Have you considered performing this function in J? It seems like it's
mostly data-copying.
Henry Rich
On 9/25/2020 11:52 AM, Raul Miller wrote:
3!:2 can construct an arbitrary nested J array and 3!:1 can serialize
an arbitrary nested J array. The cost of using this mechanism is
typically considerably lower than the cost of reading a file.
(There's another potential approach, involving cdcallback, but the
overhead and complexity of using that mechanism would not likely lead
to a better result.)
I hope this helps.
--
Raul
On Thu, Sep 24, 2020 at 4:51 PM 'Zhihao Yuan' via Source
<[email protected]> wrote:
On Thu, Sep 24, 2020 at 12:44 PM Eric Iverson <[email protected]>
wrote:
It should be possible to package it as an addon. The addon would include
shared libraries for the platforms of interest (windows/linux/macos) and
simple cover functions that did the cd calls to the libraries. This is how
Jd/lapack/etc provide extensions like this.
You are essentially asking me to write a
new library in C, since there is no such
library from the beginning -- which may
be fine. But here are the problems I
encountered:
1. How do I allocate a J array before
knowing its type and shape? Because
DLL (15!:) interface wants J side to pass
such a thing into cd. The short answer is
I can't. I must use separated calls to
negotiate the type and shape, which
leads to the next question...
2. How to pass FILE* to DLL from J?
All I can access from J code is file number;
DLL doesn't know what that is. This implies
that I may have to pass only filenames and
open a file twice -- first to parse its header,
then to load its data. But there is no
guarantee that the file is not renamed
between the two calls, or corresponds to
the same file. From a C library's point of
view, such an API will be poorly designed.
I'm leaning towards adding this
functionality as 3!:12 and 3!:13, converting
a J array to bytes in NPYand retrieving a
J array from bytes.
--
Zhihao
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