const MaxHashBits … // RequiredEntropyBits makes a quick and slightly conservative estimate of the number // of bits of hash value that are consumed in shuffle sharding a deck of the given size // to a hand of the given size. The result is meaningful only if // 1 <= handSize <= deckSize <= 1<<26. func RequiredEntropyBits(deckSize, handSize int) int { … } type Dealer … // NewDealer will create a Dealer with the given deckSize and handSize, will return error when // deckSize or handSize is invalid as below. // 1. deckSize or handSize is not positive // 2. handSize is greater than deckSize // 3. deckSize is impractically large (greater than 1<<26) // 4. required entropy bits of deckSize and handSize is greater than MaxHashBits func NewDealer(deckSize, handSize int) (*Dealer, error) { … } // Deal shuffles a card deck and deals a hand of cards, using the given hashValue as the source of entropy. // The deck size and hand size are properties of the Dealer. // This function synchronously makes sequential calls to pick, one for each dealt card. // Each card is identified by an integer in the range [0, deckSize). // For example, for deckSize=128 and handSize=4 this function might call pick(14); pick(73); pick(119); pick(26). func (d *Dealer) Deal(hashValue uint64, pick func(int)) { … } // DealIntoHand shuffles and deals according to the Dealer's parameters, // using the given hashValue as the source of entropy and then // returns the dealt cards as a slice of `int`. // If `hand` has the correct length as Dealer's handSize, it will be used as-is and no allocations will be made. // If `hand` is nil or too small, it will be extended (performing an allocation). // If `hand` is too large, a sub-slice will be returned. func (d *Dealer) DealIntoHand(hashValue uint64, hand []int) []int { … }
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