Listpack: work in progress implementation

This repository is a work in progress, currently not usable, implementation
of a data structure called listpack, suitable to store lists of string
elements in a representation which is space efficient and that can be
efficiently accessed from left to right and from right to left.

You can find the specification in the listpack.md file in this repository.

The listpack.c file implements the full specification, however since
Redis Conf 2017 is near, I’ll pause the work for some time to focus on
talks & training day material. The implementation lacks a complete fuzz testing
suite like the one of rax, the functions
to validate a listpack loaded from an untrusted source, and good API
documentation (but listpack.c top comments in functions are a good
starting point).

The code is almost completely untested, so it will likely explode while you
are reading this README file.

API TODO

int lpIsValid(unsigned char *lp, uint32_t len);
int lpSelfTest(void);
int lpSplit(unsigned char *lp, unsigned char *p, unsigned char **left, unsigned char **right);
unsigned char *lpMerge(unsigned char *left, unsigned char *right);