[Jprogramming] j807 cd - pass array arguments

Sun Nov 18 07:04:09 UTC 2018

Would this work?
(+/a),a=:*:i.10
285 0 1 4 9 16 25 36 49 64 81
Lihda
Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------
From: Ben Gorte <bgorte at gmail.com>
Date: 11/18/18 1:22 AM (GMT-05:00)
To: programming at jsoftware.com
Subject: [Jprogramming] j807 cd - pass array arguments
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: https://nam03.safelinks.protection.outlook.com/?url=www.jsoftware.com&data=02%7C01%7C%7Caea74eef88cc4956f52408d64d1e2ea8%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636781189351421900&sdata=ceCMEPnvicK08EirS1wRbf6cY9KsNvJipaklCDhhOtE%3D&reserved=0
Perhaps I'm overlooking something trivial; any help is highly appreciated!
Ben
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