OSDev.org

hello out there
i'm working on a boot sector that finds a
file in a diskette. The file sistem i'm using on is
Fat12 but i want to interpret also ex2f.
i already have the fat12 part coded but i don't
have more space in the boot sector.
could you help me!!!.
i'm looking for a packer or something like that.
Another problem is that the Fat12 final cluster mark
in my boot sector is 0xfff, not 0xff8 i have seen in all boot sector
examples. i couldn't get it works with 0xff8.
please help me!!!!!!.
sorry by the english but i don't know how to write
very well.
thank's all of you becuase of your help.

>On 2002-04-08 14:06:08, blito wrote:
>hello out there
>i'm working on a boot sector that finds a
>file in a diskette. The file sistem i'm using on is
>Fat12 but i want to interpret also ex2f.
>i already have the fat12 part coded but i don't
>have more space in the boot sector.
>could you help me!!!.

I would suggest not compressing your bootsector.
I would imagine it would get a little too complicated,
and you'd still run out of space. If you were to
do so, you couldn't compress the first part of the
boot sector, because (if you're supporting FAT)
you'll have to have that FAT disk info uncompressed
so everyone can read it, so that leaves less
room for your decompression routines, and the
standard code.

You'd probably be best to simply use a multi-stage
boot routine. Have your boot sector do some
stuff, and then load in another block of code,
and jump to it. This new block of code could,
conceviably, be compressed, if need be. It would
also be the block which would load the kernel
(which, again, could be compressed). I wouldn't
reccomend trying to compress the boot sector,
though.

>i'm looking for a packer or something like that.
>Another problem is that the Fat12 final cluster mark
>in my boot sector is 0xfff, not 0xff8 i have seen in all boot sector
>examples. i couldn't get it works with 0xff8.
>please help me!!!!!!.

Unfortunately, I can't help you on this one... I
don't know much about FAT. I'd suggest checking
out some more code, and also reread the FAT specs
(www.wotsit.org has a bunch of docs of FAT).

Jeff

>On 2002-04-09 09:16:27, J. Weeks wrote:
>>On 2002-04-08 14:06:08, blito wrote:
>>hello out there
>>i'm working on a boot sector that finds a
>>file in a diskette. The file sistem i'm using on is
>>Fat12 but i want to interpret also ex2f.
>>i already have the fat12 part coded but i don't
>>have more space in the boot sector.
>>could you help me!!!.
>
>I would suggest not compressing your bootsector.
>I would imagine it would get a little too complicated,
>and you'd still run out of space. If you were to
>do so, you couldn't compress the first part of the
>boot sector, because (if you're supporting FAT)
>you'll have to have that FAT disk info uncompressed
>so everyone can read it, so that leaves less
>room for your decompression routines, and the
>standard code.
>
>You'd probably be best to simply use a multi-stage
>boot routine. Have your boot sector do some
>stuff, and then load in another block of code,
>and jump to it. This new block of code could,
>conceviably, be compressed, if need be. It would
>also be the block which would load the kernel
>(which, again, could be compressed). I wouldn't
>reccomend trying to compress the boot sector,
>though.
>
>>i'm looking for a packer or something like that.
>>Another problem is that the Fat12 final cluster mark
>>in my boot sector is 0xfff, not 0xff8 i have seen in all boot sector
>>examples. i couldn't get it works with 0xff8.
>>please help me!!!!!!.
>
>Unfortunately, I can't help you on this one... I
>don't know much about FAT. I'd suggest checking
>out some more code, and also reread the FAT specs
>(www.wotsit.org has a bunch of docs of FAT).
>
>Jeff
thank's jeff.
i do not know what i have done withougth your help.
you've been very helpfull

>On 2002-04-10 11:41:41, blito wrote:
>>On 2002-04-09 09:16:27, J. Weeks wrote:
>>>On 2002-04-08 14:06:08, blito wrote:
>>>hello out there
>>>i'm working on a boot sector that finds a
>>>file in a diskette. The file sistem i'm using on is
>>>Fat12 but i want to interpret also ex2f.
>>>i already have the fat12 part coded but i don't
>>>have more space in the boot sector.
>>>could you help me!!!.
>>
>>I would suggest not compressing your bootsector.
>>I would imagine it would get a little too complicated,
>>and you'd still run out of space. If you were to
>>do so, you couldn't compress the first part of the
>>boot sector, because (if you're supporting FAT)
>>you'll have to have that FAT disk info uncompressed
>>so everyone can read it, so that leaves less
>>room for your decompression routines, and the
>>standard code.
>>
>>You'd probably be best to simply use a multi-stage
>>boot routine. Have your boot sector do some
>>stuff, and then load in another block of code,
>>and jump to it. This new block of code could,
>>conceviably, be compressed, if need be. It would
>>also be the block which would load the kernel
>>(which, again, could be compressed). I wouldn't
>>reccomend trying to compress the boot sector,
>>though.
>>
>>>i'm looking for a packer or something like that.
>>>Another problem is that the Fat12 final cluster mark
>>>in my boot sector is 0xfff, not 0xff8 i have seen in all boot sector
>>>examples. i couldn't get it works with 0xff8.
>>>please help me!!!!!!.
>>

0xff8 is the value Microsoft assigns for the FAT
end-of-chain. In one of their publishings, it
was stated that other software which supports FAT12
uses different values (ranging 0x0ff8 - 0x0fff, so it
is best to check for anything equal to or greater than
0x0ff8 (after clearing the high nibble). I'd direct
you to the document I read this from, but can't
seem to find it anymore. Hope this helps.

>>Unfortunately, I can't help you on this one... I
>>don't know much about FAT. I'd suggest checking
>>out some more code, and also reread the FAT specs
>>(www.wotsit.org has a bunch of docs of FAT).
>>
>>Jeff
>thank's jeff.
>i do not know what i have done withougth your help.
>you've been very helpfull