Re: RFC: sorted value_string + bsearch

[Jakub Zawadzki <darkjames () darkjames ath cx>]

On Fri, Apr 23, 2010 at 04:18:40PM +0200, Anders Broman wrote:
> +const gchar*
> +match_strval_fast(const guint32 val, const value_string_fast *vs) {
> +  guint low, idx, max;
> +  guint32 item;
> +  if(vs) {
> +       switch(vs->match_type){
> +               case VS_SEARCH:
> +                       match_strval( val, vs->vals);
> +                       break;
> +               case VS_INDEX:
> +                       return vs->vals[val].strptr;

I think you need: 
        return (val < vs->length) ? vs->vals[val].strptr : NULL;

anyway sorry, but I dislike your idea :)

I would prefer other function or even macro:

#define match_strval_hyper_fast(val, vs) \
        (val >= 0 && val < array_length(vs) && vs[val].val == val) ? \
                vs[val].strptr : match_strval(val, vs) /* fallback (?) */


> > I think this is a good idea, but it obviously requires the value string  array to be properly sorted for it to work 
> > well.
> > And the bigger the array, the more enticing it would be to use this faster method, but I think it will also be 
> > potentially harder to ensure that those bigger arrays are indeed properly sorted.
> > Developers are bound to make mistakes, especially with the very large arrays, and as other developers add new 
> > entries, they may not know that a particular array is supposed to be sorted, and even if they do, there's no 
> > guarantee that a properly sorted array will remain so.

Can't we do this check in tmp_fld_check_assert()?
I think most of value_strings are registered...
___________________________________________________________________________
Sent via:    Wireshark-dev mailing list <wireshark-dev () wireshark org>
Archives:    http://www.wireshark.org/lists/wireshark-dev
Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev
             mailto:wireshark-dev-request () wireshark org?subject=unsubscribe