Bug in ttable.c wrt storing of mate scores

[Chua Kong Sian]

There is a bug in PutInTTable() in ttable.c whereby mate scores are
incorrectly stored. This was fixed in pl68, but reappeared in pl 69
and 70. The patch for it appears below.

Kong Sian

*** /usr/people/kongsian/gnuchess-4.0/src/ttable.c Tue May 10 05:44:23 1994
--- ttable.c Sun May 15 16:17:58 1994
***************
*** 235,242 ****
#endif
if(ptbl->depth > (UCHAR)depth) return false;
/* adjust score so moves to mate is from this ply */
- if (score > 9000) score += ply;
- else if (score < -9000) score -= ply;
ptbl->hashbd = hashbd;
ptbl->depth = (UCHAR) depth;
ptbl->score = score;
--- 235,240 ----
***************
*** 254,260 ****
--- 252,262 ----
ptbl->score = beta + 1;
}
else
+ {
+ if (score > 9000) score += ply;
+ else if (score < -9000) score -= ply;
ptbl->flags = truescore;
+ }

#ifdef HASHSTATS
ttdepthin[ptbl->depth]++;

[Chua Kong Sian]

Please ignore my previous patch. Its not very correct. Here is the
correct patch.

Kong Sian

*** /usr/people/kongsian/gnuchess-4.0/src/ttable.c Tue May 10 05:44:23 1994

--- ttable.c Fri May 20 15:13:45 1994
***************
*** 234,242 ****
HashAdd++;

#endif
if(ptbl->depth > (UCHAR)depth) return false;

- /* adjust score so moves to mate is from this ply */

- if (score > 9000) score += ply;
- else if (score < -9000) score -= ply;
ptbl->hashbd = hashbd;
ptbl->depth = (UCHAR) depth;
ptbl->score = score;

--- 234,239 ----
***************
*** 254,260 ****
--- 251,263 ----

ptbl->score = beta + 1;
}
else
+ {

+ /* adjust score so moves to mate is from this ply */

+ if (score > 9000) score += ply;

+ else if (score < -9000 && score != -9999) score -= ply;
+ ptbl->score = score;