text: #ifndef CAFFE2_OPERATORS_INDEX_HASH_OPS_H_
  #define CAFFE2_OPERATORS_INDEX_HASH_OPS_H_
  
  #include "caffe2/core/asan.h"
  #include "caffe2/core/logging.h"
  #include "caffe2/core/operator.h"
  
  namespace caffe2 {
  
  template <class Context>
  class IndexHashOp : public Operator<Context> {
   public:
    USE_OPERATOR_CONTEXT_FUNCTIONS;
    IndexHashOp(const OperatorDef& operator_def, Workspace* ws)
        : Operator<Context>(operator_def, ws),
          seed_(this->template GetSingleArgument<int64_t>("seed", 0)),
          modulo_(this->template GetSingleArgument<int64_t>("modulo", 0)) {
      CAFFE_ENFORCE_GT(modulo_, 0, "MODULO should be > 0");
    }
  
    bool RunOnDevice() override {
      return DispatchHelper<TensorTypes<int32_t, int64_t>>::call(
          this, Input(INDICES));
    }
  
    template <typename T>
    bool DoRunWithType() {
      auto& indices = Input(INDICES);
      auto* hashed_indices = Output(HASHED_INDICES);
      hashed_indices->ResizeLike(indices);
  
      CAFFE_ENFORCE_GE(
          static_cast<int64_t>(std::numeric_limits<T>::max()),
          modulo_,
          "MODULO shouldn't be larger than the numeric limit of the indices");
  
      auto N = indices.numel();
      auto* indices_data = indices.template data<T>();
      auto* hashed_indices_data = hashed_indices->template mutable_data<T>();
  
      for (auto i = 0; i < N; i++) {
        hashed_indices_data[i] = hash(indices_data[i]);
      }
  
      return true;
    }
  
   protected:
    template <typename T>
    CAFFE2_NO_SANITIZE("signed-integer-overflow") T hash(T id) {
      int8_t* bytes = (int8_t*)&id;
      T hashed = seed_ * 0xDEADBEEF;
      for (int i = 0; i < sizeof(T) / sizeof(int8_t); i++) {
        hashed = hashed * 65537 + bytes[i];
      }
      // We want the result of the modulo to be positive. This works under the
      // assumption that modulo_ > 0 which is enforced in the constructor.
      auto modHashed = hashed % modulo_;
      return modHashed >= 0 ? modHashed : modHashed + modulo_;
    }
  
   private:
    INPUT_TAGS(INDICES);
    OUTPUT_TAGS(HASHED_INDICES);
  
    int64_t seed_;
    int64_t modulo_;
  };
  
  } // namespace caffe2
  
  #endif // CAFFE2_OPERATORS_INDEX_HASH_OPS_H_
  