Re: The RSVD dissector and 32-bit builds ...

[Martin Mathieson <martin.r.mathieson () googlemail com>]

The idiom I use for keys that are > 32 bits is to have a function to return
a key, with a 'persist' flag

e.g. in packet-pdcp-lte.c :

/* Convenience function to get a pointer for the hash_func to work with */
static gpointer get_report_hash_key(guint16 SN, guint32 frameNumber,
                                    pdcp_lte_info *p_pdcp_lte_info,
                                    gboolean do_persist)
{
    static pdcp_result_hash_key  key;
    pdcp_result_hash_key        *p_key;

    /* Only allocate a struct when will be adding entry */
    if (do_persist) {
        p_key = wmem_new(wmem_file_scope(), pdcp_result_hash_key);
    }
    else {
        memset(&key, 0, sizeof(pdcp_result_hash_key));
        p_key = &key;
    }

    /* Fill in details, and return pointer */
    p_key->frameNumber = frameNumber;
    p_key->SN = SN;
    p_key->plane = (guint8)p_pdcp_lte_info->plane;
    p_key->channelId = p_pdcp_lte_info->channelId;
    p_key->direction = p_pdcp_lte_info->direction;
    p_key->notUsed = 0;

    return p_key;
}

then call with do_persist=TRUE for storing, and FALSE for lookup

Martin

On Mon, Feb 16, 2015 at 3:11 PM, Evan Huus <eapache () gmail com> wrote:

> On Mon, Feb 16, 2015 at 10:08 AM, Richard Sharpe
> <realrichardsharpe () gmail com> wrote:
> > On Mon, Feb 16, 2015 at 6:55 AM, Evan Huus <eapache () gmail com> wrote:
> > > Create the wmem_map using g_int64_equal instead of g_direct_equal and
> > > wmem_int64_hash instead of g_direct_hash. Create a wmem_file_scope()
> > > copy of the key, and pass the resulting pointer to the insert
> > > function.
> >
> > Hmmm, why do we need a wmem_file_scope() copy of the key? We get the
> > key in each request and response and I don't store the key anywhere.
>
> The map itself has to store the key in order to use it for future
> lookups. When the key is only 32 bits you can make the pointer itself
> store the key, and since the pointer gets copied you don't need an
> explicit copy of the key. But when the pointer is just a pointer, you
> need a file-scope copy of the key.
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