File handling

[Mat]

Hello,

I'm needing a easy way to import and save selectable memory dumps from
within retro. To implement this, my current work-in-progress vm will
reserve 3 new port addresses:

Port 10: blockread
Port 11: blockwrite
Port 12: seek

Think, that would be useful for general usage.

-Mat.

[Charles Childers]

File support would be interesting. While I make no promises on supporting this in my vm implementation, I do have a initial few questions:

1. What stack usage do you have in mind?
2. Why 3 ports, rather than having one. For handling a file device?
3. Will you be adding a capability query?

-- crc

[Mat]

> 1. What stack usage do you have in mind?

Something in change. At current:

n = block number,
i = number of blocks,
a = address,
f = flag

blockread (i a - f)
blockwrite (i a - f)
seek (n - f)

> 2. Why 3 ports, rather than having one. For handling a file device?

Yes. My first attempt was to implement the complete ATA interface over
two port addresses for handling virtual block devices but that's too
much overhead so I end up in this tree port routines. The virtual
device is just a plain file which size and name is given on the
command line.

> 3. Will you be adding a capability query?

Surely.

-Mat.