Re: Unsigned 64 bit integer to numeric
От | Dmitry Dolgov |
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Тема | Re: Unsigned 64 bit integer to numeric |
Дата | |
Msg-id | 20191204192537.nbhjnvtcz4b2brub@localhost обсуждение исходный текст |
Ответ на | Re: Unsigned 64 bit integer to numeric (Andrew Gierth <andrew@tao11.riddles.org.uk>) |
Список | pgsql-hackers |
> On Wed, Dec 04, 2019 at 11:49:20AM +0000, Andrew Gierth wrote: > > >>>>> "Dmitry" == Dmitry Dolgov <9erthalion6@gmail.com> writes: > > Dmitry> Hi, > > Dmitry> Probably a simple question, but I don't see a simple answer so > Dmitry> far. In one extension I want to convert uint64 into a numeric > Dmitry> to put it eventually into a jsonb object. As far as I see in > Dmitry> numeric.c there are functions only for signed int64. Is there a > Dmitry> way to achive this with uint64 (without duplicating significant > Dmitry> part of numeric implementation in the extension)? > > Sure. Flip the top bit; convert the value as if signed; then subtract > -(2^63) from the result. (Easier to subtract -(2^63) than to add 2^63, > since the former can itself be represented in a signed int64 for easy > conversion to numeric.) Indeed, looks like this does the trick, thank you!
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