ae028e3a86
This huge refactoring remove the Seek and Tell routine from blockdev implementation requirements and change GetC and PutC's API so that they take an address to read and write (through HL/DE) at each call. The "PTR" approach in blockdev implementation was very redundant from device to device and it made more sense to generalize. It's possible that future device aren't "random access", but we'll be able to add more device types later. Another important change in this commit is that the "blockdev handle" is now opaque. Previously, consumers of the API would happily call routines directly from one of the 4 offsets. We can't do that any more. This makes the API more solid for future improvements. This change forced me to change a lot of things in fs, but overall, things are now simpler. No more `FS_PTR`: the "device handle" now holds the active pointer. Lots, lots of changes, but it also feels a lot cleaner and solid. |
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|---|---|---|
| .. | ||
| acia.asm | ||
| blockdev_cmds.asm | ||
| blockdev.asm | ||
| core.asm | ||
| err.h | ||
| fs_cmds.asm | ||
| fs.asm | ||
| mmap.asm | ||
| parse.asm | ||
| pgm.asm | ||
| README.md | ||
| sdc.asm | ||
| shell.asm | ||
| stdio.asm | ||
| user.h.example | ||
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.