Compression algorithm

[obscuren]

Simple RLE with magic numbers sha3('') and sha3('\x80'):

let magic = '\xfe'

Alternatives: '\xff', '\x00ff'

Compression

'\x00' * n where n >= 2, n <= 254 -> magic.chr(n - 2)
sha3('') -> magic.'\xfd'
sha3('\x80') -> magic.'\xfe'
magic -> magic.'\xff'

[obscuren]

import "github.com/ethereum/go-ethereum/compression/rle"

in := make([]byte, 5)
in = append(in, crypto.Sha3([]byte(""))...)
in = append(in, crypto.Sha3([]byte{0x80})...)
in = append(in, token)

c := rle.Compress(in)
d = rle.Decompress(c)

bytes.Compare(in, d) == 0

[obscuren]

Should be applied to the io p2p stream #172