wok-tiny annotate plop/stuff/bootloader.S @ rev 152

Add plop
author Pascal Bellard <pascal.bellard@slitaz.org>
date Thu Sep 19 20:20:35 2019 +0200 (2019-09-19)
parents
children b983dfa0a9ae
rev   line source
pascal@152 1 // Image/zImage & tiny bzImage linux kernel boot sector, (C) SliTaz, GPL2.
pascal@152 2
pascal@152 3 SYSSEG = 0x1000
pascal@152 4 setup_sects = 497
pascal@152 5 syssize = 500
pascal@152 6 cmd_line_ptr = 0x228
pascal@152 7
pascal@152 8 .text
pascal@152 9 .code16
pascal@152 10 .org 0
pascal@152 11 .globl _start
pascal@152 12 _start:
pascal@152 13
pascal@152 14 #define CODESZ 512 /* patched by installer */
pascal@152 15
pascal@152 16 // Default kernel format is 386 Image/zImage
pascal@152 17 //#define BZIMAGE 0x207 /* setup version ; for bzImage < 512 Kb only */
pascal@152 18 //#define ELKS /* 8086/286 linux port */
pascal@152 19
pascal@152 20 /* some extra features */
pascal@152 21 #define EXE_SUPPORT real mode dos .exe file support +208/264
pascal@152 22 #define CMDLINE dos kernel cmdline support +45
pascal@152 23 #define VCPI VCPI 4.0 support (386+) +109
pascal@152 24 #define SHUTDOWNDOS shutdown DOS services +29
pascal@152 25
pascal@152 26 /* some contraints to reduce the code size */
pascal@152 27 //#define FLOPPY_1440K_ONLY 1.44M floppies support only -26
pascal@152 28 #define FLOPPY_HAS_2_SIDES hardcoded heads count to 2 -15
pascal@152 29 //#define NO_CMDLINE_SHRINK remove heading spaces ? -6-21
pascal@152 30 //#define NO_CMDLINE_FILE remove @cmdline file support ? -21
pascal@152 31 //#define NO_DOTS show progression dots ? -5
pascal@152 32 #ifndef BZIMAGE
pascal@152 33 #define TINY_ZIMAGE system < 64Kb ? -11
pascal@152 34 #defime NO_MINSETUP default setup (dos only) ? -4
pascal@152 35 //#define NO_CURSOR_DEFINITION -8
pascal@152 36 #endif
pascal@152 37
pascal@152 38 #ifdef ELKS
pascal@152 39 .arch i8086
pascal@152 40 INITSEG = 0x0100
pascal@152 41 SETUPSEG = 0x0120
pascal@152 42 #define ONLY8086
pascal@152 43 #undef BZIMAGE
pascal@152 44 #undef VCPI
pascal@152 45 #else
pascal@152 46 INITSEG = 0x9000
pascal@152 47 SETUPSEG = 0x9020
pascal@152 48 #endif
pascal@152 49
pascal@152 50 .macro shlclw cnt,obj
pascal@152 51 #ifdef ONLY8086
pascal@152 52 movb \cnt,%cl
pascal@152 53 shlw %cl,\obj
pascal@152 54 #else
pascal@152 55 shlw \cnt,\obj
pascal@152 56 #endif
pascal@152 57 .endm
pascal@152 58
pascal@152 59 .macro shrclw cnt,obj
pascal@152 60 #ifdef ONLY8086
pascal@152 61 movb \cnt,%cl
pascal@152 62 shrw %cl,\obj
pascal@152 63 #else
pascal@152 64 shrw \cnt,\obj
pascal@152 65 #endif
pascal@152 66 .endm
pascal@152 67
pascal@152 68 #ifdef EXE_SUPPORT
pascal@152 69 #define EXEADRS(x) (x+0xE0)
pascal@152 70 #define FLAT20(x) (x+16*INITSEG)
pascal@152 71
pascal@152 72 .macro trace_int19
pascal@152 73 #ifdef ONLY8086
pascal@152 74 xorw %si, %si
pascal@152 75 movw %si, %ds
pascal@152 76 pushw 4+2(%si)
pascal@152 77 pushw 4(%si)
pascal@152 78 movw $step19, 4(%si)
pascal@152 79 movw $INITSEG, 4+2(%si)
pascal@152 80 #else
pascal@152 81 pushl $4
pascal@152 82 popw %si
pascal@152 83 popw %ds
pascal@152 84 pushl (%si)
pascal@152 85 movl $step19+(INITSEG<<16), (%si)
pascal@152 86 #endif
pascal@152 87 pushfw
pascal@152 88 popw %ax
pascal@152 89 incb %ah # set TF
pascal@152 90 pushw %ax
pascal@152 91 popfw
pascal@152 92 ljmp *4*0x19-4(%si)
pascal@152 93 .endm
pascal@152 94
pascal@152 95 stacktop = 0x9E00 # in 0x8000 .. 0xA000
pascal@152 96 decw %bp // Magic number: MZ
pascal@152 97 popw %dx
pascal@152 98 jmp start // Bytes on last page of file
pascal@152 99 .word (CODESZ+511)/512 // Pages in file INSTALLER
pascal@152 100 .word 0 // Relocations
pascal@152 101 .word (end_header-_start)/16 // Size of header in paragraphs
pascal@152 102 .word 4096 // Minimum extra paragraphs needed
pascal@152 103 .word -1 // Maximum extra paragraphs needed
pascal@152 104 .word (CODESZ+15)/16 // Initial (relative) SS value INSTALLER
pascal@152 105 .word stacktop // Initial SP value
pascal@152 106 .word 0 // Checksum INSTALLER?
pascal@152 107 .word EXEADRS(comstart) // Initial IP value
pascal@152 108 .word 0xFFF0 // Initial (relative) CS value
pascal@152 109 // .word 0x001C // File address of relocation table
pascal@152 110 // .word 0,0,0 // Overlay number
pascal@152 111 #else
pascal@152 112 #undef VCPI
pascal@152 113 #endif
pascal@152 114 start:
pascal@152 115 xorw %ax, %ax # %ax = 0
pascal@152 116 zeroed = 12 # zeroed registers
pascal@152 117 movw $zeroed/2, %cx # clear gdt + offset, %ds, limits
pascal@152 118 stacktop = 0x9E00 # in 0x8000 .. 0xA000 (+zeroed+12)
pascal@152 119 #ifdef ONLY8086
pascal@152 120 movw $INITSEG, %bx
pascal@152 121 #else
pascal@152 122 pushw $INITSEG
pascal@152 123 #endif
pascal@152 124 end_header:
pascal@152 125 cld # assume nothing
pascal@152 126 #if defined(BZIMAGE) && BZIMAGE >= 0x202
pascal@152 127 popw %es # %es contain INITSEG
pascal@152 128 movw %es, %di
pascal@152 129 #else
pascal@152 130 # cmdline offset at 0x22
pascal@152 131 movw $stacktop, %di # stacktop is an arbitrary value >=
pascal@152 132 # length of bootsect + length of
pascal@152 133 # setup + room for stack;
pascal@152 134 # 12 is disk parm size.
pascal@152 135 # ifdef ONLY8086
pascal@152 136 pushw %bx
pascal@152 137 # endif
pascal@152 138 popw %es # %es contain INITSEG
pascal@152 139 #endif
pascal@152 140 pushw %es
pascal@152 141 popw %ss # %es = %ss = INITSEG
pascal@152 142 movw %di, %sp # put stack at INITSEG:stacktop-...
pascal@152 143 #ifdef EXE_SUPPORT
pascal@152 144 cwd # force %dx = 0 (floppy only)
pascal@152 145 #endif
pascal@152 146
pascal@152 147 # Many BIOS's default disk parameter tables will not recognize
pascal@152 148 # multi-sector reads beyond the maximum sector number specified
pascal@152 149 # in the default diskette parameter tables - this may mean 7
pascal@152 150 # sectors in some cases.
pascal@152 151 #
pascal@152 152 # Since single sector reads are slow and out of the question,
pascal@152 153 # we must take care of this by creating new parameter tables
pascal@152 154 # (for the first disk) in RAM. We can set the maximum sector
pascal@152 155 # count to 36 - the most we will encounter on an ED 2.88.
pascal@152 156 #
pascal@152 157 # High doesn't hurt. Low does. Let's use the max: 63
pascal@152 158
pascal@152 159 rep # don't worry about cld
pascal@152 160 stosw # already done above
pascal@152 161 popw %bx # offset = 0
pascal@152 162 popw %ds # %ds = 0
pascal@152 163
pascal@152 164 movb setup_sects+0x7C00, %al # read bootsector + setup (%ds = 0)
pascal@152 165 incw %ax
pascal@152 166
pascal@152 167 ldsw 0x78(%bx), %si # %ds:%bx+0x78 is parameter table address
pascal@152 168 pushw %es
pascal@152 169 pushw %di
pascal@152 170 movb $6, %cl # copy 12 bytes
pascal@152 171 rep # don't worry about cld
pascal@152 172 movsw # already done above
pascal@152 173 movw %cx, %ds # %ds = 0
pascal@152 174 #ifdef ONLY8086
pascal@152 175 popw 0x78(%bx) # update parameter table address
pascal@152 176 popw 0x78+2(%bx)
pascal@152 177 #else
pascal@152 178 popl 0x78(%bx) # update parameter table address
pascal@152 179 #endif
pascal@152 180 pushw %ss
pascal@152 181 popw %ds # now %ds = %es = %ss = INITSEG
pascal@152 182 movb $63, 0x4-12(%di) # patch sector count, %di = stacktop
pascal@152 183
pascal@152 184 xchg %ax, %di # sector count
pascal@152 185 popw %ax # limits = 0
pascal@152 186 incw %cx # cylinder 0, sector 1, clear Z
pascal@152 187 call read_first_sectors # read setup
pascal@152 188
pascal@152 189 # This routine loads the system at address LOADSEG, making sure
pascal@152 190 # no 64kB boundaries are crossed. We try to load it as fast as
pascal@152 191 # possible, loading whole tracks whenever we can.
pascal@152 192
pascal@152 193 movw syssize, %di
pascal@152 194 decw %di
pascal@152 195 shrclw $9-4, %di
pascal@152 196 incw %di
pascal@152 197 movw $SYSSEG, %cx
pascal@152 198 #ifdef BZIMAGE
pascal@152 199 push %cx
pascal@152 200 #endif
pascal@152 201 call read_sectorsCX
pascal@152 202
pascal@152 203 # This procedure turns off the floppy drive motor, so
pascal@152 204 # that we enter the kernel in a known state, and
pascal@152 205 # don't have to worry about it later.
pascal@152 206
pascal@152 207 kill_motor:
pascal@152 208 xchgw %ax, %di # reset FDC (%di < 128)
pascal@152 209 int $0x13
pascal@152 210
pascal@152 211 # After that (everything loaded), we jump to the setup-routine
pascal@152 212 # loaded directly after the bootblock:
pascal@152 213 # Segments are as follows: %ds = %ss = INITSEG
pascal@152 214
pascal@152 215 #ifdef BZIMAGE
pascal@152 216 popw %bx
pascal@152 217 popw %si // SYSSEG:0
pascal@152 218 movesys: // %bx = DS, %si
pascal@152 219 movw $16, %ax
pascal@152 220 mulw %bx
pascal@152 221 addw %si, %ax
pascal@152 222 adcw $0x9300, %dx // %dx:%ax src flat address
pascal@152 223 movw $9, %cx
pascal@152 224 zero1:
pascal@152 225 pushw $0 // 2E..1E
pascal@152 226 loop zero1
pascal@152 227 //pushl $0x93100000 // 1A: dest
pascal@152 228 pushw $0x9310
pascal@152 229 pushw %cx
pascal@152 230 pushw $-1 // 18
pascal@152 231 pushw %cx // 16
pascal@152 232 pushw %dx // src
pascal@152 233 pushw %ax
pascal@152 234 pushw $-1 // 10
pascal@152 235 movb $8, %cl
pascal@152 236 movw %cx, %bx // will move 8*64 = 512Kb
pascal@152 237 zero2:
pascal@152 238 pushw $0 // 0E..00
pascal@152 239 loop zero2
pascal@152 240 movw %sp, %si
pascal@152 241 pushw %ss
pascal@152 242 popw %es
pascal@152 243 pushw %es
pascal@152 244 popw %ds
pascal@152 245 syslp:
pascal@152 246 movb $0x80, %ch
pascal@152 247 movb $0x87, %ah
pascal@152 248 int $0x15
pascal@152 249 incb 0x14(%si)
pascal@152 250 incb 0x1C(%si)
pascal@152 251 decw %bx
pascal@152 252 jne syslp
pascal@152 253 #endif
pascal@152 254 jmp_setup:
pascal@152 255 cli
pascal@152 256 ljmp $SETUPSEG, $0
pascal@152 257
pascal@152 258 #ifdef EXE_SUPPORT
pascal@152 259 #ifdef SHUTDOWNDOS
pascal@152 260 doiret:
pascal@152 261 iret
pascal@152 262 step19:
pascal@152 263 pushw %si
pascal@152 264 pushw %ds
pascal@152 265 movw %sp, %si
pascal@152 266 ldsw %ss:4(%si), %si
pascal@152 267 cmpw $0x19CD, (%si)
pascal@152 268 popw %ds
pascal@152 269 popw %si
pascal@152 270 jne doiret
pascal@152 271 xorw %si, %si
pascal@152 272 movw %si, %ds
pascal@152 273 pushw %cs
pascal@152 274 popw %ss
pascal@152 275 movw $stacktop-4-16, %sp
pascal@152 276 #ifdef ONLY8086
pascal@152 277 popw 4(%si)
pascal@152 278 popw 4+2(%si)
pascal@152 279 popw %bp
pascal@152 280 popw %di
pascal@152 281 popw %si
pascal@152 282 popw %dx
pascal@152 283 popw %cx
pascal@152 284 popw %bx
pascal@152 285 popw %ax
pascal@152 286 #else
pascal@152 287 popl 4(%si)
pascal@152 288 popaw
pascal@152 289 #endif
pascal@152 290 #ifdef BZIMAGE
pascal@152 291 jmp movesys
pascal@152 292 #endif
pascal@152 293 #endif
pascal@152 294 #ifndef BZIMAGE
pascal@152 295 movesys: // %ax = SYSSEG, %bx = DS, %si
pascal@152 296 shrclw $4, %si
pascal@152 297 addw %si, %bx
pascal@152 298 #ifdef TINY_ZIMAGE
pascal@152 299 movw $0xFFFF, %cx
pascal@152 300 xorw %si, %si
pascal@152 301 xorw %di, %di
pascal@152 302 cmpw %ax, %bx
pascal@152 303 jc forward
pascal@152 304 decw %si
pascal@152 305 decw %di
pascal@152 306 std
pascal@152 307 forward:
pascal@152 308 movw %ax, %es
pascal@152 309 movw %bx, %ds
pascal@152 310 rep
pascal@152 311 movsb
pascal@152 312 cld
pascal@152 313 #else
pascal@152 314 subw %ax, %bx
pascal@152 315 jnc forward
pascal@152 316 movb $0x90, %ah
pascal@152 317 ;decw %ax
pascal@152 318 forward:
pascal@152 319 movw %ax, %es
pascal@152 320 movw %ax, %di
pascal@152 321 addw %bx, %di
pascal@152 322 movw %di, %ds
pascal@152 323 sbbw %di, %di // %di = 0 : -1
pascal@152 324 cmc // C = 1 : 0
pascal@152 325 adcw %di, %ax
pascal@152 326 xorw %si, %si
pascal@152 327 xorw %di, %di
pascal@152 328 movb $0x10, %cl
pascal@152 329 cmpb %cl, %ah // move 512k
pascal@152 330 rep
pascal@152 331 movsb
pascal@152 332 jns forward
pascal@152 333 #endif
pascal@152 334 #ifndef NO_CURSOR_DEFINITION
pascal@152 335 movb $1, %ah
pascal@152 336 movb $0, %bh
pascal@152 337 movb $0x20, %ch // 0x2000
pascal@152 338 int $0x10
pascal@152 339 #endif
pascal@152 340 pushw %ss
pascal@152 341 popw %ds
pascal@152 342 jmp jmp_setup
pascal@152 343 #endif
pascal@152 344 comstart:
pascal@152 345 cld # assume nothing
pascal@152 346 #ifdef ONLY8086
pascal@152 347 movw $INITSEG, %ax
pascal@152 348 pushw %ax
pascal@152 349 #else
pascal@152 350 pushw $INITSEG
pascal@152 351 #endif
pascal@152 352 popw %es
pascal@152 353 #ifdef CMDLINE
pascal@152 354 movw %sp, %di
pascal@152 355 movw $0x80, %si
pascal@152 356 lodsb
pascal@152 357 cbw
pascal@152 358 xchgw %ax, %cx
pascal@152 359 jcxz nocmdline
pascal@152 360 # if defined(BZIMAGE) && BZIMAGE >= 0x202
pascal@152 361 movw $INITSEG/16+stacktop/256, EXEADRS(cmd_line_ptr+1)
pascal@152 362 # else
pascal@152 363 movw $0xA33F, 0x7F(%si)
pascal@152 364 # endif
pascal@152 365 # ifndef NO_CMDLINE_SHRINK
pascal@152 366 skipspace:
pascal@152 367 lodsb
pascal@152 368 cmpb $0x20, %al
pascal@152 369 je skipspace
pascal@152 370 # ifndef NO_CMDLINE_FILE
pascal@152 371 movw %si,%dx
pascal@152 372 decw %si
pascal@152 373 subb $'@',%al
pascal@152 374 jne notafile
pascal@152 375 movb $0x3D,%ah
pascal@152 376 int $0x21
pascal@152 377 jc notafile
pascal@152 378 xchgw %ax,%bx
pascal@152 379 //movw %si,%dx // ~320 bytes max
pascal@152 380 movw $EXEADRS(notafile)-130,%cx
pascal@152 381 movb $0x3F,%ah
pascal@152 382 int $0x21
pascal@152 383 xchgw %ax,%cx
pascal@152 384 notafile:
pascal@152 385 # else
pascal@152 386 decw %si
pascal@152 387 # endif
pascal@152 388 # endif
pascal@152 389 rep
pascal@152 390 movsb
pascal@152 391 nocmdline:
pascal@152 392 orb EXEADRS(setup_sects), %ch
pascal@152 393 # ifndef NO_MINSETUP
pascal@152 394 # ifndef BZIMAGE
pascal@152 395 jnz setupok
pascal@152 396 mov $4, %ch
pascal@152 397 setupok:
pascal@152 398 # endif
pascal@152 399 # endif
pascal@152 400 #else
pascal@152 401 movb EXEADRS(setup_sects), %ch
pascal@152 402 #endif
pascal@152 403 movb $(512-(end_header-_start))/2, %cl
pascal@152 404 movw $0x100, %si
pascal@152 405 movw $end_header, %di
pascal@152 406 rep
pascal@152 407 movsw
pascal@152 408 movw $SYSSEG, %ax
pascal@152 409 movw %ds, %bx
pascal@152 410 pushw %es
pascal@152 411 popw %ss
pascal@152 412 #ifndef SHUTDOWNDOS
pascal@152 413 pushw %es
pascal@152 414 pushw $movesys
pascal@152 415 #endif
pascal@152 416 #ifdef VCPI
pascal@152 417 pushaw
pascal@152 418 smsww %ax
pascal@152 419 andb $1, %al
pascal@152 420 je isrm
pascal@152 421 movw $EXEADRS(gdt_vcpi),%si
pascal@152 422 movw $pagebuf-0x90000,%di // %es = 0x9000
pascal@152 423 movl $pagebuf+3,%es:0x1000(%di)
pascal@152 424 call_vcpi:
pascal@152 425 movb $0xDE,%ah // DE01, EBX = getiface(DS:SI, ES:DI)
pascal@152 426 int $0x67
pascal@152 427 movl $FLAT20(sw2pm_params),%esi
pascal@152 428 movb $0x0C,%al // DE0C switchpm(ESI)
pascal@152 429 jmp call_vcpi
pascal@152 430 pm_code:
pascal@152 431 movl %cr0,%eax
pascal@152 432 andl $0x7FFFFFFE,%eax
pascal@152 433 movl %eax,%cr0
pascal@152 434 movl %eax,%cr3
pascal@152 435 isrm:
pascal@152 436 # ifdef SHUTDOWNDOS
pascal@152 437 trace_int19
pascal@152 438 # else
pascal@152 439 lssw %cs:EXEADRS(saved_ss_sp),%sp
pascal@152 440 popaw
pascal@152 441 retf
pascal@152 442 # endif
pascal@152 443 #else
pascal@152 444 # ifdef SHUTDOWNDOS
pascal@152 445 # ifdef ONLY8086
pascal@152 446 pushw %ax
pascal@152 447 pushw %bx
pascal@152 448 pushw %cx
pascal@152 449 pushw %dx
pascal@152 450 pushw %si
pascal@152 451 pushw %di
pascal@152 452 pushw %bp
pascal@152 453 # else
pascal@152 454 pushaw
pascal@152 455 # endif
pascal@152 456 trace_int19
pascal@152 457 # endif
pascal@152 458 retf
pascal@152 459 #endif
pascal@152 460 #endif
pascal@152 461
pascal@152 462 # read_sectors reads %di sectors into %es:0 buffer.
pascal@152 463 # %es:0 is updated to the next memory location.
pascal@152 464 # First, sectors are read sector by sector until
pascal@152 465 # sector per track count is known. Then they are
pascal@152 466 # read track by track.
pascal@152 467 # Assume no error on first track.
pascal@152 468
pascal@152 469 #ifdef FLOPPY_1440K_ONLY
pascal@152 470 #define FLOPPY_HAS_2_SIDES hardcore heads count to 2
pascal@152 471 #define FLOPPY_SECTORS 18 /* 18 sectors */
pascal@152 472 #else
pascal@152 473 #define FLOPPY_HEADS 2 /* 2 heads minimum */
pascal@152 474 #endif
pascal@152 475
pascal@152 476 return:
pascal@152 477 #ifndef NO_DOTS
pascal@152 478 movw $0xE2E,%ax
pascal@152 479 int $0x10
pascal@152 480 #endif
pascal@152 481 ret
pascal@152 482
pascal@152 483 check_limits:
pascal@152 484 #ifndef FLOPPY_1440K_ONLY
pascal@152 485 popw %dx
pascal@152 486 cmpb %al, %cl # max sector known ?
pascal@152 487 ja next_head # no -> store it
pascal@152 488 #ifndef FLOPPY_HAS_2_SIDES
pascal@152 489 #ifdef FLOPPY_HEADS
pascal@152 490 cmpb $FLOPPY_HEADS, %dh # 2 heads minimum
pascal@152 491 jb check_cylinder
pascal@152 492 #endif
pascal@152 493 cmpb %ah, %dh # max head known ?
pascal@152 494 ja next_cylinder # no -> store it
pascal@152 495 check_cylinder:
pascal@152 496 #endif
pascal@152 497 pushw %ax
pascal@152 498 cbw # %ah = 0
pascal@152 499 #else
pascal@152 500 pushw %dx
pascal@152 501 #endif
pascal@152 502 int $0x13 # reset controler
pascal@152 503 #ifndef FLOPPY_1440K_ONLY
pascal@152 504 popw %ax
pascal@152 505 movb $1, %al # sector by sector...
pascal@152 506 #else
pascal@152 507 movw $1, %ax
pascal@152 508 jmp more1trk
pascal@152 509 #endif
pascal@152 510 read_sectorslp:
pascal@152 511 pushw %dx # some bios break dx...
pascal@152 512 #ifndef FLOPPY_1440K_ONLY
pascal@152 513 pushw %ax # limits
pascal@152 514 subb %cl, %al # sectors remaining in track
pascal@152 515 ja tolastsect
pascal@152 516 movb $1, %al # first track sector by sector
pascal@152 517 tolastsect:
pascal@152 518 #else
pascal@152 519 movb $FLOPPY_SECTORS+1, %al
pascal@152 520 subb %cl, %al # sectors remaining in track
pascal@152 521 #endif
pascal@152 522 cbw
pascal@152 523 cmpw %di, %ax
pascal@152 524 jb more1trk
pascal@152 525 movw %di, %ax # sectors to read
pascal@152 526 more1trk:
pascal@152 527 pushw %ax # save context
pascal@152 528 movb $2, %ah # cmd: read chs
pascal@152 529 int $0x13
pascal@152 530 #ifndef FLOPPY_1440K_ONLY
pascal@152 531 popw %dx # save %ax
pascal@152 532 popw %ax # limits
pascal@152 533 #else
pascal@152 534 popw %ax # restore context
pascal@152 535 popw %dx
pascal@152 536 #endif
pascal@152 537 jc check_limits
pascal@152 538 #ifndef FLOPPY_1440K_ONLY
pascal@152 539 xchgw %ax, %bp
pascal@152 540 addw %dx,%cx # next sector
pascal@152 541 movw %cx, %si
pascal@152 542 pushw %dx
pascal@152 543 shlclw $5, %dx
pascal@152 544 movw %es, %cx
pascal@152 545 addw %dx, %cx
pascal@152 546 popw %dx
pascal@152 547 subw %dx,%di # update sector counter
pascal@152 548 popw %dx
pascal@152 549 #else
pascal@152 550 addw %ax,%cx # next sector
pascal@152 551 movw %cx, %si
pascal@152 552 pushw %ax
pascal@152 553 shlclw $5, %ax
pascal@152 554 movw %es, %cx
pascal@152 555 addw %ax, %cx
pascal@152 556 popw %ax
pascal@152 557 subw %ax,%di # update sector counter
pascal@152 558 #endif
pascal@152 559 read_sectorsCX:
pascal@152 560 movw %cx, %es # next location
pascal@152 561 jz return
pascal@152 562 read_sectors:
pascal@152 563 movw %si, %cx
pascal@152 564 #ifndef FLOPPY_1440K_ONLY
pascal@152 565 # al is last sector+1
pascal@152 566 # ah is last head+1
pascal@152 567 xchgw %ax, %bp
pascal@152 568 #endif
pascal@152 569 #ifndef FLOPPY_1440K_ONLY
pascal@152 570 cmpb %al,%cl # reach sector limit ?
pascal@152 571 jne bdendlp
pascal@152 572 next_head:
pascal@152 573 movb %cl,%al
pascal@152 574 #else
pascal@152 575 cmpb $FLOPPY_SECTORS+1,%cl # reach sector limit ?
pascal@152 576 jne bdendlp
pascal@152 577 #endif
pascal@152 578 movb $1,%cl # first sector
pascal@152 579 #ifndef FLOPPY_HAS_2_SIDES
pascal@152 580 incb %dh # next head
pascal@152 581 cmpb %ah, %dh # reach head limit ?
pascal@152 582 jne bdendlp
pascal@152 583 next_cylinder:
pascal@152 584 movb %dh,%ah
pascal@152 585 movb $0,%dh # first head
pascal@152 586 #else
pascal@152 587 xorb %cl,%dh # next head
pascal@152 588 jne bdendlp # reach head limit ?
pascal@152 589 #endif
pascal@152 590 # NOTE : support 256 cylinders max
pascal@152 591 incb %ch # next cylinder
pascal@152 592 read_first_sectors:
pascal@152 593 bdendlp:
pascal@152 594 jmp read_sectorslp
pascal@152 595
pascal@152 596 #ifdef VCPI
pascal@152 597 pagebuf = 0x98000
pascal@152 598 tss = gdt_abs-40
pascal@152 599 gdt = gdt_abs-32
pascal@152 600 gdt_null = gdt_abs-32
pascal@152 601 gdt_vcpi = gdt_abs-24
pascal@152 602 gdt_vcpi2 = gdt_abs-16
pascal@152 603 gdt_vcpi3 = gdt_abs-8
pascal@152 604 gdt_abs:
pascal@152 605 .word 0xFFFF
pascal@152 606 .long 0x92000000
pascal@152 607 .byte 0xCF,0
pascal@152 608 gdt_code:
pascal@152 609 .word 0xFFFF
pascal@152 610 gdt_code_base:
pascal@152 611 .long 0x9A000000+FLAT20(0)
pascal@152 612 .byte 0x8F,0
pascal@152 613 gdt_tss:
pascal@152 614 .word 0x00FF
pascal@152 615 gdt_tss_base:
pascal@152 616 .long 0x89000000+FLAT20(tss)
pascal@152 617 .byte 0,0
pascal@152 618 gdtr:
pascal@152 619 gdt_lim:
pascal@152 620 .word 0xFFFF
pascal@152 621 gdt_base:
pascal@152 622 .long FLAT20(gdt)
pascal@152 623 sw2pm_params:
pascal@152 624 sw2pm_cr3:
pascal@152 625 .long pagebuf+0x1000
pascal@152 626 sw2pm_gdtr_ptr:
pascal@152 627 .long FLAT20(gdtr)
pascal@152 628 sw2pm_idtr_ptr:
pascal@152 629 .long FLAT20(idtr)
pascal@152 630 sw2pm_ldtr:
pascal@152 631 .word 0
pascal@152 632 sw2pm_tr:
pascal@152 633 SEL_TSS = gdt_tss-gdt_null
pascal@152 634 .word SEL_TSS
pascal@152 635 sw2pm_jumpaddr:
pascal@152 636 .long pm_code
pascal@152 637 SEL_CODE = gdt_code-gdt_null
pascal@152 638 .word SEL_CODE
pascal@152 639 idtr:
pascal@152 640 idt_lim:
pascal@152 641 .word 0x03FF
pascal@152 642 idt_base:
pascal@152 643 .long 0
pascal@152 644 # ifndef SHUTDOWNDOS
pascal@152 645 saved_ss_sp:
pascal@152 646 .word stacktop-4-16-4,INITSEG
pascal@152 647 # endif
pascal@152 648 #endif
pascal@152 649 #ifdef ELKS
pascal@152 650 .org 0x1E3
pascal@152 651 .byte 13,10,7
pascal@152 652 .asciz "ELKS Boot"
pascal@152 653 #endif