Author: Ross Boyd
Date: 13:56:44 12/11/04
Go up one level in this thread
On December 11, 2004 at 15:41:22, Uri Blass wrote:
>On December 11, 2004 at 04:34:03, Michel Langeveld wrote:
>
>>To probe a tablebase you need to setup some arrays.
>>
>>You need to fill the following array:
>>
>>int rgiCounters[10] = {0,0,0,0,0,0,0,0,0,0};
>>
>>This arrays contains of each piecetype the number.
>>Fill it as follows:
>>
>>// white:
>>// rgiCounters[0] == number of pawns
>>// rgiCounters[1] == number of knights
>>// rgiCounters[2] == number of bishops
>>// rgiCounters[3] == number of rooks
>>// rgiCounters[4] == number of queens
>>
>>// black:
>>// rgiCounters[5] == number of pawns
>>// rgiCounters[6] == number of knights
>>// rgiCounters[7] == number of bishops
>>// rgiCounters[8] == number of rooks
>>// rgiCounters[9] == number of queens
>>
>>This is doable, isn't it?
>>
>>Then you need to setup the arrays W, and B as follows:
>>
>>squaret W[C_PIECES * 5 + 1];
>>squaret B[C_PIECES * 5 + 1];
>>
>> // piecetypes (1 .. 5): fieldtypes (0 to 63):
>> // 0 == PAWN A1(0), A2(1) ... A8(7)
>> // 1 == KNIGHT B1(8) ...........B8(15)
>> // 2 == BISHOP ...................
>> // 3 == ROOK ...................
>> // 4 == QUEEN .................H8(63)
>> // 5 == KING
>> //
>> // W[0] = 1st pawn W[1] 2nd pawn W[2] 3rd pawn
>> // W[3] = 1st knight W[4] 2nd knight W[5] 3rd knight
>> // W[6] = 1st bishop W[7] 2nd bishop W[8] 3rd bishop
>> // W[9] = 1st rook W[10] 2nd rook W[11] 3rd rook
>> // W[12] = 1st queen W[13] 2nd queen W[14] 3rd queen
>> // W[15] = contains always white king
>>
>>Also doable, isn't it?
>>If this is doable ... then you are over 50%!
>>
>>You need also an enpassant field as follows:
>>
>> if (p.epField == INVAL_FIELD)
>> sqEnP = 127; //ep field
>> else
>> sqEnP = field2idx64(p.epField
>>
>>If you get this ... then you are almost there.
>>
>>The namilov tables are so that white is always the won with more pieces as
>>black. So then you need to do:
>>
>> //If black is the "winning" side (more pieces) then we need
>> //to "invert" the pieces in the lists.
>>
>> if (iTb > 0) {
>> if ( p.moveColor == WHITE ) side = 0; else side = 1;
>> fInvert = 0;
>> psqW = W;
>> psqB = B;
>> }
>> else {
>> if ( p.moveColor == WHITE ) side = 1; else side = 0;
>> fInvert = 1;
>> psqW = B;
>> psqB = W;
>> iTb = -iTb;
>> }
>>
>>Then you are ready to probe the tablebases....
>>
>> //now check to see if this particular tablebase for this
>> //color to move is registered.
>> if (!FRegistered(iTb, side)) return -1;
>>
>> ind = PfnIndCalc(iTb, side) (psqW, psqB, sqEnP, fInvert);
>>
>> //Comment this line out to load all tables in memory?
>> //FReadTableToMemory (iTb, side, NULL);
>>
>> //probe the table
>> tbScore = L_TbtProbeTable (iTb, side, ind);
>>
>> //if not found
>> if(tbScore == bev_broken) return -1;
>>
>> int add = (p.moveColor == BLACK ? 1 : 0);
>>
>> //now convert to correct MATE range the value
>> //Nullmover uses
>> if(tbScore > 0)
>> return (tbScore-bev_mi1)*2 + 9999 - (ply-1) - add;
>> if(tbScore < 0)
>> return (tbScore+bev_mi1)*2 - 9999 + (ply-1) + add;
>>
>> return 0;
>>}
>>
>>Futher more you need some defines, and function defintions:
>>
>>#define XX 127
>>#define C_PIECES 3 /* Maximum # of pieces of one color OTB */
>>#define TB_FASTCALL __fastcall
>>
>>typedef unsigned __int64 INDEX;
>>typedef unsigned int squaret;
>>typedef int color;
>>
>>#define bev_broken 32767
>>#define bev_mi1 32766
>>
>>typedef INDEX(TB_FASTCALL * PfnCalcIndex)
>>(squaret *, squaret *, squaret, int fInverse);
>>
>>extern "C"
>>{
>> int IDescFindFromCounters(int *);
>> int FRegisteredFun(int, color);
>> PfnCalcIndex PfnIndCalcFun(int, color);
>> int TB_FASTCALL L_TbtProbeTable(int, color, INDEX);
>> int FTbSetCacheSize(void *, unsigned long);
>> int IInitializeTb(char *);
>>}
>>
>>#define PfnIndCalc PfnIndCalcFun
>>#define FRegistered FRegisteredFun
>>
>>void *EGTB_cache = (void*)0;
>>
>>int EGTB;
>>
>>Cheers and good luck!
>>
>>Michel
>
>Thanks for your explanations.
>
>If I understand correctly W[0]=1st pawn square when a1=0,b1=1,...h8=63
>sqnp=127 if enpassent capture is illegal.
Correct!
>
>I do not understand the meaning of field2idx64(p.epField)
>I guess that p is for position but I need to know what structure it is and I do
>not know what does field2idx64.
"field_to_idx64" is Michael's array to convert his coordinates (maybe 0x88) to
the Nalimov 64 square coordinates where a1=0 ... h8=63
>
>I understand that I need to switch colors if black has more pieces but I do not
>understand the use of P there.
p.moveColor is Michael's side-to-move flag.
Movei probably uses a global variable called 'side'. If that is true then you
must rename the locally declared 'side' variable to something else like
'side_to_move'. Then you can use something like this...
if (iTb > 0) {
side_to_move = side;
fInvert = 0;
psqW = W;
psqB = B;
}
else {
side_to_move = side ^ 1; // assuming side is either 0 or 1, (LIGHT or DARK)
fInvert = 1;
psqW = B;
psqB = W;
iTb = -iTb;
}
if (!FRegistered(iTb, side_to_move)) {
return -1;
}
etc etc...
>
>I can get the side to move based on the internal structure of movei without some
>external p and if it is not needed for the nalimov tablebases but only internal
>structure in nullmover then it is not clear from the comments.
>
Yes, that's right.
Cheers,
Ross
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