U32Classic

U32Classic is the original Lemire StreamVByte variant for u32 values. Each value is stored in 1–4 bytes depending on its magnitude.

Wire-compatible with the Lemire C library and the stream-vbyte crate.

Tag table

Example

#![allow(unused)]
fn main() {
use svb::u32::U32Classic;

let values: Vec<u32> = vec![1, 500, 70_000, 16_000_000];
let encoded = U32Classic.encode(&values);
let decoded = U32Classic.decode(&encoded, values.len()).unwrap();
assert_eq!(decoded, values);
}

Wire format example

Encoding [1, 256, 65536, 0xFFFFFFFF] produces:

byte 0:     0xE4        control byte (tags: 0, 1, 2, 3 packed LSB-first → 0b11_10_01_00)
bytes 1:    0x01        value 0: 1 (1 byte)
bytes 2-3:  0x00 0x01   value 1: 256 (2 bytes, little-endian)
bytes 4-6:  0x00 0x00 0x01   value 2: 65536 (3 bytes)
bytes 7-10: 0xFF 0xFF 0xFF 0xFF  value 3: 4294967295 (4 bytes)

When to use

U32Classic is the right default for general u32 compression and any context where wire compatibility with the C library matters. For data with many zero or small values, U32Variant0124 compresses better.