Struct Huf4 

pub struct Huf4<'a> {
    pub table: &'a [u16; 2048],
    pub src: &'a [u8],
    pub starts: [usize; 4],
    pub pos: [usize; 4],
    pub bits: [u64; 4],
    pub out: &'a mut [u8],
    pub seg: usize,
    pub done: usize,
}

The state of zstd’s four-stream Huffman fast loop (HUF_decompress4X1 “fast”): per stream a left-aligned 64-bit container with a marker bit below the unread bits, and its position in the input.

Fields

table: &'a [u16; 2048]

Entries symbol << 8 | bits, indexed by the next 11 bits.

src: &'a [u8]

The four streams, one after another.

starts: [usize; 4]

Where each stream starts in src.

pos: [usize; 4]

Each stream’s position (the 8 bytes loaded last): starts[j] <= pos[j], pos[j] + 8 <= src.len().

bits: [u64; 4]

out: &'a mut [u8]

The output: stream j writes out[j * seg + i]; stream 3 has out.len() - 3 * seg.

seg: usize

done: usize

Symbols per stream done so far.