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Related · medium · value 0.477
QUERY · ISSUE

Need to address inconsistencies between mktime and localtime.

openby dhylandsopened 2015-05-20updated 2024-09-08
needs-info

Currently, if I do:

>>> time.localtime(-1072915200)
(1966, 1, 1, 0, 0, 0, 5, 1)
>>> time.mktime((1966, 1, 1, 0, 0, 0, 5, 1))
3222052096
>>> time.localtime(3222052096)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: overflow converting long int to machine word
>>> hex(3222052096)
'0xc00c9d00'
>>> hex(0x80000000 - 1072915200)
'0x400c9d00'

I think that time.mktime((1966, 1, 1, 0, 0, 0, 5, 1)) should return the negative representation. However, I noticed that timeutils_seconds_since_2000 returns an mp_uint_t rather than an mp_int_t

So a couple of questions came to mind:
1 - Do we want to support times from 1966 to 2000 (which is the -ve small int range)?
2 - Should we support mpz ints?
3 - Adding full support for mpz ints seems like overkill, but we could get 1 extra bit by allowing mpz ints in the full 32-bit range to be supported. Then we'd be able to support dates from 2000 +/- 68 years. This would only require a slightly different conversion into and out of the timeutils functions. The actual code itself wouldn't need to change.

Thoughts?

CANDIDATE · PULL REQUEST

Add time.mktime and enhance time.localtime (for stmhal)

closedby dhylandsopened 2014-08-20updated 2015-11-08

Now you can use time.localtime on the timestamps presented by os.stat

I tested the implementation using the following script on my stmhal board:

import time

DAYS_PER_MONTH = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]

def is_leap(year):
    return (year % 4) == 0

def test():
    seconds = 0
    wday = 5    # Jan 1, 2000 was a Saturday
    for year in range(2000, 2034):
        print("Testing %d" % year)
        yday = 1
        for month in range(1, 13):
            if month == 2 and is_leap(year):
                DAYS_PER_MONTH[2] = 29
            else:
                DAYS_PER_MONTH[2] = 28
            for day in range(1, DAYS_PER_MONTH[month] + 1):
                secs = time.mktime((year, month, day, 0, 0, 0, 0, 0))
                if secs != seconds:
                    print("mktime failed for %d-%02d-%02d got %d expected %d" % (year, month, day, secs, seconds))
                tuple = time.localtime(seconds)
                secs = time.mktime(tuple)
                if secs != seconds:
                    print("localtime failed for %d-%02d-%02d got %d expected %d" % (year, month, day, secs, seconds))
                    return
                seconds += 86400
                if yday != tuple[7]:
                    print("locatime for %d-%02d-%02d got yday %d, expecting %d" % (year, month, day, tuple[7], yday))
                    return
                if wday != tuple[6]:
                    print("locatime for %d-%02d-%02d got wday %d, expecting %d" % (year, month, day, tuple[6], wday))
                    return
                yday += 1
                wday = (wday + 1) % 7

test()

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