Most of register fiddling routines (which is now the only thing contained
in care.asm) are used by almost all userspace apps, often in inner loops.
That makes the penalty of using jump tables for those a bit too high.
Moreover, it burdens jump tables needlessly.
Because this unit is very small (now that string routines are out), it makes
sense to always include it in binaries.
We use zasm's ability to use labels in .equ directive.
We didn't do it before because for a while, we were in between scas
and zasm (scas was used in automated tests) so we needed to use the
lowest common denominator: zasm doesn't have macros and scas can't
use labels in .equ directives.
This forced us to add this layer of indirection. But now that we are
completely cut from scas' dependency, we can use this nice zasm's
ability.
The pgm module implements a shell hook so that when an unknown command
is typed, we look into the mounted filesystem and look for a file with
the same name as the command. If we find one, we load it in memory and
run it.
