vint64 0.1.2

Simple and efficient variable-length integer encoding

vint64: simple and efficient variable-length integer encoding

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vint64 is an implementation of a variable-length encoding for 64-bit little endian integers which optimizes for simplicity and performance.



This crate implements a variable-length encoding for 64-bit little endian integers with a number of properties which make it superior in almost every way to other variable-length integer encodings like LEB128, SQLite "Varuints", or CBOR:

  • Capable of expressing the full 64-bit integer range with a maximum of 9-bytes
  • Total length of a vint64 can be determined via the first byte alone
  • Provides the most compact encoding possible for every value in range
  • No loops involved in decoding: just (unaligned) loads, masks, and shifts
  • No complex branch-heavy logic: decoding is CTZ + shifts and sanity checks

Some precedent for this sort of encoding can be found in the Extensible Binary Meta Language (used by e.g. the Matroska media container format), however note that the specific type of "vint" used by that format still requires a loop to decode.


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