Re: [Gpsbabel-code] Patch to memory allocator in Globalsat DG-100 handler, v1.3.5 (1/1)

[Robert L. <rob...@gm...>]

Applied.  Thanx.

On Sun, Jun 29, 2008 at 5:23 PM, Mirko Parthey <
mir...@in...> wrote:

> On Tue, Jun 17, 2008 at 12:35:52AM +0200, Mirko Parthey wrote:
> > On Sun, Jun 15, 2008 at 09:29:00PM +0100, Stephen Goudge wrote:
> > > 1) when receiving the "0 headers" a pointless call to
> dynarray16_alloc() was
> > > being made (pointless as the loop that followed would not be executed)
> and
> > > this was being passed down to realloc() which interpreted it as a
> request to
> > > simply de-allocate the memory.
>
> Thanks - I added a check to break out of the loop on "0 headers found".
>
> > > 2) when dynarray16_alloc() was being usefully called it was not doing
> the
> > > right thing: if the memory did need to be re-allocated the result from
> the
> > > xrealloc() was not being put into the correct place *and* a missing
> test
> > > before subtracting unsigned integers was causing the re-allocation to
> be done
> > > when it wasn't necessary.
>
> Thanks.
> It wasn't my intention to guarantee any sort of alignment though
> ("chunk" might be misleading here) - I just wanted to avoid frequent
> calls to xrealloc - so I dropped those parts of your patch.
>
> For my version, see below - please tell me if there are any issues left.
>
> I'll send another patch with a few cleanups in a separate mail.
>
> Regards,
> Mirko
>
>
> --- dg-100.c    2008-06-29 21:19:18.000000000 +0200
> +++ dg-100.c    2008-06-29 21:05:19.000000000 +0200
> @@ -75,7 +75,6 @@
>  };
>  const unsigned dg100_numcommands = sizeof(dg100_commands) /
> sizeof(dg100_commands[0]);
>
> -/* TODO: use obstacks or vmem_t instead? */
>  struct dynarray16 {
>        unsigned count; /* number of elements used */
>        unsigned limit; /* number of elements allocated */
> @@ -115,11 +114,11 @@
>        i = a->count;
>        a->count += n;
>
> -       need = a->count - a->limit;
> -       if (need > 0) {
> +       if (a->count > a->limit) {
> +               need = a->count - a->limit;
>                need = (need > elements_per_chunk) ? need :
> elements_per_chunk;
>                a->limit += need;
> -               xrealloc(a->data, sizeof(a->data[0]) * a->limit);
> +               a->data = xrealloc(a->data, sizeof(a->data[0]) * a->limit);
>        }
>        return(a->data + i);
>  }
> @@ -555,6 +554,10 @@
>                nextheader = be_read16(answer + 2);
>                dg100_log("found %d headers, nextheader=%d\n",
>                        numheaders, nextheader);
> +               if (numheaders <= 0) {
> +                       dg100_log("no further headers, aborting the
> loop\n");
> +                       break;
> +               }
>
>                h = dynarray16_alloc(headers, numheaders);
>                for (i = 0; i < numheaders; i++) {
>
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