[Jprogramming] j807 cd - pass array arguments

Sun Nov 18 12:55:56 UTC 2018

j807 must get from result of cd, like this
0 3{ (sqrdll, 'sqr i i *i *i') cd (#y);y;res
On Sun, Nov 18, 2018, 2:22 PM Ben Gorte <bgorte at gmail.com wrote:
> Dear All,
>> Long ago I made quite a lot of c-functions that I am calling from J using
> the cd mechanism (load 'dll') in linux.
>> They stopped working in j64-807. I see in the release notes that indeed
> something has changed, but I cannot quite relate that to my case (but maybe
> I should - I'm not sure I entirely understand the story).
>> In the simplest form it looks like this:
> First the c-code, sqr.c :
> int sqr (int n, int a[], int b[])
> {
> int i, sumsqr=0;
> for (i=0; i<n; i++)
> sumsqr += b[i] = a[i] * a[i];
> return sumsqr;
> }
>> which I compile with
> gcc -O3 -shared -fPIC -o sql.so -Wl,--no-as-needed sqr.c
> (omitting -O3 does not make a difference).
>> In J I go like:
>> load 'dll'
>> sqrdll =: jpath '~user/ext/sqr.so '
>>> sqr =: 3 : 0
>> res =. (#y)#4 NB. make sure it's integer
>> ret =. (sqrdll, 'sqr > i i *i *i') cd (#y);y;res
>> ret, res
>> )
>>> Up until j806 I would get:
>> sqr i.10
>> 285 0 1 4 9 16 25 36 49 64 81
>>> But in j807:
>> sqr i.10
>> 285 4 4 4 4 4 4 4 4 4 4
>>>> So my DLL 'reads' an array alright, but seems to be not 'writing' it.
>>> For completeness:
> JVERSION
> Engine: j807/j64/linux
> Release: commercial/2018-10-04T15:00:41
> Library: 8.07.20
> Qt IDE: 1.7.7/5.5.1
> Platform: Linux 64
> Installer: J807 install
> InstallPath: /home/ben/j64-807
> Contact: www.jsoftware.com
>> Perhaps I'm overlooking something trivial; any help is highly appreciated!
>> Ben
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