[Chicken-users] Returning f32vectors in C for Chicken's FFI

[Pierre-Alexandre Fournier]

Hi,

I'm new to Chicken and its FFI. I'm trying to make a C function return a 
f32vector when called in Scheme. A f32vector is translated in float* 
when passed to C. I would like to know how to cast this float* in f32vector.

For example:

C code (test_ffi3.h):
--------------
___declare(prefix, "mylib:")

float * f32add(float * v1, float * v2, int len)
{
  int i;
  float * v3;
  v3 = (float *) malloc (sizeof(float) * len);

  for (i=0; i<len; i++){
    v3[i] = v1[i] + v2[i];
    printf("%d:%f\n",i,v3[i]); //debugging.
  }
  return v3;
}
--------------

Scheme code:
--------------
(require-extension srfi-4)

#>!
#include "test-ffi3.h"
<#

(define va (f32vector 1.1 2.2 3.3 4.4 5.5 6.6))
(define vb (f32vector 2 2 2 2 2 2))
(define vc (mylib:f32add va vb (f32vector-length va)))
(display vc)
(newline)
--------------

Currently (display vc) prints something like:
#<pointer 9445f38>
and I would to have a #f32(...) instead. Is there any documentation on 
that subject?

I read that functions in blas.egg mutates vectors and doesn't need to 
return the f32vector (and therefore avoid that problem). I don't want to 
do that because I would like to keep a functional style when I write my 
algorithms.


Thanks for helping,

Pierre-Alexandre