Note
Although this library is fairly complete for most programmers' needs, a rewrite is currently taking place to in the rewrite branch. Definitions and names will stay the same, though.
Simply put #include "efi.h" into your source code and you're good to go.
efilib.h provides additional functionality, but is not required for it to be included.
PRs are welcome for fixing spelling or formatting mistakes, otherwise open an issue.
Simple EFI Library is licensed under the MIT license, which you can find here.