uk.co.modularaudio.util.audio.mad.hardwareio.LocklessHardwareMidiNoteRingBuffer.java Source code

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Here is the source code for uk.co.modularaudio.util.audio.mad.hardwareio.LocklessHardwareMidiNoteRingBuffer.java

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/**
 *
 * Copyright (C) 2015 - Daniel Hams, Modular Audio Limited
 *                      daniel.hams@gmail.com
 *
 * Mad is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Mad 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Mad.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

package uk.co.modularaudio.util.audio.mad.hardwareio;

import java.nio.BufferUnderflowException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import uk.co.modularaudio.util.audio.buffer.LocklessPreallocatingGenericRingBuffer;

public class LocklessHardwareMidiNoteRingBuffer
        extends LocklessPreallocatingGenericRingBuffer<HardwareMidiNoteEvent> {
    private static Log log = LogFactory.getLog(LocklessHardwareMidiNoteRingBuffer.class.getName());

    private final static HardwareMidiNoteEventCopier NOTE_COPIER = new HardwareMidiNoteEventCopier();

    public LocklessHardwareMidiNoteRingBuffer(final int capacity) {
        super(HardwareMidiNoteEvent.class, NOTE_COPIER, capacity);
        // Now initialise empty objects inside the internal array
        for (int i = 0; i < capacity; i++) {
            buffer[i] = new HardwareMidiNoteEvent();
        }
    }

    @Override
    public int read(final HardwareMidiNoteEvent[] target, final int pos, final int length)
            throws BufferUnderflowException {
        return super.read(target, pos, length);
    }

    @Override
    public int write(final HardwareMidiNoteEvent[] source, final int pos, final int length) {
        return super.write(source, pos, length);
    }

    public int readUpToMaxNumAndFrameTime(final HardwareMidiNoteEvent[] target, final int pos, final int maxNum,
            final long endFrameTime) {
        boolean success = false;
        int numRead = 0;
        while (!success) {
            final int curReadPosition = readPosition.get();
            final int curWritePosition = writePosition.get();
            final int numReadable = calcNumReadable(curReadPosition, curWritePosition);
            if (numReadable == 0) {
                return 0;
            }
            int length = (numReadable < maxNum ? numReadable : maxNum);

            // Now check the timestamp to work out how many we will actually read out
            boolean done = false;
            int numToRead = 0;
            for (int c = 0; !done && c < length; c++) {
                int posToCheck = curReadPosition + c;
                if (posToCheck > (bufferLength - 1)) {
                    posToCheck -= bufferLength;
                }
                ;
                final long bufferEventFrameTime = buffer[posToCheck].eventFrameTime;
                if (bufferEventFrameTime > endFrameTime) {
                    if (c == 0) {
                        return 0;
                    } else {
                        done = true;
                    }
                } else {
                    numToRead++;
                }
            }

            if (numToRead > 0) {
                length = numToRead;
            }

            if (curWritePosition > curReadPosition) {
                // Copy from the ring buffer directly into the output and update the read position
                copyFromToLength(buffer, curReadPosition, target, pos, length);
                numRead = length;
            } else if (curReadPosition > curWritePosition) {
                // Case where the read position might loop over the end of the buffer
                if (curReadPosition + length > bufferLength) {
                    final int numToReadFromEnd = bufferLength - curReadPosition;
                    final int numToReadFromStart = length - numToReadFromEnd;
                    copyFromToLength(buffer, curReadPosition, target, pos, numToReadFromEnd);
                    copyFromToLength(buffer, 0, target, pos + numToReadFromEnd, numToReadFromStart);
                } else {
                    // Fits before the end of the ring
                    copyFromToLength(buffer, curReadPosition, target, pos, length);
                }

                numRead = length;
            } else {
                log.error("Case analysis error in ring read");
                throw new BufferUnderflowException();
            }

            int newPosition = curReadPosition + length;

            if (newPosition >= bufferLength) {
                newPosition -= bufferLength;
            }
            success = readPosition.compareAndSet(curReadPosition, newPosition);
        }
        return numRead;
    }

}