Ointers is a library that allows programmers to represent pointers where some bits have been stolen for other uses, providing a small amount of free storage. It fully supports no_std, is dependency-free, and has less than 100 lines of code. By stealing bits from alignment and sign bits, programmers can reclaim extra bits to use in their code. The library also offers ways to steal bits from unused virtual address space. Ointers is constantly being updated, with new features added in each version. Contributors are welcome, but the test suite currently requires std. The library is licensed under the Apache License, Version 2.0, with LLVM Exceptions.
https://github.com/irrustible/ointers