diff options
Diffstat (limited to 'src/search.c')
| -rwxr-xr-x | src/search.c | 175 |
1 files changed, 4 insertions, 171 deletions
diff --git a/src/search.c b/src/search.c index 0f814ea..4ea09b0 100755 --- a/src/search.c +++ b/src/search.c @@ -999,164 +999,6 @@ QSearchFromCheckNoStandPat(IN SEARCHER_THREAD_CONTEXT *ctx, } - -/** - -Routine description: - - The QSearch (Quiescence Search) is a selective search called when - there is no remaining depth in Search. Its job is to search only - moves that stabilize the position -- once it is quiescence (quiet) - we will run a static evaluation on it and return the score. - - This branch of the QSearch is called when the side to move is in - danger somehow -- either he has two pieces en prise on the board - or some piece that seems trapped. We do not allow him an - opportunity to stand pat in this position. - -Parameters: - - IN SEARCHER_THREAD_CONTEXT *ctx, - IN SCORE iAlpha, - IN SCORE iBeta - IN SCORE iEval - -Return value: - - SCORE - -**/ -SCORE -QSearchInDangerNoStandPat(IN SEARCHER_THREAD_CONTEXT *ctx, - IN SCORE iAlpha, - IN SCORE iBeta) -{ - POSITION *pos = &ctx->sPosition; - CUMULATIVE_SEARCH_FLAGS *pf = &ctx->sSearchFlags; - ULONG x; - FLAG fIncludeChecks; - SCORE iBestScore = iAlpha; - SCORE iScore; - SCORE iFutility; - SCORE iEval = GetRoughEvalScore(ctx, iAlpha, iBeta, TRUE); - MOVE mv; - ULONG uLegalMoves = 0; - static ULONG _WhatToGen[] = - { - GENERATE_CAPTURES_PROMS, - GENERATE_CAPTURES_PROMS_CHECKS - }; - - - // Set futility: - // - // iEval + move_value + margin < alpha - // move_value < alpha - margin - iEval - iFutility = 0; - if (iAlpha < +NMATE) - { - iFutility = (iAlpha - - (FUTILITY_BASE_MARGIN + ctx->uPositional) - - iEval); - iFutility = MAX0(iFutility); - } - - // We suspect that the guy on move is in sad shape if we're - // here... he has more than one piece en prise or he seems to - // have a piece trapped. Allow him to play checks in order to try - // to save the situation. - ASSERT(!InCheck(pos, pos->uToMove)); - fIncludeChecks = ((pf->uQsearchDepth < pf->uQsearchCheckDepth) && - (pf->fCouldStandPat[FLIP(pos->uToMove)] == FALSE)); - GenerateMoves(ctx, NULLMOVE, _WhatToGen[fIncludeChecks]); - - for (x = ctx->sMoveStack.uBegin[ctx->uPly]; - x < ctx->sMoveStack.uEnd[ctx->uPly]; - x++) - { - SelectBestNoHistory(ctx, x); - mv = ctx->sMoveStack.mvf[x].mv; -#ifdef DEBUG - ASSERT(0 == (ctx->sMoveStack.mvf[x].bvFlags & MVF_MOVE_SEARCHED)); - ctx->sMoveStack.mvf[x].bvFlags |= MVF_MOVE_SEARCHED; -#endif - - // Prune except when pruning all moves could cause us to return - // -INFINITY (mated) erroneously. - if (iAlpha > -INFINITY) - { - if (ctx->sMoveStack.mvf[x].iValue <= 0) - { - ASSERT(SanityCheckMoves(ctx, x, VERIFY_BEFORE | VERIFY_AFTER)); - goto end; - } - if (FALSE == _ShouldWeConsiderThisMove(ctx, - x, - iFutility, - TRUE)) - { - continue; - } - } - - if (FALSE == fIncludeChecks) - { - mv.bvFlags |= WouldGiveCheck(ctx, mv); - } - - if (MakeMove(ctx, mv)) - { - uLegalMoves++; - pf->uQsearchNodes++; - pf->uQsearchDepth++; - iScore = -QSearch(ctx, - -iBeta, - -iAlpha); - pf->uQsearchDepth--; - UnmakeMove(ctx, mv); - if (WE_SHOULD_STOP_SEARCHING) goto end; - - if (iScore > iBestScore) - { - iBestScore = iScore; - ctx->sPlyInfo[ctx->uPly].mvBest = mv; - if (iScore > iAlpha) - { - if (iScore >= iBeta) - { - KEEP_TRACK_OF_FIRST_MOVE_FHs(uLegalMoves == 1); - ASSERT(SanityCheckMoves(ctx, x, VERIFY_BEFORE)); - goto end; - } - else - { - UpdatePV(ctx, mv); - StoreExactScore(mv, pos, iScore, 0, FALSE, ctx->uPly); - iAlpha = iScore; - } - } - } - } - } - ASSERT(SanityCheckMoves(ctx, x, VERIFY_BEFORE)); - - end: - // If iAlpha is -INFINITY and side on move has no captures, - // promotes or checks then we must make up a "stand pat" score - // here. We don't want to let him stand pat with iEval because - // the board looks dangerous. But we likewise don't want to say - // "mated" because he's not. - ASSERT((uLegalMoves > 0) || (iBestScore == iAlpha)); - if (iBestScore == -INFINITY) - { - ASSERT(iAlpha == -INFINITY); - iBestScore = iEval - VALUE_QUEEN; - } - ASSERT(IS_VALID_SCORE(iBestScore) || WE_SHOULD_STOP_SEARCHING); - return(iBestScore); -} - - /** Routine description: @@ -1193,6 +1035,7 @@ QSearch(IN SEARCHER_THREAD_CONTEXT *ctx, SCORE iScore; SCORE iEval; SCORE iFutility; + SCORE iPositional; ULONG x; ULONG uLegalMoves; FLAG fIncludeChecks; @@ -1269,16 +1112,6 @@ QSearch(IN SEARCHER_THREAD_CONTEXT *ctx, } ASSERT(!InCheck(pos, pos->uToMove)); - // Even if the side is not in check, do not let him stand pat if - // his position looks dangerous (i.e. more than one piece en prise - // or a piece trapped). Fail low if there's nothing that looks - // good on this line. - //if (SideCanStandPat(pos, pos->uToMove) == FALSE) - //{ - // iBestScore = QSearchInDangerNoStandPat(ctx, iAlpha, iBeta); - // goto end; - //} - // If we get here then side on move is not in check and this // position looks ok enough to allow him the option to stand pat // -or- we missed when we probed the dangerhash. Also remember @@ -1288,7 +1121,7 @@ QSearch(IN SEARCHER_THREAD_CONTEXT *ctx, // discovers a mate, there's no force since a stand pat // opportunity exists right here. uLegalMoves = 0; - iEval = iBestScore = Eval(ctx, iAlpha, iBeta); + iEval = iBestScore = Eval(ctx, iAlpha, iBeta, &iPositional); if (iBestScore > iAlpha) { iAlpha = iBestScore; @@ -1312,7 +1145,7 @@ QSearch(IN SEARCHER_THREAD_CONTEXT *ctx, iFutility = 0; if (iAlpha < +NMATE) { - iFutility = iAlpha - (FUTILITY_BASE_MARGIN + ctx->uPositional) - iEval; + iFutility = iAlpha - (FUTILITY_BASE_MARGIN + iPositional) - iEval; iFutility = MAX0(iFutility); } @@ -1400,7 +1233,7 @@ QSearch(IN SEARCHER_THREAD_CONTEXT *ctx, { iFutility = (iAlpha - (FUTILITY_BASE_MARGIN + - ctx->uPositional) - + iPositional) - iEval); iFutility = MAX0(iFutility); } |