COUNT_BITS
ca->array[i] &= ~(DECAY_MASK << COUNT_BITS);
ca->array[i] |= (decay << COUNT_BITS);
ca->array[to] |= DECAY_MASK << COUNT_BITS;
#define COUNT_MASK ((1ULL << COUNT_BITS) - 1)
#define DECAY(e) (((e) >> COUNT_BITS) & DECAY_MASK)