Mirror of CollapseOS

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

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.