/*

 * Copyright 2010 The Android Open Source Project

 *

 * Use of this source code is governed by a BSD-style license that can be

 * found in the LICENSE file.

 */

#include "include/core/SkMath.h"

#include "include/core/SkScalar.h"

SkScalar SkScalarInterpFunc(SkScalar searchKey, const SkScalar keys[],

                            const SkScalar values[], int length) {

    SkASSERT(length > 0);

    SkASSERT(keys != nullptr);

    SkASSERT(values != nullptr);

#ifdef SK_DEBUG

    for (int i = 1; i < length; i++) {

        SkASSERT(keys[i-1] <= keys[i]);

    }

#endif

    int right = 0;

    while (right < length && keys[right] < searchKey) {

        ++right;

    }

    // Could use sentinel values to eliminate conditionals, but since the

    // tables are taken as input, a simpler format is better.

    if (right == length) {

        return values[length-1];

    }

    if (right == 0) {

        return values[0];

    }

    // Otherwise, interpolate between right - 1 and right.

    SkScalar leftKey = keys[right-1];

    SkScalar rightKey = keys[right];

    SkScalar fract = (searchKey - leftKey) / (rightKey - leftKey);

    return SkScalarInterp(values[right-1], values[right], fract);

}