RE: [bigloo] let binding with c

[Bruant, Michel]

Hi Manuel,

You can compile the files I copy/paste in the email, below  =  "bigloo -c 
failc.c ;   bigloo fail.scm failc.o -o toto"
Then execute, and see the result:
> toto
dataOK1 = 12346789-123456789-123456789-, len is: 30
dataOK2 = 12346789-123456789-123456789-, len is: 30
data-not-KO = 1234, len is: 30

Let me comment:
- we have a C structure, a kind of buffer with 2 fields 'data' and 'length'
And we have a C function that set 'data' to a buf (filled) in the global area, 
and set 'len' to 30.
In the scheme part, we construct an instance of  c-struct and call the 
c-function that initialize  it; in a  'let*'
then, we try to retrieve the data content in the scheme, thanks to 3 bindings,  
corresponding to 3 trials.
I would expect 3 identical  results. I can't explain why the latest trial is 
not ok.
It looks like the 'if' says 'true' in the 3rd binding , but we expect 'false' 
that leads to a correct bind of the data.
...at the same time , a similar 'if' in the 2nd binding works fine ... that's 
even more strange.

Tell me if you need more info. 
Thanks, regards,
Michel




::::::::::::::
fail.h
::::::::::::::

typedef struct {
  int len;
  char* data;
} c_struct;

::::::::::::::
fail.scm
::::::::::::::
(module main
        (main main)
        (extern
         (include "fail.h")
         (type c_struct
               (struct (len::int "len")
                       (data::string "data"))
               "c_struct")
         (c_fill_struct::int (c_struct*) "c_fill_struct"))
        )

(define (main argv)
  (let ((my-struct     (c_struct* 0 "old")))
    (process my-struct)))

(define (process my-struct)
   (let* ((my-struct  (c_struct* -1 "init-content"))
          (res        (c_fill_struct my-struct))
          (dataOK1    (pragma::bstring "string_to_bstring_len( $1, $2 )" 
(c_struct*-data my-struct)  (c_struct*-len my-struct)))
          (dataOK2    (if (equal? (c_struct*-len my-struct) 999)
                                "we should not get this because -len is not 999"
                                (pragma::bstring "string_to_bstring_len( $1, $2 
)" (c_struct*-data my-struct)  (c_struct*-len my-struct))))
          (data-not-KO     (if (equal? (c_struct*-len my-struct) 999)
                                (c_struct*-data my-struct) ;; we should not get 
this, ...but it looks we get it !!
                                (pragma::bstring "string_to_bstring_len( $1, $2 
)" (c_struct*-data my-struct)  (c_struct*-len my-struct))))
          )
     
    (print "dataOK1 = " dataOK1 ", len is: " (c_struct*-len my-struct) )
    (print "dataOK2 = " dataOK2 ", len is: " (c_struct*-len my-struct) )
    (print "data-not-KO = " data-not-KO ", len is: " (c_struct*-len my-struct) )
   ))

::::::::::::::
failc.c
::::::::::::::
#include <stdlib.h>
#include "./fail.h"


char buf[100] = "123456789-123456789-123456789-zzzzzz.....";

int c_fill_struct (c_struct * my_c_struct) {
  buf[4] = 0;

  // return 'buf' , declare 30 bytes are significant, 
  my_c_struct->len = 30 ;
  my_c_struct->data = buf;
  return 0;

}


-----Original Message-----
From: manuel.serr...@inria.fr [mailto:manuel.serr...@inria.fr] 
Sent: Friday, October 21, 2016 8:43 AM
To: Bruant, Michel
Cc: bigloo@inria.fr
Subject: RE: [bigloo] let binding with c

> If few lines can illustrate it, then that may be manageable.
Yes. That will help a lot.

Thanks in advance,

-- 
Manuel