Man, that looks really smooth.
Well done!

What is the format for colors with nSDL?

Good news!

I've now added real color support and with "real" textures! I removed the plain color/texture division and used the whole byte as a palette index (i.e., 8-bit, 256 colors). It was the best method speed/simplicity/size-wise.

After some nitpicky optimization, I managed to push the framerate to 90+ FPS on Touchpad/Clickpad, and to a constant 45 FPS on CX! I believe it's soon pretty much the theoretical maximum performance you can expect.

Aaaand a screenshot because everyone loves 'em:



Source code and binary attached!

This'll be my final update.

Changes:
- Performance (oncalc): 100 FPS on Touchpad, most probably ~50 FPS on CX (can't test it, lil' brother lost his calc)
- Separated the mode7 part more and renamed stuff for more consistency (resembles much more like an engine)
- Fixed some issue with positions on the map being wrong
- Added a simple function to load textures (only works with 8-bit surfaces, i.e. surface has to be converted first if necessary)
- Cleaned up stuff

Code & binary attached.

EDIT:
One thing I've noticed is that accessing global variables is much slower than accessing any other type of variable. Just using the global screen SDL_Surface in the rendering function decreased the framerate by nearly 10 FPS! It might be good to know if speed is of your concern. IIRC it also applied to accessing structure items.

I wonder why accessing global variables are slower.

Ndless fake relocation atm.

Hoffa recommended to me to use it in my F-Zero game (see my sig). I think that it's what I gonna do, if t0xic_kitt3n agree.

I guess it would be a good idea unless you manage to make yours faster or something. (Or if t0xic's stopped being updated regularly and it slowed you down in your project due to having to wait or something)

What does __attribute__ do?
static __inline__ __attribute__((always_inline))
m7Vec_t* m7AddVec(m7Vec_t* a, m7Vec_t* b) {
    a->x += b->x;
    a->y += b->y;
    return a;
}