#include "tt.hpp"

void TranspositionTable::newSearch()

{

time = 0;

}

void TranspositionTable::store(uint64_t hash, chess::Move best, int16_t score, int8_t depth, TTFlag flag)

{

// 2 entries per bucket

if (buckets == 0)

return;

uint64_t index = hash % buckets;

if (index >= buckets - 1)

index = buckets - 2; // Ensure we don't overflow

TTEntry &e0 = table[index], &e1 = table[index + 1];

// Store the entry

++time; // monotonically increasing stamp

for (TTEntry *e : {&e0, &e1})

{

if (!e->valid() || e->hash == hash || e->depth() < depth)

{

e->hash = hash;

e->set(depth, flag, score, time, true, best);

return;

}

}

// If we get here, we need to evict an entry

// Find the oldest entry

TTEntry *oldest = (e0.timestamp() < e1.timestamp()) ? &e0 : &e1;

// Evict it

oldest->hash = hash;

oldest->set(depth, flag, score, time, true, best);

}

TTEntry *TranspositionTable::lookup(uint64_t hash)

{

// 2 entries per bucket

if (buckets == 0)

return nullptr;

uint64_t index = hash % buckets;

if (index >= buckets - 1)

index = buckets - 2; // Ensure we don't overflow

TTEntry &e0 = table[index], &e1 = table[index + 1];

// Check the entries

for (TTEntry *e : {&e0, &e1})

{

if (e->valid() && e->hash == hash)

return e;

}

return nullptr;

}