reactos/freeldr/bootsect/fat.asm

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; FAT.ASM
; FAT12/16 Boot Sector
; Copyright (c) 1998, 2001, 2002 Brian Palmer
; This is a FAT12/16 file system boot sector
; that searches the entire root directory
; for the file freeldr.sys and loads it into
; memory.
;
; The stack is set to 0000:7BF2 so that the first
; WORD pushed will be placed at 0000:7BF0
;
; The DWORD at 0000:7BFC or BP-04h is the logical
; sector number of the start of the data area.
;
; The DWORD at 0000:7BF8 or BP-08h is the total
; sector count of the boot drive as reported by
; the computers bios.
;
; The WORD at 0000:7BF6 or BP-0ah is the offset
; of the ReadSectors function in the boot sector.
;
; The WORD at 0000:7BF4 or BP-0ch is the offset
; of the ReadCluster function in the boot sector.
;
; The WORD at 0000:7BF2 or BP-0eh is the offset
; of the PutChars function in the boot sector.
;
; When it locates freeldr.sys on the disk it will
; load the first sector of the file to 0000:8000
; With the help of this sector we should be able
; to load the entire file off the disk, no matter
; how fragmented it is.
;
; We load the entire FAT table into memory at
; 7000:0000. This improves the speed of floppy disk
; boots dramatically.
BootSectorStackTop equ 0x7bf2
DataAreaStartHigh equ 0x2
DataAreaStartLow equ 0x4
BiosCHSDriveSizeHigh equ 0x6
BiosCHSDriveSizeLow equ 0x8
Changes in v1.7.4 (8/20/2002) (brianp) - Boot sector code now reports to freeldr.sys the partition that it was installed on. This is specified by a byte value in the boot sector code. By default the boot partition is set to zero which indicates the active (bootable) partition, unless the installer sets the value to non-zero. If FreeLoader is installed on a partition other than the active (bootable) partition then the installer must set this byte to that partition number. Otherwise FreeLoader will not be able to find freeldr.ini. - i386trap.S: Added debug macros BREAKPOINT(), INSTRUCTION_BREAKPOINTX(), MEMORY_READWRITE_BREAKPOINTX(), & MEMORY_WRITE_BREAKPOINTX(). - partition.c (DiskGetPartitionEntry): Add the relative offset of the extended partition to the partitions start sector. - ext2.c (Ext2ReadBlockPointerList, Ext2CopyIndirectBlockPointers, Ext2CopyDoubleIndirectBlockPointers, Ext2CopyTripleIndirectBlockPointers): Rewrote the block pointer functions so they actually work. - ini_init.c (IniFileInitialize, IniOpenIniFile): Looks for freeldr.ini on both the active (bootable) partition and the partition passed in from the boot sector code. - meminit.c (MmInitializeMemoryManager, MmFixupSystemMemoryMap, MmGetEndAddressOfAnyMemory, MmGetAddressablePageCountIncludingHoles, MmInitPageLookupTable): Fixed bug that would cause FreeLoader to have an off-by-one error when accessing the last entry in the page lookup table on systems with 4GB of memory (or memory mapped at the end of the address space). svn path=/trunk/; revision=3372
2002-08-21 03:32:49 +00:00
BiosCHSDriveSize equ 0x8
ReadSectorsOffset equ 0xa
ReadClusterOffset equ 0xc
PutCharsOffset equ 0xe
org 7c00h
segment .text
bits 16
start:
jmp short main
nop
OEMName db 'FrLdr1.0'
BytesPerSector dw 512
SectsPerCluster db 1
ReservedSectors dw 1
NumberOfFats db 2
MaxRootEntries dw 224
TotalSectors dw 2880
MediaDescriptor db 0f0h
SectorsPerFat dw 9
SectorsPerTrack dw 18
NumberOfHeads dw 2
HiddenSectors dd 0
TotalSectorsBig dd 0
BootDrive db 0
Reserved db 0
ExtendSig db 29h
SerialNumber dd 00000000h
VolumeLabel db 'NO NAME '
FileSystem db 'FAT12 '
main:
xor ax,ax
mov ss,ax
mov bp,7c00h
mov sp,BootSectorStackTop ; Setup a stack
mov ds,ax ; Make DS correct
mov es,ax ; Make ES correct
Changes in v1.7.4 (8/20/2002) (brianp) - Boot sector code now reports to freeldr.sys the partition that it was installed on. This is specified by a byte value in the boot sector code. By default the boot partition is set to zero which indicates the active (bootable) partition, unless the installer sets the value to non-zero. If FreeLoader is installed on a partition other than the active (bootable) partition then the installer must set this byte to that partition number. Otherwise FreeLoader will not be able to find freeldr.ini. - i386trap.S: Added debug macros BREAKPOINT(), INSTRUCTION_BREAKPOINTX(), MEMORY_READWRITE_BREAKPOINTX(), & MEMORY_WRITE_BREAKPOINTX(). - partition.c (DiskGetPartitionEntry): Add the relative offset of the extended partition to the partitions start sector. - ext2.c (Ext2ReadBlockPointerList, Ext2CopyIndirectBlockPointers, Ext2CopyDoubleIndirectBlockPointers, Ext2CopyTripleIndirectBlockPointers): Rewrote the block pointer functions so they actually work. - ini_init.c (IniFileInitialize, IniOpenIniFile): Looks for freeldr.ini on both the active (bootable) partition and the partition passed in from the boot sector code. - meminit.c (MmInitializeMemoryManager, MmFixupSystemMemoryMap, MmGetEndAddressOfAnyMemory, MmGetAddressablePageCountIncludingHoles, MmInitPageLookupTable): Fixed bug that would cause FreeLoader to have an off-by-one error when accessing the last entry in the page lookup table on systems with 4GB of memory (or memory mapped at the end of the address space). svn path=/trunk/; revision=3372
2002-08-21 03:32:49 +00:00
cmp BYTE [BYTE bp+BootDrive],BYTE 0xff ; If they have specified a boot drive then use it
jne GetDriveParameters
mov [BYTE bp+BootDrive],dl ; Save the boot drive
GetDriveParameters:
mov ah,08h
mov dl,[BYTE bp+BootDrive] ; Get boot drive in dl
int 13h ; Request drive parameters from the bios
jnc CalcDriveSize ; If the call succeeded then calculate the drive size
; If we get here then the call to the BIOS failed
; so just set CHS equal to the maximum addressable
; size
mov cx,0ffffh
mov dh,cl
CalcDriveSize:
; Now that we have the drive geometry
; lets calculate the drive size
mov bl,ch ; Put the low 8-bits of the cylinder count into BL
mov bh,cl ; Put the high 2-bits in BH
shr bh,6 ; Shift them into position, now BX contains the cylinder count
and cl,3fh ; Mask off cylinder bits from sector count
; CL now contains sectors per track and DH contains head count
movzx eax,dh ; Move the heads into EAX
movzx ebx,bx ; Move the cylinders into EBX
movzx ecx,cl ; Move the sectors per track into ECX
inc eax ; Make it one based because the bios returns it zero based
inc ebx ; Make the cylinder count one based also
mul ecx ; Multiply heads with the sectors per track, result in edx:eax
mul ebx ; Multiply the cylinders with (heads * sectors) [stored in edx:eax already]
; We now have the total number of sectors as reported
; by the bios in eax, so store it in our variable
mov [BYTE bp-BiosCHSDriveSize],eax
; Now we must find our way to the first sector of the root directory
xor ax,ax
xor cx,cx
mov al,[BYTE bp+NumberOfFats] ; Number of fats
mul WORD [BYTE bp+SectorsPerFat] ; Times sectors per fat
add ax,WORD [BYTE bp+HiddenSectors]
adc dx,WORD [BYTE bp+HiddenSectors+2] ; Add the number of hidden sectors
add ax,WORD [BYTE bp+ReservedSectors] ; Add the number of reserved sectors
adc dx,cx ; Add carry bit
mov WORD [BYTE bp-DataAreaStartLow],ax ; Save the starting sector of the root directory
mov WORD [BYTE bp-DataAreaStartHigh],dx ; Save it in the first 4 bytes before the boot sector
mov si,WORD [BYTE bp+MaxRootEntries] ; Get number of root dir entries in SI
pusha ; Save 32-bit logical start sector of root dir
; DX:AX now has the number of the starting sector of the root directory
; Now calculate the size of the root directory
mov ax,0020h ; Size of dir entry
mul si ; Times the number of entries
mov bx,[BYTE bp+BytesPerSector]
add ax,bx
dec ax
div bx ; Divided by the size of a sector
; AX now has the number of root directory sectors
add [BYTE bp-DataAreaStartLow],ax ; Add the number of sectors of the root directory to our other value
adc [BYTE bp-DataAreaStartHigh],cx ; Now the first 4 bytes before the boot sector contain the starting sector of the data area
popa ; Restore root dir logical sector start to DX:AX
LoadRootDirSector:
mov bx,7e0h ; We will load the root directory sector
mov es,bx ; Right after the boot sector in memory
xor bx,bx ; We will load it to [0000:7e00h]
xor cx,cx ; Zero out CX
inc cx ; Now increment it to 1, we are reading one sector
xor di,di ; Zero out di
push es ; Save ES because it will get incremented by 20h
call ReadSectors ; Read the first sector of the root directory
pop es ; Restore ES (ES:DI = 07E0:0000)
SearchRootDirSector:
cmp [es:di],ch ; If the first byte of the directory entry is zero then we have
jz ErrBoot ; reached the end of the directory and FREELDR.SYS is not here so reboot
pusha ; Save all registers
mov cl,0xb ; Put 11 in cl (length of filename in directory entry)
mov si,filename ; Put offset of filename string in DS:SI
repe cmpsb ; Compare this directory entry against 'FREELDR SYS'
popa ; Restore all the registers
jz FoundFreeLoader ; If we found it then jump
dec si ; SI holds MaxRootEntries, subtract one
jz ErrBoot ; If we are out of root dir entries then reboot
add di,BYTE +0x20 ; Increment DI by the size of a directory entry
cmp di,0200h ; Compare DI to 512 (DI has offset to next dir entry, make sure we haven't gone over one sector)
jc SearchRootDirSector ; If DI is less than 512 loop again
jmp short LoadRootDirSector ; Didn't find FREELDR.SYS in this directory sector, try again
FoundFreeLoader:
; We found freeldr.sys on the disk
; so we need to load the first 512
; bytes of it to 0000:8000
; ES:DI has dir entry (ES:DI == 07E0:XXXX)
mov ax,WORD [es:di+1ah] ; Get start cluster
push ax ; Save start cluster
push WORD 800h ; Put 800h on the stack and load it
pop es ; Into ES so that we load the cluster at 0000:8000
call ReadCluster ; Read the cluster
pop ax ; Restore start cluster of FreeLoader
; Save the addresses of needed functions so
; the helper code will know where to call them.
mov WORD [BYTE bp-ReadSectorsOffset],ReadSectors ; Save the address of ReadSectors
mov WORD [BYTE bp-ReadClusterOffset],ReadCluster ; Save the address of ReadCluster
mov WORD [BYTE bp-PutCharsOffset],PutChars ; Save the address of PutChars
; Now AX has start cluster of FreeLoader and we
; have loaded the helper code in the first 512 bytes
; of FreeLoader to 0000:8000. Now transfer control
; to the helper code. Skip the first three bytes
; because they contain a jump instruction to skip
; over the helper code in the FreeLoader image.
;jmp 0000:8003h
jmp 8003h
; Displays an error message
; And reboots
ErrBoot:
mov si,msgFreeLdr ; FreeLdr not found message
call PutChars ; Display it
Reboot:
Changes in v1.7.4 (8/20/2002) (brianp) - Boot sector code now reports to freeldr.sys the partition that it was installed on. This is specified by a byte value in the boot sector code. By default the boot partition is set to zero which indicates the active (bootable) partition, unless the installer sets the value to non-zero. If FreeLoader is installed on a partition other than the active (bootable) partition then the installer must set this byte to that partition number. Otherwise FreeLoader will not be able to find freeldr.ini. - i386trap.S: Added debug macros BREAKPOINT(), INSTRUCTION_BREAKPOINTX(), MEMORY_READWRITE_BREAKPOINTX(), & MEMORY_WRITE_BREAKPOINTX(). - partition.c (DiskGetPartitionEntry): Add the relative offset of the extended partition to the partitions start sector. - ext2.c (Ext2ReadBlockPointerList, Ext2CopyIndirectBlockPointers, Ext2CopyDoubleIndirectBlockPointers, Ext2CopyTripleIndirectBlockPointers): Rewrote the block pointer functions so they actually work. - ini_init.c (IniFileInitialize, IniOpenIniFile): Looks for freeldr.ini on both the active (bootable) partition and the partition passed in from the boot sector code. - meminit.c (MmInitializeMemoryManager, MmFixupSystemMemoryMap, MmGetEndAddressOfAnyMemory, MmGetAddressablePageCountIncludingHoles, MmInitPageLookupTable): Fixed bug that would cause FreeLoader to have an off-by-one error when accessing the last entry in the page lookup table on systems with 4GB of memory (or memory mapped at the end of the address space). svn path=/trunk/; revision=3372
2002-08-21 03:32:49 +00:00
mov si,msgAnyKey ; Press any key message
call PutChars ; Display it
xor ax,ax
int 16h ; Wait for a keypress
int 19h ; Reboot
PutChars:
lodsb
or al,al
jz short Done
mov ah,0eh
mov bx,07h
int 10h
jmp short PutChars
Done:
retn
; Displays a bad boot message
; And reboots
BadBoot:
mov si,msgDiskError ; Bad boot disk message
call PutChars ; Display it
jmp short Reboot
Changes in v1.7.4 (8/20/2002) (brianp) - Boot sector code now reports to freeldr.sys the partition that it was installed on. This is specified by a byte value in the boot sector code. By default the boot partition is set to zero which indicates the active (bootable) partition, unless the installer sets the value to non-zero. If FreeLoader is installed on a partition other than the active (bootable) partition then the installer must set this byte to that partition number. Otherwise FreeLoader will not be able to find freeldr.ini. - i386trap.S: Added debug macros BREAKPOINT(), INSTRUCTION_BREAKPOINTX(), MEMORY_READWRITE_BREAKPOINTX(), & MEMORY_WRITE_BREAKPOINTX(). - partition.c (DiskGetPartitionEntry): Add the relative offset of the extended partition to the partitions start sector. - ext2.c (Ext2ReadBlockPointerList, Ext2CopyIndirectBlockPointers, Ext2CopyDoubleIndirectBlockPointers, Ext2CopyTripleIndirectBlockPointers): Rewrote the block pointer functions so they actually work. - ini_init.c (IniFileInitialize, IniOpenIniFile): Looks for freeldr.ini on both the active (bootable) partition and the partition passed in from the boot sector code. - meminit.c (MmInitializeMemoryManager, MmFixupSystemMemoryMap, MmGetEndAddressOfAnyMemory, MmGetAddressablePageCountIncludingHoles, MmInitPageLookupTable): Fixed bug that would cause FreeLoader to have an off-by-one error when accessing the last entry in the page lookup table on systems with 4GB of memory (or memory mapped at the end of the address space). svn path=/trunk/; revision=3372
2002-08-21 03:32:49 +00:00
; Reads cluster number in AX into [ES:0000]
ReadCluster:
; StartSector = ((Cluster - 2) * SectorsPerCluster) + ReservedSectors + HiddenSectors;
dec ax ; Adjust start cluster by 2
dec ax ; Because the data area starts on cluster 2
xor ch,ch
mov cl,BYTE [BYTE bp+SectsPerCluster]
mul cx ; Times sectors per cluster
add ax,[BYTE bp-DataAreaStartLow] ; Add start of data area
adc dx,[BYTE bp-DataAreaStartHigh] ; Now we have DX:AX with the logical start sector of OSLOADER.SYS
xor bx,bx ; We will load it to [ES:0000], ES loaded before function call
mov cl,BYTE [BYTE bp+SectsPerCluster]
;call ReadSectors
;ret
; Reads logical sectors into [ES:BX]
; DX:AX has logical sector number to read
; CX has number of sectors to read
ReadSectors:
Changes in v1.7.4 (8/20/2002) (brianp) - Boot sector code now reports to freeldr.sys the partition that it was installed on. This is specified by a byte value in the boot sector code. By default the boot partition is set to zero which indicates the active (bootable) partition, unless the installer sets the value to non-zero. If FreeLoader is installed on a partition other than the active (bootable) partition then the installer must set this byte to that partition number. Otherwise FreeLoader will not be able to find freeldr.ini. - i386trap.S: Added debug macros BREAKPOINT(), INSTRUCTION_BREAKPOINTX(), MEMORY_READWRITE_BREAKPOINTX(), & MEMORY_WRITE_BREAKPOINTX(). - partition.c (DiskGetPartitionEntry): Add the relative offset of the extended partition to the partitions start sector. - ext2.c (Ext2ReadBlockPointerList, Ext2CopyIndirectBlockPointers, Ext2CopyDoubleIndirectBlockPointers, Ext2CopyTripleIndirectBlockPointers): Rewrote the block pointer functions so they actually work. - ini_init.c (IniFileInitialize, IniOpenIniFile): Looks for freeldr.ini on both the active (bootable) partition and the partition passed in from the boot sector code. - meminit.c (MmInitializeMemoryManager, MmFixupSystemMemoryMap, MmGetEndAddressOfAnyMemory, MmGetAddressablePageCountIncludingHoles, MmInitPageLookupTable): Fixed bug that would cause FreeLoader to have an off-by-one error when accessing the last entry in the page lookup table on systems with 4GB of memory (or memory mapped at the end of the address space). svn path=/trunk/; revision=3372
2002-08-21 03:32:49 +00:00
; We can't just check if the start sector is
; in the BIOS CHS range. We have to check if
; the start sector + length is in that range.
pusha
dec cx
add ax,cx
adc dx,byte 0
cmp dx,WORD [BYTE bp-BiosCHSDriveSizeHigh] ; Check if they are reading a sector within CHS range
jb ReadSectorsCHS ; Yes - go to the old CHS routine
cmp ax,WORD [BYTE bp-BiosCHSDriveSizeLow] ; Check if they are reading a sector within CHS range
jbe ReadSectorsCHS ; Yes - go to the old CHS routine
ReadSectorsLBA:
Changes in v1.7.4 (8/20/2002) (brianp) - Boot sector code now reports to freeldr.sys the partition that it was installed on. This is specified by a byte value in the boot sector code. By default the boot partition is set to zero which indicates the active (bootable) partition, unless the installer sets the value to non-zero. If FreeLoader is installed on a partition other than the active (bootable) partition then the installer must set this byte to that partition number. Otherwise FreeLoader will not be able to find freeldr.ini. - i386trap.S: Added debug macros BREAKPOINT(), INSTRUCTION_BREAKPOINTX(), MEMORY_READWRITE_BREAKPOINTX(), & MEMORY_WRITE_BREAKPOINTX(). - partition.c (DiskGetPartitionEntry): Add the relative offset of the extended partition to the partitions start sector. - ext2.c (Ext2ReadBlockPointerList, Ext2CopyIndirectBlockPointers, Ext2CopyDoubleIndirectBlockPointers, Ext2CopyTripleIndirectBlockPointers): Rewrote the block pointer functions so they actually work. - ini_init.c (IniFileInitialize, IniOpenIniFile): Looks for freeldr.ini on both the active (bootable) partition and the partition passed in from the boot sector code. - meminit.c (MmInitializeMemoryManager, MmFixupSystemMemoryMap, MmGetEndAddressOfAnyMemory, MmGetAddressablePageCountIncludingHoles, MmInitPageLookupTable): Fixed bug that would cause FreeLoader to have an off-by-one error when accessing the last entry in the page lookup table on systems with 4GB of memory (or memory mapped at the end of the address space). svn path=/trunk/; revision=3372
2002-08-21 03:32:49 +00:00
popa
pusha ; Save logical sector number & sector count
o32 push byte 0
push dx ; Put 64-bit logical
push ax ; block address on stack
push es ; Put transfer segment on stack
push bx ; Put transfer offset on stack
push byte 1 ; Set transfer count to 1 sector
push byte 0x10 ; Set size of packet to 10h
mov si,sp ; Setup disk address packet on stack
; We are so totally out of space here that I am forced to
; comment out this very beautifully written piece of code
; It would have been nice to have had this check...
;CheckInt13hExtensions: ; Now make sure this computer supports extended reads
; mov ah,0x41 ; AH = 41h
; mov bx,0x55aa ; BX = 55AAh
; mov dl,[BYTE bp+BootDrive] ; DL = drive (80h-FFh)
; int 13h ; IBM/MS INT 13 Extensions - INSTALLATION CHECK
; jc PrintDiskError ; CF set on error (extensions not supported)
; cmp bx,0xaa55 ; BX = AA55h if installed
; jne PrintDiskError
; test cl,1 ; CX = API subset support bitmap
; jz PrintDiskError ; Bit 0, extended disk access functions (AH=42h-44h,47h,48h) supported
; Good, we're here so the computer supports LBA disk access
; So finish the extended read
mov dl,[BYTE bp+BootDrive] ; Drive number
mov ah,42h ; Int 13h, AH = 42h - Extended Read
int 13h ; Call BIOS
jc BadBoot ; If the read failed then abort
Changes in v1.7.4 (8/20/2002) (brianp) - Boot sector code now reports to freeldr.sys the partition that it was installed on. This is specified by a byte value in the boot sector code. By default the boot partition is set to zero which indicates the active (bootable) partition, unless the installer sets the value to non-zero. If FreeLoader is installed on a partition other than the active (bootable) partition then the installer must set this byte to that partition number. Otherwise FreeLoader will not be able to find freeldr.ini. - i386trap.S: Added debug macros BREAKPOINT(), INSTRUCTION_BREAKPOINTX(), MEMORY_READWRITE_BREAKPOINTX(), & MEMORY_WRITE_BREAKPOINTX(). - partition.c (DiskGetPartitionEntry): Add the relative offset of the extended partition to the partitions start sector. - ext2.c (Ext2ReadBlockPointerList, Ext2CopyIndirectBlockPointers, Ext2CopyDoubleIndirectBlockPointers, Ext2CopyTripleIndirectBlockPointers): Rewrote the block pointer functions so they actually work. - ini_init.c (IniFileInitialize, IniOpenIniFile): Looks for freeldr.ini on both the active (bootable) partition and the partition passed in from the boot sector code. - meminit.c (MmInitializeMemoryManager, MmFixupSystemMemoryMap, MmGetEndAddressOfAnyMemory, MmGetAddressablePageCountIncludingHoles, MmInitPageLookupTable): Fixed bug that would cause FreeLoader to have an off-by-one error when accessing the last entry in the page lookup table on systems with 4GB of memory (or memory mapped at the end of the address space). svn path=/trunk/; revision=3372
2002-08-21 03:32:49 +00:00
add sp,byte 0x10 ; Remove disk address packet from stack
Changes in v1.7.4 (8/20/2002) (brianp) - Boot sector code now reports to freeldr.sys the partition that it was installed on. This is specified by a byte value in the boot sector code. By default the boot partition is set to zero which indicates the active (bootable) partition, unless the installer sets the value to non-zero. If FreeLoader is installed on a partition other than the active (bootable) partition then the installer must set this byte to that partition number. Otherwise FreeLoader will not be able to find freeldr.ini. - i386trap.S: Added debug macros BREAKPOINT(), INSTRUCTION_BREAKPOINTX(), MEMORY_READWRITE_BREAKPOINTX(), & MEMORY_WRITE_BREAKPOINTX(). - partition.c (DiskGetPartitionEntry): Add the relative offset of the extended partition to the partitions start sector. - ext2.c (Ext2ReadBlockPointerList, Ext2CopyIndirectBlockPointers, Ext2CopyDoubleIndirectBlockPointers, Ext2CopyTripleIndirectBlockPointers): Rewrote the block pointer functions so they actually work. - ini_init.c (IniFileInitialize, IniOpenIniFile): Looks for freeldr.ini on both the active (bootable) partition and the partition passed in from the boot sector code. - meminit.c (MmInitializeMemoryManager, MmFixupSystemMemoryMap, MmGetEndAddressOfAnyMemory, MmGetAddressablePageCountIncludingHoles, MmInitPageLookupTable): Fixed bug that would cause FreeLoader to have an off-by-one error when accessing the last entry in the page lookup table on systems with 4GB of memory (or memory mapped at the end of the address space). svn path=/trunk/; revision=3372
2002-08-21 03:32:49 +00:00
popa ; Restore sector count & logical sector number
inc ax ; Increment Sector to Read
Changes in v1.7.4 (8/20/2002) (brianp) - Boot sector code now reports to freeldr.sys the partition that it was installed on. This is specified by a byte value in the boot sector code. By default the boot partition is set to zero which indicates the active (bootable) partition, unless the installer sets the value to non-zero. If FreeLoader is installed on a partition other than the active (bootable) partition then the installer must set this byte to that partition number. Otherwise FreeLoader will not be able to find freeldr.ini. - i386trap.S: Added debug macros BREAKPOINT(), INSTRUCTION_BREAKPOINTX(), MEMORY_READWRITE_BREAKPOINTX(), & MEMORY_WRITE_BREAKPOINTX(). - partition.c (DiskGetPartitionEntry): Add the relative offset of the extended partition to the partitions start sector. - ext2.c (Ext2ReadBlockPointerList, Ext2CopyIndirectBlockPointers, Ext2CopyDoubleIndirectBlockPointers, Ext2CopyTripleIndirectBlockPointers): Rewrote the block pointer functions so they actually work. - ini_init.c (IniFileInitialize, IniOpenIniFile): Looks for freeldr.ini on both the active (bootable) partition and the partition passed in from the boot sector code. - meminit.c (MmInitializeMemoryManager, MmFixupSystemMemoryMap, MmGetEndAddressOfAnyMemory, MmGetAddressablePageCountIncludingHoles, MmInitPageLookupTable): Fixed bug that would cause FreeLoader to have an off-by-one error when accessing the last entry in the page lookup table on systems with 4GB of memory (or memory mapped at the end of the address space). svn path=/trunk/; revision=3372
2002-08-21 03:32:49 +00:00
adc dx,byte 0
mov dx,es
add dx,byte 20h ; Increment read buffer for next sector
mov es,dx
loop ReadSectorsLBA ; Read next sector
ret
; Reads logical sectors into [ES:BX]
; DX:AX has logical sector number to read
; CX has number of sectors to read
; CarryFlag set on error
ReadSectorsCHS:
Changes in v1.7.4 (8/20/2002) (brianp) - Boot sector code now reports to freeldr.sys the partition that it was installed on. This is specified by a byte value in the boot sector code. By default the boot partition is set to zero which indicates the active (bootable) partition, unless the installer sets the value to non-zero. If FreeLoader is installed on a partition other than the active (bootable) partition then the installer must set this byte to that partition number. Otherwise FreeLoader will not be able to find freeldr.ini. - i386trap.S: Added debug macros BREAKPOINT(), INSTRUCTION_BREAKPOINTX(), MEMORY_READWRITE_BREAKPOINTX(), & MEMORY_WRITE_BREAKPOINTX(). - partition.c (DiskGetPartitionEntry): Add the relative offset of the extended partition to the partitions start sector. - ext2.c (Ext2ReadBlockPointerList, Ext2CopyIndirectBlockPointers, Ext2CopyDoubleIndirectBlockPointers, Ext2CopyTripleIndirectBlockPointers): Rewrote the block pointer functions so they actually work. - ini_init.c (IniFileInitialize, IniOpenIniFile): Looks for freeldr.ini on both the active (bootable) partition and the partition passed in from the boot sector code. - meminit.c (MmInitializeMemoryManager, MmFixupSystemMemoryMap, MmGetEndAddressOfAnyMemory, MmGetAddressablePageCountIncludingHoles, MmInitPageLookupTable): Fixed bug that would cause FreeLoader to have an off-by-one error when accessing the last entry in the page lookup table on systems with 4GB of memory (or memory mapped at the end of the address space). svn path=/trunk/; revision=3372
2002-08-21 03:32:49 +00:00
popa
ReadSectorsCHSLoop:
Changes in v1.7.4 (8/20/2002) (brianp) - Boot sector code now reports to freeldr.sys the partition that it was installed on. This is specified by a byte value in the boot sector code. By default the boot partition is set to zero which indicates the active (bootable) partition, unless the installer sets the value to non-zero. If FreeLoader is installed on a partition other than the active (bootable) partition then the installer must set this byte to that partition number. Otherwise FreeLoader will not be able to find freeldr.ini. - i386trap.S: Added debug macros BREAKPOINT(), INSTRUCTION_BREAKPOINTX(), MEMORY_READWRITE_BREAKPOINTX(), & MEMORY_WRITE_BREAKPOINTX(). - partition.c (DiskGetPartitionEntry): Add the relative offset of the extended partition to the partitions start sector. - ext2.c (Ext2ReadBlockPointerList, Ext2CopyIndirectBlockPointers, Ext2CopyDoubleIndirectBlockPointers, Ext2CopyTripleIndirectBlockPointers): Rewrote the block pointer functions so they actually work. - ini_init.c (IniFileInitialize, IniOpenIniFile): Looks for freeldr.ini on both the active (bootable) partition and the partition passed in from the boot sector code. - meminit.c (MmInitializeMemoryManager, MmFixupSystemMemoryMap, MmGetEndAddressOfAnyMemory, MmGetAddressablePageCountIncludingHoles, MmInitPageLookupTable): Fixed bug that would cause FreeLoader to have an off-by-one error when accessing the last entry in the page lookup table on systems with 4GB of memory (or memory mapped at the end of the address space). svn path=/trunk/; revision=3372
2002-08-21 03:32:49 +00:00
pusha
xchg ax,cx
xchg ax,dx
xor dx,dx
div WORD [BYTE bp+SectorsPerTrack]
xchg ax,cx
div WORD [BYTE bp+SectorsPerTrack] ; Divide logical by SectorsPerTrack
inc dx ; Sectors numbering starts at 1 not 0
xchg cx,dx
div WORD [BYTE bp+NumberOfHeads] ; Number of heads
mov dh,dl ; Head to DH, drive to DL
mov dl,[BYTE bp+BootDrive] ; Drive number
mov ch,al ; Cylinder in CX
ror ah,2 ; Low 8 bits of cylinder in CH, high 2 bits
; in CL shifted to bits 6 & 7
or cl,ah ; Or with sector number
mov ax,0201h
int 13h ; DISK - READ SECTORS INTO MEMORY
; AL = number of sectors to read, CH = track, CL = sector
; DH = head, DL = drive, ES:BX -> buffer to fill
; Return: CF set on error, AH = status (see AH=01h), AL = number of sectors read
jc BadBoot
Changes in v1.7.4 (8/20/2002) (brianp) - Boot sector code now reports to freeldr.sys the partition that it was installed on. This is specified by a byte value in the boot sector code. By default the boot partition is set to zero which indicates the active (bootable) partition, unless the installer sets the value to non-zero. If FreeLoader is installed on a partition other than the active (bootable) partition then the installer must set this byte to that partition number. Otherwise FreeLoader will not be able to find freeldr.ini. - i386trap.S: Added debug macros BREAKPOINT(), INSTRUCTION_BREAKPOINTX(), MEMORY_READWRITE_BREAKPOINTX(), & MEMORY_WRITE_BREAKPOINTX(). - partition.c (DiskGetPartitionEntry): Add the relative offset of the extended partition to the partitions start sector. - ext2.c (Ext2ReadBlockPointerList, Ext2CopyIndirectBlockPointers, Ext2CopyDoubleIndirectBlockPointers, Ext2CopyTripleIndirectBlockPointers): Rewrote the block pointer functions so they actually work. - ini_init.c (IniFileInitialize, IniOpenIniFile): Looks for freeldr.ini on both the active (bootable) partition and the partition passed in from the boot sector code. - meminit.c (MmInitializeMemoryManager, MmFixupSystemMemoryMap, MmGetEndAddressOfAnyMemory, MmGetAddressablePageCountIncludingHoles, MmInitPageLookupTable): Fixed bug that would cause FreeLoader to have an off-by-one error when accessing the last entry in the page lookup table on systems with 4GB of memory (or memory mapped at the end of the address space). svn path=/trunk/; revision=3372
2002-08-21 03:32:49 +00:00
popa
inc ax ;Increment Sector to Read
jnz NoCarryCHS
inc dx
NoCarryCHS:
push bx
mov bx,es
add bx,byte 20h
mov es,bx
pop bx
; Increment read buffer for next sector
loop ReadSectorsCHSLoop ; Read next sector
ret
msgDiskError db 'Disk error',0dh,0ah,0
Changes in v1.7.4 (8/20/2002) (brianp) - Boot sector code now reports to freeldr.sys the partition that it was installed on. This is specified by a byte value in the boot sector code. By default the boot partition is set to zero which indicates the active (bootable) partition, unless the installer sets the value to non-zero. If FreeLoader is installed on a partition other than the active (bootable) partition then the installer must set this byte to that partition number. Otherwise FreeLoader will not be able to find freeldr.ini. - i386trap.S: Added debug macros BREAKPOINT(), INSTRUCTION_BREAKPOINTX(), MEMORY_READWRITE_BREAKPOINTX(), & MEMORY_WRITE_BREAKPOINTX(). - partition.c (DiskGetPartitionEntry): Add the relative offset of the extended partition to the partitions start sector. - ext2.c (Ext2ReadBlockPointerList, Ext2CopyIndirectBlockPointers, Ext2CopyDoubleIndirectBlockPointers, Ext2CopyTripleIndirectBlockPointers): Rewrote the block pointer functions so they actually work. - ini_init.c (IniFileInitialize, IniOpenIniFile): Looks for freeldr.ini on both the active (bootable) partition and the partition passed in from the boot sector code. - meminit.c (MmInitializeMemoryManager, MmFixupSystemMemoryMap, MmGetEndAddressOfAnyMemory, MmGetAddressablePageCountIncludingHoles, MmInitPageLookupTable): Fixed bug that would cause FreeLoader to have an off-by-one error when accessing the last entry in the page lookup table on systems with 4GB of memory (or memory mapped at the end of the address space). svn path=/trunk/; revision=3372
2002-08-21 03:32:49 +00:00
msgFreeLdr db 'freeldr.sys not found',0dh,0ah,0
; Sorry, need the space...
;msgAnyKey db 'Press any key to restart',0dh,0ah,0
msgAnyKey db 'Press any key',0dh,0ah,0
filename db 'FREELDR SYS'
Changes in v1.7.4 (8/20/2002) (brianp) - Boot sector code now reports to freeldr.sys the partition that it was installed on. This is specified by a byte value in the boot sector code. By default the boot partition is set to zero which indicates the active (bootable) partition, unless the installer sets the value to non-zero. If FreeLoader is installed on a partition other than the active (bootable) partition then the installer must set this byte to that partition number. Otherwise FreeLoader will not be able to find freeldr.ini. - i386trap.S: Added debug macros BREAKPOINT(), INSTRUCTION_BREAKPOINTX(), MEMORY_READWRITE_BREAKPOINTX(), & MEMORY_WRITE_BREAKPOINTX(). - partition.c (DiskGetPartitionEntry): Add the relative offset of the extended partition to the partitions start sector. - ext2.c (Ext2ReadBlockPointerList, Ext2CopyIndirectBlockPointers, Ext2CopyDoubleIndirectBlockPointers, Ext2CopyTripleIndirectBlockPointers): Rewrote the block pointer functions so they actually work. - ini_init.c (IniFileInitialize, IniOpenIniFile): Looks for freeldr.ini on both the active (bootable) partition and the partition passed in from the boot sector code. - meminit.c (MmInitializeMemoryManager, MmFixupSystemMemoryMap, MmGetEndAddressOfAnyMemory, MmGetAddressablePageCountIncludingHoles, MmInitPageLookupTable): Fixed bug that would cause FreeLoader to have an off-by-one error when accessing the last entry in the page lookup table on systems with 4GB of memory (or memory mapped at the end of the address space). svn path=/trunk/; revision=3372
2002-08-21 03:32:49 +00:00
times 509-($-$$) db 0 ; Pad to 509 bytes
BootPartition:
db 0
BootSignature:
dw 0aa55h ; BootSector signature