3 ms·

I think it’s important to be explicit about whether or not signed integers are used. From reading the document it seems that they may be signed but they could n

I think it’s important to be explicit about whether or not signed integers are used. From reading the document it seems that they may be signed but they could not be. If they are signed then you could have multiple bit strings that represent the same date and time which is not great.

deleted 2y ago
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jagged-chisel 2y ago
Definitely signed - “use negative duration to subtract” But bit pattern is an issue internal to the library. If you can find a bug in the code, certainly point it out and offer a fix if it’s in your skillset.
- sigseg1v 2y ago
  I think the negative number here refers to the amount of days/etc to subtract (eg. add negative days to subtract, not supply a negative date). However, at the same time it seems to indicate that it stores data using sqlites built in number type, which to my understanding does not support unsigned? Secondly, the docs mention you can store with a range of 290 years and the precision is nanoseconds, which if you calculate it out works out to about 63 bits of information, suggesting a signed implementation.
  - tyingq 2y ago
    Yes, it's signed...https://www.sqlite.org/datatype3.html https://www.sqlite.org/datatype3.html Each value stored in an SQLite database (or manipulated by the database engine) has one of the following storage classes: # some omitted... INTEGER. The value is a signed integer, stored in 0, 1, 2, 3, 4, 6, or 8 bytes depending on the magnitude of the value.
- gcr 2y ago
  Subtraction of unsigned negative values still works just fine because of two’s compliment. (uint8)(-3) is 253, for example, and (uint8)5-(uint8)253 = (uint8)8, corresponding to 5 - (-3)
kaoD 2y ago
> multiple bit strings that represent the same date and time How so?
- davidhyde 2y ago
  You’re right, whether or not the integers are signed has nothing to do with the issue above. Unsigned integers have the same issue. Here is an example for signed integers. These represent zero time but have different representations in memory: Seconds: 2 Nanoseconds: -2,000,000,000 (fits in a 32 bit number) Time: zero seconds Seconds: -2 Nanoseconds: 2,000,000,000 Time: zero seconds Here is an example for unsigned: Seconds: 1 Nanoseconds: 0 Time: 1 second Seconds: 0 Nanoseconds: 1,000,000,000 Time 1 second
  - kaoD 2y ago
    Thanks, but I'm not gonna pretend that was my point. Dumb question from me, I just forgot the context that time was a pair of integers and was utterly confused, haha. You're spot on!

deleted 2y ago

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jagged-chisel 2y ago

Definitely signed - “use negative duration to subtract” But bit pattern is an issue internal to the library. If you can find a bug in the code, certainly point it out and offer a fix if it’s in your skillset.

sigseg1v 2y ago
I think the negative number here refers to the amount of days/etc to subtract (eg. add negative days to subtract, not supply a negative date). However, at the same time it seems to indicate that it stores data using sqlites built in number type, which to my understanding does not support unsigned? Secondly, the docs mention you can store with a range of 290 years and the precision is nanoseconds, which if you calculate it out works out to about 63 bits of information, suggesting a signed implementation.
- tyingq 2y ago
  Yes, it's signed...https://www.sqlite.org/datatype3.html https://www.sqlite.org/datatype3.html Each value stored in an SQLite database (or manipulated by the database engine) has one of the following storage classes: # some omitted... INTEGER. The value is a signed integer, stored in 0, 1, 2, 3, 4, 6, or 8 bytes depending on the magnitude of the value.
gcr 2y ago
Subtraction of unsigned negative values still works just fine because of two’s compliment. (uint8)(-3) is 253, for example, and (uint8)5-(uint8)253 = (uint8)8, corresponding to 5 - (-3)

kaoD 2y ago

> multiple bit strings that represent the same date and time How so?

davidhyde 2y ago
You’re right, whether or not the integers are signed has nothing to do with the issue above. Unsigned integers have the same issue. Here is an example for signed integers. These represent zero time but have different representations in memory: Seconds: 2 Nanoseconds: -2,000,000,000 (fits in a 32 bit number) Time: zero seconds Seconds: -2 Nanoseconds: 2,000,000,000 Time: zero seconds Here is an example for unsigned: Seconds: 1 Nanoseconds: 0 Time: 1 second Seconds: 0 Nanoseconds: 1,000,000,000 Time 1 second
- kaoD 2y ago
  Thanks, but I'm not gonna pretend that was my point. Dumb question from me, I just forgot the context that time was a pair of integers and was utterly confused, haha. You're spot on!