[Freeciv-Dev] Re: Tech cost patch v6

[Reinier Post <rp@xxxxxxxxxx>]

On Thu, Nov 29, 2001 at 03:14:12PM +0100, Raimar Falke wrote:
> On Thu, Nov 29, 2001 at 03:28:49PM +0200, Juha Litola wrote:
> > On Thu, Nov 29, 2001 at 02:11:34PM +0100, Raimar Falke wrote:
> > 
> > > Problem: where is num_reqs set to 0 (initialized)?
> > Hmm, it seems to be 0 when I test it, but maybe it's just good luck.
> > 
> > > Suggestion: at the correct places (one for the server and one for the 
> > > client) do:
> > >   for each tech:
> > >      tech.num_reqs=0;
> > >   for each tech:
> > >      num_req_techs(tech)
> > > and later doesn't use num_req_techs() anymore.
> > Where is the right place in client. In server it could be in
> > ruleset.c, but I couldn't find suitable place in client.
> 
> Good question. Possible answers:
>  - client/packhand.c:handle_ruleset_tech: you have to count the
>  received techs OR trust that the server sents them in ascending order
>  and catch the last one
>  - depending on the game state
> 
> I'm not sure what is the correct way. Can anybody help here?

Doesn't it suffice to add it to packet_ruleset_tech ?

struct packet_ruleset_tech {
  int id, req[2];               /* indices for advances[] */
  int flags;
  char name[MAX_LEN_NAME];
  char *helptext;               /* same as for packet_ruleset_unit, above */
};

By the way, the algorithm is wrong: it only works on a tech *tree*,
but we really have an acyclic graph.

+/**************************************************************************
+ Count number of requirements technology has including itself.
+ Cache result to advances[tech].num_reqs.
+**************************************************************************/
+int num_req_techs(Tech_Type_id tech)
+{
+  int value = 1;
+  if (tech == A_NONE)
+    return 0;
+  if (advances[tech].num_reqs != 0)    /* Precalculated value */
+    return advances[tech].num_reqs;
+
+  value += num_req_techs(advances[tech].req[0]);
+  value += num_req_techs(advances[tech].req[1]);
+  advances[tech].num_reqs = value;
+  return value;
+}

You have to scan and mark the whole tree for req[0], then read the
marks for req[1].

>       Raimar

-- 
Reinier