DuetPkg/BootSector/start64.S

   1 #------------------------------------------------------------------------------
   2 #*
   3 #*   Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
   4 #*   This program and the accompanying materials
   5 #*   are licensed and made available under the terms and conditions of the BSD License
   6 #*   which accompanies this distribution.  The full text of the license may be found at
   7 #*   http://opensource.org/licenses/bsd-license.php
   8 #*
   9 #*   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 #*   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11 #*
  12 #*    start64.asm
  13 #*
  14 #*   Abstract:
  15 #*
  16 #------------------------------------------------------------------------------
  17
  18
  19         .stack:
  20         .486p:
  21         .code16
  22
  23 .equ                        FAT_DIRECTORY_ENTRY_SIZE, 0x020
  24 .equ                        FAT_DIRECTORY_ENTRY_SHIFT, 5
  25 .equ                        BLOCK_SIZE, 0x0200
  26 .equ                        BLOCK_MASK, 0x01ff
  27 .equ                        BLOCK_SHIFT, 9
  28
  29         .org 0x0
  30
  31 .global _start
  32 _start:
  33
  34 Ia32Jump:
  35   jmp   BootSectorEntryPoint  # JMP inst    - 3 bytes
  36   nop
  37
  38 OemId:              .ascii  "INTEL   "        # OemId               - 8 bytes
  39
  40 SectorSize:         .word  0                  # Sector Size         - 16 bits
  41 SectorsPerCluster:  .byte  0                  # Sector Per Cluster  - 8 bits
  42 ReservedSectors:    .word  0                  # Reserved Sectors    - 16 bits
  43 NoFats:             .byte  0                  # Number of FATs      - 8 bits
  44 RootEntries:        .word  0                  # Root Entries        - 16 bits
  45 Sectors:            .word  0                  # Number of Sectors   - 16 bits
  46 Media:              .byte  0                  # Media               - 8 bits  - ignored
  47 SectorsPerFat:      .word  0                  # Sectors Per FAT     - 16 bits
  48 SectorsPerTrack:    .word  0                  # Sectors Per Track   - 16 bits - ignored
  49 Heads:              .word  0                  # Heads               - 16 bits - ignored
  50 HiddenSectors:      .long  0                  # Hidden Sectors      - 32 bits - ignored
  51 LargeSectors:       .long  0                  # Large Sectors       - 32 bits
  52 PhysicalDrive:      .byte  0                  # PhysicalDriveNumber - 8 bits  - ignored
  53 CurrentHead:        .byte  0                  # Current Head        - 8 bits
  54 Signature:          .byte  0                  # Signature           - 8 bits  - ignored
  55 VolId:              .ascii "    "             # Volume Serial Number- 4 bytes
  56 FatLabel:           .ascii "           "      # Label               - 11 bytes
  57 SystemId:           .ascii "FAT12   "         # SystemId            - 8 bytes
  58
  59 BootSectorEntryPoint:
  60       # ASSUME  ds:@code"
  61       # ASSUME  ss:@code"
  62       # ds = 1000, es = 2000 + x (size of first cluster >> 4)
  63       # cx = Start Cluster of EfiLdr
  64       # dx = Start Cluster of Efivar.bin
  65
  66 # Re use the BPB data stored in Boot Sector
  67         movw    $0x7c00,%bp
  68
  69         pushw   %cx
  70 # Read Efivar.bin
  71 #       1000:dx    = DirectoryEntry of Efivar.bin -> BS.com has filled already
  72         movw    $0x1900,%ax
  73         movw    %ax,%es
  74         testw   %dx,%dx
  75         jnz     CheckVarStoreSize
  76
  77         movb    $1,%al
  78 NoVarStore:
  79         pushw   %es
  80 # Set the 5th byte start @ 0:19000 to non-zero indicating we should init var store header in DxeIpl
  81         movb    %al, %es:(4)
  82         jmp     SaveVolumeId
  83
  84 CheckVarStoreSize:
  85         movw    %dx,%di
  86         cmpl    $0x4000, %ds:2(%di)
  87         movb    $2,%al
  88         jne     NoVarStore
  89
  90 LoadVarStore:
  91         movb    $0,%al
  92         movb    %al, %es:(4)
  93         movw    (%di), %cx
  94 #       ES:DI = 1500:0
  95         xorw    %di,%di
  96         pushw   %es
  97         movw    $0x1500,%ax
  98         movw    %ax,%es
  99         call    ReadFile
 100 SaveVolumeId:
 101         popw    %es
 102         movw    VolId(%bp), %ax
 103         movw    %ax, %es:(0)
 104         movw    VolId+2(%bp), %ax
 105         movw    %ax, %es:(2)
 106
 107 # Read Efildr
 108         popw    %cx
 109 #       cx    = Start Cluster of Efildr -> BS.com has filled already
 110 #       ES:DI = 2000:0, first cluster will be read again
 111         xorw    %di,%di                             # di = 0
 112         movw    $0x2000,%ax
 113         movw    %ax,%es
 114         call    ReadFile
 115         movw    %cs,%ax
 116         movw    %ax, %cs:JumpSegment
 117
 118 CheckEm64T:
 119         movl $0x80000001,%eax
 120 #        cpuid
 121         .word 0xA20F
 122         btl  $29,%edx
 123         jc   CheckEm64TPass
 124         pushw %cs
 125         popw %ds
 126         leaw Em64String,%si
 127         movw $18,%cx
 128         jmp  PrintStringAndHalt
 129 CheckEm64TPass:
 130 JumpFarInstruction:
 131         .byte 0xea
 132 JumpOffset:
 133         .word 0x200
 134 JumpSegment:
 135         .word 0x2000
 136
 137
 138
 139 # ****************************************************************************
 140 # ReadFile
 141 #
 142 # Arguments:
 143 #   CX    = Start Cluster of File
 144 #   ES:DI = Buffer to store file content read from disk
 145 #
 146 # Return:
 147 #   (ES << 4 + DI) = end of file content Buffer
 148 #
 149 # ****************************************************************************
 150 ReadFile:
 151 # si      = NumberOfClusters
 152 # cx      = ClusterNumber
 153 # dx      = CachedFatSectorNumber
 154 # ds:0000 = CacheFatSectorBuffer
 155 # es:di   = Buffer to load file
 156 # bx      = NextClusterNumber
 157         pusha
 158         movw    $1,%si                              # NumberOfClusters = 1
 159         pushw   %cx                                 # Push Start Cluster onto stack
 160         movw    $0xfff,%dx                          # CachedFatSectorNumber = 0xfff
 161 FatChainLoop:
 162         movw    %cx,%ax                             # ax = ClusterNumber
 163         andw    $0xff8,%ax                          # ax = ax & 0xff8
 164         cmpw    $0xff8,%ax                          # See if this is the last cluster
 165         je      FoundLastCluster                    # Jump if last cluster found
 166         movw    %cx,%ax                             # ax = ClusterNumber
 167         shlw    %ax                                 # ax = ClusterNumber * 2
 168         addw    %cx,%ax                             # ax = ClusterNumber * 2 + ClusterNumber = ClusterNumber * 3
 169         shrw    %ax                                 # FatOffset = ClusterNumber*3 / 2
 170         pushw   %si                                 # Save si
 171         movw    %ax,%si                             # si = FatOffset
 172         shrw    $BLOCK_SHIFT, %ax                   # ax = FatOffset >> BLOCK_SHIFT
 173         addw    ReservedSectors(%bp), %ax           # ax = FatSectorNumber = ReservedSectors + (FatOffset >> BLOCK_OFFSET)
 174         andw    $BLOCK_MASK, %si                    # si = FatOffset & BLOCK_MASK
 175         cmpw    %dx,%ax                             # Compare FatSectorNumber to CachedFatSectorNumber
 176         je      SkipFatRead
 177         movw    $2,%bx
 178         pushw   %es
 179         pushw   %ds
 180         popw    %es
 181         call    ReadBlocks                          # Read 2 blocks starting at AX storing at ES:DI
 182         popw    %es
 183         movw    %ax,%dx                             # CachedFatSectorNumber = FatSectorNumber
 184 SkipFatRead:
 185         movw    (%si), %bx                          # bx = NextClusterNumber
 186         movw    %cx,%ax                             # ax = ClusterNumber
 187         andw    $1,%ax                              # See if this is an odd cluster number
 188         je      EvenFatEntry
 189         shrw    $4,%bx                              # NextClusterNumber = NextClusterNumber >> 4
 190 EvenFatEntry:
 191         andw    $0xfff,%bx                          # Strip upper 4 bits of NextClusterNumber
 192         popw    %si                                 # Restore si
 193         decw    %bx                                 # bx = NextClusterNumber - 1
 194         cmpw    %cx,%bx                             # See if (NextClusterNumber-1)==ClusterNumber
 195         jne     ReadClusters
 196         incw    %bx                                 # bx = NextClusterNumber
 197         incw    %si                                 # NumberOfClusters++
 198         movw    %bx,%cx                             # ClusterNumber = NextClusterNumber
 199         jmp     FatChainLoop
 200 ReadClusters:
 201         incw    %bx
 202         popw    %ax                                 # ax = StartCluster
 203         pushw   %bx                                 # StartCluster = NextClusterNumber
 204         movw    %bx,%cx                             # ClusterNumber = NextClusterNumber
 205         subw    $2,%ax                              # ax = StartCluster - 2
 206         xorb    %bh,%bh
 207         movb    SectorsPerCluster(%bp), %bl         # bx = SectorsPerCluster
 208         mulw    %bx                                 # ax = (StartCluster - 2) * SectorsPerCluster
 209         addw    (%bp), %ax                          # ax = FirstClusterLBA + (StartCluster-2)*SectorsPerCluster
 210         pushw   %ax                                 # save start sector
 211         movw    %si,%ax                             # ax = NumberOfClusters
 212         mulw    %bx                                 # ax = NumberOfClusters * SectorsPerCluster
 213         movw    %ax,%bx                             # bx = Number of Sectors
 214         popw    %ax                                 # ax = Start Sector
 215         call    ReadBlocks
 216         movw    $1,%si                              # NumberOfClusters = 1
 217         jmp     FatChainLoop
 218 FoundLastCluster:
 219         popw    %cx
 220         popa
 221         ret
 222
 223
 224 # ****************************************************************************
 225 # ReadBlocks - Reads a set of blocks from a block device
 226 #
 227 # AX    = Start LBA
 228 # BX    = Number of Blocks to Read
 229 # ES:DI = Buffer to store sectors read from disk
 230 # ****************************************************************************
 231
 232 # cx = Blocks
 233 # bx = NumberOfBlocks
 234 # si = StartLBA
 235
 236 ReadBlocks:
 237         pusha
 238         addl    LBAOffsetForBootSector(%bp), %eax   # Add LBAOffsetForBootSector to Start LBA
 239         addl    HiddenSectors(%bp), %eax            # Add HiddenSectors to Start LBA
 240         movl    %eax,%esi                           # esi = Start LBA
 241         movw    %bx,%cx                             # cx = Number of blocks to read
 242 ReadCylinderLoop:
 243         movw    $0x7bfc,%bp                         # bp = 0x7bfc
 244         movl    %esi,%eax                           # eax = Start LBA
 245         xorl    %edx,%edx                           # edx = 0
 246         movzwl  (%bp), %ebx                         # bx = MaxSector
 247         divl    %ebx                                # ax = StartLBA / MaxSector
 248         incw    %dx                                 # dx = (StartLBA % MaxSector) + 1
 249
 250         movw    (%bp), %bx                          # bx = MaxSector
 251         subw    %dx,%bx                             # bx = MaxSector - Sector
 252         incw    %bx                                 # bx = MaxSector - Sector + 1
 253         cmpw    %bx,%cx                             # Compare (Blocks) to (MaxSector - Sector + 1)
 254         jg      LimitTransfer
 255         movw    %cx,%bx                             # bx = Blocks
 256 LimitTransfer:
 257         pushw   %ax                                 # save ax
 258         movw    %es,%ax                             # ax = es
 259         shrw    $(BLOCK_SHIFT-4), %ax               # ax = Number of blocks into mem system
 260         andw    $0x7f,%ax                           # ax = Number of blocks into current seg
 261         addw    %bx,%ax                             # ax = End Block number of transfer
 262         cmpw    $0x80,%ax                           # See if it crosses a 64K boundry
 263         jle     NotCrossing64KBoundry               # Branch if not crossing 64K boundry
 264         subw    $0x80,%ax                           # ax = Number of blocks past 64K boundry
 265         subw    %ax,%bx                             # Decrease transfer size by block overage
 266 NotCrossing64KBoundry:
 267         popw    %ax                                 # restore ax
 268
 269         pushw   %cx
 270         movb    %dl,%cl                             # cl = (StartLBA % MaxSector) + 1 = Sector
 271         xorw    %dx,%dx                             # dx = 0
 272         divw    2(%bp)                              # ax = ax / (MaxHead + 1) = Cylinder
 273                                                     # dx = ax % (MaxHead + 1) = Head
 274
 275         pushw   %bx                                 # Save number of blocks to transfer
 276         movb    %dl,%dh                             # dh = Head
 277         movw    $0x7c00,%bp                         # bp = 0x7c00
 278         movb    PhysicalDrive(%bp), %dl             # dl = Drive Number
 279         movb    %al,%ch                             # ch = Cylinder
 280         movb    %bl,%al                             # al = Blocks
 281         movb    $2,%ah                              # ah = Function 2
 282         movw    %di,%bx                             # es:bx = Buffer address
 283         int     $0x13
 284         jc      DiskError
 285         popw    %bx
 286         popw    %cx
 287         movzwl  %bx,%ebx
 288         addl    %ebx,%esi                           # StartLBA = StartLBA + NumberOfBlocks
 289         subw    %bx,%cx                             # Blocks = Blocks - NumberOfBlocks
 290         movw    %es,%ax
 291         shlw    $(BLOCK_SHIFT-4), %bx
 292         addw    %bx,%ax
 293         movw    %ax,%es                             # es:di = es:di + NumberOfBlocks*BLOCK_SIZE
 294         cmpw    $0,%cx
 295         jne     ReadCylinderLoop
 296         popa
 297         ret
 298
 299 DiskError:
 300         pushw %cs
 301         popw %ds
 302         leaw ErrorString,%si
 303         movw $7,%cx
 304         jmp  PrintStringAndHalt
 305
 306 PrintStringAndHalt:
 307         movw $0xb800,%ax
 308         movw %ax,%es
 309         movw $160,%di
 310         rep
 311         movsw
 312 Halt:
 313         jmp   Halt
 314
 315 ErrorString:
 316         .byte 'S', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, 'o', 0x0c, 'r', 0x0c, '!',0x0c
 317
 318         .org     0x01fa
 319 LBAOffsetForBootSector:
 320         .long 0x0
 321
 322         .org    0x01fe
 323         .word 0xaa55
 324
 325 #******************************************************************************
 326 #******************************************************************************
 327 #******************************************************************************
 328
 329 .equ                 DELAY_PORT, 0x0ed           # Port to use for 1uS delay
 330 .equ                 KBD_CONTROL_PORT, 0x060     # 8042 control port
 331 .equ                 KBD_STATUS_PORT, 0x064      # 8042 status port
 332 .equ                 WRITE_DATA_PORT_CMD, 0x0d1  # 8042 command to write the data port
 333 .equ                 ENABLE_A20_CMD, 0x0df       # 8042 command to enable A20
 334
 335         .org     0x200
 336         jmp start
 337 Em64String:
 338 .byte 'E', 0x0c, 'm', 0x0c, '6', 0x0c, '4', 0x0c, 'T', 0x0c, ' ', 0x0c, 'U', 0x0c, 'n', 0x0c, 's', 0x0c, 'u', 0x0c, 'p', 0x0c, 'p', 0x0c, 'o', 0x0c, 'r', 0x0c, 't', 0x0c, 'e', 0x0c, 'd', 0x0c, '!', 0x0c
 339
 340 start:
 341         movw %cs,%ax
 342         movw %ax,%ds
 343         movw %ax,%es
 344         movw %ax,%ss
 345         movw $MyStack, %sp
 346
 347 #        mov ax,0b800h
 348 #        mov es,ax
 349 #        mov byte ptr es:[160],'a'
 350 #        mov ax,cs
 351 #        mov es,ax
 352
 353         movl $0,%ebx
 354         leal MemoryMap, %edi
 355 MemMapLoop:
 356         movl $0xe820,%eax
 357         movl $20,%ecx
 358         movl $0x534d4150, %edx  # SMAP
 359         int $0x15
 360         jc  MemMapDone
 361         addl $20,%edi
 362         cmpl $0,%ebx
 363         je  MemMapDone
 364         jmp MemMapLoop
 365 MemMapDone:
 366         leal MemoryMap, %eax
 367         subl %eax,%edi                      # Get the address of the memory map
 368         movl %edi, MemoryMapSize            # Save the size of the memory map
 369
 370         xorl    %ebx,%ebx
 371         movw    %cs,%bx                     # BX=segment
 372         shll    $4,%ebx                     # BX="linear" address of segment base
 373         leal    GDT_BASE(%ebx), %eax        # EAX=PHYSICAL address of gdt
 374         movl    %eax, (gdtr + 2)            # Put address of gdt into the gdtr
 375         leal    IDT_BASE(%ebx), %eax        # EAX=PHYSICAL address of idt
 376         movl    %eax, (idtr + 2)            # Put address of idt into the idtr
 377         leal    MemoryMapSize(%ebx), %edx   # Physical base address of the memory map
 378
 379 #        mov ax,0b800h
 380 #        mov es,ax
 381 #        mov byte ptr es:[162],'b'
 382 #        mov ax,cs
 383 #        mov es,ax
 384
 385 #
 386 # Enable A20 Gate
 387 #
 388
 389         movw $0x2401,%ax                    # Enable A20 Gate
 390         int $0x15
 391         jnc A20GateEnabled                  # Jump if it suceeded
 392
 393 #
 394 # If INT 15 Function 2401 is not supported, then attempt to Enable A20 manually.
 395 #
 396
 397         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 398         jnz     Timeout8042                 # Jump if the 8042 timed out
 399         outw    %ax, $DELAY_PORT            # Delay 1 uS
 400         movb    $WRITE_DATA_PORT_CMD, %al   # 8042 cmd to write output port
 401         outb    %al, $KBD_STATUS_PORT       # Send command to the 8042
 402         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 403         jnz     Timeout8042                 # Jump if the 8042 timed out
 404         movb    $ENABLE_A20_CMD, %al        # gate address bit 20 on
 405         outb    %al, $KBD_CONTROL_PORT      # Send command to thre 8042
 406         call    Empty8042InputBuffer        # Empty the Input Buffer on the 8042 controller
 407         movw    $25,%cx                     # Delay 25 uS for the command to complete on the 8042
 408 Delay25uS:
 409         outw    %ax, $DELAY_PORT            # Delay 1 uS
 410         loop    Delay25uS
 411 Timeout8042:
 412
 413
 414 A20GateEnabled:
 415
 416 #
 417 # DISABLE INTERRUPTS - Entering Protected Mode
 418 #
 419
 420         cli
 421
 422 #        mov ax,0b800h
 423 #        mov es,ax
 424 #        mov byte ptr es:[164],'c'
 425 #        mov ax,cs
 426 #        mov es,ax
 427
 428     leal OffsetIn32BitProtectedMode, %eax
 429     addl $0x20000+0x6,%eax
 430     movl %eax, OffsetIn32BitProtectedMode
 431
 432     leal OffsetInLongMode, %eax
 433     addl $0x20000+0x6,%eax
 434     movl %eax, OffsetInLongMode
 435
 436     #
 437     # load GDT
 438     #
 439     .byte 0x66
 440     lgdt    gdtr
 441
 442     #
 443     # Enable Protect Mode (set CR0.PE=1)
 444     #
 445     movl  %cr0, %eax      # Read CR0.
 446     orl   $0x1,%eax       # Set PE=1
 447     movl  %eax, %cr0      # Write CR0.
 448     .byte 0x66
 449     .byte 0xea                        # jmp far 16:32
 450 OffsetIn32BitProtectedMode:
 451     .long 0x0000000                   # offset $+8   (In32BitProtectedMode)
 452     .word 0x10                        # selector  (flat CS)
 453 In32BitProtectedMode:
 454
 455 #
 456 # Entering Long Mode
 457 #
 458     .byte 0x66
 459     movw $8,%ax
 460     movw %ax,%ds
 461     movw %ax,%es
 462     movw %ax,%ss
 463
 464     #
 465     # Enable the 64-bit page-translation-table entries by
 466     # setting CR4.PAE=1 (this is _required_ before activating
 467     # long mode). Paging is not enabled until after long mode
 468     # is enabled.
 469     #
 470     .byte 0xf
 471     .byte 0x20
 472     .byte 0xe0
 473 #    mov eax, cr4
 474     btsl $5,%eax
 475     .byte 0xf
 476     .byte 0x22
 477     .byte 0xe0
 478 #    mov cr4, eax
 479
 480     #
 481     # This is the Trapolean Page Tables that are guarenteed
 482     #  under 4GB.
 483     #
 484     # Address Map:
 485     #    10000 ~    12000 - efildr (loaded)
 486     #    20000 ~    21000 - start64.com
 487     #    21000 ~    22000 - efi64.com
 488     #    22000 ~    90000 - efildr
 489     #    90000 ~    96000 - 4G pagetable (will be reload later)
 490     #
 491     .byte 0xb8
 492     .long 0x90000
 493 #    mov eax, 90000h
 494     movl %eax, %cr3
 495
 496     #
 497     # Enable long mode (set EFER.LME=1).
 498     #
 499     .byte 0xb9
 500     .long 0xc0000080
 501 #    mov   ecx, 0c0000080h ; EFER MSR number.
 502     .byte 0xf
 503     .byte 0x32
 504 #    rdmsr                 ; Read EFER.
 505     .byte 0xf
 506     .byte 0xba
 507     .byte 0xe8
 508     .byte 0x8
 509 #    bts   eax, 8          ; Set LME=1.
 510     .byte 0xf
 511     .byte 0x30
 512 #    wrmsr                 ; Write EFER.
 513
 514     #
 515     # Enable paging to activate long mode (set CR0.PG=1)
 516     #
 517     movl  %cr0, %eax      # Read CR0.
 518     .byte 0xf
 519     .byte 0xba
 520     .byte 0xe8
 521     .byte 0x1f
 522 #    bts   eax, 31         ; Set PG=1.
 523     movl  %eax, %cr0      # Write CR0.
 524     jmp   GoToLongMode
 525 GoToLongMode:
 526
 527     .byte 0x67
 528     .byte 0xea                  # Far Jump $+9:Selector to reload CS
 529 OffsetInLongMode:
 530     .long 00000000              #   $+9 Offset is ensuing instruction boundary
 531     .word 0x38                  #   Selector is our code selector, 38h
 532
 533 InLongMode:
 534     .byte 0x66
 535     movw    $0x30,%ax
 536     movw    %ax,%ds
 537
 538     .byte 0x66
 539     movw    $0x18,%ax
 540     movw    %ax,%es
 541     movw    %ax,%ss
 542     movw    %ax,%ds
 543
 544     .byte 0xbd
 545     .long 0x400000
 546 #    mov ebp,000400000h                  ; Destination of EFILDR32
 547     .byte 0xbb
 548     .long 0x70000
 549 #    mov ebx,000070000h                  ; Length of copy
 550
 551     #
 552     # load idt later
 553     #
 554     .byte 0x48
 555     .byte 0x33
 556     .byte 0xc0
 557 #    xor rax, rax
 558     .byte 0x66
 559      movw $idtr, %ax
 560     .byte 0x48
 561     .byte 0x5
 562     .long 0x20000
 563 #    add rax, 20000h
 564
 565     .byte 0xf
 566     .byte 0x1
 567     .byte 0x18
 568 #    lidt    fword ptr [rax]
 569
 570     .byte 0x48
 571     .byte 0xc7
 572     .byte 0xc0
 573     .long 0x21000
 574 #   mov rax, 21000h
 575     .byte 0x50
 576 #   push rax
 577
 578 # ret
 579     .byte 0xc3
 580
 581 Empty8042InputBuffer:
 582         movw $0,%cx
 583 Empty8042Loop:
 584         outw    %ax, $DELAY_PORT            # Delay 1us
 585         inb     $KBD_STATUS_PORT, %al       # Read the 8042 Status Port
 586         andb    $0x2,%al                    # Check the Input Buffer Full Flag
 587         loopnz  Empty8042Loop               # Loop until the input buffer is empty or a timout of 65536 uS
 588         ret
 589
 590 ##############################################################################
 591 # data
 592 ##############################################################################
 593
 594         .p2align 1
 595
 596         gdtr:    .long  GDT_END - GDT_BASE - 1  # GDT limit
 597         .long 0                     # (GDT base gets set above)
 598 ##############################################################################
 599 #   global descriptor table (GDT)
 600 ##############################################################################
 601
 602         .p2align 1
 603
 604 GDT_BASE:
 605 # null descriptor
 606 .equ                NULL_SEL, .-GDT_BASE    # Selector [0x0]
 607         .word 0         # limit 15:0
 608         .word 0         # base 15:0
 609         .byte 0         # base 23:16
 610         .byte 0         # type
 611         .byte 0         # limit 19:16, flags
 612         .byte 0         # base 31:24
 613
 614 # linear data segment descriptor
 615 .equ            LINEAR_SEL, .-GDT_BASE  # Selector [0x8]
 616         .word 0xFFFF    # limit 0xFFFFF
 617         .word 0         # base 0
 618         .byte 0
 619         .byte 0x92      # present, ring 0, data, expand-up, writable
 620         .byte 0xCF              # page-granular, 32-bit
 621         .byte 0
 622
 623 # linear code segment descriptor
 624 .equ            LINEAR_CODE_SEL, .-GDT_BASE # Selector [0x10]
 625         .word 0xFFFF    # limit 0xFFFFF
 626         .word 0         # base 0
 627         .byte 0
 628         .byte 0x9A      # present, ring 0, data, expand-up, writable
 629         .byte 0xCF              # page-granular, 32-bit
 630         .byte 0
 631
 632 # system data segment descriptor
 633 .equ            SYS_DATA_SEL, .-GDT_BASE # Selector [0x18]
 634         .word 0xFFFF    # limit 0xFFFFF
 635         .word 0         # base 0
 636         .byte 0
 637         .byte 0x92      # present, ring 0, data, expand-up, writable
 638         .byte 0xCF              # page-granular, 32-bit
 639         .byte 0
 640
 641 # system code segment descriptor
 642 .equ            SYS_CODE_SEL, .-GDT_BASE # Selector [0x20]
 643         .word 0xFFFF    # limit 0xFFFFF
 644         .word 0         # base 0
 645         .byte 0
 646         .byte 0x9A      # present, ring 0, data, expand-up, writable
 647         .byte 0xCF              # page-granular, 32-bit
 648         .byte 0
 649
 650 # spare segment descriptor
 651 .equ        SPARE3_SEL, .-GDT_BASE  # Selector [0x28]
 652         .word 0         # limit 0xFFFFF
 653         .word 0         # base 0
 654         .byte 0
 655         .byte 0         # present, ring 0, data, expand-up, writable
 656         .byte 0         # page-granular, 32-bit
 657         .byte 0
 658
 659 #
 660 # system data segment descriptor
 661 #
 662 .equ              SYS_DATA64_SEL, .-GDT_BASE # Selector [0x30]
 663         .word 0xFFFF    # limit 0xFFFFF
 664         .word 0         # base 0
 665         .byte 0
 666         .byte 0x92      # P | DPL [1..2] | 1   | 1   | C | R | A
 667         .byte 0xCF      # G | D   | L    | AVL | Segment [19..16]
 668         .byte 0
 669
 670 #
 671 # system code segment descriptor
 672 #
 673 .equ              SYS_CODE64_SEL, .-GDT_BASE # Selector [0x38]
 674         .word 0xFFFF    # limit 0xFFFFF
 675         .word 0         # base 0
 676         .byte 0
 677         .byte 0x9A      # P | DPL [1..2] | 1   | 1   | C | R | A
 678         .byte 0xAF      # G | D   | L    | AVL | Segment [19..16]
 679         .byte 0
 680
 681 # spare segment descriptor
 682 .equ        SPARE4_SEL, .-GDT_BASE    # Selector [0x40]
 683         .word 0         # limit 0xFFFFF
 684         .word 0         # base 0
 685         .byte 0
 686         .byte 0         # present, ring 0, data, expand-up, writable
 687         .byte 0         # page-granular, 32-bit
 688         .byte 0
 689
 690 GDT_END:
 691
 692         .p2align 1
 693
 694
 695
 696 idtr:   .long  IDT_END - IDT_BASE - 1 # IDT limit
 697         .quad 0                       # (IDT base gets set above)
 698
 699 ##############################################################################
 700 #   interrupt descriptor table (IDT)
 701 #
 702 #   Note: The hardware IRQ's specified in this table are the normal PC/AT IRQ
 703 #       mappings.  This implementation only uses the system timer and all other
 704 #       IRQs will remain masked.  The descriptors for vectors 33+ are provided
 705 #       for convenience.
 706 ##############################################################################
 707
 708 #idt_tag db "IDT",0
 709         .p2align 1
 710
 711
 712 IDT_BASE:
 713 # divide by zero (INT 0)
 714 .equ                DIV_ZERO_SEL, .-IDT_BASE
 715         .word 0               # offset 15:0
 716         .long SYS_CODE64_SEL  # selector 15:0
 717         .byte 0               # 0 for interrupt gate
 718         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 719         .word 0               # offset 31:16
 720         .long 0               # offset 63:32
 721         .long 0               # 0 for reserved
 722
 723 # debug exception (INT 1)
 724 .equ                DEBUG_EXCEPT_SEL, .-IDT_BASE
 725         .word 0               # offset 15:0
 726         .long SYS_CODE64_SEL  # selector 15:0
 727         .byte 0               # 0 for interrupt gate
 728         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 729         .word 0               # offset 31:16
 730         .long 0               # offset 63:32
 731         .long 0               # 0 for reserved
 732
 733 # NMI (INT 2)
 734 .equ                NMI_SEL, .-IDT_BASE
 735         .word 0               # offset 15:0
 736         .long SYS_CODE64_SEL  # selector 15:0
 737         .byte 0               # 0 for interrupt gate
 738         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 739         .word 0               # offset 31:16
 740         .long 0               # offset 63:32
 741         .long 0               # 0 for reserved
 742
 743 # soft breakpoint (INT 3)
 744 .equ                BREAKPOINT_SEL, .-IDT_BASE
 745         .word 0               # offset 15:0
 746         .long SYS_CODE64_SEL  # selector 15:0
 747         .byte 0               # 0 for interrupt gate
 748         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 749         .word 0               # offset 31:16
 750         .long 0               # offset 63:32
 751         .long 0               # 0 for reserved
 752
 753 # overflow (INT 4)
 754 .equ                OVERFLOW_SEL, .-IDT_BASE
 755         .word 0               # offset 15:0
 756         .long SYS_CODE64_SEL  # selector 15:0
 757         .byte 0               # 0 for interrupt gate
 758         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 759         .word 0               # offset 31:16
 760         .long 0               # offset 63:32
 761         .long 0               # 0 for reserved
 762
 763 # bounds check (INT 5)
 764 .equ                BOUNDS_CHECK_SEL, .-IDT_BASE
 765         .word 0               # offset 15:0
 766         .long SYS_CODE64_SEL  # selector 15:0
 767         .byte 0               # 0 for interrupt gate
 768         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 769         .word 0               # offset 31:16
 770         .long 0               # offset 63:32
 771         .long 0               # 0 for reserved
 772
 773 # invalid opcode (INT 6)
 774 .equ                INVALID_OPCODE_SEL, .-IDT_BASE
 775         .word 0               # offset 15:0
 776         .long SYS_CODE64_SEL  # selector 15:0
 777         .byte 0               # 0 for interrupt gate
 778         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 779         .word 0               # offset 31:16
 780         .long 0               # offset 63:32
 781         .long 0               # 0 for reserved
 782
 783 # device not available (INT 7)
 784 .equ                DEV_NOT_AVAIL_SEL, .-IDT_BASE
 785         .word 0               # offset 15:0
 786         .long SYS_CODE64_SEL  # selector 15:0
 787         .byte 0               # 0 for interrupt gate
 788         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 789         .word 0               # offset 31:16
 790         .long 0               # offset 63:32
 791         .long 0               # 0 for reserved
 792
 793 # double fault (INT 8)
 794 .equ                DOUBLE_FAULT_SEL, .-IDT_BASE
 795         .word 0               # offset 15:0
 796         .long SYS_CODE64_SEL  # selector 15:0
 797         .byte 0               # 0 for interrupt gate
 798         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 799         .word 0               # offset 31:16
 800         .long 0               # offset 63:32
 801         .long 0               # 0 for reserved
 802
 803 # Coprocessor segment overrun - reserved (INT 9)
 804 .equ                RSVD_INTR_SEL1, .-IDT_BASE
 805         .word 0               # offset 15:0
 806         .long SYS_CODE64_SEL  # selector 15:0
 807         .byte 0               # 0 for interrupt gate
 808         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 809         .word 0               # offset 31:16
 810         .long 0               # offset 63:32
 811         .long 0               # 0 for reserved
 812
 813 # invalid TSS (INT 0ah)
 814 .equ                INVALID_TSS_SEL, .-IDT_BASE
 815         .word 0               # offset 15:0
 816         .long SYS_CODE64_SEL  # selector 15:0
 817         .byte 0               # 0 for interrupt gate
 818         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 819         .word 0               # offset 31:16
 820         .long 0               # offset 63:32
 821         .long 0               # 0 for reserved
 822
 823 # segment not present (INT 0bh)
 824 .equ                SEG_NOT_PRESENT_SEL, .-IDT_BASE
 825         .word 0               # offset 15:0
 826         .long SYS_CODE64_SEL  # selector 15:0
 827         .byte 0               # 0 for interrupt gate
 828         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 829         .word 0               # offset 31:16
 830         .long 0               # offset 63:32
 831         .long 0               # 0 for reserved
 832
 833 # stack fault (INT 0ch)
 834 .equ                STACK_FAULT_SEL, .-IDT_BASE
 835         .word 0               # offset 15:0
 836         .long SYS_CODE64_SEL  # selector 15:0
 837         .byte 0               # 0 for interrupt gate
 838         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 839         .word 0               # offset 31:16
 840         .long 0               # offset 63:32
 841         .long 0               # 0 for reserved
 842
 843 # general protection (INT 0dh)
 844 .equ                GP_FAULT_SEL, .-IDT_BASE
 845         .word 0               # offset 15:0
 846         .long SYS_CODE64_SEL  # selector 15:0
 847         .byte 0               # 0 for interrupt gate
 848         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 849         .word 0               # offset 31:16
 850         .long 0               # offset 63:32
 851         .long 0               # 0 for reserved
 852
 853 # page fault (INT 0eh)
 854 .equ                PAGE_FAULT_SEL, .-IDT_BASE
 855         .word 0               # offset 15:0
 856         .long SYS_CODE64_SEL  # selector 15:0
 857         .byte 0               # 0 for interrupt gate
 858         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 859         .word 0               # offset 31:16
 860         .long 0               # offset 63:32
 861         .long 0               # 0 for reserved
 862
 863 # Intel reserved - do not use (INT 0fh)
 864 .equ                RSVD_INTR_SEL2, .-IDT_BASE
 865         .word 0               # offset 15:0
 866         .long SYS_CODE64_SEL  # selector 15:0
 867         .byte 0               # 0 for interrupt gate
 868         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 869         .word 0               # offset 31:16
 870         .long 0               # offset 63:32
 871         .long 0               # 0 for reserved
 872
 873 # floating point error (INT 10h)
 874 .equ                FLT_POINT_ERR_SEL, .-IDT_BASE
 875         .word 0               # offset 15:0
 876         .long SYS_CODE64_SEL  # selector 15:0
 877         .byte 0               # 0 for interrupt gate
 878         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 879         .word 0               # offset 31:16
 880         .long 0               # offset 63:32
 881         .long 0               # 0 for reserved
 882
 883 # alignment check (INT 11h)
 884 .equ                ALIGNMENT_CHECK_SEL, .-IDT_BASE
 885         .word 0               # offset 15:0
 886         .long SYS_CODE64_SEL  # selector 15:0
 887         .byte 0               # 0 for interrupt gate
 888         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 889         .word 0               # offset 31:16
 890         .long 0               # offset 63:32
 891         .long 0               # 0 for reserved
 892
 893 # machine check (INT 12h)
 894 .equ                MACHINE_CHECK_SEL, .-IDT_BASE
 895         .word 0               # offset 15:0
 896         .long SYS_CODE64_SEL  # selector 15:0
 897         .byte 0               # 0 for interrupt gate
 898         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 899         .word 0               # offset 31:16
 900         .long 0               # offset 63:32
 901         .long 0               # 0 for reserved
 902
 903 # SIMD floating-point exception (INT 13h)
 904 .equ                SIMD_EXCEPTION_SEL, .-IDT_BASE
 905         .word 0               # offset 15:0
 906         .long SYS_CODE64_SEL  # selector 15:0
 907         .byte 0               # 0 for interrupt gate
 908         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 909         .word 0               # offset 31:16
 910         .long 0               # offset 63:32
 911         .long 0               # 0 for reserved
 912
 913 # 85 unspecified descriptors, First 12 of them are reserved, the rest are avail
 914         .fill 85 * 16, 1, 0   # db (85 * 16) dup(0)
 915
 916 # IRQ 0 (System timer) - (INT 68h)
 917 .equ                IRQ0_SEL, .-IDT_BASE
 918         .word 0               # offset 15:0
 919         .long SYS_CODE64_SEL  # selector 15:0
 920         .byte 0               # 0 for interrupt gate
 921         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 922         .word 0               # offset 31:16
 923         .long 0               # offset 63:32
 924         .long 0               # 0 for reserved
 925
 926 # IRQ 1 (8042 Keyboard controller) - (INT 69h)
 927 .equ                IRQ1_SEL, .-IDT_BASE
 928         .word 0               # offset 15:0
 929         .long SYS_CODE64_SEL  # selector 15:0
 930         .byte 0               # 0 for interrupt gate
 931         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 932         .word 0               # offset 31:16
 933         .long 0               # offset 63:32
 934         .long 0               # 0 for reserved
 935
 936 # Reserved - IRQ 2 redirect (IRQ 2) - DO NOT USE!!! - (INT 6ah)
 937 .equ                IRQ2_SEL, .-IDT_BASE
 938         .word 0               # offset 15:0
 939         .long SYS_CODE64_SEL  # selector 15:0
 940         .byte 0               # 0 for interrupt gate
 941         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 942         .word 0               # offset 31:16
 943         .long 0               # offset 63:32
 944         .long 0               # 0 for reserved
 945
 946 # IRQ 3 (COM 2) - (INT 6bh)
 947 .equ                IRQ3_SEL, .-IDT_BASE
 948         .word 0               # offset 15:0
 949         .long SYS_CODE64_SEL  # selector 15:0
 950         .byte 0               # 0 for interrupt gate
 951         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 952         .word 0               # offset 31:16
 953         .long 0               # offset 63:32
 954         .long 0               # 0 for reserved
 955
 956 # IRQ 4 (COM 1) - (INT 6ch)
 957 .equ                IRQ4_SEL, .-IDT_BASE
 958         .word 0               # offset 15:0
 959         .long SYS_CODE64_SEL  # selector 15:0
 960         .byte 0               # 0 for interrupt gate
 961         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 962         .word 0               # offset 31:16
 963         .long 0               # offset 63:32
 964         .long 0               # 0 for reserved
 965
 966 # IRQ 5 (LPT 2) - (INT 6dh)
 967 .equ                IRQ5_SEL, .-IDT_BASE
 968         .word 0               # offset 15:0
 969         .long SYS_CODE64_SEL  # selector 15:0
 970         .byte 0               # 0 for interrupt gate
 971         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 972         .word 0               # offset 31:16
 973         .long 0               # offset 63:32
 974         .long 0               # 0 for reserved
 975
 976 # IRQ 6 (Floppy controller) - (INT 6eh)
 977 .equ                IRQ6_SEL, .-IDT_BASE
 978         .word 0               # offset 15:0
 979         .long SYS_CODE64_SEL  # selector 15:0
 980         .byte 0               # 0 for interrupt gate
 981         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 982         .word 0               # offset 31:16
 983         .long 0               # offset 63:32
 984         .long 0               # 0 for reserved
 985
 986 # IRQ 7 (LPT 1) - (INT 6fh)
 987 .equ                IRQ7_SEL, .-IDT_BASE
 988         .word 0               # offset 15:0
 989         .long SYS_CODE64_SEL  # selector 15:0
 990         .byte 0               # 0 for interrupt gate
 991         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
 992         .word 0               # offset 31:16
 993         .long 0               # offset 63:32
 994         .long 0               # 0 for reserved
 995
 996 # IRQ 8 (RTC Alarm) - (INT 70h)
 997 .equ                IRQ8_SEL, .-IDT_BASE
 998         .word 0               # offset 15:0
 999         .long SYS_CODE64_SEL  # selector 15:0
1000         .byte 0               # 0 for interrupt gate
1001         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
1002         .word 0               # offset 31:16
1003         .long 0               # offset 63:32
1004         .long 0               # 0 for reserved
1005
1006 # IRQ 9 - (INT 71h)
1007 .equ                IRQ9_SEL, .-IDT_BASE
1008         .word 0               # offset 15:0
1009         .long SYS_CODE64_SEL  # selector 15:0
1010         .byte 0               # 0 for interrupt gate
1011         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
1012         .word 0               # offset 31:16
1013         .long 0               # offset 63:32
1014         .long 0               # 0 for reserved
1015
1016 # IRQ 10 - (INT 72h)
1017 .equ                 IRQ10_SEL, .-IDT_BASE
1018         .word 0               # offset 15:0
1019         .long SYS_CODE64_SEL  # selector 15:0
1020         .byte 0               # 0 for interrupt gate
1021         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
1022         .word 0               # offset 31:16
1023         .long 0               # offset 63:32
1024         .long 0               # 0 for reserved
1025
1026 # IRQ 11 - (INT 73h)
1027 .equ                 IRQ11_SEL, .-IDT_BASE
1028         .word 0               # offset 15:0
1029         .long SYS_CODE64_SEL  # selector 15:0
1030         .byte 0               # 0 for interrupt gate
1031         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
1032         .word 0               # offset 31:16
1033         .long 0               # offset 63:32
1034         .long 0               # 0 for reserved
1035
1036 # IRQ 12 (PS/2 mouse) - (INT 74h)
1037 .equ                 IRQ12_SEL, .-IDT_BASE
1038         .word 0               # offset 15:0
1039         .long SYS_CODE64_SEL  # selector 15:0
1040         .byte 0               # 0 for interrupt gate
1041         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
1042         .word 0               # offset 31:16
1043         .long 0               # offset 63:32
1044         .long 0               # 0 for reserved
1045
1046 # IRQ 13 (Floating point error) - (INT 75h)
1047 .equ                 IRQ13_SEL, .-IDT_BASE
1048         .word 0               # offset 15:0
1049         .long SYS_CODE64_SEL  # selector 15:0
1050         .byte 0               # 0 for interrupt gate
1051         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
1052         .word 0               # offset 31:16
1053         .long 0               # offset 63:32
1054         .long 0               # 0 for reserved
1055
1056 # IRQ 14 (Secondary IDE) - (INT 76h)
1057 .equ                 IRQ14_SEL, .-IDT_BASE
1058         .word 0               # offset 15:0
1059         .long SYS_CODE64_SEL  # selector 15:0
1060         .byte 0               # 0 for interrupt gate
1061         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
1062         .word 0               # offset 31:16
1063         .long 0               # offset 63:32
1064         .long 0               # 0 for reserved
1065
1066 # IRQ 15 (Primary IDE) - (INT 77h)
1067 .equ                 IRQ15_SEL, .-IDT_BASE
1068         .word 0               # offset 15:0
1069         .long SYS_CODE64_SEL  # selector 15:0
1070         .byte 0               # 0 for interrupt gate
1071         .byte 0x0e | 0x80     # type = 386 interrupt gate, present
1072         .word 0               # offset 31:16
1073         .long 0               # offset 63:32
1074         .long 0               # 0 for reserved
1075
1076 IDT_END:
1077
1078         .p2align 1
1079
1080 MemoryMapSize:  .long 0
1081 MemoryMap:  .long 0,0,0,0,0,0,0,0
1082         .long 0,0,0,0,0,0,0,0
1083         .long 0,0,0,0,0,0,0,0
1084         .long 0,0,0,0,0,0,0,0
1085         .long 0,0,0,0,0,0,0,0
1086         .long 0,0,0,0,0,0,0,0
1087         .long 0,0,0,0,0,0,0,0
1088         .long 0,0,0,0,0,0,0,0
1089         .long 0,0,0,0,0,0,0,0
1090         .long 0,0,0,0,0,0,0,0
1091         .long 0,0,0,0,0,0,0,0
1092         .long 0,0,0,0,0,0,0,0
1093         .long 0,0,0,0,0,0,0,0
1094         .long 0,0,0,0,0,0,0,0
1095         .long 0,0,0,0,0,0,0,0
1096         .long 0,0,0,0,0,0,0,0
1097         .long 0,0,0,0,0,0,0,0
1098         .long 0,0,0,0,0,0,0,0
1099         .long 0,0,0,0,0,0,0,0
1100         .long 0,0,0,0,0,0,0,0
1101         .long 0,0,0,0,0,0,0,0
1102         .long 0,0,0,0,0,0,0,0
1103         .long 0,0,0,0,0,0,0,0
1104         .long 0,0,0,0,0,0,0,0
1105         .long 0,0,0,0,0,0,0,0
1106         .long 0,0,0,0,0,0,0,0
1107         .long 0,0,0,0,0,0,0,0
1108         .long 0,0,0,0,0,0,0,0
1109         .long 0,0,0,0,0,0,0,0
1110         .long 0,0,0,0,0,0,0,0
1111
1112         .long 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
1113
1114         .org 0x0fe0
1115 MyStack:
1116         # below is the pieces of the IVT that is used to redirect INT 68h - 6fh
1117         #    back to INT 08h - 0fh  when in real mode...  It is 'org'ed to a
1118         #    known low address (20f00) so it can be set up by PlMapIrqToVect in
1119         #    8259.c
1120
1121         int $8
1122         iret
1123
1124         int $9
1125         iret
1126
1127         int $10
1128         iret
1129
1130         int $11
1131         iret
1132
1133         int $12
1134         iret
1135
1136         int $13
1137         iret
1138
1139         int $14
1140         iret
1141
1142         int $15
1143         iret
1144
1145
1146         .org 0x0ffe
1147 BlockSignature:
1148         .word 0xaa55
1149