collapseos/kernel
Virgil Dupras 73c3fc7947 shell/stdio: decouple from blkdev (again)
Move load/save to blkdev_cmds and add a new "poke" builtin shell cmd
that is the mirror of "peek" and strictly uses stdio (no blkdev
involved).

This allows us to slim the minimal OS size but, more importantly, change
the behavior of "load" so that we don't expect GetC to block until Z is
set. This way, using "load X" with X being larger than the blkdev size
won't block forever.

This also brings our RC2014 minimal kernel below the 1K mark again.
2019-06-02 11:06:38 -04:00
..
acia.asm Move /parts/z80 to /kernel 2019-05-19 11:19:41 -04:00
blockdev_cmds.asm shell/stdio: decouple from blkdev (again) 2019-06-02 11:06:38 -04:00
blockdev.asm shell/stdio: decouple from blkdev (again) 2019-06-02 11:06:38 -04:00
core.asm fs: check for file size bounds in GetC 2019-05-31 11:12:29 -04:00
fs_cmds.asm fs: standardize file handle routine argument to IX 2019-05-31 14:28:06 -04:00
fs.asm fs: standardize file handle routine argument to IX 2019-05-31 14:28:06 -04:00
mmap.asm Move /parts/z80 to /kernel 2019-05-19 11:19:41 -04:00
parse.asm Move /parts/z80 to /kernel 2019-05-19 11:19:41 -04:00
pgm.asm pgm: new kernel module 2019-05-31 14:54:15 -04:00
README.md Move /parts/z80 to /kernel 2019-05-19 11:19:41 -04:00
sdc.asm sdc: add sdcPutC 2019-06-01 19:53:42 -04:00
shell.asm shell/stdio: decouple from blkdev (again) 2019-06-02 11:06:38 -04:00
stdio.asm shell/stdio: decouple from blkdev (again) 2019-06-02 11:06:38 -04:00
user.h.example zasm emul: bring back kernel/user distinction 2019-05-19 12:57:59 -04:00

Kernel

Bits and pieces of code that you can assemble to build a kernel for your machine.

These parts are made to be glued together in a single glue.asm file you write yourself.

As of now, the z80 assembler code is written to be assembled with scas, but this is going to change in the future as a new hosted assembler is written.

Defines

Each part can have its own constants, but some constant are made to be defined externally. We already have some of those external definitions in platform includes, but we can have more defines than this.

Each part has a "DEFINES" section listing the constant it expects to be defined. Make sure that you have these constants defined before you include the file.

Variable management

Each part can define variables. These variables are defined as addresses in RAM. We know where RAM start from the RAMSTART constant in platform includes, but because those parts are made to be glued together in no pre-defined order, we need a system to align variables from different modules in RAM.

This is why each part that has variable expect a <PARTNAME>_RAMSTART constant to be defined and, in turn, defines a <PARTNAME>_RAMEND constant to carry to the following part.

Thus, code that glue parts together coould look like:

MOD1_RAMSTART .equ RAMSTART
#include "mod1.asm"
MOD2_RAMSTART .equ MOD1_RAMEND
#include "mod2.asm"

Code style

The asm code used in these parts is heavily dependent on what scas offers. I try to be as "low-tech" as possible because the implementation of the assembler to be implemented for the z80 will likely be more limited. For example, we don't use macros.