diff options
Diffstat (limited to 'src/evalhash.c')
| -rw-r--r-- | src/evalhash.c | 173 |
1 files changed, 16 insertions, 157 deletions
diff --git a/src/evalhash.c b/src/evalhash.c index fc29b88..4df6e23 100644 --- a/src/evalhash.c +++ b/src/evalhash.c @@ -8,7 +8,11 @@ Module Name: Abstract: - Evaluation score hashing code. + Rough (mid-tree) eval estimation. Used to hold the eval-score + hashing code (EVAL_HASH) too; that subsystem was cut for good + (measured as slow as or slower than just computing eval) and is + not coming back in this form, so this file is now just + GetRoughEvalScore(). Author: @@ -20,8 +24,6 @@ Revision History: #include "chess.h" -extern ULONG g_uIterateDepth; - SCORE GetRoughEvalScore(IN OUT SEARCHER_THREAD_CONTEXT *ctx, IN SCORE iAlpha, @@ -34,23 +36,22 @@ Routine description: This is meant to be the "one place" that code looks when it needs to get an idea of the estimated evaluation of a position (in mid tree, not at the leaves... at the leaves just call Eval directly). - - The thought is that: - - 1. The top of the tree (near the root) represents very few nodes - which have big subtrees. Use the real Eval here. - - 2. Otherwise possibly probe the eval hash -- if there's a score in - it then we can return quickly. - - 3. Otherwise do a (very) rough material estimate. + + Just calls Eval() -- its own lazy-exit machinery already is the + cheap, calibrated estimate this function exists to provide, so + there's no separate "rough" estimator to maintain here. Used to + fall back to material + a stale ctx->uPositional EWMA left over + from whatever full eval last ran anywhere in the tree, fed by an + eval-hash probe (fUseHash); both are gone now (see the commit + removing ctx->uPositional and EVAL_HASH), and this is the direct + replacement. Parameters: IN OUT SEARCHER_THREAD_CONTEXT *ctx, IN SCORE iAlpha, IN SCORE iBeta, - IN FLAG fUseHash + IN FLAG fUseHash : unused, kept for call-site compatibility Return value: @@ -58,148 +59,6 @@ Return value: --*/ { - POSITION *pos = &(ctx->sPosition); - UINT64 u64Key; - ULONG u; - - if (ctx->uPly <= 4) - { - return Eval(ctx, iAlpha, iBeta, NULL); - } -#ifdef EVAL_HASH - else if ((fUseHash) || (ctx->uPly <= (g_uIterateDepth / 2))) - { - u64Key = (pos->u64PawnSig ^ pos->u64NonPawnSig); - u = (ULONG)u64Key & (EVAL_HASH_TABLE_SIZE - 1); - if (ctx->rgEvalHash[u].u64Key == u64Key) - { - switch(ctx->rgEvalHash[u].bvFlags) - { - case EVAL_HASH_EXACT: - ctx->uPositional = ctx->rgEvalHash[u].uPositional; - return(ctx->rgEvalHash[u].iEval); - case EVAL_HASH_UPPER: - if (ctx->rgEvalHash[u].iBound <= iAlpha) - { - return(ctx->rgEvalHash[u].iEval); - } - break; - case EVAL_HASH_LOWER: - if (ctx->rgEvalHash[u].iBound >= iBeta) - { - return(ctx->rgEvalHash[u].iEval); - } - break; - } - } - } -#else - (void)u64Key; - (void)u; (void)fUseHash; -#endif - return(pos->iMaterialBalance[pos->uToMove] + ctx->uPositional); -} - -#ifdef EVAL_HASH - - -SCORE -ProbeEvalHash(IN OUT SEARCHER_THREAD_CONTEXT *ctx, IN SCORE iAlpha, IN SCORE iBeta) -/*++ - -Routine description: - - Probe the eval hash; return a real score if there's a hit - otherwise return INVALID_SCORE. An EXACT entry is always usable. - An UPPER/LOWER entry (recorded from a lazy-eval early exit) is - only usable if the bound it proved still resolves the caller's - current alpha/beta window; otherwise it's treated as a miss and - the caller must actually compute something. - -Parameters: - - IN OUT SEARCHER_THREAD_CONTEXT *ctx : note that in the case - of a hit, *ctx is modified also. - IN SCORE iAlpha, IN SCORE iBeta : caller's current window - -Return value: - - SCORE - ---*/ -{ - POSITION *pos = &(ctx->sPosition); - UINT64 u64Key = (pos->u64PawnSig ^ pos->u64NonPawnSig); - ULONG u = (ULONG)u64Key & (EVAL_HASH_TABLE_SIZE - 1); - - if (ctx->rgEvalHash[u].u64Key == u64Key) - { - switch(ctx->rgEvalHash[u].bvFlags) - { - case EVAL_HASH_EXACT: - ctx->uPositional = ctx->rgEvalHash[u].uPositional; - pos->cTrapped[WHITE] = ctx->rgEvalHash[u].cTrapped[WHITE]; - pos->cTrapped[BLACK] = ctx->rgEvalHash[u].cTrapped[BLACK]; - return(ctx->rgEvalHash[u].iEval); - case EVAL_HASH_UPPER: - if (ctx->rgEvalHash[u].iBound <= iAlpha) - { - return(ctx->rgEvalHash[u].iEval); - } - break; - case EVAL_HASH_LOWER: - if (ctx->rgEvalHash[u].iBound >= iBeta) - { - return(ctx->rgEvalHash[u].iEval); - } - break; - } - } - return(INVALID_SCORE); -} - -void -StoreEvalHash(IN OUT SEARCHER_THREAD_CONTEXT *ctx, - IN SCORE iScore, - IN SCORE iBound, - IN UCHAR bvFlags) -/*++ - -Routine description: - - Store a score in the eval hash table (which is pointed to - indirectly via ctx). bvFlags is EVAL_HASH_EXACT for a fully - computed eval (iBound ignored) or EVAL_HASH_UPPER/EVAL_HASH_LOWER - for a bound proven by a lazy-eval early exit (iScore is the - uncorrected partial score that would be returned, iBound is the - proven bound on the true eval). - -Parameters: - - SEARCHER_THREAD_CONTEXT *ctx, - SCORE iScore, - SCORE iBound, - UCHAR bvFlags - -Return value: - - void - ---*/ -{ - POSITION *pos = &(ctx->sPosition); - UINT64 u64Key = (pos->u64PawnSig ^ pos->u64NonPawnSig); - ULONG u = (ULONG)u64Key & (EVAL_HASH_TABLE_SIZE - 1); - ctx->rgEvalHash[u].u64Key = u64Key; - ctx->rgEvalHash[u].iEval = iScore; - ctx->rgEvalHash[u].iBound = iBound; - ctx->rgEvalHash[u].bvFlags = bvFlags; - if (bvFlags == EVAL_HASH_EXACT) - { - ctx->rgEvalHash[u].uPositional = ctx->uPositional; - ctx->rgEvalHash[u].cTrapped[WHITE] = pos->cTrapped[WHITE]; - ctx->rgEvalHash[u].cTrapped[BLACK] = pos->cTrapped[BLACK]; - } + return Eval(ctx, iAlpha, iBeta, NULL); } -#endif // EVAL_HASH |