Varuint

Variable length signed and unsigned integer types. Types support up to 64-bit integers (128-bit integers support will be added when Rust has the i128 and u128 types).

Encoding rules are based on SQLite 4 Varuint type with modifications for future support of 128-bit long integers. Varint is encoded using the Protobuf ZigZag approach and reuses Varuint as a storage.

Unlike the Protobuf encoding rules, Varuint needs the first byte only to find out the length of the whole value. Microbenchmarks say that it is a lot faster.

See crate docs for more details.

How to use

Add dependency to Cargo.toml: cargo [dependencies] varuint = "0.3"

Update you project: ```rust extern crate varuint;

use std::mem;

use varuint::{Varuint, Serializable, Deserializable}; use std::io::{Read, Write};

fn testvaruint(v: u64, size: usize) { let v = Varuint(v); asserteq!(size, v.sizehint()); let mut arr: [u8; 9] = unsafe { mem::uninitialized() }; { let mut buf = &mut arr as &mut [u8]; asserteq!(size, v.serialize(&mut buf).unwrap()); } let mut buf: &[u8] = &arr; let mut read: &mut Read = &mut buf; assert_eq!(v, Varuint::deserialize(read).unwrap()); }

fn main() { testvaruint(0, 1); testvaruint(240, 1);

test_varuint(241, 2);
test_varuint(2031, 2);

test_varuint(2032, 3);
test_varuint(67567, 3);

test_varuint(67568, 4);
test_varuint(16777215, 4);

test_varuint(16777216, 5);
test_varuint(4294967295, 5);

test_varuint(4294967296, 6);
test_varuint(1099511627775, 6);

test_varuint(1099511627776, 7);
test_varuint(281474976710655, 7);

test_varuint(281474976710656, 8);
test_varuint(72057594037927935, 8);

test_varuint(72057594037927936, 9);
test_varuint(u64::max_value(), 9);

} ```