int64_t random_64(void)
{
int64_t r = random_32();
r <<= 32;
r |= random_32();
return r;
}
uint64 random_64()
{
uint64 a = random_32();
uint64 b = random_32();
return (a << 32) + b;
}
/*
* Pick a move out of the current book. If |pos| is not in the book, return
* NO_MOVE. If more than one alternative exists, choose randomly among all
* weighted possibilities.
*/
move_t get_poly_book_move(position_t* pos)
{
uint64_t key = book_hash(pos);
int offset = find_book_key(key);
if (offset == -1) return NO_MOVE;
move_t moves[255];
uint16_t weights[255];
uint16_t total_weight = 0;
int index = 0;
book_entry_t entry;
// Read all book entries with the correct key. They're all stored
// contiguously, so just scan through as long as the key matches.
while (true) {
assert(offset+index < num_entries);
read_book_entry(offset+index, &entry);
if (entry.key != key) break;
moves[index] = book_move_to_move(pos, entry.move);
printf("info string book move ");
print_coord_move(moves[index]);
printf("weight %d\n", entry.weight);
weights[index++] = total_weight + entry.weight;
total_weight += entry.weight;
}
if (index == 0) return NO_MOVE;
// Choose randomly amonst the weighted options.
uint16_t choice = random_32() % total_weight;
int i;
for (i=0; choice >= weights[i]; ++i) {}
assert(i < index);
return moves[i];
}
uint32 random_between(uint32 min, uint32 max)
{
if(min == max)
{
return min;
}
if(min > max)
{
swap(min, max);
}
const uint32 diff = max - min + 1;
return min + random_32() % diff;
}