raptorq/src/base.rs

use std::cmp::min;

// As defined in section 3.2
pub struct PayloadId {
    pub source_block_number: u8,
    pub encoding_symbol_id: u32
}

impl PayloadId {
    pub fn new(source_block_number: u8, encoding_symbol_id: u32) -> Option<PayloadId> {
        // Encoding Symbol ID must be a 24-bit unsigned int
        if encoding_symbol_id >= 16777216 {
            return None
        }
        Some(PayloadId {
            source_block_number,
            encoding_symbol_id
        })
    }
}

// As defined in section 4.4.2
pub struct EncodingPacket {
    pub payload_id: PayloadId,
    pub symbol: Vec<u8>
}

// Deg[v] as defined in section 5.3.5.2
pub fn deg(v: u32, lt_symbols: u32) -> u32 {
    assert!(v < 1048576);
    let f: [u32; 31] = [
        0, 5243, 529531, 704294, 791675, 844104, 879057, 904023, 922747, 937311, 948962,
        958494, 966438, 973160, 978921, 983914, 988283, 992138, 995565, 998631, 1001391,
        1003887, 1006157, 1008229, 1010129, 1011876, 1013490, 1014983, 1016370, 1017662, 1048576];

    for d in 1..f.len() {
        if v < f[d] {
            return min(d as u32, lt_symbols - 2);
        }
    }
    panic!();
}