- if (key16 != (k >> 48))
- {
- key16 = (uint16_t)(k >> 48);
- move16 = (uint16_t)m;
- value16 = (int16_t)v;
- eval16 = (int16_t)ev;
- genBound8 = (uint8_t)(g | b);
- depth8 = (int8_t)d;
- }
- else
- {
- // Preserve any existing move for the same position
- if (m)
- move16 = (uint16_t)m;
-
- // Don't overwrite more valuable values
- if ( d + 2 > depth8
- || g != (genBound8 & 0xFC)
- || b == BOUND_EXACT)
- {
- value16 = (int16_t)v;
- genBound8 = (uint8_t)(g | b);
- depth8 = (int8_t)d;
- }
-
- if (ev != VALUE_NONE)
- eval16 = (int16_t)ev;
- }
+ assert(d / ONE_PLY * ONE_PLY == d);
+
+ // Preserve any existing move for the same position
+ if (m || (k >> 48) != key16)
+ move16 = (uint16_t)m;
+
+ // Don't overwrite more valuable entries
+ if ( (k >> 48) != key16
+ || d / ONE_PLY > depth8 - 4
+ /* || g != (genBound8 & 0xFC) // Matching non-zero keys are already refreshed by probe() */
+ || b == BOUND_EXACT)
+ {
+ key16 = (uint16_t)(k >> 48);
+ value16 = (int16_t)v;
+ eval16 = (int16_t)ev;
+ genBound8 = (uint8_t)(g | b);
+ depth8 = (int8_t)(d / ONE_PLY);
+ }