filetime.md

Topic :: FileTime

{% hint style="info" %} Note: This guide assumes that Celeste is running on Windows. If you play on Mac or Linux, please feel free to contribute! {% endhint %}

FileTime is an an element that appears on numerous occasions in the Celeste savefile, usually denoting a duration of playtime. After extensive calculations and testing (cc), it was determined that this value is a 64-bit integer representing 100-nanosecond intervals since January 1, 1601. [1] This is the standard structure that Win32 uses to determine time. [2]

Within our context of measuring playtime, we can ignore the epoch (Jan 1, 1601), and reduce the measurement to 10,000 units per ms.

$$milliseconds = filetime / 10000$$

For example, the FileTime 864000000000 translates to 86400000 milliseconds, which is exactly 24 hours.

If you were to put that in a Savefile:

{% code title="0.celeste" %}

<Time>864000000000</Time>

{% endcode %}

Celeste would display 24:00:00.000 on the savefile associated with that time.

So, interpreting this value in other languages (besides C, C++, and C# which have native implementations of FileTime on Windows), can be done by dividing the value by 10,000 and reading that into a naïve datetime in your language of choice as milliseconds. (Or a time delta, which is more convinent in this context.)

Code Samples:

{% tabs %} {% tab title="Python" %}

>>> import datetime as dt
>>> units = 864000000000
>>> delta = dt.timedelta(milliseconds=units // 10000)
>>> delta.days
1

{% endtab %}

{% tab title="Ruby" %}

irb(main):001:0> require 'time'
irb(main):002:0> units = 864000000000
irb(main):003:0> time = Time.at units / 10000 / 1000
irb(main):004:0> time.to_i / 86400
=> 1

{% endtab %} {% endtabs %}