Struct SourceBlockPartition 

pub struct SourceBlockPartition {
    pub transfer_length: u64,
    pub encoding_symbol_length: u32,
    pub source_symbols: u64,
    pub num_blocks: u64,
    pub larger_block_len: u64,
    pub smaller_block_len: u64,
    pub larger_blocks: u64,
}

The source-block structure of a transport object, per RFC 5052 §9.1’s Block Partitioning Algorithm.

Given a transport object of transfer_length octets (L), an encoding_symbol_length (E) and a max_source_block_length (B), RFC 5052 splits the object into num_blocks (N) source blocks: the first larger_blocks (I) blocks each have larger_block_len (A_large) source symbols, and the remaining num_blocks - larger_blocks blocks each have smaller_block_len (A_small) source symbols. Every source symbol is E octets, except the very last source symbol of the very last source block (Self::last_symbol_len).

All three inputs are RFC 5052 Common FEC OTI elements (§6.2.4) — this type does not read wire bytes; the caller supplies them from wherever the CDP carried them (ALC’s EXT_FTI, a FLUTE FDT attribute, …).

Fields

transfer_length: u64

The transport object length in octets (L, Transfer-Length).

encoding_symbol_length: u32

The encoding symbol length in octets (E, Encoding-Symbol-Length).

source_symbols: u64

Total source symbols in the object (T = ceil(L / E)).

num_blocks: u64

Number of source blocks (N = ceil(T / B)).

larger_block_len: u64

Source symbols in each of the first larger_blocks blocks (A_large = ceil(T / N)).

smaller_block_len: u64

Source symbols in each of the remaining blocks (A_small = floor(T / N)).

larger_blocks: u64

Number of “larger” blocks (I = T - A_small * N).

Implementations

impl SourceBlockPartition

pub fn new( transfer_length: u64, encoding_symbol_length: u32, max_source_block_length: u32, ) -> Result<Self>

Apply RFC 5052 §9.1’s Block Partitioning Algorithm.

transfer_length is the transport object length in octets (L), encoding_symbol_length is E, and max_source_block_length is B.

A zero-length object (transfer_length == 0) yields zero source symbols and zero source blocks — RFC 5052’s ceiling division treats ceil(0/E) as 0, not 1.

Errors

Returns Error::InvalidField if encoding_symbol_length or max_source_block_length is 0 (both are divisors in the algorithm; RFC 5052 gives no meaning to either being zero).

pub fn block_len(&self, index: u64) -> Option<u64>

Number of source symbols in source block index (0-based), or None if index >= num_blocks.

The first larger_blocks blocks (indices 0..larger_blocks) each have larger_block_len symbols; the remaining blocks have smaller_block_len.

pub fn last_symbol_len(&self) -> Option<u32>

Length in octets of the very last source symbol of the very last source block (RFC 5052 §9.1: L - floor((L-1)/E)*E) — the object’s actual trailing remainder, since L is not generally an exact multiple of E. None if the object has zero source symbols (there is no “last symbol” to speak of).

Trait Implementations

impl Clone for SourceBlockPartition

fn clone(&self) -> SourceBlockPartition

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for SourceBlockPartition

impl Debug for SourceBlockPartition

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for SourceBlockPartition

impl Hash for SourceBlockPartition

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for SourceBlockPartition

fn eq(&self, other: &SourceBlockPartition) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for SourceBlockPartition

Available on crate feature serde only.

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for SourceBlockPartition