Crate vu64

The variable length integer encoding of u64. This is a simple and fast encoder/decoder.

Features

• integer value length compaction
• minimum support rustc 1.58.1 (db9d1b20b 2022-01-20)

format pattern

Prefix	Precision	Total Bytes
0xxxxxxx	7 bits	1 byte
10xxxxxx	14 bits	2 bytes
110xxxxx	21 bits	3 bytes
1110xxxx	28 bits	4 bytes
11110xxx	35 bits	5 bytes
111110xx	42 bits	6 bytes
1111110x	49 bits	7 bytes
11111110	56 bits	8 bytes
11111111	64 bits	9 bytes

This format is a like vint64, but 0x00 is represented by 0x00.

Examples

Encode

use vu64::encode;
assert_eq!(encode(0x0f0f).as_ref(), &[0x8F, 0x3c]);

Decode

use vu64::decode;
let slice = [0x8F, 0x3c].as_ref();
assert_eq!(decode(slice).unwrap(), 0x0f0f);

Encode and decode

use vu64::{encode, decode};
let val = 1234;
assert_eq!(decode(encode(val).as_ref()).unwrap(), val);

Read from buffer and decode

use vu64::io::ReadVu64;
let vec: Vec<u8> = vec![0xFF, 0xf0, 0xf0, 0x0f, 0x0f, 0xf0, 0xf0, 0x0f, 0x0f];
let mut crsr = std::io::Cursor::new(vec);
let r = crsr.read_and_decode_vu64();
assert!(r.is_ok());
assert_eq!(r.unwrap(), 0x0f0f_f0f0_0f0f_f0f0);

Encode and write to buffer

use vu64::io::WriteVu64;
let vec_0: Vec<u8> = vec![0xFF, 0xf0, 0xf0, 0x0f, 0x0f, 0xf0, 0xf0, 0x0f, 0x0f];
let vec: Vec<u8> = Vec::new();
let mut crsr = std::io::Cursor::new(vec);
let r = crsr.encode_and_write_vu64(0x0f0f_f0f0_0f0f_f0f0);
assert!(r.is_ok());
assert_eq!(crsr.get_ref().as_slice(), vec_0.as_slice());

Modules

io

Supports of std::io.

signed

Supports of encoding signed integers as Vu64.

Structs

Vu64

vu64: serialized variable-length 64-bit integers.

Enums

Error

Error type

Constants

MAX_BYTES

Maximum length of a vu64 in bytes

MAX_LEN1

Maximun integer whose length of vu64 is 1 byte.

MAX_LEN2

Maximun integer whose length of vu64 is 2 byte.

MAX_LEN3

Maximun integer whose length of vu64 is 3 byte.

MAX_LEN4

Maximun integer whose length of vu64 is 4 byte.

MAX_LEN5

Maximun integer whose length of vu64 is 5 byte.

MAX_LEN6

Maximun integer whose length of vu64 is 6 byte.

MAX_LEN7

Maximun integer whose length of vu64 is 7 byte.

MAX_LEN8

Maximun integer whose length of vu64 is 8 byte.

MAX_LEN9

Maximun integer whose length of vu64 is 9 byte.

Functions

check_result_with_length

decode

Decode vu64-encoded bytes to unsigned 64-bit integer.

decode2

Decode vu64-encoded bytes to unsigned 64-bit integer.

decode3

Decode vu64-encoded bytes to unsigned 64-bit integer.

decode_with_first_and_follow

decode_with_first_and_follow_le

decode_with_length

decoded_len

Get the length of a vu64 from the first byte.

encode

Encode an unsigned 64-bit integer as vu64.

encoded_len

Get the length of an encoded vu64 for the given value in bytes.