Port Intel .asm to GAS S

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@7557 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
gikidy 2009-02-20 08:22:04 +00:00
parent 01f1138afe
commit ccec4c3969
3 changed files with 1517 additions and 4 deletions

581
DuetPkg/BootSector/efi32.S Normal file
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#------------------------------------------------------------------------------
#*
#* Copyright 2006, Intel Corporation
#* All rights reserved. This program and the accompanying materials
#* are licensed and made available under the terms and conditions of the BSD License
#* which accompanies this distribution. The full text of the license may be found at
#* http://opensource.org/licenses/bsd-license.php
#*
#* THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
#* WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
#*
#* efi32.asm
#*
#* Abstract:
#*
#------------------------------------------------------------------------------
##############################################################################
# Now in 32-bit protected mode.
##############################################################################
.486:
#.MODEL flat
.stack:
.code:
.org 0x21000
.equ DEFAULT_HANDLER_SIZE, INT1 - INT0
.macro jmpCommonIdtEntry
# jmp commonIdtEntry - this must be hand coded to keep the assembler from
# using a 8 bit reletive jump when the entries are
# within 255 bytes of the common entry. This must
# be done to maintain the consistency of the size
# of entry points...
.byte 0xe9 # jmp 16 bit relative
.long commonIdtEntry - . - 4 # A problem
.endm
Start:
movw %ax, %ds
movw %ax, %es
movw %ax, %fs
movw %ax, %gs
movw %ax, %ss
movl $0x001ffff0, %esp
call ClearScreen
# Populate IDT with meaningful offsets for exception handlers...
sidt Idtr
movl Halt, %eax
movl %eax, %ebx # use bx to copy 15..0 to descriptors
shrl $16, %eax # use ax to copy 31..16 to descriptors
movl $0x78, %ecx # 78h IDT entries to initialize with unique entry points (exceptions)
movl (Idtr + 2), %esi
movl (%esi), %edi
LOOP_1: # loop through all IDT entries exception handlers and initialize to default handler
movw %bx, (%edi) # write bits 15..0 of offset
movw $0x20, 2(%edi) # SYS_CODE_SEL from GDT
movw $(0x0e00 | 0x8000), 4(%edi) # type = 386 interrupt gate, present
movw %ax, 6(%edi) # write bits 31..16 of offset
addl $8, %edi # move up to next descriptor
addw DEFAULT_HANDLER_SIZE, %bx # move to next entry point
loopl LOOP_1 # loop back through again until all descriptors are initialized
## at this point edi contains the offset of the descriptor for INT 20
## and bx contains the low 16 bits of the offset of the default handler
## so initialize all the rest of the descriptors with these two values...
# mov ecx, 101 ; there are 100 descriptors left (INT 20 (14h) - INT 119 (77h)
#@@: ; loop through all IDT entries exception handlers and initialize to default handler
# mov word ptr [edi], bx ; write bits 15..0 of offset
# mov word ptr [edi+2], 20h ; SYS_CODE_SEL from GDT
# mov word ptr [edi+4], 0e00h OR 8000h ; type = 386 interrupt gate, present
# mov word ptr [edi+6], ax ; write bits 31..16 of offset
# add edi, 8 ; move up to next descriptor
# loop @b ; loop back through again until all descriptors are initialized
## DUMP location of IDT and several of the descriptors
# mov ecx, 8
# mov eax, [offset Idtr + 2]
# mov eax, [eax]
# mov edi, 0b8000h
# call PrintDword
# mov esi, eax
# mov edi, 0b80a0h
# jmp OuterLoop
##
## just for fun, let's do a software interrupt to see if we correctly land in the exception handler...
# mov eax, 011111111h
# mov ebx, 022222222h
# mov ecx, 033333333h
# mov edx, 044444444h
# mov ebp, 055555555h
# mov esi, 066666666h
# mov edi, 077777777h
# push 011111111h
# push 022222222h
# push 033333333h
# int 119
movl $0x22000, %esi # esi = 22000
movl 0x14(%esi), %eax # eax = [22014]
addl %eax, %esi # esi = 22000 + [22014] = Base of EFILDR.C
movl 0x3c(%esi), %ebp # ebp = [22000 + [22014] + 3c] = NT Image Header for EFILDR.C
addl %esi, %ebp
movl 0x34(%ebp), %edi # edi = [[22000 + [22014] + 3c] + 30] = ImageBase
movl 0x28(%ebp), %eax # eax = [[22000 + [22014] + 3c] + 24] = EntryPoint
addl %edi, %eax # eax = ImageBase + EntryPoint
movl %eax, EfiLdrOffset # Modify far jump instruction for correct entry point
movw 6(%ebp), %bx # bx = Number of sections
xorl %eax, %eax
movw 0x14(%ebp), %ax # ax = Optional Header Size
addl %eax, %ebp
addl $0x18, %ebp # ebp = Start of 1st Section
SectionLoop:
pushl %esi # Save Base of EFILDR.C
pushl %edi # Save ImageBase
addl 0x14(%ebp), %esi # esi = Base of EFILDR.C + PointerToRawData
addl 0x0c(%ebp), %edi # edi = ImageBase + VirtualAddress
movl 0x10(%ebp), %ecx # ecs = SizeOfRawData
cld
shrl $2, %ecx
rep
movsl
popl %edi # Restore ImageBase
popl %esi # Restore Base of EFILDR.C
addw $0x28, %bp # ebp = ebp + 028h = Pointer to next section record
decw %bx
cmpw $0, %bx
jne SectionLoop
movzwl Idtr, %eax # get size of IDT
incl %eax
addl Idtr + 2, %eax # add to base of IDT to get location of memory map...
pushl %eax # push memory map location on stack for call to EFILDR...
pushl %eax # push return address (useless, just for stack balance)
.byte 0xb8
EfiLdrOffset:
.long 0x00401000 # Offset of EFILDR
# mov eax, 401000h
pushl %eax
ret
# db "**** DEFAULT IDT ENTRY ***",0
.align 0x2
Halt:
INT0:
pushl $0x0 # push error code place holder on the stack
pushl $0x0
jmpCommonIdtEntry
# db 0e9h ; jmp 16 bit reletive
# dd commonIdtEntry - $ - 4 ; offset to jump to
INT1:
pushl $0x0 # push error code place holder on the stack
pushl $0x1
jmpCommonIdtEntry
INT2:
pushl $0x0 # push error code place holder on the stack
pushl $0x2
jmpCommonIdtEntry
INT3:
pushl $0x0 # push error code place holder on the stack
pushl $0x3
jmpCommonIdtEntry
INT4:
pushl $0x0 # push error code place holder on the stack
pushl $0x4
jmpCommonIdtEntry
INT5:
pushl $0x0 # push error code place holder on the stack
pushl $0x5
jmpCommonIdtEntry
INT6:
pushl $0x0 # push error code place holder on the stack
pushl $0x6
jmpCommonIdtEntry
INT7:
pushl $0x0 # push error code place holder on the stack
pushl $0x7
jmpCommonIdtEntry
INT8:
# Double fault causes an error code to be pushed so no phony push necessary
nop
nop
pushl $0x8
jmpCommonIdtEntry
INT9:
pushl $0x0 # push error code place holder on the stack
pushl $0x9
jmpCommonIdtEntry
INT10:
# Invalid TSS causes an error code to be pushed so no phony push necessary
nop
nop
pushl $10
jmpCommonIdtEntry
INT11:
# Segment Not Present causes an error code to be pushed so no phony push necessary
nop
nop
pushl $11
jmpCommonIdtEntry
INT12:
# Stack fault causes an error code to be pushed so no phony push necessary
nop
nop
pushl $12
jmpCommonIdtEntry
INT13:
# GP fault causes an error code to be pushed so no phony push necessary
nop
nop
pushl $13
jmpCommonIdtEntry
INT14:
# Page fault causes an error code to be pushed so no phony push necessary
nop
nop
pushl $14
jmpCommonIdtEntry
INT15:
pushl $0x0 # push error code place holder on the stack
pushl $15
jmpCommonIdtEntry
INT16:
pushl $0x0 # push error code place holder on the stack
pushl $16
jmpCommonIdtEntry
INT17:
# Alignment check causes an error code to be pushed so no phony push necessary
nop
nop
pushl $17
jmpCommonIdtEntry
INT18:
pushl $0x0 # push error code place holder on the stack
pushl $18
jmpCommonIdtEntry
INT19:
pushl $0x0 # push error code place holder on the stack
pushl $19
jmpCommonIdtEntry
INTUnknown:
.rept (0x78 - 20)
pushl $0x0 # push error code place holder on the stack
# push $0xxx # push vector number
.byte 0x6a
.long ( . - INTUnknown - 3 ) / 9 + 20 # vector number
jmpCommonIdtEntry
.endr
commonIdtEntry:
pushal
movl %esp, %ebp
##
## At this point the stack looks like this:
##
## eflags
## Calling CS
## Calling EIP
## Error code or 0
## Int num or 0ffh for unknown int num
## eax
## ecx
## edx
## ebx
## esp
## ebp
## esi
## edi <------- ESP, EBP
##
call ClearScreen
movl String1, %esi
call PrintString
movl 32(%ebp), %eax ## move Int number into EAX
cmpl $19, %eax
ja PrintDefaultString
PrintExceptionString:
shll $2, %eax ## multiply by 4 to get offset from StringTable to actual string address
addl StringTable, %eax
movl (%eax), %esi
jmp PrintTheString
PrintDefaultString:
movl IntUnknownString, %esi
# patch Int number
movl %eax, %edx
call A2C
movb %al, 1(%esi)
movl %edx, %eax
shrl $4, %eax
call A2C
movb %al, (%esi)
PrintTheString:
call PrintString
movl String2, %esi
call PrintString
movl 44(%ebp), %eax # CS
call PrintDword
movb ':', %al
movb %al, (%edi)
addl $2, %edi
movl 40(%ebp), %eax # EIP
call PrintDword
movl String3, %esi
call PrintString
movl $0xb8140, %edi
movl StringEax, %esi # eax
call PrintString
movl 28(%ebp), %eax
call PrintDword
movl StringEbx, %esi # ebx
call PrintString
movl 16(%ebp), %eax
call PrintDword
movl StringEcx, %esi # ecx
call PrintString
movl 24(%ebp), %eax
call PrintDword
movl StringEdx, %esi # edx
call PrintString
movl 20(%ebp), %eax
call PrintDword
movl StringEcode, %esi # error code
call PrintString
movl 36(%ebp), %eax
call PrintDword
movl $0xb81e0, %edi
movl StringEsp, %esi # esp
call PrintString
movl 12(%ebp), %eax
call PrintDword
movl StringEbp, %esi # ebp
call PrintString
movl 8(%ebp), %eax
call PrintDword
movl StringEsi, %esi # esi
call PrintString
movl 4(%ebp), %eax
call PrintDword
movl StringEdi, %esi # edi
call PrintString
movl (%ebp), %eax
call PrintDword
movl StringEflags, %esi # eflags
call PrintString
movl 48(%ebp), %eax
call PrintDword
movl $0xb8320, %edi
movl %ebp, %esi
addl $52, %esi
movl $8, %ecx
OuterLoop:
pushl %ecx
movl $8, %ecx
movl %edi, %edx
InnerLoop:
movl (%esi), %eax
call PrintDword
addl $4, %esi
movb ' ', %al
movb %al, (%edi)
addl $2, %edi
loop InnerLoop
popl %ecx
addl $0xa0, %edx
movl %edx, %edi
loop OuterLoop
movl $0xb8960, %edi
movl 40(%ebp), %eax # EIP
subl $32*4, %eax
movl %eax, %esi # esi = eip - 32 DWORD linear (total 64 DWORD)
movl $8, %ecx
OuterLoop1:
pushl %ecx
movl $8, %ecx
movl %edi, %edx
InnerLoop1:
movl (%esi), %eax
call PrintDword
addl $4, %esi
movb ' ', %al
movb %al, (%edi)
addl $2, %edi
loop InnerLoop1
popl %ecx
addl $0xa0, %edx
movl %edx, %edi
loop OuterLoop1
# wbinvd ; this intruction does not support in early than 486 arch
LN_C1:
jmp LN_C1
#
# return
#
movl %ebp, %esp
popal
addl $8, %esp # error code and INT number
iretl
PrintString:
pushl %eax
LN_C2:
movb (%esi), %al
cmpb $0, %al
je LN_C3
movb %al, (%edi)
incl %esi
addl $2, %edi
jmp LN_C2
LN_C3:
popl %eax
ret
## EAX contains dword to print
## EDI contains memory location (screen location) to print it to
PrintDword:
pushl %ecx
pushl %ebx
pushl %eax
movl $8, %ecx
looptop:
roll $4, %eax
movb %al, %bl
andb $0xf, %bl
addb '0', %bl
cmpb '9', %bl
jle LN_C4
addb $7, %bl
LN_C4:
movb %bl, (%edi)
addl $2, %edi
loop looptop
#wbinvd
popl %eax
popl %ebx
popl %ecx
ret
ClearScreen:
pushl %eax
pushl %ecx
movb ' ', %al
movb $0xc, %ah
movl $0xb8000, %edi
movl $80*24, %ecx
LN_C5:
movw %ax, (%edi)
addl $2, %edi
loop LN_C5
movl $0xb8000, %edi
popl %ecx
popl %eax
ret
A2C:
andb $0xf, %al
addb '0', %al
cmpb '9', %al
jle LN_C6
addb $7, %al
LN_C6:
ret
String1: .asciz "*** INT "
Int0String: .asciz "00h Divide by 0 -"
Int1String: .asciz "01h Debug exception -"
Int2String: .asciz "02h NMI -"
Int3String: .asciz "03h Breakpoint -"
Int4String: .asciz "04h Overflow -"
Int5String: .asciz "05h Bound -"
Int6String: .asciz "06h Invalid opcode -"
Int7String: .asciz "07h Device not available -"
Int8String: .asciz "08h Double fault -"
Int9String: .asciz "09h Coprocessor seg overrun (reserved) -"
Int10String: .asciz "0Ah Invalid TSS -"
Int11String: .asciz "0Bh Segment not present -"
Int12String: .asciz "0Ch Stack fault -"
Int13String: .asciz "0Dh General protection fault -"
Int14String: .asciz "0Eh Page fault -"
Int15String: .asciz "0Fh (Intel reserved) -"
Int16String: .asciz "10h Floating point error -"
Int17String: .asciz "11h Alignment check -"
Int18String: .asciz "12h Machine check -"
Int19String: .asciz "13h SIMD Floating-Point Exception -"
IntUnknownString: .asciz "??h Unknown interrupt -"
StringTable: .long Int0String, Int1String, Int2String, Int3String, \
Int4String, Int5String, Int6String, Int7String, \
Int8String, Int9String, Int10String, Int11String, \
Int12String, Int13String, Int14String, Int15String,\
Int16String, Int17String, Int18String, Int19String
String2: .asciz " HALT!! *** ("
String3: .asciz ")"
StringEax: .asciz "EAX="
StringEbx: .asciz "EBX="
StringEcx: .asciz "ECX="
StringEdx: .asciz "EDX="
StringEcode: .asciz "ECODE="
StringEsp: .asciz "ESP="
StringEbp: .asciz "EBP="
StringEsi: .asciz "ESI="
StringEdi: .asciz "EDI="
StringEflags: .asciz "EFLAGS="
Idtr: .float 0
.org 0x21ffe
BlockSignature:
.word 0xaa55

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@ -15,6 +15,10 @@
#*
#------------------------------------------------------------------------------
.equ FAT_DIRECTORY_ENTRY_SIZE, 0x020
.equ FAT_DIRECTORY_ENTRY_SHIFT, 5
@ -149,9 +153,9 @@ FatChainLoop:
shrw %ax # FatOffset = ClusterNumber*3 / 2
pushw %si # Save si
movw %ax, %si # si = FatOffset
shrw %ax # ax = FatOffset >> BLOCK_SHIFT
shrw $BLOCK_SHIFT, %ax # ax = FatOffset >> BLOCK_SHIFT
addw ReservedSectors(%bp), %ax # ax = FatSectorNumber = ReservedSectors + (FatOffset >> BLOCK_OFFSET)
andw BLOCK_MASK,%si # si = FatOffset & BLOCK_MASK
andw $BLOCK_MASK,%si # si = FatOffset & BLOCK_MASK
cmpw %dx, %ax # Compare FatSectorNumber to CachedFatSectorNumber
je SkipFatRead
movw $2, %bx
@ -279,7 +283,7 @@ NotCrossing64KBoundry:
DiskError:
pushw %cs
popw %ds
leaw %cs:ErrorString, %si
leaw ErrorString, %si
movw $7, %cx
jmp PrintStringAndHalt
@ -295,7 +299,7 @@ Halt:
ErrorString:
.byte 'S', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, 'o', 0x0c, 'r', 0x0c, '!',0x0c
#.org 0x0242 # For Code size overflow, Modified this just for pass build
.org 0x0241 # For Code size overflow, Modified this just for pass build
LBAOffsetForBootSector:
.long 0x0

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@ -0,0 +1,928 @@
#------------------------------------------------------------------------------
#*
#* Copyright 2006 - 2007, Intel Corporation
#* All rights reserved. This program and the accompanying materials
#* are licensed and made available under the terms and conditions of the BSD License
#* which accompanies this distribution. The full text of the license may be found at
#* http://opensource.org/licenses/bsd-license.php
#*
#* THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
#* WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
#*
#* start32.asm
#*
#* Abstract:
#*
#------------------------------------------------------------------------------
#.MODEL small
.stack:
.486p:
.code:
.equ FAT_DIRECTORY_ENTRY_SIZE, 0x020
.equ FAT_DIRECTORY_ENTRY_SHIFT, 5
.equ BLOCK_SIZE, 0x0200
.equ BLOCK_MASK, 0x01ff
.equ BLOCK_SHIFT, 9
.org 0x0
Ia32Jump:
jmp BootSectorEntryPoint # JMP inst - 3 bytes
nop
OemId: .ascii "INTEL " # OemId - 8 bytes
SectorSize: .word 0 # Sector Size - 2 bytes
SectorsPerCluster: .byte 0 # Sector Per Cluster - 1 byte
ReservedSectors: .word 0 # Reserved Sectors - 2 bytes
NoFats: .byte 0 # Number of FATs - 1 byte
RootEntries: .word 0 # Root Entries - 2 bytes
Sectors: .word 0 # Number of Sectors - 2 bytes
Media: .byte 0 # Media - 1 byte
SectorsPerFat16: .word 0 # Sectors Per FAT for FAT12/FAT16 - 2 byte
SectorsPerTrack: .word 0 # Sectors Per Track - 2 bytes
Heads: .word 0 # Heads - 2 bytes
HiddenSectors: .long 0 # Hidden Sectors - 4 bytes
LargeSectors: .long 0 # Large Sectors - 4 bytes
#******************************************************************************
#
#The structure for FAT32 starting at offset 36 of the boot sector. (At this point,
#the BPB/boot sector for FAT12 and FAT16 differs from the BPB/boot sector for FAT32.)
#
#******************************************************************************
SectorsPerFat32: .long 0 # Sectors Per FAT for FAT32 - 4 bytes
ExtFlags: .word 0 # Mirror Flag - 2 bytes
FSVersion: .word 0 # File System Version - 2 bytes
RootCluster: .long 0 # 1st Cluster Number of Root Dir - 4 bytes
FSInfo: .word 0 # Sector Number of FSINFO - 2 bytes
BkBootSector: .word 0 # Sector Number of Bk BootSector - 2 bytes
Reserved: .fill 12,1,0 # Reserved Field - 12 bytes
PhysicalDrive: .byte 0 # Physical Drive Number - 1 byte
Reserved1: .byte 0 # Reserved Field - 1 byte
Signature: .byte 0 # Extended Boot Signature - 1 byte
VolId: .ascii " " # Volume Serial Number - 4 bytes
FatLabel: .ascii " " # Volume Label - 11 bytes
FileSystemType: .ascii "FAT32 " # File System Type - 8 bytes
BootSectorEntryPoint:
#ASSUME ds:@code
#ASSUME ss:@code
# ds = 1000, es = 2000 + x (size of first cluster >> 4)
# cx = Start Cluster of EfiLdr
# dx = Start Cluster of Efivar.bin
# Re use the BPB data stored in Boot Sector
movw $0x7c00, %bp
pushw %cx
# Read Efivar.bin
# 1000:dx = DirectoryEntry of Efivar.bin -> BS.com has filled already
movw $0x1900, %ax
movw %ax, %es
testw %dx, %dx
jnz CheckVarStoreSize
movb $1, %al
NoVarStore:
pushw %es
# Set the 5th byte start @ 0:19000 to non-zero indicating we should init var store header in DxeIpl
movb %al, %es:($4)
jmp SaveVolumeId
CheckVarStoreSize:
movw %dx, %di
cmpl $0x4000, %ds:2(%di)
movb $2, %al
jne NoVarStore
LoadVarStore:
movb $0, %al
movb %al, %es:($4)
movw (%di), %cx
# ES:DI = 1500:0
xorw %di, %di
pushw %es
movw $0x1500, %ax
movw %ax, %es
call ReadFile
SaveVolumeId:
popw %es
movw VolId(%bp), %ax
movw %ax, %es:($0) # Save Volume Id to 0:19000. we will find the correct volume according to this VolumeId
movw VolId+2(%bp), %ax
movw %ax, %es:($2)
# Read Efildr
popw %cx
# cx = Start Cluster of Efildr -> BS.com has filled already
# ES:DI = 2000:0, first cluster will be read again
xorw %di, %di # di = 0
movw $0x2000, %ax
movw %ax, %es
call ReadFile
movw %cs, %ax
movw %ax, %cs:JumpSegment
JumpFarInstruction:
.byte 0xea
JumpOffset:
.word 0x200
JumpSegment:
.word 0x2000
# ****************************************************************************
# ReadFile
#
# Arguments:
# CX = Start Cluster of File
# ES:DI = Buffer to store file content read from disk
#
# Return:
# (ES << 4 + DI) = end of file content Buffer
#
# ****************************************************************************
ReadFile:
# si = NumberOfClusters
# cx = ClusterNumber
# dx = CachedFatSectorNumber
# ds:0000 = CacheFatSectorBuffer
# es:di = Buffer to load file
# bx = NextClusterNumber
pusha
movw $1, %si # NumberOfClusters = 1
pushw %cx # Push Start Cluster onto stack
movw $0xfff, %dx # CachedFatSectorNumber = 0xfff
FatChainLoop:
movw %cx, %ax # ax = ClusterNumber
andw $0xfff8, %ax # ax = ax & 0xfff8
cmpw $0xfff8, %ax # See if this is the last cluster
je FoundLastCluster # Jump if last cluster found
movw %cx, %ax # ax = ClusterNumber
shlw $2, %ax # FatOffset = ClusterNumber * 4
pushw %si # Save si
movw %ax, %si # si = FatOffset
shrw $BLOCK_SHIFT, %ax # ax = FatOffset >> BLOCK_SHIFT
addw ReservedSectors(%bp), %ax # ax = FatSectorNumber = ReservedSectors + (FatOffset >> BLOCK_OFFSET)
andw $BLOCK_MASK, %si # si = FatOffset & BLOCK_MASK
cmpw %dx, %ax # Compare FatSectorNumber to CachedFatSectorNumber
je SkipFatRead
movw $2, %bx
pushw %es
pushw %ds
popw %es
call ReadBlocks # Read 2 blocks starting at AX storing at ES:DI
popw %es
movw %ax, %dx # CachedFatSectorNumber = FatSectorNumber
SkipFatRead:
movw (%si), %bx # bx = NextClusterNumber
movw %cx, %ax # ax = ClusterNumber
popw %si # Restore si
decw %bx # bx = NextClusterNumber - 1
cmpw %cx, %bx # See if (NextClusterNumber-1)==ClusterNumber
jne ReadClusters
incw %bx # bx = NextClusterNumber
incw %si # NumberOfClusters++
movw %bx, %cx # ClusterNumber = NextClusterNumber
jmp FatChainLoop
ReadClusters:
incw %bx
popw %ax # ax = StartCluster
pushw %bx # StartCluster = NextClusterNumber
movw %bx, %cx # ClusterNumber = NextClusterNumber
subw $2, %ax # ax = StartCluster - 2
xorb %bh, %bh
movb SectorsPerCluster(%bp), %bl # bx = SectorsPerCluster
mulw %bx # ax = (StartCluster - 2) * SectorsPerCluster
addw (%bp), %ax # ax = FirstClusterLBA + (StartCluster-2)*SectorsPerCluster
pushw %ax # save start sector
movw %si, %ax # ax = NumberOfClusters
mulw %bx # ax = NumberOfClusters * SectorsPerCluster
movw %ax, %bx # bx = Number of Sectors
popw %ax # ax = Start Sector
call ReadBlocks
movw $1, %si # NumberOfClusters = 1
jmp FatChainLoop
FoundLastCluster:
popw %cx
popa
ret
# ****************************************************************************
# ReadBlocks - Reads a set of blocks from a block device
#
# AX = Start LBA
# BX = Number of Blocks to Read
# ES:DI = Buffer to store sectors read from disk
# ****************************************************************************
# cx = Blocks
# bx = NumberOfBlocks
# si = StartLBA
ReadBlocks:
pusha
addl LBAOffsetForBootSector(%bp), %eax # Add LBAOffsetForBootSector to Start LBA
addl HiddenSectors(%bp), %eax # Add HiddenSectors to Start LBA
movl %eax, %esi # esi = Start LBA
movw %bx, %cx # cx = Number of blocks to read
ReadCylinderLoop:
movw $0x7bfc, %bp # bp = 0x7bfc
movl %esi, %eax # eax = Start LBA
xorl %edx, %edx # edx = 0
movzwl (%bp), %ebx # bx = MaxSector
divl %ebx # ax = StartLBA / MaxSector
incw %dx # dx = (StartLBA % MaxSector) + 1
movw (%bp), %bx # bx = MaxSector
subw %dx, %bx # bx = MaxSector - Sector
incw %bx # bx = MaxSector - Sector + 1
cmpw %bx, %cx # Compare (Blocks) to (MaxSector - Sector + 1)
jg LimitTransfer
movw %cx, %bx # bx = Blocks
LimitTransfer:
pushw %ax # save ax
movw %es, %ax # ax = es
shrw $(BLOCK_SHIFT-4), %ax # ax = Number of blocks into mem system
andw $0x7f, %ax # ax = Number of blocks into current seg
addw %bx, %ax # ax = End Block number of transfer
cmpw $0x80, %ax # See if it crosses a 64K boundry
jle NotCrossing64KBoundry # Branch if not crossing 64K boundry
subw $0x80, %ax # ax = Number of blocks past 64K boundry
subw %ax, %bx # Decrease transfer size by block overage
NotCrossing64KBoundry:
popw %ax # restore ax
pushw %cx
movb %dl, %cl # cl = (StartLBA % MaxSector) + 1 = Sector
xorw %dx, %dx # dx = 0
divw 2(%bp) # ax = ax / (MaxHead + 1) = Cylinder
# dx = ax % (MaxHead + 1) = Head
pushw %bx # Save number of blocks to transfer
movb %dl, %dh # dh = Head
movw $0x7c00, %bp # bp = 0x7c00
movb PhysicalDrive(%bp), %dl # dl = Drive Number
movb %al, %ch # ch = Cylinder
movb %bl, %al # al = Blocks
movb $2, %ah # ah = Function 2
movw %di, %bx # es:bx = Buffer address
int $0x13
jc DiskError
popw %bx
popw %cx
movzwl %bx, %ebx
addl %ebx, %esi # StartLBA = StartLBA + NumberOfBlocks
subw %bx, %cx # Blocks = Blocks - NumberOfBlocks
movw %es, %ax
shlw $(BLOCK_SHIFT-4), %bx
addw %bx, %ax
movw %ax, %es # es:di = es:di + NumberOfBlocks*BLOCK_SIZE
cmpw $0, %cx
jne ReadCylinderLoop
popa
ret
DiskError:
pushw %cs
popw %ds
leaw ErrorString, %si
movw $7, %cx
jmp PrintStringAndHalt
PrintStringAndHalt:
movw $0xb800, %ax
movw %ax, %es
movw $160, %di
rep
movsw
Halt:
jmp Halt
ErrorString:
.byte 'S', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, 'o', 0x0c, 'r', 0x0c, '!', 0x0c
.org 0x01fa # Will cause build break
LBAOffsetForBootSector:
.long 0x0
.org 0x01fe # Will cause build break
.word 0xaa55
#******************************************************************************
#******************************************************************************
#******************************************************************************
.equ DELAY_PORT, 0x0ed # Port to use for 1uS delay
.equ KBD_CONTROL_PORT, 0x060 # 8042 control port
.equ KBD_STATUS_PORT, 0x064 # 8042 status port
.equ WRITE_DATA_PORT_CMD, 0x0d1 # 8042 command to write the data port
.equ ENABLE_A20_CMD, 0x0df # 8042 command to enable A20
.org 0x200 # Will cause build break
jmp start
Em64String:
.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
start:
movw %cs, %ax
movw %ax, %ds
movw %ax, %es
movw %ax, %ss
movw $MyStack, %sp
# mov ax,0b800h
# mov es,ax
# mov byte ptr es:[160],'a'
# mov ax,cs
# mov es,ax
movl $0, %ebx
leal MemoryMap, %edi
MemMapLoop:
movl $0xe820, %eax
movl $20, %ecx
movl $0x534d4150, %edx # 0x534d4150 = 'SMAP'
int $0x15
jc MemMapDone
addl $20, %edi
cmpl $0, %ebx
je MemMapDone
jmp MemMapLoop
MemMapDone:
leal MemoryMap, %eax
subl %eax, %edi # Get the address of the memory map
movl %edi, MemoryMapSize # Save the size of the memory map
xorl %ebx, %ebx
movw %cs, %bx # BX=segment
shll $4, %ebx # BX="linear" address of segment base
leal GDT_BASE(%ebx), %eax # EAX=PHYSICAL address of gdt
movl %eax, gdtr + 2 # Put address of gdt into the gdtr
leal IDT_BASE(%ebx), %eax # EAX=PHYSICAL address of idt
movl %eax, idtr + 2 # Put address of idt into the idtr
leal MemoryMapSize(%ebx), %edx # Physical base address of the memory map
addl $0x1000, %ebx # Source of EFI32
movl %ebx, JUMP+2
addl $0x1000, %ebx
movl %ebx, %esi # Source of EFILDR32
# mov ax,0b800h
# mov es,ax
# mov byte ptr es:[162],'b'
# mov ax,cs
# mov es,ax
#
# Enable A20 Gate
#
movw $0x2401, %ax # Enable A20 Gate
int $0x15
jnc A20GateEnabled # Jump if it suceeded
#
# If INT 15 Function 2401 is not supported, then attempt to Enable A20 manually.
#
call Empty8042InputBuffer # Empty the Input Buffer on the 8042 controller
jnz Timeout8042 # Jump if the 8042 timed out
outw %ax, $DELAY_PORT # Delay 1 uS
movb $WRITE_DATA_PORT_CMD, %al # 8042 cmd to write output port
outb %al, $KBD_STATUS_PORT # Send command to the 8042
call Empty8042InputBuffer # Empty the Input Buffer on the 8042 controller
jnz Timeout8042 # Jump if the 8042 timed out
movb $ENABLE_A20_CMD, %al # gate address bit 20 on
outb %al, $KBD_CONTROL_PORT # Send command to thre 8042
call Empty8042InputBuffer # Empty the Input Buffer on the 8042 controller
movw $25, %cx # Delay 25 uS for the command to complete on the 8042
Delay25uS:
outw %ax, $DELAY_PORT # Delay 1 uS
loopl Delay25uS
Timeout8042:
A20GateEnabled:
#
# DISABLE INTERRUPTS - Entering Protected Mode
#
cli
# mov ax,0b800h
# mov es,ax
# mov byte ptr es:[164],'c'
# mov ax,cs
# mov es,ax
.byte 0x66
lgdt gdtr
.byte 0x66
lidt idtr
movl %cr0, %eax
orb $1, %al
movl %eax, %cr0
movl $0x008, %eax # Flat data descriptor
movl $0x00400000, %ebp # Destination of EFILDR32
movl $0x00070000, %ebx # Length of copy
JUMP:
# jmp far 0010:00020000
.byte 0x66
.byte 0xea
.long 0x00020000
.word 0x0010
Empty8042InputBuffer:
movw $0, %cx
Empty8042Loop:
outw %ax, $DELAY_PORT # Delay 1us
inb $KBD_STATUS_PORT, %al # Read the 8042 Status Port
andb $0x2, %al # Check the Input Buffer Full Flag
loopnz Empty8042Loop # Loop until the input buffer is empty or a timout of 65536 uS
ret
##############################################################################
# data
##############################################################################
.align 0x2
gdtr: .word GDT_END - GDT_BASE - 1
.long 0 # (GDT base gets set above)
##############################################################################
# global descriptor table (GDT)
##############################################################################
.align 0x2
GDT_BASE:
# null descriptor
.equ NULL_SEL, .-GDT_BASE
.word 0 # limit 15:0
.word 0 # base 15:0
.byte 0 # base 23:16
.byte 0 # type
.byte 0 # limit 19:16, flags
.byte 0 # base 31:24
# linear data segment descriptor
.equ LINEAR_SEL, .-GDT_BASE
.word 0xFFFF # limit 0xFFFFF
.word 0 # base 0
.byte 0
.byte 0x92 # present, ring 0, data, expand-up, writable
.byte 0xCF # page-granular, 32-bit
.byte 0
# linear code segment descriptor
.equ LINEAR_CODE_SEL, .-GDT_BASE
.word 0xFFFF # limit 0xFFFFF
.word 0 # base 0
.byte 0
.byte 0x9A # present, ring 0, data, expand-up, writable
.byte 0xCF # page-granular, 32-bit
.byte 0
# system data segment descriptor
.equ SYS_DATA_SEL, .-GDT_BASE
.word 0xFFFF # limit 0xFFFFF
.word 0 # base 0
.byte 0
.byte 0x92 # present, ring 0, data, expand-up, writable
.byte 0xCF # page-granular, 32-bit
.byte 0
# system code segment descriptor
.equ SYS_CODE_SEL, .-GDT_BASE
.word 0xFFFF # limit 0xFFFFF
.word 0 # base 0
.byte 0
.byte 0x9A # present, ring 0, data, expand-up, writable
.byte 0xCF # page-granular, 32-bit
.byte 0
# spare segment descriptor
.equ SPARE3_SEL, .-GDT_BASE
.word 0 # limit 0xFFFFF
.word 0 # base 0
.byte 0
.byte 0 # present, ring 0, data, expand-up, writable
.byte 0 # page-granular, 32-bit
.byte 0
# spare segment descriptor
.equ SPARE4_SEL, .-GDT_BASE
.word 0 # limit 0xFFFFF
.word 0 # base 0
.byte 0
.byte 0 # present, ring 0, data, expand-up, writable
.byte 0 # page-granular, 32-bit
.byte 0
# spare segment descriptor
.equ SPARE5_SEL, .-GDT_BASE
.word 0 # limit 0xFFFFF
.word 0 # base 0
.byte 0
.byte 0 # present, ring 0, data, expand-up, writable
.byte 0 # page-granular, 32-bit
.byte 0
GDT_END:
.align 0x2
idtr: .word IDT_END - IDT_BASE - 1
.long 0 # (IDT base gets set above)
##############################################################################
# interrupt descriptor table (IDT)
#
# Note: The hardware IRQ's specified in this table are the normal PC/AT IRQ
# mappings. This implementation only uses the system timer and all other
# IRQs will remain masked. The descriptors for vectors 33+ are provided
# for convenience.
##############################################################################
#idt_tag db "IDT",0
.align 0x2
IDT_BASE:
# divide by zero (INT 0)
.equ DIV_ZERO_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# debug exception (INT 1)
.equ DEBUG_EXCEPT_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# NMI (INT 2)
.equ NMI_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# soft breakpoint (INT 3)
.equ BREAKPOINT_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# overflow (INT 4)
.equ OVERFLOW_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# bounds check (INT 5)
.equ BOUNDS_CHECK_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# invalid opcode (INT 6)
.equ INVALID_OPCODE_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# device not available (INT 7)
.equ DEV_NOT_AVAIL_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# double fault (INT 8)
.equ DOUBLE_FAULT_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# Coprocessor segment overrun - reserved (INT 9)
.equ RSVD_INTR_SEL1, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# invalid TSS (INT 0ah)
.equ INVALID_TSS_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# segment not present (INT 0bh)
.equ SEG_NOT_PRESENT_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# stack fault (INT 0ch)
.equ STACK_FAULT_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# general protection (INT 0dh)
.equ GP_FAULT_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# page fault (INT 0eh)
.equ PAGE_FAULT_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# Intel reserved - do not use (INT 0fh)
.equ RSVD_INTR_SEL2, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# floating point error (INT 10h)
.equ FLT_POINT_ERR_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# alignment check (INT 11h)
.equ ALIGNMENT_CHECK_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# machine check (INT 12h)
.equ MACHINE_CHECK_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# SIMD floating-point exception (INT 13h)
.equ SIMD_EXCEPTION_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# 85 unspecified descriptors, First 12 of them are reserved, the rest are avail
.fill 85 * 8, 1, 0
# IRQ 0 (System timer) - (INT 68h)
.equ IRQ0_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# IRQ 1 (8042 Keyboard controller) - (INT 69h)
.equ IRQ1_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# Reserved - IRQ 2 redirect (IRQ 2) - DO NOT USE!!! - (INT 6ah)
.equ IRQ2_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# IRQ 3 (COM 2) - (INT 6bh)
.equ IRQ3_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# IRQ 4 (COM 1) - (INT 6ch)
.equ IRQ4_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# IRQ 5 (LPT 2) - (INT 6dh)
.equ IRQ5_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# IRQ 6 (Floppy controller) - (INT 6eh)
.equ IRQ6_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# IRQ 7 (LPT 1) - (INT 6fh)
.equ IRQ7_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# IRQ 8 (RTC Alarm) - (INT 70h)
.equ IRQ8_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# IRQ 9 - (INT 71h)
.equ IRQ9_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# IRQ 10 - (INT 72h)
.equ IRQ10_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# IRQ 11 - (INT 73h)
.equ IRQ11_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# IRQ 12 (PS/2 mouse) - (INT 74h)
.equ IRQ12_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# IRQ 13 (Floating point error) - (INT 75h)
.equ IRQ13_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# IRQ 14 (Secondary IDE) - (INT 76h)
.equ IRQ14_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
# IRQ 15 (Primary IDE) - (INT 77h)
.equ IRQ15_SEL, .-IDT_BASE
.word 0 # offset 15:0
.word SYS_CODE_SEL # selector 15:0
.byte 0 # 0 for interrupt gate
.byte 0x0e | 0x80 # type = 386 interrupt gate, present
.word 0 # offset 31:16
IDT_END:
.align 0x2
MemoryMapSize: .long 0
MemoryMap: .long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.long 0,0,0,0,0,0,0,0
.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
.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
.org 0x0fe0
MyStack:
# below is the pieces of the IVT that is used to redirect INT 68h - 6fh
# back to INT 08h - 0fh when in real mode... It is 'org'ed to a
# known low address (20f00) so it can be set up by PlMapIrqToVect in
# 8259.c
int $8
iret
int $9
iret
int $10
iret
int $11
iret
int $12
iret
int $13
iret
int $14
iret
int $15
iret
.org 0x0ffe
BlockSignature:
.word 0xaa55