Deliver an integrated program to illustrate SDL-oriented system calls

[jserv]

In order to illustrate how to use SDL-oriented system calls, we can deliver an integrated program which utilizes SDL window system and input events. smolnes is ideal for its small footprint and powerful features -- a NES emulator less than 500 lines of code (deobfuscated.c). We can redistribute the open source NES ROM files such as falling-nes.

Expected output:

1. Replace SDL functions in smolnes with rv32emu specific SDL oriented system calls.
2. Verify the functionality of NES emulation with falling-nes and some NES games.
3. By default, the emulator looks for rom.nes and fallbacks to use falling.nes if the former is not found.
4. Add some preliminary documentation on the usage of SDL-oriented system calls in the source code of modified smolnes.

Later, we might initiate the binary translator which converts 6502 opcode into RV32 or specific IR when we proceed #81, meaning that the NES emulation can be quite efficient.

[jserv]

Besides a functioned NES emulator, we can still provide a standalone renderer (or tiny game engine) to present the ability of SDL oriented system call. @alanjian85, do you have something in mind?

[alanjian85]

Besides a functioned NES emulator, we can still provide a standalone renderer (or tiny game engine) to present the ability of SDL oriented system call. @alanjian85, do you have something in mind?

I have previously satisfied all the four requirements listed above. However, I'm hesitating whether to create a static binary translator that converts a 6502 ROM file to a RISC-V executable file, eliminating the necessity of using smolnes; or a JIT compiler in smolnes; or even optimize rv32emu itself. Furthermore, the lack of memory mapping and translation in rv32emu places limitations on optimization techniques, making some of them infeasible.

[jserv]

Thank @alanjian85 again for the great work!

Later, we might consider enhancing smolnes using the cached interpreter technique, which would avoid unnecessary instruction decoding efforts and reduce instruction dispatch overhead.