mc-varint

Minecraft VarInt and VarLong implemetation in Rust, providing minimum memory usage and maximum performance.

Example

Read a VarInt from a Read

use mc_varint::VarIntRead;
use std::io::Cursor;
fn main() {
    // firstly we create a Cursor
    let mut cur = Cursor::new(vec![0xff, 0xff, 0xff, 0xff, 0x07]);
    // secondly we read from it
    let value = cur.read_var_i32().unwrap();
    // the value is 2147483647
    assert_eq!(value, 2147483647);
}

Write a VarInt to a Write

use mc_varint::{VarInt, VarIntWrite};
use std::io::Cursor;
fn main() {
    // firstly we create a Cursor and a VarInt
    let mut cur = Cursor::new(Vec::with_capacity(5));
    // secondly we write the VarInt to the Cursor
    cur.write_var_i32(2147483647).unwrap();
    // now the value is written to cur.
    assert_eq!(cur.into_inner(), vec![0xff, 0xff, 0xff, 0xff, 0x07]);
}

Performance

Platform: 3.4GHz Intel Core i5

running 8 tests
test read_i32  ... bench:           5 ns/iter (+/- 1)
test read_i64  ... bench:           4 ns/iter (+/- 1)
test read_u32  ... bench:           4 ns/iter (+/- 1)
test read_u64  ... bench:           4 ns/iter (+/- 0)
test write_i32 ... bench:           4 ns/iter (+/- 0)
test write_i64 ... bench:           4 ns/iter (+/- 0)
test write_u32 ... bench:           4 ns/iter (+/- 0)
test write_u64 ... bench:           4 ns/iter (+/- 0)

test result: ok. 0 passed; 0 failed; 0 ignored; 8 measured; 0 filtered out