[SDL] Pixel access in SDL_Surface

[Mason Wheeler]

How do you access pixels directly?  The SDL_Surface struct has a "pixels" member, but it's defined as a void*, which really doesn't provide much useful data, and I can't seem to find any tutorials on how it works.  I'm trying to write an import routine for a graphics format that SDL_Image doesn't support.  It's 8-bit and palletized, and I've got the palette stuff all figured out, but I can't figure out how to set the pixels themselves.  Any help?