Gelthor
46abf8d893
Added support for global variables. This requires including `start.asm` as the first code. This includes a `jmp` to 0x100 for user code, and a magic number that modules can check to verify th the user has correctly reserved the space. The magic number is 0xb301534c: * This has the high bit set so is not a valid instruction * On builds that ignore the high bit this decodes to `nor zr, zr, 0x534c` a no-op. * The immediate is "SL" for standardl ibrary. Due to a bug start pads with U... 0, instead of @addr. `start.asm` also initialises `sp` so it start just below the 64KiB LUT memory alocation. Added some error codes for the upcoming graphics module.
1.6 KiB
Contributing
Code of Conduct
Be nice, we are all just doing this to have fun
General rules
- All text (names, comments, etc.) has to be in English
- You are responsible for ensuring that you have the rights for us to use the code you contribute to the project
- follow the guidelines, for code, documentation, etc.
- all code has to work with the standard symphony ISA
Documenting Functions
All functions in the standard library should follow the following outline:
; <description>
; Arguments: <which register contains what argument>
; Result: <what is the result, and where is it stored>
; Clobbers: <list of registers that are clobbered>
; Globals: <list of globals are accessed. OPTIONAL>
<label>: <;SHOULD BE INLINED>
<CODE>
Functions should be in the appropriate asm file, if you are unsure where functionality fits make a seperate file and ask in the pull request
Functions that are provided for convenience/reference but should be inlined in production code should be marked with ;SHOULD BE INLINED after their label.
If the function returns a status code in flags, the preamble should list all it might return.
Globals
Any function that uses global variables should document this in the preamble comment, see above.
A file/module should check on intialisation that the address globals.MAGIC_ADDRESS contains the 16 bit value globals.MAGIC_VALUE, to ensure that the user has properly included src/start.asm and reservered the global variable area.
No opinion is offered on whether modules can assume globals variables are initialised to zero.