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 * Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

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package com.sun.media.sound;

import java.io.IOException;

import java.util.Objects;

import java.util.Vector;

import javax.sound.sampled.AudioFormat;

import javax.sound.sampled.AudioInputStream;

import javax.sound.sampled.AudioSystem;

/**

 * A-law encodes linear data, and decodes a-law data to linear data.

 *

 * @author Kara Kytle

 */

public final class AlawCodec extends SunCodec {

    /* Tables used for A-law decoding */

    private static final byte[] ALAW_TABH = new byte[256];

    private static final byte[] ALAW_TABL = new byte[256];

    private static final AudioFormat.Encoding[] alawEncodings = { AudioFormat.Encoding.ALAW, AudioFormat.Encoding.PCM_SIGNED };

    private static final short seg_end [] = {0xFF, 0x1FF, 0x3FF,

                                             0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF};

    /**

     * Initializes the decode tables

     */

    static {

        for (int i=0;i<256;i++) {

            int input    = i ^ 0x55;

            int mantissa = (input & 0xf ) << 4;

            int segment  = (input & 0x70) >> 4;

            int value    = mantissa+8;

            if(segment>=1)

                value+=0x100;

            if(segment>1)

                value <<= (segment -1);

            if( (input & 0x80)==0 )

                value = -value;

            ALAW_TABL[i] = (byte)value;

            ALAW_TABH[i] = (byte)(value>>8);

        }

    }

    /**

     * Constructs a new ALAW codec object.

     */

    public AlawCodec() {

        super(alawEncodings, alawEncodings);

    }

    // NEW CODE

    /**

     */

    public AudioFormat.Encoding[] getTargetEncodings(AudioFormat sourceFormat){

        if( sourceFormat.getEncoding().equals( AudioFormat.Encoding.PCM_SIGNED )) {

            if( sourceFormat.getSampleSizeInBits() == 16 ) {

                AudioFormat.Encoding enc[] = new AudioFormat.Encoding[1];

                enc[0] = AudioFormat.Encoding.ALAW;

                return enc;

            } else {

                return new AudioFormat.Encoding[0];

            }

        } else if( sourceFormat.getEncoding().equals( AudioFormat.Encoding.ALAW ) ) {

            if( sourceFormat.getSampleSizeInBits() == 8 ) {

                AudioFormat.Encoding enc[] = new AudioFormat.Encoding[1];

                enc[0] = AudioFormat.Encoding.PCM_SIGNED;

                return enc;

            } else {

                return new AudioFormat.Encoding[0];

            }

        } else {

            return new AudioFormat.Encoding[0];

        }

    }

    /**

     */

    public AudioFormat[] getTargetFormats(AudioFormat.Encoding targetEncoding, AudioFormat sourceFormat){

        Objects.requireNonNull(sourceFormat);

        if( (targetEncoding.equals( AudioFormat.Encoding.PCM_SIGNED ) && sourceFormat.getEncoding().equals( AudioFormat.Encoding.ALAW)) ||

            (targetEncoding.equals( AudioFormat.Encoding.ALAW) && sourceFormat.getEncoding().equals( AudioFormat.Encoding.PCM_SIGNED)) ) {

                return getOutputFormats( sourceFormat );

            } else {

                return new AudioFormat[0];

            }

    }

    /**

     */

    public AudioInputStream getAudioInputStream(AudioFormat.Encoding targetEncoding, AudioInputStream sourceStream){

        AudioFormat sourceFormat = sourceStream.getFormat();

        AudioFormat.Encoding sourceEncoding = sourceFormat.getEncoding();

        if( !isConversionSupported(targetEncoding,sourceStream.getFormat()) ) {

            throw new IllegalArgumentException("Unsupported conversion: " + sourceStream.getFormat().toString() + " to " + targetEncoding.toString());

        }

        if( sourceEncoding.equals( targetEncoding ) ) {

            return sourceStream;

        }

        AudioFormat targetFormat = null;

        if( sourceEncoding.equals( AudioFormat.Encoding.ALAW ) &&

            targetEncoding.equals( AudioFormat.Encoding.PCM_SIGNED ) ) {

            targetFormat = new AudioFormat( targetEncoding,

                                            sourceFormat.getSampleRate(),

                                            16,

                                            sourceFormat.getChannels(),

                                            2*sourceFormat.getChannels(),

                                            sourceFormat.getSampleRate(),

                                            sourceFormat.isBigEndian());

        } else if( sourceEncoding.equals( AudioFormat.Encoding.PCM_SIGNED ) &&

                   targetEncoding.equals( AudioFormat.Encoding.ALAW ) ) {

            targetFormat = new AudioFormat( targetEncoding,

                                            sourceFormat.getSampleRate(),

                                            8,

                                            sourceFormat.getChannels(),

                                            sourceFormat.getChannels(),

                                            sourceFormat.getSampleRate(),

                                            false);

        } else {

            throw new IllegalArgumentException("Unsupported conversion: " + sourceStream.getFormat().toString() + " to " + targetEncoding.toString());

        }

        return getConvertedStream(targetFormat, sourceStream);

    }

    /**

     * use old code...

     */

    public AudioInputStream getAudioInputStream(AudioFormat targetFormat, AudioInputStream sourceStream){

        if (!isConversionSupported(targetFormat, sourceStream.getFormat()))

            throw new IllegalArgumentException("Unsupported conversion: "

                                               + sourceStream.getFormat().toString() + " to "

                                               + targetFormat.toString());

        return getConvertedStream( targetFormat, sourceStream );

    }

    // OLD CODE

    /**

     * Opens the codec with the specified parameters.

     * @param stream stream from which data to be processed should be read

     * @param outputFormat desired data format of the stream after processing

     * @return stream from which processed data may be read

     * @throws IllegalArgumentException if the format combination supplied is

     * not supported.

     */

    /*  public AudioInputStream getConvertedStream(AudioFormat outputFormat, AudioInputStream stream) { */

    private AudioInputStream getConvertedStream(AudioFormat outputFormat, AudioInputStream stream) {

        AudioInputStream cs = null;

        AudioFormat inputFormat = stream.getFormat();

        if( inputFormat.matches(outputFormat) ) {

            cs = stream;

        } else {

            cs = (AudioInputStream) (new AlawCodecStream(stream, outputFormat));

        }

        return cs;

    }

    /**

     * Obtains the set of output formats supported by the codec

     * given a particular input format.

     * If no output formats are supported for this input format,

     * returns an array of length 0.

     * @return array of supported output formats.

     */

    /*  public AudioFormat[] getOutputFormats(AudioFormat inputFormat) { */

    private AudioFormat[] getOutputFormats(AudioFormat inputFormat) {

        Vector<AudioFormat> formats = new Vector<>();

        AudioFormat format;

        if (inputFormat.getSampleSizeInBits() == 16

                && AudioFormat.Encoding.PCM_SIGNED.equals(inputFormat.getEncoding())) {

            format = new AudioFormat(AudioFormat.Encoding.ALAW,

                                     inputFormat.getSampleRate(), 8,

                                     inputFormat.getChannels(),

                                     inputFormat.getChannels(),

                                     inputFormat.getSampleRate(), false);

            formats.addElement(format);

        }

        if (inputFormat.getSampleSizeInBits() == 8

                && AudioFormat.Encoding.ALAW.equals(inputFormat.getEncoding())) {

            format = new AudioFormat(AudioFormat.Encoding.PCM_SIGNED,

                                     inputFormat.getSampleRate(), 16,

                                     inputFormat.getChannels(),

                                     inputFormat.getChannels() * 2,

                                     inputFormat.getSampleRate(), false);

            formats.addElement(format);

            format = new AudioFormat(AudioFormat.Encoding.PCM_SIGNED,

                                     inputFormat.getSampleRate(), 16,

                                     inputFormat.getChannels(),

                                     inputFormat.getChannels() * 2,

                                     inputFormat.getSampleRate(), true);

            formats.addElement(format);

        }

        AudioFormat[] formatArray = new AudioFormat[formats.size()];

        for (int i = 0; i < formatArray.length; i++) {

            formatArray[i] = formats.elementAt(i);

        }

        return formatArray;

    }

    private final class AlawCodecStream extends AudioInputStream {

        // tempBuffer required only for encoding (when encode is true)

        private static final int tempBufferSize = 64;

        private byte tempBuffer [] = null;

        /**

         * True to encode to a-law, false to decode to linear

         */

        boolean encode = false;

        AudioFormat encodeFormat;

        AudioFormat decodeFormat;

        byte tabByte1[] = null;

        byte tabByte2[] = null;

        int highByte = 0;

        int lowByte  = 1;

        AlawCodecStream(AudioInputStream stream, AudioFormat outputFormat) {

            super(stream, outputFormat, -1);

            AudioFormat inputFormat = stream.getFormat();

            // throw an IllegalArgumentException if not ok

            if ( ! (isConversionSupported(outputFormat, inputFormat)) ) {

                throw new IllegalArgumentException("Unsupported conversion: " + inputFormat.toString() + " to " + outputFormat.toString());

            }

            //$$fb 2002-07-18: fix for 4714846: JavaSound ULAW (8-bit) encoder erroneously depends on endian-ness

            boolean PCMIsBigEndian;

            // determine whether we are encoding or decoding

            if (AudioFormat.Encoding.ALAW.equals(inputFormat.getEncoding())) {

                encode = false;

                encodeFormat = inputFormat;

                decodeFormat = outputFormat;

                PCMIsBigEndian = outputFormat.isBigEndian();

            } else {

                encode = true;

                encodeFormat = outputFormat;

                decodeFormat = inputFormat;

                PCMIsBigEndian = inputFormat.isBigEndian();

                tempBuffer = new byte[tempBufferSize];

            }

            if (PCMIsBigEndian) {

                tabByte1 = ALAW_TABH;

                tabByte2 = ALAW_TABL;

                highByte = 0;

                lowByte  = 1;

            } else {

                tabByte1 = ALAW_TABL;

                tabByte2 = ALAW_TABH;

                highByte = 1;

                lowByte  = 0;

            }

            // set the AudioInputStream length in frames if we know it

            if (stream instanceof AudioInputStream) {

                frameLength = stream.getFrameLength();

            }

            // set framePos to zero

            framePos = 0;

            frameSize = inputFormat.getFrameSize();

            if( frameSize==AudioSystem.NOT_SPECIFIED ) {

                frameSize=1;

            }

        }

        /*

         * $$jb 2/23/99

         * Used to determine segment number in aLaw encoding

         */

        private short search(short val, short table[], short size) {

            for(short i = 0; i < size; i++) {

                if (val <= table[i]) { return i; }

            }

            return size;

        }

        /**

         * Note that this won't actually read anything; must read in

         * two-byte units.

         */

        public int read() throws IOException {

            byte[] b = new byte[1];

            return read(b, 0, b.length);

        }

        public int read(byte[] b) throws IOException {

            return read(b, 0, b.length);

        }

        public int read(byte[] b, int off, int len) throws IOException {

            // don't read fractional frames

            if( len%frameSize != 0 ) {

                len -= (len%frameSize);

            }

            if (encode) {

                short QUANT_MASK = 0xF;

                short SEG_SHIFT = 4;

                short mask;

                short seg;

                int adj;

                int i;

                short sample;

                byte enc;

                int readCount = 0;

                int currentPos = off;

                int readLeft = len*2;

                int readLen = ( (readLeft>tempBufferSize) ? tempBufferSize : readLeft );

                while ((readCount = super.read(tempBuffer,0,readLen))>0) {

                    for (i = 0; i < readCount; i+=2) {

                        /* Get the sample from the tempBuffer */

                        sample = (short)(( (tempBuffer[i + highByte]) << 8) & 0xFF00);

                        sample |= (short)( (tempBuffer[i + lowByte]) & 0xFF);

                        if(sample >= 0) {

                            mask = 0xD5;

                        } else {

                            mask = 0x55;

                            sample = (short)(-sample - 8);

                        }

                        /* Convert the scaled magnitude to segment number. */

                        seg = search(sample, seg_end, (short) 8);

                        /*

                         * Combine the sign, segment, quantization bits

                         */

                        if (seg >= 8) {  /* out of range, return maximum value. */

                            enc = (byte) (0x7F ^ mask);

                        } else {

                            enc = (byte) (seg << SEG_SHIFT);

                            if(seg < 2) {

                                enc |= (byte) ( (sample >> 4) & QUANT_MASK);

                            } else {

                                enc |= (byte) ( (sample >> (seg + 3)) & QUANT_MASK );

                            }

                            enc ^= mask;

                        }

                        /* Now put the encoded sample where it belongs */

                        b[currentPos] = enc;

                        currentPos++;

                    }

                    /* And update pointers and counters for next iteration */

                    readLeft -= readCount;

                    readLen = ( (readLeft>tempBufferSize) ? tempBufferSize : readLeft );

                }

                if( currentPos==off && readCount<0 ) {  // EOF or error

                    return readCount;

                }

                return (currentPos - off);  /* Number of bytes written to new buffer */

            } else {

                int i;

                int readLen = len/2;

                int readOffset = off + len/2;

                int readCount = super.read(b, readOffset, readLen);

                for (i = off; i < (off + (readCount*2)); i+=2) {

                    b[i]        = tabByte1[b[readOffset] & 0xFF];

                    b[i+1]      = tabByte2[b[readOffset] & 0xFF];

                    readOffset++;

                }

                if( readCount<0 ) {             // EOF or error

                    return readCount;

                }

                return (i - off);

            }

        }

        @Override

        public long skip(final long n) throws IOException {

            // Implementation of this method assumes that we support

            // encoding/decoding from/to 8/16 bits only

            return encode ? super.skip(n * 2) / 2 : super.skip(n / 2) * 2;

        }

    } // end class AlawCodecStream

} // end class ALAW