// Step 6. Razoring
+ // Maximum depth for razoring
const Depth RazorDepth = 4 * OnePly;
+
+ // Dynamic razoring margin based on depth
inline Value razor_margin(Depth d) { return Value(0x200 + 0x10 * d); }
// Step 8. Null move search with verification search
// evaluation of the position is more than NullMoveMargin below beta.
const Value NullMoveMargin = Value(0x200);
+ // Maximum depth for use of dynamic threat detection when null move fails low
+ const Depth ThreatDepth = 5 * OnePly;
+
// Step 9. Internal iterative deepening
+ // Minimum depth for use of internal iterative deepening
const Depth IIDDepthAtPVNodes = 5 * OnePly;
const Depth IIDDepthAtNonPVNodes = 8 * OnePly;
// search when the static evaluation is at most IIDMargin below beta.
const Value IIDMargin = Value(0x100);
- // Search depth at iteration 1
- const Depth InitialDepth = OnePly;
+ // Step 11. Decide the new search depth
- // Easy move margin. An easy move candidate must be at least this much
- // better than the second best move.
- const Value EasyMoveMargin = Value(0x200);
-
- // If the TT move is at least SingleReplyMargin better then the
- // remaining ones we will extend it.
- const Value SingleReplyMargin = Value(0x20);
+ // Extensions. Configurable UCI options.
+ // Array index 0 is used at non-PV nodes, index 1 at PV nodes.
+ Depth CheckExtension[2], SingleEvasionExtension[2], PawnPushTo7thExtension[2];
+ Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2];
- /// Lookup tables initialized at startup
+ // Minimum depth for use of singular extension
+ const Depth SingularExtensionDepthAtPVNodes = 6 * OnePly;
+ const Depth SingularExtensionDepthAtNonPVNodes = 8 * OnePly;
- // Reduction lookup tables and their getter functions
- int8_t PVReductionMatrix[64][64]; // [depth][moveNumber]
- int8_t NonPVReductionMatrix[64][64]; // [depth][moveNumber]
+ // If the TT move is at least SingularExtensionMargin better then the
+ // remaining ones we will extend it.
+ const Value SingularExtensionMargin = Value(0x20);
- inline Depth pv_reduction(Depth d, int mn) { return (Depth) PVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; }
- inline Depth nonpv_reduction(Depth d, int mn) { return (Depth) NonPVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; }
+ // Step 12. Futility pruning
- // Futility lookup tables and their getter functions
+ // Futility margin for quiescence search
const Value FutilityMarginQS = Value(0x80);
+
+ // Futility lookup tables (initialized at startup) and their getter functions
int32_t FutilityMarginsMatrix[14][64]; // [depth][moveNumber]
int FutilityMoveCountArray[32]; // [depth]
inline Value futility_margin(Depth d, int mn) { return Value(d < 7*OnePly ? FutilityMarginsMatrix[Max(d, 0)][Min(mn, 63)] : 2 * VALUE_INFINITE); }
inline int futility_move_count(Depth d) { return d < 16*OnePly ? FutilityMoveCountArray[d] : 512; }
- /// Variables initialized by UCI options
+ // Step 14. Reduced search
+
+ // Reduction lookup tables (initialized at startup) and their getter functions
+ int8_t PVReductionMatrix[64][64]; // [depth][moveNumber]
+ int8_t NonPVReductionMatrix[64][64]; // [depth][moveNumber]
+
+ inline Depth pv_reduction(Depth d, int mn) { return (Depth) PVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; }
+ inline Depth nonpv_reduction(Depth d, int mn) { return (Depth) NonPVReductionMatrix[Min(d / 2, 63)][Min(mn, 63)]; }
+
+ // Step. Common adjustments
+
+ // Search depth at iteration 1
+ const Depth InitialDepth = OnePly;
- // Depth limit for use of dynamic threat detection
- Depth ThreatDepth;
+ // Easy move margin. An easy move candidate must be at least this much
+ // better than the second best move.
+ const Value EasyMoveMargin = Value(0x200);
// Last seconds noise filtering (LSN)
const bool UseLSNFiltering = true;
const Value LSNValue = value_from_centipawns(200);
bool loseOnTime = false;
- // Extensions. Array index 0 is used at non-PV nodes, index 1 at PV nodes.
- Depth CheckExtension[2], SingleEvasionExtension[2], PawnPushTo7thExtension[2];
- Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2];
+
+ /// Global variables
// Iteration counters
int Iteration;
MateThreatExtension[1] = Depth(get_option_value_int("Mate Threat Extension (PV nodes)"));
MateThreatExtension[0] = Depth(get_option_value_int("Mate Threat Extension (non-PV nodes)"));
- ThreatDepth = get_option_value_int("Threat Depth") * OnePly;
-
Chess960 = get_option_value_bool("UCI_Chess960");
ShowCurrentLine = get_option_value_bool("UCI_ShowCurrLine");
UseLogFile = get_option_value_bool("Use Search Log");
// Singular extension search. We extend the TT move if its value is much better than
// its siblings. To verify this we do a reduced search on all the other moves but the
// ttMove, if result is lower then ttValue minus a margin then we extend ttMove.
- if ( depth >= 6 * OnePly
+ if ( depth >= SingularExtensionDepthAtPVNodes
&& tte
&& move == tte->move()
&& ext < OnePly
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
- Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move);
+ Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move);
- if (excValue < ttValue - SingleReplyMargin)
+ if (excValue < ttValue - SingularExtensionMargin)
ext = OnePly;
}
}
// Loop through all legal moves until no moves remain or a beta cutoff occurs
// Initialize a MovePicker object for the current position
- MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]);
+ MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply], beta);
CheckInfo ci(pos);
while ( bestValue < beta
// Singular extension search. We extend the TT move if its value is much better than
// its siblings. To verify this we do a reduced search on all the other moves but the
// ttMove, if result is lower then ttValue minus a margin then we extend ttMove.
- if ( depth >= 8 * OnePly
+ if ( depth >= SingularExtensionDepthAtNonPVNodes
&& tte
&& move == tte->move()
&& !excludedMove // Do not allow recursive single-reply search
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
- Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move);
+ Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move);
- if (excValue < ttValue - SingleReplyMargin)
+ if (excValue < ttValue - SingularExtensionMargin)
ext = OnePly;
}
}
continue;
// Value based pruning
- Depth predictedDepth = newDepth - nonpv_reduction(depth, moveCount); //FIXME: We are ignoring condition: depth >= 3*OnePly, BUG??
+ Depth predictedDepth = newDepth - nonpv_reduction(depth, moveCount); // We illogically ignore reduction condition depth >= 3*OnePly
futilityValueScaled = ss[ply].eval + futility_margin(predictedDepth, moveCount)
+ H.gain(pos.piece_on(move_from(move)), move_to(move)) + 45;
if (ActiveThreads == 1)
return;
- for (int i = 1; i < ActiveThreads; i++)
- assert(threads[i].state == THREAD_SLEEPING);
-
#if !defined(_MSC_VER)
pthread_mutex_lock(&WaitLock);
pthread_cond_broadcast(&WaitCond);
projects / stockfish / blobdiff