wok annotate ipxe/stuff/bootloader.S @ rev 24593

updated geos and geos-dev (3.8.0 -> 3.10.2)
author Hans-G?nter Theisgen
date Tue Mar 01 13:55:15 2022 +0100 (2022-03-01)
parents ccdba9b27403
children d1f31f5f6401
rev   line source
pascal@20179 1 // Image/zImage & tiny bzImage linux kernel boot sector, (C) SliTaz, GPL2.
pascal@20179 2
pascal@20179 3 SYSSEG = 0x1000
pascal@20179 4 setup_sects = 497
pascal@20179 5 syssize = 500
pascal@20179 6 cmd_line_ptr = 0x228
pascal@20179 7
pascal@20179 8 .text
pascal@20179 9 .code16
pascal@20179 10 .org 0
pascal@20179 11 .globl _start
pascal@20179 12 _start:
pascal@20179 13
pascal@20179 14 #define CODESZ 512 /* patched by installer */
pascal@20179 15
pascal@20184 16 // Default kernel format is 386 Image/zImage
pascal@20179 17 #define BZIMAGE 0x207 /* setup version ; for bzImage < 512 Kb only */
pascal@20184 18 //#define ELKS /* 8086/286 linux port */
pascal@20179 19
pascal@20179 20 /* some extra features */
pascal@20184 21 #define EXE_SUPPORT real mode dos .exe file support +208/264
pascal@20184 22 #define CMDLINE dos kernel cmdline support +45
pascal@20184 23 #define VCPI VCPI 4.0 support (386+) +109
pascal@20184 24 #define SHUTDOWNDOS shutdown DOS services +29
pascal@20179 25
pascal@20179 26 /* some contraints to reduce the code size */
pascal@20184 27 //#define FLOPPY_1440K_ONLY 1.44M floppies support only -26
pascal@20184 28 //#define FLOPPY_HAS_2_SIDES hardcoded heads count to 2 -15
pascal@20184 29 //#define NO_CMDLINE_SHRINK remove heading spaces ? -6-21
pascal@20184 30 //#define NO_CMDLINE_FILE remove @cmdline file support ? -21
pascal@20184 31 //#define NO_DOTS show progression dots ? -5
pascal@20179 32 #ifndef BZIMAGE
pascal@20184 33 //#define TINY_ZIMAGE system < 64Kb ? -11
pascal@24045 34 //#define NO_MINSETUP default setup (dos only) ? -4
pascal@20179 35 //#define NO_CURSOR_DEFINITION -8
pascal@20179 36 #endif
pascal@20179 37
pascal@20184 38 #ifdef ELKS
pascal@20184 39 .arch i8086
pascal@20184 40 INITSEG = 0x0100
pascal@20184 41 SETUPSEG = 0x0120
pascal@20184 42 #define ONLY8086
pascal@20184 43 #undef BZIMAGE
pascal@20184 44 #undef VCPI
pascal@20184 45 #else
pascal@20184 46 INITSEG = 0x9000
pascal@20184 47 SETUPSEG = 0x9020
pascal@20184 48 #endif
pascal@20184 49
pascal@20184 50 .macro shlclw cnt,obj
pascal@20184 51 #ifdef ONLY8086
pascal@20184 52 movb \cnt,%cl
pascal@20184 53 shlw %cl,\obj
pascal@20184 54 #else
pascal@20184 55 shlw \cnt,\obj
pascal@20184 56 #endif
pascal@20184 57 .endm
pascal@20184 58
pascal@20184 59 .macro shrclw cnt,obj
pascal@20184 60 #ifdef ONLY8086
pascal@20184 61 movb \cnt,%cl
pascal@20184 62 shrw %cl,\obj
pascal@20184 63 #else
pascal@20184 64 shrw \cnt,\obj
pascal@20184 65 #endif
pascal@20184 66 .endm
pascal@20184 67
pascal@20179 68 #ifdef EXE_SUPPORT
pascal@20179 69 #define EXEADRS(x) (x+0xE0)
pascal@20179 70 #define FLAT20(x) (x+16*INITSEG)
pascal@20179 71
pascal@20179 72 .macro trace_int19
pascal@20184 73 #ifdef ONLY8086
pascal@20184 74 xorw %si, %si
pascal@20184 75 movw %si, %ds
pascal@20184 76 pushw 4+2(%si)
pascal@20184 77 pushw 4(%si)
pascal@20184 78 movw $step19, 4(%si)
pascal@20184 79 movw $INITSEG, 4+2(%si)
pascal@20184 80 #else
pascal@20179 81 pushl $4
pascal@20179 82 popw %si
pascal@20179 83 popw %ds
pascal@20179 84 pushl (%si)
pascal@20179 85 movl $step19+(INITSEG<<16), (%si)
pascal@20184 86 #endif
pascal@20179 87 pushfw
pascal@20179 88 popw %ax
pascal@20179 89 incb %ah # set TF
pascal@20179 90 pushw %ax
pascal@20179 91 popfw
pascal@20179 92 ljmp *4*0x19-4(%si)
pascal@20179 93 .endm
pascal@20179 94
pascal@20179 95 stacktop = 0x9E00 # in 0x8000 .. 0xA000
pascal@20179 96 decw %bp // Magic number: MZ
pascal@20179 97 popw %dx
pascal@20179 98 jmp start // Bytes on last page of file
pascal@20179 99 .word (CODESZ+511)/512 // Pages in file INSTALLER
pascal@20179 100 .word 0 // Relocations
pascal@20179 101 .word (end_header-_start)/16 // Size of header in paragraphs
pascal@20179 102 .word 4096 // Minimum extra paragraphs needed
pascal@20179 103 .word -1 // Maximum extra paragraphs needed
pascal@20179 104 .word (CODESZ+15)/16 // Initial (relative) SS value INSTALLER
pascal@20179 105 .word stacktop // Initial SP value
pascal@20179 106 .word 0 // Checksum INSTALLER?
pascal@20179 107 .word EXEADRS(comstart) // Initial IP value
pascal@20179 108 .word 0xFFF0 // Initial (relative) CS value
pascal@20179 109 // .word 0x001C // File address of relocation table
pascal@20179 110 // .word 0,0,0 // Overlay number
pascal@20184 111 #else
pascal@20184 112 #undef VCPI
pascal@20179 113 #endif
pascal@20179 114 start:
pascal@20179 115 xorw %ax, %ax # %ax = 0
pascal@20179 116 zeroed = 12 # zeroed registers
pascal@20179 117 movw $zeroed/2, %cx # clear gdt + offset, %ds, limits
pascal@20179 118 stacktop = 0x9E00 # in 0x8000 .. 0xA000 (+zeroed+12)
pascal@20184 119 #ifdef ONLY8086
pascal@20184 120 movw $INITSEG, %bx
pascal@20184 121 #else
pascal@20179 122 pushw $INITSEG
pascal@20184 123 #endif
pascal@20179 124 end_header:
pascal@20179 125 cld # assume nothing
pascal@20179 126 #if defined(BZIMAGE) && BZIMAGE >= 0x202
pascal@20179 127 popw %es # %es contain INITSEG
pascal@20179 128 movw %es, %di
pascal@20179 129 #else
pascal@20179 130 # cmdline offset at 0x22
pascal@20179 131 movw $stacktop, %di # stacktop is an arbitrary value >=
pascal@20179 132 # length of bootsect + length of
pascal@20179 133 # setup + room for stack;
pascal@20179 134 # 12 is disk parm size.
pascal@20184 135 # ifdef ONLY8086
pascal@20184 136 pushw %bx
pascal@20184 137 # endif
pascal@20179 138 popw %es # %es contain INITSEG
pascal@20179 139 #endif
pascal@20179 140 pushw %es
pascal@20179 141 popw %ss # %es = %ss = INITSEG
pascal@20179 142 movw %di, %sp # put stack at INITSEG:stacktop-...
pascal@20179 143 #ifdef EXE_SUPPORT
pascal@20179 144 cwd # force %dx = 0 (floppy only)
pascal@20179 145 #endif
pascal@20179 146
pascal@20179 147 # Many BIOS's default disk parameter tables will not recognize
pascal@20179 148 # multi-sector reads beyond the maximum sector number specified
pascal@20179 149 # in the default diskette parameter tables - this may mean 7
pascal@20179 150 # sectors in some cases.
pascal@20179 151 #
pascal@20179 152 # Since single sector reads are slow and out of the question,
pascal@20179 153 # we must take care of this by creating new parameter tables
pascal@20179 154 # (for the first disk) in RAM. We can set the maximum sector
pascal@20179 155 # count to 36 - the most we will encounter on an ED 2.88.
pascal@20179 156 #
pascal@20179 157 # High doesn't hurt. Low does. Let's use the max: 63
pascal@20179 158
pascal@20179 159 rep # don't worry about cld
pascal@20179 160 stosw # already done above
pascal@20179 161 popw %bx # offset = 0
pascal@20179 162 popw %ds # %ds = 0
pascal@20179 163
pascal@20179 164 movb setup_sects+0x7C00, %al # read bootsector + setup (%ds = 0)
pascal@20179 165 incw %ax
pascal@20179 166
pascal@20179 167 ldsw 0x78(%bx), %si # %ds:%bx+0x78 is parameter table address
pascal@20179 168 pushw %es
pascal@20179 169 pushw %di
pascal@20179 170 movb $6, %cl # copy 12 bytes
pascal@20179 171 rep # don't worry about cld
pascal@20179 172 movsw # already done above
pascal@20222 173 movw %cx, %ds # %ds = 0
pascal@20184 174 #ifdef ONLY8086
pascal@20184 175 popw 0x78(%bx) # update parameter table address
pascal@20184 176 popw 0x78+2(%bx)
pascal@20184 177 #else
pascal@20184 178 popl 0x78(%bx) # update parameter table address
pascal@20184 179 #endif
pascal@20179 180 pushw %ss
pascal@20179 181 popw %ds # now %ds = %es = %ss = INITSEG
pascal@20179 182 movb $63, 0x4-12(%di) # patch sector count, %di = stacktop
pascal@20179 183
pascal@20179 184 xchg %ax, %di # sector count
pascal@20179 185 popw %ax # limits = 0
pascal@20179 186 incw %cx # cylinder 0, sector 1, clear Z
pascal@20179 187 call read_first_sectors # read setup
pascal@20179 188
pascal@20179 189 # This routine loads the system at address LOADSEG, making sure
pascal@20179 190 # no 64kB boundaries are crossed. We try to load it as fast as
pascal@20179 191 # possible, loading whole tracks whenever we can.
pascal@20179 192
pascal@20179 193 movw syssize, %di
pascal@20179 194 decw %di
pascal@20184 195 shrclw $9-4, %di
pascal@20179 196 incw %di
pascal@20179 197 movw $SYSSEG, %cx
pascal@20179 198 #ifdef BZIMAGE
pascal@20179 199 push %cx
pascal@20179 200 #endif
pascal@20179 201 call read_sectorsCX
pascal@20179 202
pascal@20179 203 # This procedure turns off the floppy drive motor, so
pascal@20179 204 # that we enter the kernel in a known state, and
pascal@20179 205 # don't have to worry about it later.
pascal@20179 206
pascal@20179 207 kill_motor:
pascal@20179 208 xchgw %ax, %di # reset FDC (%di < 128)
pascal@20179 209 int $0x13
pascal@20179 210
pascal@20179 211 # After that (everything loaded), we jump to the setup-routine
pascal@20179 212 # loaded directly after the bootblock:
pascal@20179 213 # Segments are as follows: %ds = %ss = INITSEG
pascal@20179 214
pascal@20179 215 #ifdef BZIMAGE
pascal@20179 216 popw %bx
pascal@20179 217 popw %si // SYSSEG:0
pascal@20179 218 movesys: // %bx = DS, %si
pascal@20179 219 movw $16, %ax
pascal@20179 220 mulw %bx
pascal@20179 221 addw %si, %ax
pascal@20179 222 adcw $0x9300, %dx // %dx:%ax src flat address
pascal@20179 223 movw $9, %cx
pascal@20179 224 zero1:
pascal@20179 225 pushw $0 // 2E..1E
pascal@20179 226 loop zero1
pascal@20179 227 //pushl $0x93100000 // 1A: dest
pascal@20179 228 pushw $0x9310
pascal@20179 229 pushw %cx
pascal@20179 230 pushw $-1 // 18
pascal@20179 231 pushw %cx // 16
pascal@20179 232 pushw %dx // src
pascal@20179 233 pushw %ax
pascal@20179 234 pushw $-1 // 10
pascal@20179 235 movb $8, %cl
pascal@20179 236 movw %cx, %bx // will move 8*64 = 512Kb
pascal@20179 237 zero2:
pascal@20179 238 pushw $0 // 0E..00
pascal@20179 239 loop zero2
pascal@20179 240 movw %sp, %si
pascal@20179 241 pushw %ss
pascal@20179 242 popw %es
pascal@20179 243 pushw %es
pascal@20179 244 popw %ds
pascal@20179 245 syslp:
pascal@20179 246 movb $0x80, %ch
pascal@20179 247 movb $0x87, %ah
pascal@20179 248 int $0x15
pascal@20179 249 incb 0x14(%si)
pascal@20179 250 incb 0x1C(%si)
pascal@20179 251 decw %bx
pascal@20179 252 jne syslp
pascal@20179 253 #endif
pascal@20179 254 jmp_setup:
pascal@20184 255 cli
pascal@20179 256 ljmp $SETUPSEG, $0
pascal@20179 257
pascal@20179 258 #ifdef EXE_SUPPORT
pascal@20179 259 #ifdef SHUTDOWNDOS
pascal@20179 260 doiret:
pascal@20179 261 iret
pascal@20179 262 step19:
pascal@20179 263 pushw %si
pascal@20179 264 pushw %ds
pascal@20179 265 movw %sp, %si
pascal@20179 266 ldsw %ss:4(%si), %si
pascal@20179 267 cmpw $0x19CD, (%si)
pascal@20179 268 popw %ds
pascal@20179 269 popw %si
pascal@20179 270 jne doiret
pascal@20179 271 xorw %si, %si
pascal@20179 272 movw %si, %ds
pascal@20179 273 pushw %cs
pascal@20179 274 popw %ss
pascal@20179 275 movw $stacktop-4-16, %sp
pascal@20184 276 #ifdef ONLY8086
pascal@20184 277 popw 4(%si)
pascal@20184 278 popw 4+2(%si)
pascal@20184 279 popw %bp
pascal@20184 280 popw %di
pascal@20184 281 popw %si
pascal@20184 282 popw %dx
pascal@20184 283 popw %cx
pascal@20184 284 popw %bx
pascal@20184 285 popw %ax
pascal@20184 286 #else
pascal@20179 287 popl 4(%si)
pascal@20179 288 popaw
pascal@20184 289 #endif
pascal@20179 290 #ifdef BZIMAGE
pascal@20179 291 jmp movesys
pascal@20179 292 #endif
pascal@20179 293 #endif
pascal@20179 294 #ifndef BZIMAGE
pascal@20179 295 movesys: // %ax = SYSSEG, %bx = DS, %si
pascal@20184 296 shrclw $4, %si
pascal@20179 297 addw %si, %bx
pascal@20184 298 #ifdef TINY_ZIMAGE
pascal@20184 299 movw $0xFFFF, %cx
pascal@20184 300 xorw %si, %si
pascal@20184 301 xorw %di, %di
pascal@20184 302 cmpw %ax, %bx
pascal@24045 303 jnc forward
pascal@20184 304 decw %si
pascal@20184 305 decw %di
pascal@20184 306 std
pascal@20184 307 forward:
pascal@20184 308 movw %ax, %es
pascal@20184 309 movw %bx, %ds
pascal@20184 310 rep
pascal@20184 311 movsb
pascal@20184 312 cld
pascal@20184 313 #else
pascal@20179 314 subw %ax, %bx
pascal@20179 315 jnc forward
pascal@24045 316 //movw $0x8FFF, %ax
pascal@20179 317 movb $0x90, %ah
pascal@20179 318 forward:
pascal@20179 319 movw %ax, %es
pascal@20179 320 movw %ax, %di
pascal@20179 321 addw %bx, %di
pascal@20179 322 movw %di, %ds
pascal@20179 323 sbbw %di, %di // %di = 0 : -1
pascal@20179 324 cmc // C = 1 : 0
pascal@20179 325 adcw %di, %ax
pascal@20179 326 xorw %si, %si
pascal@20179 327 xorw %di, %di
pascal@20179 328 movb $0x10, %cl
pascal@20179 329 cmpb %cl, %ah // move 512k
pascal@20179 330 rep
pascal@20179 331 movsb
pascal@20179 332 jns forward
pascal@20184 333 #endif
pascal@20179 334 #ifndef NO_CURSOR_DEFINITION
pascal@20179 335 movb $1, %ah
pascal@20179 336 movb $0, %bh
pascal@20179 337 movb $0x20, %ch // 0x2000
pascal@20179 338 int $0x10
pascal@20179 339 #endif
pascal@20179 340 pushw %ss
pascal@20179 341 popw %ds
pascal@20179 342 jmp jmp_setup
pascal@20179 343 #endif
pascal@20179 344 comstart:
pascal@20179 345 cld # assume nothing
pascal@20184 346 #ifdef ONLY8086
pascal@20184 347 movw $INITSEG, %ax
pascal@20184 348 pushw %ax
pascal@20184 349 #else
pascal@20179 350 pushw $INITSEG
pascal@20184 351 #endif
pascal@20179 352 popw %es
pascal@20179 353 #ifdef CMDLINE
pascal@20179 354 movw %sp, %di
pascal@20179 355 movw $0x80, %si
pascal@20179 356 lodsb
pascal@20179 357 cbw
pascal@20179 358 xchgw %ax, %cx
pascal@20179 359 jcxz nocmdline
pascal@20179 360 # if defined(BZIMAGE) && BZIMAGE >= 0x202
pascal@20179 361 movw $INITSEG/16+stacktop/256, EXEADRS(cmd_line_ptr+1)
pascal@20179 362 # else
pascal@20179 363 movw $0xA33F, 0x7F(%si)
pascal@20179 364 # endif
pascal@20179 365 # ifndef NO_CMDLINE_SHRINK
pascal@20179 366 skipspace:
pascal@20179 367 lodsb
pascal@20179 368 cmpb $0x20, %al
pascal@20179 369 je skipspace
pascal@20179 370 # ifndef NO_CMDLINE_FILE
pascal@20179 371 movw %si,%dx
pascal@20179 372 decw %si
pascal@20179 373 subb $'@',%al
pascal@20179 374 jne notafile
pascal@20179 375 movb $0x3D,%ah
pascal@20179 376 int $0x21
pascal@20179 377 jc notafile
pascal@20179 378 xchgw %ax,%bx
pascal@20179 379 //movw %si,%dx // ~320 bytes max
pascal@20179 380 movw $EXEADRS(notafile)-130,%cx
pascal@20179 381 movb $0x3F,%ah
pascal@20179 382 int $0x21
pascal@20179 383 xchgw %ax,%cx
pascal@20179 384 notafile:
pascal@20179 385 # else
pascal@20179 386 decw %si
pascal@20179 387 # endif
pascal@20179 388 # endif
pascal@20179 389 rep
pascal@20179 390 movsb
pascal@20179 391 nocmdline:
pascal@20179 392 orb EXEADRS(setup_sects), %ch
pascal@20179 393 # ifndef NO_MINSETUP
pascal@20179 394 # ifndef BZIMAGE
pascal@20179 395 jnz setupok
pascal@20179 396 mov $4, %ch
pascal@20179 397 setupok:
pascal@20179 398 # endif
pascal@20179 399 # endif
pascal@20179 400 #else
pascal@20179 401 movb EXEADRS(setup_sects), %ch
pascal@20179 402 #endif
pascal@20179 403 movb $(512-(end_header-_start))/2, %cl
pascal@20179 404 movw $0x100, %si
pascal@20179 405 movw $end_header, %di
pascal@20179 406 rep
pascal@20179 407 movsw
pascal@20179 408 movw $SYSSEG, %ax
pascal@20179 409 movw %ds, %bx
pascal@20179 410 pushw %es
pascal@20179 411 popw %ss
pascal@20179 412 #ifndef SHUTDOWNDOS
pascal@20179 413 pushw %es
pascal@20179 414 pushw $movesys
pascal@20179 415 #endif
pascal@20179 416 #ifdef VCPI
pascal@20179 417 pushaw
pascal@20179 418 smsww %ax
pascal@20179 419 andb $1, %al
pascal@20179 420 je isrm
pascal@20179 421 movw $EXEADRS(gdt_vcpi),%si
pascal@20179 422 movw $pagebuf-0x90000,%di // %es = 0x9000
pascal@20179 423 movl $pagebuf+3,%es:0x1000(%di)
pascal@20179 424 call_vcpi:
pascal@20179 425 movb $0xDE,%ah // DE01, EBX = getiface(DS:SI, ES:DI)
pascal@20179 426 int $0x67
pascal@20179 427 movl $FLAT20(sw2pm_params),%esi
pascal@20179 428 movb $0x0C,%al // DE0C switchpm(ESI)
pascal@20179 429 jmp call_vcpi
pascal@20179 430 pm_code:
pascal@20179 431 movl %cr0,%eax
pascal@20179 432 andl $0x7FFFFFFE,%eax
pascal@20179 433 movl %eax,%cr0
pascal@20179 434 movl %eax,%cr3
pascal@20179 435 isrm:
pascal@20179 436 # ifdef SHUTDOWNDOS
pascal@20179 437 trace_int19
pascal@20179 438 # else
pascal@20179 439 lssw %cs:EXEADRS(saved_ss_sp),%sp
pascal@20179 440 popaw
pascal@20179 441 retf
pascal@20179 442 # endif
pascal@20179 443 #else
pascal@20179 444 # ifdef SHUTDOWNDOS
pascal@20184 445 # ifdef ONLY8086
pascal@20184 446 pushw %ax
pascal@20184 447 pushw %bx
pascal@20184 448 pushw %cx
pascal@20184 449 pushw %dx
pascal@20184 450 pushw %si
pascal@20184 451 pushw %di
pascal@20184 452 pushw %bp
pascal@20184 453 # else
pascal@20179 454 pushaw
pascal@20184 455 # endif
pascal@20179 456 trace_int19
pascal@20179 457 # endif
pascal@20179 458 retf
pascal@20179 459 #endif
pascal@20179 460 #endif
pascal@20179 461
pascal@20179 462 # read_sectors reads %di sectors into %es:0 buffer.
pascal@20179 463 # %es:0 is updated to the next memory location.
pascal@20179 464 # First, sectors are read sector by sector until
pascal@20179 465 # sector per track count is known. Then they are
pascal@20179 466 # read track by track.
pascal@20179 467 # Assume no error on first track.
pascal@20179 468
pascal@20179 469 #ifdef FLOPPY_1440K_ONLY
pascal@24045 470 #ifndef FLOPPY_HAS_2_SIDES
pascal@20179 471 #define FLOPPY_HAS_2_SIDES hardcore heads count to 2
pascal@24045 472 #endif
pascal@20179 473 #define FLOPPY_SECTORS 18 /* 18 sectors */
pascal@20179 474 #else
pascal@20179 475 #define FLOPPY_HEADS 2 /* 2 heads minimum */
pascal@20179 476 #endif
pascal@20179 477
pascal@20179 478 return:
pascal@20179 479 #ifndef NO_DOTS
pascal@20179 480 movw $0xE2E,%ax
pascal@20179 481 int $0x10
pascal@20179 482 #endif
pascal@20179 483 ret
pascal@20179 484
pascal@20179 485 check_limits:
pascal@20179 486 #ifndef FLOPPY_1440K_ONLY
pascal@20179 487 popw %dx
pascal@20179 488 cmpb %al, %cl # max sector known ?
pascal@20179 489 ja next_head # no -> store it
pascal@20179 490 #ifndef FLOPPY_HAS_2_SIDES
pascal@20179 491 #ifdef FLOPPY_HEADS
pascal@20179 492 cmpb $FLOPPY_HEADS, %dh # 2 heads minimum
pascal@20179 493 jb check_cylinder
pascal@20179 494 #endif
pascal@20179 495 cmpb %ah, %dh # max head known ?
pascal@20179 496 ja next_cylinder # no -> store it
pascal@20179 497 check_cylinder:
pascal@20179 498 #endif
pascal@20184 499 pushw %ax
pascal@20179 500 cbw # %ah = 0
pascal@20184 501 #else
pascal@20184 502 pushw %dx
pascal@20179 503 #endif
pascal@20179 504 int $0x13 # reset controler
pascal@20184 505 #ifndef FLOPPY_1440K_ONLY
pascal@20184 506 popw %ax
pascal@20179 507 movb $1, %al # sector by sector...
pascal@20184 508 #else
pascal@20184 509 movw $1, %ax
pascal@20184 510 jmp more1trk
pascal@20184 511 #endif
pascal@20179 512 read_sectorslp:
pascal@20179 513 pushw %dx # some bios break dx...
pascal@20179 514 #ifndef FLOPPY_1440K_ONLY
pascal@20179 515 pushw %ax # limits
pascal@20179 516 subb %cl, %al # sectors remaining in track
pascal@20179 517 ja tolastsect
pascal@20184 518 movb $1, %al # first track sector by sector
pascal@20179 519 tolastsect:
pascal@20179 520 #else
pascal@20179 521 movb $FLOPPY_SECTORS+1, %al
pascal@20179 522 subb %cl, %al # sectors remaining in track
pascal@20179 523 #endif
pascal@20179 524 cbw
pascal@20179 525 cmpw %di, %ax
pascal@20179 526 jb more1trk
pascal@20179 527 movw %di, %ax # sectors to read
pascal@20179 528 more1trk:
pascal@20179 529 pushw %ax # save context
pascal@20179 530 movb $2, %ah # cmd: read chs
pascal@20179 531 int $0x13
pascal@20179 532 #ifndef FLOPPY_1440K_ONLY
pascal@20179 533 popw %dx # save %ax
pascal@20179 534 popw %ax # limits
pascal@20179 535 #else
pascal@20179 536 popw %ax # restore context
pascal@20179 537 popw %dx
pascal@20179 538 #endif
pascal@20179 539 jc check_limits
pascal@20179 540 #ifndef FLOPPY_1440K_ONLY
pascal@20179 541 xchgw %ax, %bp
pascal@20179 542 addw %dx,%cx # next sector
pascal@20184 543 movw %cx, %si
pascal@20184 544 pushw %dx
pascal@20184 545 shlclw $5, %dx
pascal@20179 546 movw %es, %cx
pascal@20179 547 addw %dx, %cx
pascal@20179 548 popw %dx
pascal@20179 549 subw %dx,%di # update sector counter
pascal@20179 550 popw %dx
pascal@20179 551 #else
pascal@20179 552 addw %ax,%cx # next sector
pascal@20184 553 movw %cx, %si
pascal@20184 554 pushw %ax
pascal@20184 555 shlclw $5, %ax
pascal@20179 556 movw %es, %cx
pascal@20179 557 addw %ax, %cx
pascal@20179 558 popw %ax
pascal@20179 559 subw %ax,%di # update sector counter
pascal@20179 560 #endif
pascal@20179 561 read_sectorsCX:
pascal@20179 562 movw %cx, %es # next location
pascal@20179 563 jz return
pascal@20179 564 read_sectors:
pascal@20184 565 movw %si, %cx
pascal@20179 566 #ifndef FLOPPY_1440K_ONLY
pascal@20179 567 # al is last sector+1
pascal@20184 568 # ah is last head+1
pascal@20179 569 xchgw %ax, %bp
pascal@20179 570 #endif
pascal@20179 571 #ifndef FLOPPY_1440K_ONLY
pascal@20179 572 cmpb %al,%cl # reach sector limit ?
pascal@20179 573 jne bdendlp
pascal@20179 574 next_head:
pascal@20179 575 movb %cl,%al
pascal@20179 576 #else
pascal@20179 577 cmpb $FLOPPY_SECTORS+1,%cl # reach sector limit ?
pascal@20179 578 jne bdendlp
pascal@20179 579 #endif
pascal@20179 580 movb $1,%cl # first sector
pascal@20179 581 #ifndef FLOPPY_HAS_2_SIDES
pascal@20179 582 incb %dh # next head
pascal@20179 583 cmpb %ah, %dh # reach head limit ?
pascal@20179 584 jne bdendlp
pascal@20179 585 next_cylinder:
pascal@20179 586 movb %dh,%ah
pascal@20179 587 movb $0,%dh # first head
pascal@20179 588 #else
pascal@20179 589 xorb %cl,%dh # next head
pascal@20179 590 jne bdendlp # reach head limit ?
pascal@20179 591 #endif
pascal@20179 592 # NOTE : support 256 cylinders max
pascal@20179 593 incb %ch # next cylinder
pascal@20179 594 read_first_sectors:
pascal@20179 595 bdendlp:
pascal@20179 596 jmp read_sectorslp
pascal@20179 597
pascal@20179 598 #ifdef VCPI
pascal@20179 599 pagebuf = 0x98000
pascal@20179 600 tss = gdt_abs-40
pascal@20179 601 gdt = gdt_abs-32
pascal@20179 602 gdt_null = gdt_abs-32
pascal@20179 603 gdt_vcpi = gdt_abs-24
pascal@20179 604 gdt_vcpi2 = gdt_abs-16
pascal@20179 605 gdt_vcpi3 = gdt_abs-8
pascal@20179 606 gdt_abs:
pascal@20179 607 .word 0xFFFF
pascal@20179 608 .long 0x92000000
pascal@20179 609 .byte 0xCF,0
pascal@20179 610 gdt_code:
pascal@20179 611 .word 0xFFFF
pascal@20179 612 gdt_code_base:
pascal@20179 613 .long 0x9A000000+FLAT20(0)
pascal@20179 614 .byte 0x8F,0
pascal@20179 615 gdt_tss:
pascal@20179 616 .word 0x00FF
pascal@20179 617 gdt_tss_base:
pascal@20179 618 .long 0x89000000+FLAT20(tss)
pascal@20179 619 .byte 0,0
pascal@20179 620 gdtr:
pascal@20179 621 gdt_lim:
pascal@20179 622 .word 0xFFFF
pascal@20179 623 gdt_base:
pascal@20179 624 .long FLAT20(gdt)
pascal@20179 625 sw2pm_params:
pascal@20179 626 sw2pm_cr3:
pascal@20179 627 .long pagebuf+0x1000
pascal@20179 628 sw2pm_gdtr_ptr:
pascal@20179 629 .long FLAT20(gdtr)
pascal@20179 630 sw2pm_idtr_ptr:
pascal@20179 631 .long FLAT20(idtr)
pascal@20179 632 sw2pm_ldtr:
pascal@20179 633 .word 0
pascal@20179 634 sw2pm_tr:
pascal@20179 635 SEL_TSS = gdt_tss-gdt_null
pascal@20179 636 .word SEL_TSS
pascal@20179 637 sw2pm_jumpaddr:
pascal@20179 638 .long pm_code
pascal@20179 639 SEL_CODE = gdt_code-gdt_null
pascal@20179 640 .word SEL_CODE
pascal@20179 641 idtr:
pascal@20179 642 idt_lim:
pascal@20179 643 .word 0x03FF
pascal@20179 644 idt_base:
pascal@20179 645 .long 0
pascal@20179 646 # ifndef SHUTDOWNDOS
pascal@20179 647 saved_ss_sp:
pascal@20179 648 .word stacktop-4-16-4,INITSEG
pascal@20179 649 # endif
pascal@20179 650 #endif
pascal@20184 651 #ifdef ELKS
pascal@20184 652 .org 0x1E3
pascal@20184 653 .byte 13,10,7
pascal@20184 654 .asciz "ELKS Boot"
pascal@20184 655 #endif