;*************************************************************
;* 28.01.2006 find all Fat16/32 partition in all input point *
;* to MBR - Mario79 *
;*************************************************************
align 4
;******************************************************
; Please do not change this place - variables in text
; Mario79
; START place
;******************************************************
PARTITION_START dd 0x3f
PARTITION_END dd 0
SECTORS_PER_FAT dd 0x1f3a
NUMBER_OF_FATS dd 0x2
SECTORS_PER_CLUSTER dd 0x8
BYTES_PER_SECTOR dd 0x200 ; Note: if BPS <> 512 need lots of changes
ROOT_CLUSTER dd 2 ; first rootdir cluster
FAT_START dd 0 ; start of fat table
ROOT_START dd 0 ; start of rootdir (only fat16)
ROOT_SECTORS dd 0 ; count of rootdir sectors (only fat16)
DATA_START dd 0 ; start of data area (=first cluster 2)
LAST_CLUSTER dd 0 ; last availabe cluster
ADR_FSINFO dd 0 ; used only by fat32
fatRESERVED dd 0x0FFFFFF6
fatBAD dd 0x0FFFFFF7
fatEND dd 0x0FFFFFF8
fatMASK dd 0x0FFFFFFF
fat_type db 0 ; 0=none, 16=fat16, 32=fat32
;***************************************************************************
; End place
; Mario79
;***************************************************************************
iglobal
partition_types: ; list of fat16/32 partitions
db 0x04 ; DOS: fat16 <32M
db 0x06 ; DOS: fat16 >32M
db 0x0b ; WIN95: fat32
db 0x0c ; WIN95: fat32, LBA-mapped
db 0x0e ; WIN95: fat16, LBA-mapped
db 0x14 ; Hidden DOS: fat16 <32M
db 0x16 ; Hidden DOS: fat16 >32M
db 0x1b ; Hidden WIN95: fat32
db 0x1c ; Hidden WIN95: fat32, LBA-mapped
db 0x1e ; Hidden WIN95: fat16, LBA-mapped
db 0xc4 ; DRDOS/secured: fat16 <32M
db 0xc6 ; DRDOS/secured: fat16 >32M
db 0xcb ; DRDOS/secured: fat32
db 0xcc ; DRDOS/secured: fat32, LBA-mapped
db 0xce ; DRDOS/secured: fat16, LBA-mapped
db 0xd4 ; Old Multiuser DOS secured: fat16 <32M
db 0xd6 ; Old Multiuser DOS secured: fat16 >32M
partition_types_end:
extended_types: ; list of extended partitions
db 0x05 ; DOS: extended partition
db 0x0f ; WIN95: extended partition, LBA-mapped
db 0xc5 ; DRDOS/secured: extended partition
db 0xd5 ; Old Multiuser DOS secured: extended partition
extended_types_end:
endg
; Partition chain used:
; MBR ; PARTITION2 ; PARTITION3 ; PARTITION4
;==========================================================
; fat16/32 +-- fat16/32 +-- fat16/32 +-- fat16/32 +--
; extended --+ extended --+ extended --+ extended --+
; 0 0 0 0
; 0 0 0 0
; Notes:
; - extended partition need to be in second entry on table
; - it will skip over removed partitions
set_FAT32_variables:
mov [0xfe10],dword 0 ; entries in hd cache
mov [problem_partition],0
call reserve_hd1
call clear_hd_cache
cmp dword [hdpos],0
je problem_hd
pushad
xor ecx,ecx ; partition count
mov edx,-1 ; flag for partition
xor eax,eax ; read MBR
xor ebp,ebp ; extended partition start
new_partition:
test ebp,ebp ; is there extended partition?
jnz extended_already_set ; yes
xchg ebp,eax ; no. set it now
extended_already_set:
add eax,ebp ; mbr=mbr+0, ext_part=ext_start+relat_start
mov ebx,buffer
call hd_read
cmp word [ebx+0x1fe],0xaa55 ; is it valid boot sector?
jnz end_partition_chain
cmp dword [ebx+0x1be+0xc],0 ; skip over empty partition
jz next_partition
push eax
mov al,[ebx+0x1be+4] ; get primary partition type
call scan_partition_types
pop eax
jnz next_primary_partition ; no. skip over
inc ecx
cmp ecx,[fat32part] ; is it wanted partition?
jnz next_primary_partition ; no
mov edx,eax ; start sector
add edx,[ebx+0x1be+8] ; add relative start
next_primary_partition:
push eax
mov al,[ebx+0x1be+4+16] ; get primary partition type
call scan_partition_types
pop eax
jnz next_primary_partition_1 ; no. skip over
inc ecx
cmp ecx,[fat32part] ; is it wanted partition?
jnz next_primary_partition_1 ; no
mov edx,eax ; start sector
add edx,[ebx+0x1be+8+16] ; add relative start
next_primary_partition_1:
push eax
mov al,[ebx+0x1be+4+16+16] ; get primary partition type
call scan_partition_types
pop eax
jnz next_primary_partition_2 ; no. skip over
inc ecx
cmp ecx,[fat32part] ; is it wanted partition?
jnz next_primary_partition_2 ; no
mov edx,eax ; start sector
add edx,[ebx+0x1be+8+16+16] ; add relative start
next_primary_partition_2:
push eax
mov al,[ebx+0x1be+4+16+16+16] ; get primary partition type
call scan_partition_types
pop eax
jnz next_partition ; no. skip over
inc ecx
cmp ecx,[fat32part] ; is it wanted partition?
jnz next_partition ; no
mov edx,eax ; start sector
add edx,[ebx+0x1be+8+16+16+16] ; add relative start
next_partition:
push eax
mov al,[ebx+0x1be+4] ; get extended partition type
call scan_extended_types
pop eax
jnz next_partition_1
mov eax,[ebx+0x1be+8] ; add relative start
test eax,eax ; is there extended partition?
jnz new_partition ; yes. read it
next_partition_1:
push eax
mov al,[ebx+0x1be+4+16] ; get extended partition type
call scan_extended_types
pop eax
jnz next_partition_2
mov eax,[ebx+0x1be+8+16] ; add relative start
test eax,eax ; is there extended partition?
jnz new_partition ; yes. read it
next_partition_2:
push eax
mov al,[ebx+0x1be+4+16+16] ; get extended partition type
call scan_extended_types
pop eax
jnz next_partition_3
mov eax,[ebx+0x1be+8+16+16] ; add relative start
test eax,eax ; is there extended partition?
jnz new_partition ; yes. read it
next_partition_3:
push eax
mov al,[ebx+0x1be+4+16+16+16] ; get extended partition type
call scan_extended_types
pop eax
jnz end_partition_chain ; no. end chain
mov eax,[ebx+0x1be+8+16+16+16] ; get start of extended partition
test eax,eax ; is there extended partition?
jnz new_partition ; yes. read it
end_partition_chain:
mov [partition_count],ecx
cmp edx,-1 ; found wanted partition?
jnz hd_and_partition_ok ; yes. install it
jmp problem_partition_or_fat
scan_partition_types:
push ecx
mov edi,partition_types
mov ecx,partition_types_end-partition_types
cld
repne scasb ; is partition type ok?
pop ecx
ret
scan_extended_types:
push ecx
mov edi,extended_types
mov ecx,extended_types_end-extended_types
cld
repne scasb ; is it extended partition?
pop ecx
ret
problem_fat_dec_count: ; bootsector is missing or another problem
dec [partition_count] ; remove it from partition_count
problem_partition_or_fat:
popad
problem_hd:
mov [fat_type],0
mov [hd1_status],0 ; free
mov [problem_partition],1
ret
hd_and_partition_ok:
mov eax,edx
mov [PARTITION_START],eax
mov [hd_setup],1
mov ebx,buffer
call hd_read ; read boot sector of partition
mov [hd_setup],0
cmp word [ebx+0x1fe],0xaa55 ; is it valid boot sector?
jnz problem_fat_dec_count
movzx eax,word [ebx+0xe] ; sectors reserved
add eax,[PARTITION_START]
mov [FAT_START],eax ; fat_start = partition_start + reserved
movzx eax,byte [ebx+0xd] ; sectors per cluster
mov [SECTORS_PER_CLUSTER],eax
movzx ecx,word [ebx+0xb] ; bytes per sector
mov [BYTES_PER_SECTOR],ecx
movzx eax,word [ebx+0x11] ; count of rootdir entries (=0 fat32)
mov edx,32
mul edx
dec ecx
add eax,ecx ; round up if not equal count
inc ecx ; bytes per sector
div ecx
mov [ROOT_SECTORS],eax ; count of rootdir sectors
movzx eax,word [ebx+0x16] ; sectors per fat <65536
test eax,eax
jnz fat16_fatsize
mov eax,[ebx+0x24] ; sectors per fat
fat16_fatsize:
mov [SECTORS_PER_FAT],eax
movzx eax,byte [ebx+0x10] ; number of fats
test eax,eax ; if 0 it's not fat partition
jz problem_fat_dec_count
mov [NUMBER_OF_FATS],eax
imul eax,[SECTORS_PER_FAT]
add eax,[FAT_START]
mov [ROOT_START],eax ; rootdir = fat_start + fat_size * fat_count
add eax,[ROOT_SECTORS] ; rootdir sectors should be 0 on fat32
mov [DATA_START],eax ; data area = rootdir + rootdir_size
movzx eax,word [ebx+0x13] ; total sector count <65536
test eax,eax
jnz fat16_total
mov eax,[ebx+0x20] ; total sector count
fat16_total:
add eax,[PARTITION_START]
dec eax
mov [PARTITION_END],eax
inc eax
sub eax,[DATA_START] ; eax = count of data sectors
xor edx,edx
div dword [SECTORS_PER_CLUSTER]
inc eax
mov [LAST_CLUSTER],eax
dec eax ; cluster count
; limits by Microsoft Hardware White Paper v1.03
cmp eax,4085 ; 0xff5
jb problem_fat_dec_count ; fat12 not supported
cmp eax,65525 ; 0xfff5
jb fat16_partition
fat32_partition:
mov eax,[ebx+0x2c] ; rootdir cluster
mov [ROOT_CLUSTER],eax
movzx eax,word [ebx+0x30] ; fs info sector
add eax,[PARTITION_START]
mov [ADR_FSINFO],eax
popad
mov [fatRESERVED],0x0FFFFFF6
mov [fatBAD],0x0FFFFFF7
mov [fatEND],0x0FFFFFF8
mov [fatMASK],0x0FFFFFFF
mov [fat_type],32 ; Fat32
mov [hd1_status],0 ; free
ret
fat16_partition:
xor eax,eax
mov [ROOT_CLUSTER],eax
popad
mov [fatRESERVED],0x0000FFF6
mov [fatBAD],0x0000FFF7
mov [fatEND],0x0000FFF8
mov [fatMASK],0x0000FFFF
mov [fat_type],16 ; Fat16
mov [hd1_status],0 ; free
ret