Re: Unsigned 64 bit integer to numeric

> On Wed, Dec 04, 2019 at 11:49:20AM +0000, Andrew Gierth wrote:
>
> >>>>> "Dmitry" == Dmitry Dolgov <9erthalion6(at)gmail(dot)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!