fountain

type Codec interface {
	// SourceBlocks returns the number of source blocks to be used in the
	// codec. Note that this may not be the same number as the number of intermediate
	// code blocks. It is the minimum number of encoded blocks necessary to
	// reconstruct the original message.
	SourceBlocks() int

	// GenerateIntermediateBlocks prepares a set of precode blocks given the input
	// message. The precode blocks may just be identically the blocks in the
	// original message, or it may be a transformation on those source blocks
	// derived from a codec-specific relationship.
	// For example, in Online codes, this consists of adding auxiliary blocks.
	// In a Raptor code, the entire set of source blocks is transformed into a
	// different set of precode blocks.
	GenerateIntermediateBlocks(message []byte, numBlocks int) []block

	// PickIndices asks the codec to select the (non-strict subset of the) precode
	// blocks to be used in the LT composition of a particular code block. These
	// blocks will then be XORed to produce the code block.
	PickIndices(codeBlockIndex int64) []int

	// NewDecoder creates a decoder suitable for use with blocks encoded using this
	// codec for a known message size (in bytes). The decoder will be initialized
	// and ready to receive incoming blocks for decoding.
	NewDecoder(messageLength int) Decoder
}

type Decoder interface {
	// AddBlocks adds a set of encoded blocks to the decoder. Returns true if the
	// message can be fully decoded. False if there is insufficient information.
	AddBlocks(blocks []LTBlock) bool

	// Decode extracts the decoded message from the decoder. If the decoder does
	// not have sufficient information to produce an output, returns a nil slice.
	Decode() []byte
}

type LTBlock struct {
	// BlockCode is the ID used to construct the encoded block.
	// The way in which the ID is mapped to the choice of blocks will vary by
	// codec.
	BlockCode int64

	// Data is the contents of the encoded block.
	Data []byte
}

type MersenneTwister struct {
	// contains filtered or unexported fields
}

type MersenneTwister64 struct {
	// contains filtered or unexported fields
}