Neko Library for SNES programming
This library is a simple starting point for writing SNES applications. It includes basic functionality like transferring data into VRAM and CG-RAM. It is written in 65816 assembly and can be built with cc65.
This is not a full engine, but rather a set of basic routines and structures to start or add to your own project. The code is geared towards flexibility rather than speed. You will probably need to adjust it to your own code and project.
This is work in progress. There is only basic input handling available and no music functionality whatsoever.
There is a separate repository that hosts a simple example project. You can find it here. Build this ROM to see how to use the Neko library.
General Design Considerations
The wider idea of this library is to provide a common set of subroutines for SNES homebrew developers. The goal is to write a robust library that can easily be integrated with little to no modifications. To this end there are several differences compared to other SNES engines and libraries.
As stated above, this is not an engine. This library provides easy to use subroutines for common task like VRAM, CG-RAM, and OAMRAM operations, reading input, etc. There are no subroutines for higher game logic functionality like collision detection, sprite management, etc. These are game specific tasks.
Another difference is the way arguments are passed to subroutines. This library tries to avoid the need for large variable tables. Instead, arguments and variables are stored on stack. See Passing Arguments to Subroutines below for details.
Usage
The simplest way to use Neko Library with your project is to add is as a git submodule - see this sample project. You only need to include NekoLib.inc in your source file and you're good to go.
Passing Arguments to Subroutines
Unlike most other projects the arguments for the subroutines for loading VRAM, etc. are passed by stack, not by register. This is a deliberate design choice to ensure that call stacks with varying depths work without loss of (register) data. It will also make the subroutines re-entrant and eliminates the need to keep (intermittent) variables for a given subroutine in WRAM. Each level of nesting keeps its own variables on the stack, and when they are no longer needed they simply disappear.
I am aware that subroutines for loading VRAM, CG-RAM, etc. do not necessarily need to be re-entrant, but other subroutines certainly will, so I choose to pass all parameters by stack to keep my codebase consistent.
Important: The parameters listed in the subroutine header must be passed from right to left on the stack.
Structure
In src/ you will find several directories. Here is a short description of the contents:
init/: Headers and simple reset routines required by the SNES so start correctly.input/: These routines handle reading both joypads of the SNES.launcher/: Use this routines to call library subroutinesmacros/: Macros to change register sizes, etc.memory/: Subroutines to transfer memory with DMA to VRAM, CGRAM, etc.
Generally, you will find a *.s and *.inc file of the same name. Include the *.inc file with .include in your source code to use the subroutines in the matching *.s file.
Just include NekoLib.inc in your source file to use Neko Library.
There is no documentation yet, check the comments in the source files for details for now.