scputil.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import struct

def b2s(bytes):
    if len(bytes) != 2:
        raise ValueError("bytes must be exactly 2 bytes long")
    return struct.unpack('h', bytes)

def b2b(bytes):
    if len(bytes) != 1:
        raise ValueError("bytes must be exactly 1 byte long")
    return struct.unpack('B', bytes)

def b2i(bytes):
    """Convert bytes to unsigned integer (little endian)"""
    return int.from_bytes(bytes, 'little')

def b2si(bytes):
    """Convert bytes to signed integer (little endian)"""
    return int.from_bytes(bytes, 'little', signed=True)

def bdecode(bytes):
    """Decode bytes as iso-8859-1 and remove null terminators"""
    # remove null terminators
    return bytes.decode('iso-8859-1').rstrip('\0')


def lead_dic():
    """Return lead dictionary from file"""
    return file2dict('leadtable.csv')


def file2dict(file):
    """Converts a file to dictionary"""
    d = {}
    with open(file) as f:
        for line in f:
            (key, val) = line.split(',')
            d[int(key.strip())] = val.strip()
    return d

# https://gist.github.com/oysstu/68072c44c02879a2abf94ef350d1c7c6


def crc16(data: bytes, poly=0x1021):
    '''
    CRC-16-CCITT Algorithm checksum
    '''
    #data = bytearray(data)
    crc = 0xFFFF
    for b in data:
        cur_byte = 0xFF & b
        for _ in range(0, 8):
            if (crc & 0x0001) ^ (cur_byte & 0x0001):
                crc = (crc >> 1) ^ poly
            else:
                crc >>= 1
            cur_byte >>= 1
    crc = (~crc & 0xFFFF)
    crc = (crc << 8) | ((crc >> 8) & 0xFF)

    return crc & 0xFFFF


class ScpPrinter:
    """A simple printer class to print a pair of arguments"""
    def __init__(self):
        pass

    def p(self, p1, p2):
        print('{0} {1}'.format(str(p1).ljust(30), p2))