Hacker News: billpg

Will We Run Out of Unicodes?

billpg — Sat, 30 May 2026 09:57:32 +0000

Article URL: https://owl.billpg.com/the-expanding-universe-of-unicode/

Comments URL: https://news.ycombinator.com/item?id=48334522

Points: 5

# Comments: 0

New comment by billpg in "Let's Standardize the 1970 Epoch"

billpg — Fri, 29 May 2026 17:02:29 +0000

Thanks, and that POSIX link is exactly the one I expected someone to bring up.

The key point is that POSIX does not actually define a real, physical epoch, and it explicitly avoids doing so. POSIX says every day is exactly 86400 seconds, leap seconds are ignored, the relationship between POSIX time and UTC is unspecified. In other words, POSIX defines how the "time()" API behaves, not what the underlying timeline is. It’s an OS level contract, not a timekeeping standard.

The problem I’m addressing is that POSIX retroactively assumes a form of UTC that didn’t exist in 1970–1971 and it provides no authoritative mapping between POSIX time and actual UTC. That’s why you can’t use POSIX as a normative reference for "seconds since 1970". It’s not a definition of time, it’s a behavioural model for system clocks.

This document is trying to define the actual timeline that people implicitly assume when they say "Unix timestamp", in a way that’s historically honest and citable. When I was looking at a number of RFCs that use these timestamps they didn't cite this reference, but went with the wooly "Number of seconds since 1970".

Let's Standardize the 1970 Epoch

billpg — Fri, 29 May 2026 16:26:20 +0000

Article URL: https://github.com/billpg/1970EpochalTime/

Comments URL: https://news.ycombinator.com/item?id=48325409

Points: 2

# Comments: 2

New comment by billpg in "Bijou64: A variable-length integer encoding"

billpg — Fri, 29 May 2026 16:21:27 +0000

I forget where I encountered it, but I've seen similar encodings that eliminated the possibility of many possible encodings for the same number by making the length part of the value.

Values 0-127 are a single byte, but if that first byte has the continuation bit set, not only does that indicate the next byte has 7 more bits to contribute, it also moves the base up to the next window.

10000000 00000000 is the only way to represent 128.

10000000 10000000 00000000 is the only way to represent 16512.

Does this encoding have a name?

Oh No! I've invented SVG badly!

billpg — Fri, 29 May 2026 06:26:54 +0000

Article URL: https://owl.billpg.com/on-no-ive-invented-svg-badly/

Comments URL: https://news.ycombinator.com/item?id=48319732

Points: 4

# Comments: 0

New comment by billpg in "Make ZIP files smaller with ZIP Shrinker"

billpg — Tue, 19 May 2026 11:06:44 +0000

Do any formats using ZIP as the underlying format use ZIP comments for metadata? Unless there's a lot of compressors leaving "Zip file generated by MySuperZipper™" then I imagine any comments left were probably done for a good reason.

Let's Standardize the 1970 Epoch

billpg — Fri, 08 May 2026 12:51:23 +0000

Article URL: https://github.com/billpg/1970EpochalTime/

Comments URL: https://news.ycombinator.com/item?id=48062332

Points: 4

# Comments: 0

New comment by billpg in "Let's Measure Gravity"

billpg — Wed, 22 Apr 2026 08:35:41 +0000

True, but I wanted this to be something anyone could do with equipment they might already have lying around and also get a feel for what gravity is actually doing.

Switching on a machine that displays "9.8m/s²" isn't that much removed from looking it up in a book.

New comment by billpg in "XOR'ing a register with itself is the idiom for zeroing it out. Why not sub?"

billpg — Wed, 22 Apr 2026 08:01:11 +0000

I had a similar reaction when learning 8086 assembly and finding the correct way to do `if x==y` was a CMP instruction which performed a subtraction and set only the flags. (The book had a section with all the branch instructions to use for a variety of comparison operators.) I think I spent a few minutes experimenting with XOR to see if I could fashion a compare-two-values-and-branch macro that avoided any subtraction.

Let's Measure Gravity

billpg — Wed, 22 Apr 2026 07:49:16 +0000

Article URL: https://owl.billpg.com/lets-measure-gravity/

Comments URL: https://news.ycombinator.com/item?id=47860406

Points: 2

# Comments: 3

2001: A TV Series

billpg — Sat, 18 Apr 2026 14:18:42 +0000

Article URL: https://owl.billpg.com/2001-a-tv-series/

Comments URL: https://news.ycombinator.com/item?id=47816124

Points: 1

# Comments: 0

Are we going to run out of Unicodes?

billpg — Wed, 15 Apr 2026 15:05:06 +0000

Article URL: https://owl.billpg.com/the-expanding-universe-of-unicode/

Comments URL: https://news.ycombinator.com/item?id=47780135

Points: 2

# Comments: 0

Let's Standardize the 1970 Epoch

billpg — Thu, 26 Mar 2026 16:28:25 +0000

Article URL: https://github.com/billpg/1970EpochalTime/

Comments URL: https://news.ycombinator.com/item?id=47532527

Points: 2

# Comments: 0

New comment by billpg in "Aliens.gov ~ domain registered 17MAR2026"

billpg — Wed, 18 Mar 2026 14:27:56 +0000

It's a cookbook!

New comment by billpg in "The Road Not Taken: A World Where IPv4 Evolved"

billpg — Mon, 16 Mar 2026 09:18:48 +0000

An earlier draft had a section discussing how IPv4x would work with NAT routers. Essentially, an IPv4x packet would be a UDP/IPv4 packet using a port number (84) that's been allocated to IPv4x.

Old routers would be a normal UDP packet inside a normal IPv4 and route it normally. New routers would detect UDP port 84 and treat it as an extended IPv4x packet.

I took all that out because I wasn't writing a proposal for something we should actually implement in the real world, but an alternate history "What if people who wanted IPv4 but with extra space got their way" and the story was already too long.

New comment by billpg in "The Road Not Taken: A World Where IPv4 Evolved"

billpg — Fri, 13 Mar 2026 07:55:50 +0000

le sigh

Thanks though. Your comment really cheered me up.

New comment by billpg in "The Road Not Taken: A World Where IPv4 Evolved"

billpg — Fri, 13 Mar 2026 00:20:39 +0000

"I bet one _could_ accelerate IPv6 deployment a lot by have a standard ..."

ahem

https://owl.billpg.com/sixgate/

New comment by billpg in "The Road Not Taken: A World Where IPv4 Evolved"

billpg — Thu, 12 Mar 2026 23:24:19 +0000

Yes. The router in your home would absolutely need to support IPv4x if you wanted to make use of the extended address space, just like how in the real world your home router needs to support NAT if you want to make use of shared IP.

New comment by billpg in "The Road Not Taken: A World Where IPv4 Evolved"

billpg — Thu, 12 Mar 2026 23:11:37 +0000

My point is that we're still dependent on IPv4. For all the progress IPv6 has made, no-one is willing to switch IPv4 off yet. Until we do, we're still constrained by all the problems IPv4 has.

New comment by billpg in "The Road Not Taken: A World Where IPv4 Evolved"

billpg — Thu, 12 Mar 2026 23:02:22 +0000

Until you would happily deploy a service on IPv6 only, I suggest that you're still dependent on IPv4.