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Code Issues Releases Wiki Activity

Simplify scale factors implementation

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No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2010-09-24 10:33:16 +02:00
parent 0e3535ea23
commit 045beac156
1 changed files with 10 additions and 20 deletions
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30
src/evaluate.cpp
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@ -251,7 +251,7 @@ namespace {
Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
Score apply_weight(Score v, Score weight);
Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
Value scale_by_game_phase(const Score& v, Phase ph, ScaleFactor sf);
Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
void init_safety();
}
@ -285,7 +285,6 @@ template<bool HasPopCnt>
Value do_evaluate(const Position& pos, Value& margin) {
EvalInfo ei;
ScaleFactor factor[2];
Score mobilityWhite, mobilityBlack;
assert(pos.is_ok());
@ -309,10 +308,6 @@ Value do_evaluate(const Position& pos, Value& margin) {
if (mi->specialized_eval_exists())
return mi->evaluate(pos);
// After get_material_info() call that modifies them
factor[WHITE] = mi->scale_factor(pos, WHITE);
factor[BLACK] = mi->scale_factor(pos, BLACK);
// Probe the pawn hash table
ei.pi = PawnTable[pos.thread()]->get_pawn_info(pos);
bonus += apply_weight(ei.pi->pawns_value(), Weights[PawnStructure]);
@ -349,15 +344,16 @@ Value do_evaluate(const Position& pos, Value& margin) {
bonus += apply_weight(make_score(s * mi->space_weight(), 0), Weights[Space]);
}
// Scale winning side if position is more drawish that what it appears
ScaleFactor sf = eg_value(bonus) > VALUE_ZERO ? mi->scale_factor(pos, WHITE)
: mi->scale_factor(pos, BLACK);
// If we don't already have an unusual scale factor, check for opposite
// colored bishop endgames, and use a lower scale for those
// colored bishop endgames, and use a lower scale for those.
if ( phase < PHASE_MIDGAME
&& pos.opposite_colored_bishops()
&& ( (factor[WHITE] == SCALE_FACTOR_NORMAL && eg_value(bonus) > VALUE_ZERO)
|| (factor[BLACK] == SCALE_FACTOR_NORMAL && eg_value(bonus) < VALUE_ZERO)))
&& sf == SCALE_FACTOR_NORMAL)
{
ScaleFactor sf;
// Only the two bishops ?
if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
&& pos.non_pawn_material(BLACK) == BishopValueMidgame)
@ -371,15 +367,10 @@ Value do_evaluate(const Position& pos, Value& margin) {
// Endgame with opposite-colored bishops, but also other pieces. Still
// a bit drawish, but not as drawish as with only the two bishops.
sf = ScaleFactor(50);
if (factor[WHITE] == SCALE_FACTOR_NORMAL)
factor[WHITE] = sf;
if (factor[BLACK] == SCALE_FACTOR_NORMAL)
factor[BLACK] = sf;
}
// Interpolate between the middle game and the endgame score
Value v = scale_by_game_phase(bonus, phase, factor);
Value v = scale_by_game_phase(bonus, phase, sf);
return pos.side_to_move() == WHITE ? v : -v;
}
@ -908,15 +899,14 @@ namespace {
// scale_by_game_phase() interpolates between a middle game and an endgame score,
// based on game phase. It also scales the return value by a ScaleFactor array.
Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
Value scale_by_game_phase(const Score& v, Phase ph, ScaleFactor sf) {
assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
Value eg = eg_value(v);
ScaleFactor f = sf[eg > VALUE_ZERO ? WHITE : BLACK];
Value ev = Value((eg * int(f)) / SCALE_FACTOR_NORMAL);
Value ev = Value((eg * int(sf)) / SCALE_FACTOR_NORMAL);
int result = (mg_value(v) * int(ph) + ev * int(128 - ph)) / 128;
return Value(result & ~(GrainSize - 1));