Mirror of CollapseOS

History

Virgil Dupras 839ba91312 mmap: make zasm-friendly		5 years ago
..
README.md	Move /parts/z80 to /kernel	5 years ago
acia.asm	Move /parts/z80 to /kernel	5 years ago
blockdev.asm	blkdev: make load command stop and the end of the stream	5 years ago
blockdev_cmds.asm	blkdev: make load command stop and the end of the stream	5 years ago
core.asm	fs: check for file size bounds in GetC	5 years ago
err.h	Make userspace parse args the same way the shell does	5 years ago
fs.asm	fs: standardize file handle routine argument to IX	5 years ago
fs_cmds.asm	fs: standardize file handle routine argument to IX	5 years ago
mmap.asm	mmap: make zasm-friendly	5 years ago
parse.asm	Make parseArgs not expect a leading space	5 years ago
pgm.asm	pgm: have its own file handle	5 years ago
sdc.asm	sdc: add sdcPutC	5 years ago
shell.asm	Make parseArgs not expect a leading space	5 years ago
stdio.asm	shell/stdio: decouple from blkdev (again)	5 years ago
user.h.example	zasm emul: bring back kernel/user distinction	5 years ago

README.md

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.