bitops-event-mask.py

#!/usr/bin/env python3
# -*- coding: UTF-8 -*-
# vim: ts=4 sw=4 et ai si

from __future__ import print_function

import random
import sys

def handle(event, state, bit):
    oe = event
    if state:
        ne = oe | bit
    else:
        ne = oe & ~bit
    return (ne ^ oe) == bit

def handle_and_print(iteration, event, state, bit):
    r = handle(event, state, bit)
    print(f"[{iteration}] 0x{event:02x} {state and "|" or "&"} 0x{bit:02x} --> {r:d}:", r and "handle" or "return")

def test_event(event, state, bit):
    orig = event
    print(f"Initial event: 0x{orig:02x}, new state: {state} for bit 0x{bit:02x}")
    handle_and_print("-", 0, state, bit)
    for iteration in range(0, 8):
        handle_and_print(iteration, event, state, bit)
        if state:
            event |= (1 << iteration)
        else:
            event &= ~(1 << iteration)
    handle_and_print("-", event, state, bit)

def test_events(event, bit):
    if event > 0:
        test_event(event, False, bit)
    if not (event & bit):
        test_event(event, True, bit)

def main(argv):
    try:
        event = int(argv[1], 0)
    except:
        event = random.randint(0, 255)
    try:
        bitnum = int(argv[2], 0)
    except:
        bitnum = random.randint(0, 7)
    bit = 1 << bitnum
    if (event & bit):
        test_event(event, False, bit)
    else:
        test_event(event, True, bit)
    test_events(0, bit)
    test_events(bit, bit)

if __name__ == "__main__":
    sys.exit(main(sys.argv))