# Marshal format for Time **URL:** \ **Category:** IronRuby\ **Created:** [September 16, 2008, 1:53am UTC](https://www.ruby-forum.com/t/marshal-format-for-time/148669 "2008-09-16T01:53:28Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![curthibbs](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/ac91a4/32.png) [@curthibbs](https://www.ruby-forum.com/u/curthibbs)\ **Post date:** [September 16, 2008, 1:53am UTC](https://www.ruby-forum.com/t/marshal-format-for-time/148669/1 "2008-09-16T01:53:28Z")
Can someone help me by summarizing the Marshal format for Time in Ruby 1.8.6? Here’s what I’ve worked out: 1. ``` The time is always based on the UNIX epoch ``` 2. ``` When the fourth byte is less than 128, it implies some kind of ``` older format. This format is read but not written a. The first four bytes _seem_ to represent the standard UNIX time value 1. ``` When the fourth byte is equal to 128, it implies the "1.8.6 ``` format". The implications are a. The first byte represents number of hours b. The second byte represents number of 8-day blocks c. The third byte represents 4-year blocks d. The eighth byte represents 4-second blocks e. Bytes 5-7 represent microseconds as a 3-byte little-endian value 1. ``` When the fourth byte is greater than 128, or if the byte count ``` is not 8, an error is raised What I’d like to understand is a) How this works with leap years b) What kinds of legacy formats are supported, as I seem to be getting inconsistent answers when the fourth byte is less than 128 I’d appreciate any assistance, as this format appears to be totally undocumented. Please don’t post any actual source code, as I would be required by our lawyers to “do an Oedipus” on my eyeballs if I so much as glance at it :). Thanks, -Curt ---
**Author:** ![curthibbs](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/ac91a4/32.png) [@curthibbs](https://www.ruby-forum.com/u/curthibbs)\ **Post date:** [September 17, 2008, 12:27am UTC](https://www.ruby-forum.com/t/marshal-format-for-time/148669/2 "2008-09-17T00:27:22Z")
In case anyone was wondering, here’s a partial decoding: dword 1, little-endian bits 0-4: Hour bits 5-9: Day, 1=1st bits 10-13: Month, 0=January bits 14-29: Year, 0=1900 bit 30: 0=Local, 1=Utc. 1.8.6 always writes 0 here bit 31: 1 to indicate this format dword 2, little-endian bits 0-19: Microseconds bits 20-25: Seconds bits 26-31: Minutes From: removed\_email\_address@domain.invalid [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)] On Behalf Of Curt Hagenlocher Sent: Montag, 15. September 2008 16:52 To: removed\_email\_address@domain.invalid Subject: [Ironruby-core] Marshal format for Time Can someone help me by summarizing the Marshal format for Time in Ruby 1.8.6? Here’s what I’ve worked out: 1. ``` The time is always based on the UNIX epoch ``` 2. ``` When the fourth byte is less than 128, it implies some kind of ``` older format. This format is read but not written a. The first four bytes _seem_ to represent the standard UNIX time value 1. ``` When the fourth byte is equal to 128, it implies the "1.8.6 ``` format". The implications are a. The first byte represents number of hours b. The second byte represents number of 8-day blocks c. The third byte represents 4-year blocks d. The eighth byte represents 4-second blocks e. Bytes 5-7 represent microseconds as a 3-byte little-endian value 1. ``` When the fourth byte is greater than 128, or if the byte count ``` is not 8, an error is raised What I’d like to understand is a) How this works with leap years b) What kinds of legacy formats are supported, as I seem to be getting inconsistent answers when the fourth byte is less than 128 I’d appreciate any assistance, as this format appears to be totally undocumented. Please don’t post any actual source code, as I would be required by our lawyers to “do an Oedipus” on my eyeballs if I so much as glance at it :). Thanks, -Curt