[Parted-maintainers] Bug#239816: bug#16134: libparted Atari partition table support

[Michael Schmitz]

Thorsten,

Am 16.10.2016 um 11:42 schrieb Thorsten Glaser:
> Michael Schmitz dixit:
> 
>> Did you write the table on the host and then had to byte swap to get it
>> read in ARAnyM?
>>
>> Just checked - Atari byte order disk image files of IDE disks don't need
>> byte swapping. Host native byte order ones do, that suggests your
> 
> ARAnyM writes in byte-swapped order by default, to enable some sort
> of optimisations. When dd(1)ing onto IDE/CF discs used by real hardware

Thanks for clarifying this - the IDE disk image file I mentioned above
was one created from my Falcon disk on the PC so unreadable on the PC
directly but works by implicit swapping in ARAnyM.

> Ataris, you do *not* need to byte-swap from x86, but you *do* need to
> byte-swap relative to standard ARAnyM disc images. (Or enable swapping
> in ARAnyM… disable really, but that means to enable its option.)

Now I'm officially confused. What do you consider a standard ARAnyM disk
image - ARAnyM (Atari) byte order or host (really IDE standard) byte order?

The way you describe it, the standard disk image format (which needs the
byteswap option enabled, or swapping by DD when copying to media
intended for use on Atari) would be in PC host byte order?

> Took me some time to figure this out, but in the end, we had it.
> 
> The same applies for floppy discs in ARAnyM vs. real x86/Atari HW.

The floppy interface is 8 bit so needs no swapping, or wired up the
right way. Either way, on-disk byte order is the same on Atari and PC.
(Atari only managed to botch up the IDE interface, apparently estimating
the chance of someone using an IDE disk to transfer data very small...)

Cheers,

	Michael


> 
> bye,
> //mirabilos
>