hz_250_interger_round.py

#!/usr/bin/python3

NSEC_PER_SEC = 10 ** 9
MAX_U64 = 2 ** 64


def jiffies_to_clock_t(user_hz, hz, jiffies):
    tick_nsec = (NSEC_PER_SEC + hz / 2) / hz
    if (tick_nsec % (NSEC_PER_SEC / user_hz)) == 0:
        if hz < user_hz:
            return int(jiffies * (user_hz / hz))
        else:
            return int(jiffies / (hz / user_hz))
    else:
        return int(jiffies * tick_nsec / (NSEC_PER_SEC / user_hz))


def clock_t_to_jiffies(user_hz, hz, clock):
    if hz % user_hz == 0:
        if clock >= MAX_U64 / (hz / user_hz):
            return MAX_U64
        return int(clock * (hz / user_hz))
    if clock >= MAX_U64 / hz * user_hz:
        return MAX_U64
    return int(clock * hz / user_hz)


max_deviation = 0
for original_num in range(0, 2 ** 32):
    user_hz = 100
    hz = 250
    new_num = jiffies_to_clock_t(
        user_hz, hz, clock_t_to_jiffies(user_hz, hz, original_num)
    )
    a = abs(original_num - new_num)
    if a > max_deviation:
        max_deviation = a
        print(f"{original_num}: {max_deviation}")

print(max_deviation)