bytes.py

import binascii
import machine
import os

def int_to_bytes(i, lenght=None):
    if lenght is None:
        import math
        h = hex(i)
        l = len(h)
        lenght = (l - 2) # subtract the length of 0x
        lenght = math.ceil(lenght/2) # divice by two to get number of bytes and ceil to correct for missing leading zero, e.g. i=1 -> 0x1 instead of 0x01
        print(h, l, lenght)
    return i.to_bytes(lenght, "big")

def bytes_to_int(b):
    return int.from_bytes(b, "big")

def str_to_bytes(s):
    return bytes(s, "utf-8")

def bytes_to_str(b):
    return b.decode('utf-8')

def int_to_bitstring(i):
    return bin(i)

def hexstring_to_int(h):
    return int(h, 16)


# An easy way that I was able to do a variable length when packing a string is:
# pack('{}s'.format(len(string)), string)
# when unpacking it is kind of the same way
# unpack('{}s'.format(len(data)), data)

if __name__ == "__main__":

    r = machine.rng()
    b = int_to_bytes(r,3)
    print("int to bytes:", hex(r), "=", r, "->", end="")
    # print(b[0])
    # print(ubinascii.hexlify(b))
    for i in range(0, len(b)):
        print(binascii.hexlify(b[i:i+1]), end=" ")
    print()

    b = os.urandom(3)
    #i = int.from_bytes(b, "big")
    i = bytes_to_int(b)
    print("bytes to int:", binascii.hexlify(b), "->", hex(i), "=", i)

    b = b'\x13'
    print(b, "->", int_to_bitstring(bytes_to_int(b)))