collapseos/kernel
Virgil Dupras 83e375936c shell: make seek cmd init DE to 0
So that blkdev not supporting 32-bit aren't messed up.
2019-05-30 14:54:28 -04:00
..
acia.asm Move /parts/z80 to /kernel 2019-05-19 11:19:41 -04:00
blockdev_cmds.asm shell: make seek cmd init DE to 0 2019-05-30 14:54:28 -04:00
blockdev.asm Make blockdev pointers 32 bits 2019-05-28 19:42:35 -04:00
core.asm Make blockdev pointers 32 bits 2019-05-28 19:42:35 -04:00
fs_cmds.asm Make the shell emulator be built by zasm 2019-05-20 07:29:19 -04:00
fs.asm Make blockdev pointers 32 bits 2019-05-28 19:42:35 -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
README.md Move /parts/z80 to /kernel 2019-05-19 11:19:41 -04:00
sdc.asm sdc: fix bug preventing us from reading beyond first sector 2019-05-28 13:12:08 -04:00
shell.asm Fix broken shell 2019-05-20 07:38:15 -04:00
stdio.asm Move /parts/z80 to /kernel 2019-05-19 11:19:41 -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.