Unsigned 64 bit integer to numeric
Hi,
Probably a simple question, but I don't see a simple answer so far. In
one extension I want to convert uint64 into a numeric to put it
eventually into a jsonb object. As far as I see in numeric.c there are
functions only for signed int64. Is there a way to achive this with
uint64 (without duplicating significant part of numeric implementation
in the extension)?
Hi,
I don't think so, but there's an (unmaintained?) uint extension at
https://github.com/petere/pguint.git
On Wed, Dec 4, 2019 at 11:24 AM Dmitry Dolgov <9erthalion6@gmail.com> wrote:
Show quoted text
Hi,
Probably a simple question, but I don't see a simple answer so far. In
one extension I want to convert uint64 into a numeric to put it
eventually into a jsonb object. As far as I see in numeric.c there are
functions only for signed int64. Is there a way to achive this with
uint64 (without duplicating significant part of numeric implementation
in the extension)?
"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.)
--
Andrew (irc:RhodiumToad)
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!