common/simple-adder.h

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef LIBTEXTCLASSIFIER_COMMON_SIMPLE_ADDER_H_
#define LIBTEXTCLASSIFIER_COMMON_SIMPLE_ADDER_H_

#include "util/base/integral_types.h"
#include "util/base/port.h"

namespace libtextclassifier {
namespace nlp_core {

// Implements add and scaleadd in the most straight-forward way, and it doesn't
// have any additional requirement on the alignment and array size.
class SimpleAdder {
 public:
  TC_ATTRIBUTE_ALWAYS_INLINE SimpleAdder(float *dest, int num_floats)
      : dest_(dest), num_floats_(num_floats) {}

  TC_ATTRIBUTE_ALWAYS_INLINE void LazyAdd(const float *source) const {
    AddImpl(source, num_floats_, dest_);
  }

  TC_ATTRIBUTE_ALWAYS_INLINE void LazyScaleAdd(const float *source,
                                               const float scale) const {
    ScaleAddImpl(source, num_floats_, scale, dest_);
  }

  // Simple fast while loop to implement dest += source.
  TC_ATTRIBUTE_ALWAYS_INLINE static void AddImpl(const float *__restrict source,
                                                 uint32 size,
                                                 float *__restrict dest) {
    for (uint32 i = 0; i < size; ++i) {
      dest[i] += source[i];
    }
  }

  // Simple fast while loop to implement dest += scale * source.
  TC_ATTRIBUTE_ALWAYS_INLINE static void ScaleAddImpl(
      const float *__restrict source, uint32 size, const float scale,
      float *__restrict dest) {
    for (uint32 i = 0; i < size; ++i) {
      dest[i] += source[i] * scale;
    }
  }

 private:
  float *dest_;
  int num_floats_;
};

}  // namespace nlp_core
}  // namespace libtextclassifier

#endif  // LIBTEXTCLASSIFIER_COMMON_SIMPLE_ADDER_H_