collapseos/kernel
Virgil Dupras 4327153ffd zasm: fix include EOF detection
That was an interesting bug. It didn't cause a problem in emulation, but
in an RC2014 on an SD card, an include that didn't end with two newlines
would cause an infinite loop.
2019-06-15 15:50:27 -04:00
..
acia.asm Move /parts/z80 to /kernel 2019-05-19 11:19:41 -04:00
blockdev_cmds.asm Fix error handling when writing to files in emulated shell 2019-06-05 16:13:15 -04:00
blockdev.asm fs: further adjust to previous blkdev refactoring 2019-06-04 20:45:01 -04:00
core.asm shell: add support for backspace 2019-06-14 22:14:09 -04:00
err.h blockdev: make implementors "random access" 2019-06-04 15:36:20 -04:00
fs_cmds.asm fs: fix broken fopn on id > 0 2019-06-05 15:40:56 -04:00
fs.asm zasm: fix include EOF detection 2019-06-15 15:50:27 -04:00
mmap.asm blockdev: make implementors "random access" 2019-06-04 15:36:20 -04:00
parse.asm parse: fix option word default value 2019-06-14 21:10:18 -04:00
pgm.asm pgm: adapt to recent blkdev change 2019-06-05 14:45:38 -04:00
README.md Move /parts/z80 to /kernel 2019-05-19 11:19:41 -04:00
sdc.asm sdc: support 24-bit addressing 2019-06-15 13:41:20 -04:00
shell.asm shell: add support for backspace 2019-06-14 22:14:09 -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.