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package com.sun.media.sound;

A resampler that uses third-order (cubic) interpolation.
Author:
Karl Helgason/**
 * A resampler that uses third-order (cubic) interpolation.
 *
 * @author Karl Helgason
 */
public final class SoftCubicResampler extends SoftAbstractResampler {

    @Override
    public int getPadding() {
        return 3;
    }

    @Override
    public void interpolate(float[] in, float[] in_offset, float in_end,
                            float[] startpitch, float pitchstep, float[] out, int[] out_offset,
                            int out_end) {
        float pitch = startpitch[0];
        float ix = in_offset[0];
        int ox = out_offset[0];
        float ix_end = in_end;
        int ox_end = out_end;
        if (pitchstep == 0) {
            while (ix < ix_end && ox < ox_end) {
                int iix = (int) ix;
                float fix = ix - iix;
                float y0 = in[iix - 1];
                float y1 = in[iix];
                float y2 = in[iix + 1];
                float y3 = in[iix + 2];
                float a0 = y3 - y2 + y1 - y0;
                float a1 = y0 - y1 - a0;
                float a2 = y2 - y0;
                float a3 = y1;
                //float fix2 = fix * fix;
                //out[ox++] = (a0 * fix + a1) * fix2 + (a2 * fix + a3);
                out[ox++] = ((a0 * fix + a1) * fix + a2) * fix + a3;
                ix += pitch;
            }
        } else {
            while (ix < ix_end && ox < ox_end) {
                int iix = (int) ix;
                float fix = ix - iix;
                float y0 = in[iix - 1];
                float y1 = in[iix];
                float y2 = in[iix + 1];
                float y3 = in[iix + 2];
                float a0 = y3 - y2 + y1 - y0;
                float a1 = y0 - y1 - a0;
                float a2 = y2 - y0;
                float a3 = y1;
                //float fix2 = fix * fix;
                //out[ox++] = (a0 * fix + a1) * fix2 + (a2 * fix + a3);
                out[ox++] = ((a0 * fix + a1) * fix + a2) * fix + a3;
                ix += pitch;
                pitch += pitchstep;
            }
        }
        in_offset[0] = ix;
        out_offset[0] = ox;
        startpitch[0] = pitch;

    }
}