leb128rs

This crate provides LEB128 serialization and deserialization routines for the following types:

• Unsigned:
  • u16
  • u32
  • u64
  • u128
  • usize
• Signed:
  • i16
  • i32
  • i64
  • i128
  • isize

There are no functions for u8 and i8 as actual LEB128 encoding would never save space. If there is a need to encode these types, let me know.

The deserialization functions

• refuse to read more bytes than could be serialized for a type but
• do not check whether the last byte indicates more bytes (i.e., has its high bit set).

If there is demand for a pedantic (and thus, slower) deserialization variant, let me know.

Tests

Commonly agreed-upon conversions can be found in

• https://en.wikipedia.org/wiki/LEB128, namely
  • 624485: 0xE5 0x8E 0x26
  • -123456: 0xC0 0xBB 0x78
• DWARF Debugging Information Format, Version 4, SECTION 7-- DATA REPRESENTATION:
  • Unsigned:
    • 2: 0x02
    • 127: 0x7f
    • 128: 0x80 0x01
    • 129: 0x81 0x01
    • 130: 0x82 0x01
    • 12857: 0xB9 0x64
  • Signed:
    • 2: 0x02
    • -2: 0x7E
    • 127: 0xFF 0x00
    • -127: 0x81 0x7F
    • 128: 0x80 0x01
    • -128: 0x80 0x7F
    • 129: 0x81 0x01
    • -129: 0xFF 0x7E

The default unit tests also test the full range of

• u16,
• i16,

as well as

• patterns for all types and
• steps of regular intervals for types with more than 16 bits and
• reads from invalid encodings (i.e., values which indicate more bytes after the maximum number of bytes for a type).