[Coco] Disk subroutines for Assembly?

[Don Barber]

Thanks Robert. I got something put together; mostly with help from 
Unravelled and the guidance from Will's DoD code.

I'm just hacking together stuff to learn 6809 and coco programming. 
Basically, I've got a pretty decent RSA key generator put together, with 
a pseudorandom number generator, a pseudoprime checker (using 
miller-rabin) all using multiprecisionbyte arithmetic (started with 
Leventhal's subroutines but needed to write my own euclid gcd and 
modular exponentiation subroutines). Right now its limited to 1016 bit 
keys (I can go into why if anyone actually cares) - and that takes a day 
or three to generate depending upon how lucky the random number 
generator is at hitting near a prime. But generating small (like 32 bit 
keys) only takes several minutes. I wanted to write the public and 
private key files out to disk so I can separate out key generation from 
the actual decrypt/encrypt programs.

FWIW I do have it writing out the key files great now. Right now its 
outputting them in ASN1 format which most tools (like openssl) can read 
fine, though its supposed to be in DER format (a more size-efficient 
subset of ASN1); it will just take a few more tweaks to get that right, 
but will require either implementing a large buffer to assemble the file 
in memory or implementing a fseek() type routine. Haven't decided yet - 
or even if I'll fix that little detail at all.

Will all this be useful to anyone? No. But its a fun little project for me.

Thanks,

Don

On 2/4/22 19:32, robert.gault at att.net wrote:
> Don, If you say exactly what you want to do with disk access, I may be able to send you some example code. I wrote an asm program to open a .bin file and indicate what sectors it occupied and where it would load into memory. The code works for both 1.0 and 1.1 Disk Basic.Sent from my LG Mobile
>