there and nresrv is not big enough, complain and exit. 286 * I've blown away my partition table too many times. 287 */ 288 void 289 sanitycheck(Disk *disk) 290 { 291 char buf[512]; 292 int bad; 293 294 if(xflag) 295 return; 296 297 bad = 0; 298 if(dos && nresrv < 2 && seek(disk->fd, disk->secsize, 0) == disk->secsize 299 && read(disk->fd, buf, sizeof(buf)) >= 5 && strncmp(buf, "part ", 5) == 0) { 300 fprint(2, 301 "there's a plan9 partition on the disk\n" 302 "and you didn't specify -r 2 (or greater).\n" 303 "either specify -r 2 or -x to disable this check.\n"); 304 bad = 1; 305 } 306 307 if(disk->type == Tsd && disk->offset == 0LL) { 308 fprint(2, 309 "you're attempting to format your disk (/dev/sdXX/data)\n" 310 "rather than a partition like /dev/sdXX/9fat;\n" 311 "this is likely a mistake. specify -x to disable this check.\n"); 312 bad = 1; 313 } 314 315 if(bad) 316 exits("failed disk sanity check"); 317 } 318 319 /* 320 * Return the BIOS drive number for the disk. 321 * 0x80 is the first fixed disk, 0x81 the next, etc. 322 * We map sdC0=0x80, sdC1=0x81, sdD0=0x82, sdD1=0x83 323 */ 324 int 325 getdriveno(Disk *disk) 326 { 327 char buf[64], *p; 328 329 if(disk->type != Tsd) 330 return 0x80; /* first hard disk */ 331 332 if(fd2path(disk->fd, buf, sizeof(buf)) < 0) 333 return 0x80; 334 335 /* 336 * The name is of the format #SsdC0/foo 337 * or /dev/sdC0/foo. 338 * So that we can just look for /sdC0, turn 339 * #SsdC0/foo into #/sdC0/foo. 340 */ 341 if(buf[0] == '#' && buf[1] == 'S') 342 buf[1] = '/'; 343 344 for(p=buf; *p; p++) 345 if(p[0] == 's' && p[1] == 'd' && (p[2]=='C' || p[2]=='D') && (p[3]=='0' || p[3]=='1')) 346 return 0x80 + (p[2]-'C')*2 + (p[3]-'0'); 347 348 return 0x80; 349 } 350 351 void 352 dosfs(int dofat, int dopbs, Disk *disk, char *label, int argc, char *argv[], int commit) 353 { 354 char r[16]; 355 Dosboot *b; 356 uchar *buf, *pbsbuf, *p; 357 Dir *d; 358 int npbs, n, sysfd; 359 ulong x; 360 vlong length; 361 vlong secsize; 362 363 if(dofat == 0 && dopbs == 0) 364 return; 365 366 for(t = floppytype; t < &floppytype[NTYPES]; t++) 367 if(strcmp(type, t->name) == 0) 368 break; 369 if(t == &floppytype[NTYPES]) 370 fatal("unknown floppy type %s", type); 371 372 if(t->sectors == 0 && strcmp(type, "hard") == 0) { 373 t->sectors = disk->s; 374 t->heads = disk->h; 375 t->tracks = disk->c; 376 } 377 378 if(t->sectors == 0 && dofat) 379 fatal("cannot format fat with type %s: geometry unknown\n", type); 380 381 if(fflag){ 382 disk->size = t->bytes*t->sectors*t->heads*t->tracks; 383 disk->secsize = t->bytes; 384 disk->secs = disk->size / disk->secsize; 385 } 386 387 secsize = disk->secsize; 388 length = disk->size; 389 390 buf = malloc(secsize); 391 if(buf == 0) 392 fatal("out of memory"); 393 394 /* 395 * Make disk full size if a file. 396 */ 397 if(fflag && disk->type == Tfile){ 398 if((d = dirfstat(disk->wfd)) == nil) 399 fatal("fstat disk: %r"); 400 if(commit && d->length < disk->size) { 401 if(seek(disk->wfd, disk->size-1, 0) < 0) 402 fatal("seek to 9: %r"); 403 if(write(disk->wfd, "9", 1) < 0) 404 fatal("writing 9: @%lld %r", seek(disk->wfd, 0LL, 1)); 405 } 406 free(d); 407 } 408 409 /* 410 * Start with initial sector from disk 411 */ 412 if(seek(disk->fd, 0, 0) < 0) 413 fatal("seek to boot sector: %r\n"); 414 if(commit && read(disk->fd, buf, secsize) != secsize) 415 fatal("reading boot sector: %r"); 416 417 if(dofat) 418 memset(buf, 0, sizeof(Dosboot)); 419 420 /* 421 * Jump instruction and OEM name. 422 */ 423 b = (Dosboot*)buf; 424 b->magic[0] = 0xEB; 425 b->magic[1] = 0x3C; 426 b->magic[2] = 0x90; 427 memmove(b->version, "Plan9.00", sizeof(b->version)); 428 429 /* 430 * Add bootstrapping code; assume it starts 431 * at 0x3E (the destination of the jump we just 432 * wrote to b->magic). 433 */ 434 if(dopbs) { 435 pbsbuf = malloc(secsize); 436 if(pbsbuf == 0) 437 fatal("out of memory"); 438 439 if(pbs){ 440 if((sysfd = open(pbs, OREAD)) < 0) 441 fatal("open %s: %r", pbs); 442 if((npbs = read(sysfd, pbsbuf, secsize)) < 0) 443 fatal("read %s: %r", pbs); 444 445 if(npbs > secsize-2) 446 fatal("boot block too large"); 447 448 close(sysfd); 449 } 450 else { 451 memmove(pbsbuf, bootprog, sizeof(bootprog)); 452 npbs = nbootprog; 453 } 454 if(npbs <= 0x3E) 455 fprint(2, "warning: pbs too small\n"); 456 else 457 memmove(buf+0x3E, pbsbuf+0x3E, npbs-0x3E); 458 459 free(pbsbuf); 460 } 461 462 /* 463 * Add FAT BIOS parameter block. 464 */ 465 if(dofat) { 466 if(commit) { 467 print("Initialising FAT file system\n"); 468 print("type %s, %d tracks, %d heads, %d sectors/track, %lld bytes/sec\n", 469 t->name, t->tracks, t->heads, t->sectors, secsize); 470 } 471 472 if(clustersize == 0) 473 clustersize = t->cluster; 474 clusters = length/(secsize*clustersize); 475 if(clusters < 4087) 476 fatbits = 12; 477 else if(clusters < 65527) /* no idea if this is right -rsc */ 478 fatbits = 16; 479 else 480 fatal("disk too big; implement fat32"); 481 482 volsecs = length/secsize; 483 fatsecs = (fatbits*clusters + 8*secsize - 1)/(8*secsize); 484 rootsecs = volsecs/200; 485 rootfiles = rootsecs * (secsize/sizeof(Dosdir)); 486 if(rootfiles > 512){ 487 rootfiles = 512; 488 rootsecs = rootfiles/(secsize/sizeof(Dosdir)); 489 } 490 491 PUTSHORT(b->sectsize, secsize); 492 b->clustsize = clustersize; 493 PUTSHORT(b->nresrv, nresrv); 494 b->nfats = 2; 495 PUTSHORT(b->rootsize, rootfiles); 496 if(volsecs < (1<<16)) 497 PUTSHORT(b->volsize, volsecs); 498 b->mediadesc = t->media; 499 PUTSHORT(b->fatsize, fatsecs); 500 PUTSHORT(b->trksize, t->sectors); 501 PUTSHORT(b->nheads, t->heads); 502 PUTLONG(b->nhidden, disk->offset); 503 PUTLONG(b->bigvolsize, volsecs); 504 505 /* 506 * Extended BIOS Parameter Block. 507 */ 508 if(t->media == 0xF8) 509 b->driveno = getdriveno(disk); 510 else 511 b->driveno = 0; 512 if(chatty) print("driveno = %ux\n", b->driveno); 513 514 b->bootsig = 0x29; 515 x = disk->offset + b->nfats*fatsecs + nresrv; 516 PUTLONG(b->volid, x); 517 if(chatty) print("volid = %lux %lux\n", x, GETLONG(b->volid)); 518 memmove(b->label, label, sizeof(b->label)); 519 sprint(r, "FAT%d ", fatbits); 520 memmove(b->type, r, sizeof(b->type)); 521 } 522 523 buf[secsize-2] = 0x55; 524 buf[secsize-1] = 0xAA; 525 526 if(commit) { 527 if(seek(disk->wfd, 0, 0) < 0) 528 fatal("seek to boot sector: %r\n"); 529 if(write(disk->wfd, buf, secsize) != secsize) 530 fatal("writing boot sector: %r"); 531 } 532 533 free(buf); 534 535 /* 536 * If we were only called to write the PBS, leave now. 537 */ 538 if(dofat == 0) 539 return; 540 541 /* 542 * allocate an in memory fat 543 */ 544 if(seek(disk->wfd, nresrv*secsize, 0) < 0) 545 fatal("seek to fat: %r\n"); 546 if(chatty) print("fat @%lluX\n", seek(disk->wfd, 0, 1)); 547 fat = malloc(fatsecs*secsize); 548 if(fat == 0) 549 fatal("out of memory"); 550 memset(fat, 0, fatsecs*secsize); 551 fat[0] = t->media; 552 fat[1] = 0xff; 553 fat[2] = 0xff; 554 if(fatbits == 16) 555 fat[3] = 0xff; 556 fatlast = 1; 557 if(seek(disk->wfd, 2*fatsecs*secsize, 1) < 0) /* 2 fats */ 558 fatal("seek to root: %r"); 559 if(chatty) print("root @%lluX\n", seek(disk->wfd, 0LL, 1)); 560 561 /* 562 * allocate an in memory root 563 */ 564 root = malloc(rootsecs*secsize); 565 if(root == 0) 566 fatal("out of memory"); 567 memset(root, 0, rootsecs*secsize); 568 if(seek(disk->wfd, rootsecs*secsize, 1) < 0) /* rootsecs */ 569 fatal("seek to files: %r"); 570 if(chatty) print("files @%lluX\n", seek(disk->wfd, 0LL, 1)); 571 572 /* 573 * Now positioned at the Files Area. 574 * If we have any arguments, process 575 * them and write out. 576 */ 577 for(p = root; argc > 0; argc--, argv++, p += sizeof(Dosdir)){ 578 if(p >= (root+(rootsecs*secsize))) 579 fatal("too many files in root"); 580 /* 581 * Open the file and get its length. 582 */ 583 if((sysfd = open(*argv, OREAD)) < 0) 584 fatal("open %s: %r", *argv); 585 if((d = dirfstat(sysfd)) == nil) 586 fatal("stat %s: %r", *argv); 587 if(d->length > 0xFFFFFFFF) 588 fatal("file %s too big\n", *argv, d->length); 589 if(commit) 590 print("Adding file %s, length %lld\n", *argv, d->length); 591 592 length = d->length; 593 if(length){ 594 /* 595 * Allocate a buffer to read the entire file into. 596 * This must be rounded up to a cluster boundary. 597 * 598 * Read the file and write it out to the Files Area. 599 */ 600 length += secsize*clustersize - 1; 601 length /= secsize*clustersize; 602 length *= secsize*clustersize; 603 if((buf = malloc(length)) == 0) 604 fatal("out of memory"); 605 606 if(read(sysfd, buf, d->length) < 0) 607 fatal("read %s: %r", *argv); 608 memset(buf+d->length, 0, length-d->length); 609 if(chatty) print("%s @%lluX\n", d->name, seek(disk->wfd, 0LL, 1)); 610 if(commit && write(disk->wfd, buf, length) < 0) 611 fatal("write %s: %r", *argv); 612 free(buf); 613 614 close(sysfd); 615 616 /* 617 * Allocate the FAT clusters. 618 * We're assuming here that where we 619 * wrote the file is in sync with 620 * the cluster allocation. 621 * Save the starting cluster. 622 */ 623 length /= secsize*clustersize; 624 x = clustalloc(Sof); 625 for(n = 0; n < length-1; n++) 626 clustalloc(0); 627 clustalloc(Eof); 628 } 629 else 630 x = 0; 631 632 /* 633 * Add the filename to the root. 634 */ 635 addrname(p, d, *argv, x); 636 free(d); 637 } 638 639 /* 640 * write the fats and root 641 */ 642 if(commit) { 643 if(seek(disk->wfd, nresrv*secsize, 0) < 0) 644 fatal("seek to fat #1: %r"); 645 if(write(disk->wfd, fat, fatsecs*secsize) < 0) 646 fatal("writing fat #1: %r"); 647 if(write(disk->wfd, fat, fatsecs*secsize) < 0) 648 fatal("writing fat #2: %r"); 649 if(write(disk->wfd, root, rootsecs*secsize) < 0) 650 fatal("writing root: %r"); 651 } 652 653 free(fat); 654 free(root); 655 } 656 657 /* 658 * allocate a cluster 659 */ 660 ulong 661 clustalloc(int flag) 662 { 663 ulong o, x; 664 665 if(flag != Sof){ 666 x = (flag == Eof) ? 0xffff : (fatlast+1); 667 if(fatbits == 12){ 668 x &= 0xfff; 669 o = (3*fatlast)/2; 670 if(fatlast & 1){ 671 fat[o] = (fat[o]&0x0f) | (x<<4); 672 fat[o+1] = (x>>4); 673 } else { 674 fat[o] = x; 675 fat[o+1] = (fat[o+1]&0xf0) | ((x>>8) & 0x0F); 676 } 677 } else { 678 o = 2*fatlast; 679 fat[o] = x; 680 fat[o+1] = x>>8; 681 } 682 } 683 684 if(flag == Eof) 685 return 0; 686 else{ 687 ++fatlast; 688 if(fatlast >= clusters) 689 sysfatal("data does not fit on disk (%d %d)", fatlast, clusters); 690 return fatlast; 691 } 692 } 693 694 void 695 putname(char *p, Dosdir *d) 696 { 697 int i; 698 699 memset(d->name, ' ', sizeof d->name+sizeof d->ext); 700 for(i = 0; i< sizeof(d->name); i++){ 701 if(*p == 0 || *p == '.') 702 break; 703 d->name[i] = toupper(*p++); 704 } 705 p = strrchr(p, '.'); 706 if(p){ 707 for(i = 0; i < sizeof d->ext; i++){ 708 if(*++p == 0) 709 break; 710 d->ext[i] = toupper(*p); 711 } 712 } 713 } 714 715 void 716 puttime(Dosdir *d) 717 { 718 Tm *t = localtime(time(0)); 719 ushort x; 720 721 x = (t->hour<<11) | (t->min<<5) | (t->sec>>1); 722 d->time[0] = x; 723 d->time[1] = x>>8; 724 x = ((t->year-80)<<9) | ((t->mon+1)<<5) | t->mday; 725 d->date[0] = x; 726 d->date[1] = x>>8; 727 } 728 729 void 730 addrname(uchar *entry, Dir *dir, char *name, ulong start) 731 { 732 char *s; 733 Dosdir *d; 734 735 s = strrchr(name, '/'); 736 if(s) 737 s++; 738 else 739 s = name; 740 741 d = (Dosdir*)entry; 742 putname(s, d); 743 if(strcmp(s, "9load") == 0) 744 d->attr = DSYSTEM; 745 else 746 d->attr = 0; 747 puttime(d); 748 d->start[0] = start; 749 d->start[1] = start>>8; 750 d->length[0] = dir->length; 751 d->length[1] = dir->length>>8; 752 d->length[2] = dir->length>>16; 753 d->length[3] = dir->length>>24; 754 } 755