[gambit-list] Returning a byte array from C
Vijay Mathew
vijay.the.lisper at gmail.com
Thu Sep 26 00:21:49 EDT 2013
Thanks again for all the great feedback!
I think the call to ____FIX() is not required if Scheme code access the C
function through a declaration like this:
(define read-bytes (c-lambda (int unsigned-int scheme-object) int
"read_bytes"))
Is that correct?
Thanks,
--Vijay
On Wed, Sep 25, 2013 at 8:34 PM, Marc Feeley <feeley at iro.umontreal.ca>wrote:
>
> On 2013-09-25, at 4:48 AM, Vijay Mathew <vijay.the.lisper at gmail.com>
> wrote:
>
> > Hi,
> >
> > Thanks for reviewing my code.
> >
> > I have updated the C function as follows:
> >
> > int read_bytes (int fd, size_t count, ___SCMOBJ data_vect)
> > {
> > void *data = malloc (count);
> > int result;
> >
> > if (data == NULL)
> > result = -1;
> > else
> > {
> > result = read (fd, data, count);
> > if (result > 0)
> > memcpy (___BODY (data_vect), data, result);
> > free (data);
> > }
> > return result;
> > }
> >
> > A call from scheme will look like:
> >
> > (read-bytes fd count (make-u8vector count 0))
> >
> > I suppose now I don't have to worry about leaks or
> heap-overflow-exceptions.
>
> You can simplify you code further to:
>
> int read_bytes (int fd, size_t count, ___SCMOBJ data_vect)
> {
> return ___FIX(read (fd, ___BODY(data_vect), count));
> }
>
> Marc
>
>
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