conv.py

#!/usr/bin/python3
# -*- coding: utf-8 -*-

BYTE_HASH_LENGTH = 48
TRIT_HASH_LENGTH = 243

tryte_table = {
        '9': [ 0,  0,  0],  #   0
        'A': [ 1,  0,  0],  #   1
        'B': [-1,  1,  0],  #   2
        'C': [ 0,  1,  0],  #   3
        'D': [ 1,  1,  0],  #   4
        'E': [-1, -1,  1],  #   5
        'F': [ 0, -1,  1],  #   6
        'G': [ 1, -1,  1],  #   7
        'H': [-1,  0,  1],  #   8
        'I': [ 0,  0,  1],  #   9
        'J': [ 1,  0,  1],  #  10
        'K': [-1,  1,  1],  #  11
        'L': [ 0,  1,  1],  #  12
        'M': [ 1,  1,  1],  #  13
        'N': [-1, -1, -1],  # -13
        'O': [ 0, -1, -1],  # -12
        'P': [ 1, -1, -1],  # -11
        'Q': [-1,  0, -1],  # -10
        'R': [ 0,  0, -1],  #  -9
        'S': [ 1,  0, -1],  #  -8
        'T': [-1,  1, -1],  #  -7
        'U': [ 0,  1, -1],  #  -6
        'V': [ 1,  1, -1],  #  -5
        'W': [-1, -1,  0],  #  -4
        'X': [ 0, -1,  0],  #  -3
        'Y': [ 1, -1,  0],  #  -2
        'Z': [-1,  0,  0],  #  -1
        }

# Invert for trit -> tryte lookup
trit_table = {tuple(v): k for k, v in tryte_table.items()}

def trytes_to_trits(trytes):
    trits = []
    for tryte in trytes:
        trits.extend(tryte_table[tryte])

    return trits

def trits_to_trytes(trits):
    trytes = []
    trits_chunks = [trits[i:i + 3] for i in range(0, len(trits), 3)]

    for trit in trits_chunks:
        trytes.extend(trit_table[tuple(trit)])

    return ''.join(trytes)

def convertToTrits(bytes_k):
    bigInt = convertBytesToBigInt(bytes_k)
    trits = convertBigintToBase(bigInt, 3, TRIT_HASH_LENGTH)
    return trits

def convertToBytes(trits):
    bigInt = convertBaseToBigint(trits, 3)
    bytes_k = convertBigintToBytes(bigInt)
    return bytes_k

def convertBytesToBigInt(ba):
    # copy of array
    bytesArray = list(map(lambda x: x, ba))

    # number sign in MSB
    signum = (1 if bytesArray[0] >= 0 else -1)

    if signum == -1:
        # sub1
        for pos in reversed(range(len(bytesArray))):
            sub = (bytesArray[pos] & 0xFF) - 1
            bytesArray[pos] = (sub if sub <= 0x7F else sub - 0x100)
            if bytesArray[pos] != -1:
                break

        # 1-compliment
        bytesArray = list(map(lambda x: ~x, bytesArray))

    # sum magnitudes and set sign
    return sum((x & 0xFF) << pos * 8 for (pos, x) in
               enumerate(reversed(bytesArray))) * signum


def convertBigintToBytes(big):
    bytesArrayTemp = [(abs(big) >> pos * 8) % (1 << 8) for pos in
                      range(48)]

    # big endian and balanced
    bytesArray = list(map(lambda x: (x if x <= 0x7F else x - 0x100),
                     reversed(bytesArrayTemp)))

    if big < 0:
        # 1-compliment
        bytesArray = list(map(lambda x: ~x, bytesArray))

        # add1
        for pos in reversed(range(len(bytesArray))):
            add = (bytesArray[pos] & 0xFF) + 1
            bytesArray[pos] = (add if add <= 0x7F else add - 0x100)
            if bytesArray[pos] != 0:
                break

    return bytesArray

def convertBaseToBigint(array, base):
    bigint = 0

    for i in range(len(array)):
        bigint += array[i] * (base ** i)

    return bigint

def convertBigintToBase(bigInt, base, length):
    result = []

    is_negative = bigInt < 0
    quotient = abs(bigInt)

    MAX = (base-1) // 2
    if is_negative:
        MAX = base // 2

    for i in range(length):
        quotient, remainder = divmod(quotient, base)

        if remainder > MAX:
            # Lend 1 to the next place so we can make this digit negative.
            quotient += 1
            remainder -= base

        if is_negative:
            remainder = remainder * -1

        result.append(remainder)

    return result

def convert_sign(byte):
    """
    Convert between signed and unsigned bytes
    """
    if byte < 0:
        return 256 + byte
    elif byte > 127:
        return -256 + byte
    return byte