[aw1621107]

> enough bits to go backward from the epoch at t=0 to the big bang at t=negative whatever.

For reference, the universe is about 13.787 billion years old [0]. That's about 13.787 * 10^9 * 365 * 24 * 3600 = 4.348 * 10^17 seconds, which (I think?) is a 59-bit number [1]. 10ths of a second will require 62 bits, which is right about at the edge of what a 64-bit signed integer will allow.

If you want milliseconds, you'll need at least 69 bits. For nanoseconds, you'll need at least 89 bits.

So you'll either need an integer type that's wider than what's natively supported in most hardware (thus potentially sacrificing performance), or you'll have to sacrifice precision.

[0]: https://en.wikipedia.org/wiki/Age_of_the_universe

[1]: https://www.wolframalpha.com/input/?i=13.787+*+10%5E9+*+365+...

[syrrim]

struct timespec already exists and stores time as two 64 bit integers. Should last a little while.

[aw1621107]

Ah, that's something I wasn't aware of. Yeah, that scheme could work if you didn't need a single integer to represent time.

[AnimalMuppet]

Just go for it. In the larger scheme of things, it's not that long until 128-bit CPUs.

I'm mostly kidding. But if you're thinking of representing nanoseconds since the big bang, the wait for 128-bit CPUs is not very long...

[shakna]

GNU has extensions to support 128bit number types [0] already, for systems that can handle it.

[0] https://gcc.gnu.org/onlinedocs/gcc/_005f_005fint128.html