// Copyright (c) Google LLC 2019

//

// Use of this source code is governed by an MIT-style

// license that can be found in the LICENSE file or at

// https://opensource.org/licenses/MIT.

#include "./predict.h"

#include <brunsli/jpeg_data.h>

namespace brunsli {

namespace {

int AdaptiveMedian(int w, int n, int nw) {

  const int mx = (w > n) ? w : n;

  const int mn = w + n - mx;

  if (nw > mx) {

    return mn;

  } else if (nw < mn) {

    return mx;

  } else {

    return n + w - nw;

  }

}

}  // namespace

int PredictWithAdaptiveMedian(const coeff_t* coeffs, int x, int y, int stride) {

  const int offset1 = -kDCTBlockSize;

  const int offset2 = -stride;

  const int offset3 = offset2 + offset1;

  if (y != 0) {

    if (x != 0) {

      return AdaptiveMedian(coeffs[offset1], coeffs[offset2], coeffs[offset3]);

    } else {

      return coeffs[offset2];

    }

  } else {

    return x ? coeffs[offset1] : 0;

  }

}

}  // namespace brunsli