soundtouch/source/SoundTouch/FIFOSampleBuffer.cpp

////////////////////////////////////////////////////////////////////////////////
///
/// A buffer class for temporarily storaging sound samples, operates as a 
/// first-in-first-out pipe.
///
/// Samples are added to the end of the sample buffer with the 'putSamples' 
/// function, and are received from the beginning of the buffer by calling
/// the 'receiveSamples' function. The class automatically removes the 
/// outputted samples from the buffer, as well as grows the buffer size 
/// whenever necessary.
///
/// Author        : Copyright (c) Olli Parviainen
/// Author e-mail : oparviai 'at' iki.fi
/// SoundTouch WWW: http://www.surina.net/soundtouch
///
////////////////////////////////////////////////////////////////////////////////
//
// Last changed  : $Date$
// File revision : $Revision: 4 $
//
// $Id$
//
////////////////////////////////////////////////////////////////////////////////
//
// License :
//
//  SoundTouch audio processing library
//  Copyright (c) Olli Parviainen
//
//  This library is free software; you can redistribute it and/or
//  modify it under the terms of the GNU Lesser General Public
//  License as published by the Free Software Foundation; either
//  version 2.1 of the License, or (at your option) any later version.
//
//  This library 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
//  Lesser General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public
//  License along with this library; if not, write to the Free Software
//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
////////////////////////////////////////////////////////////////////////////////

#include <stdlib.h>
#include <memory.h>
#include <string.h>
#include <assert.h>
#include <stdexcept>

#include "FIFOSampleBuffer.h"

using namespace soundtouch;

// Constructor
FIFOSampleBuffer::FIFOSampleBuffer(int numChannels)
{
    assert(numChannels > 0);
    sizeInBytes = 0; // reasonable initial value
    buffer = NULL;
    bufferUnaligned = NULL;
    samplesInBuffer = 0;
    bufferPos = 0;
    channels = (uint)numChannels;
}


// destructor
FIFOSampleBuffer::~FIFOSampleBuffer()
{
    delete[] bufferUnaligned;
    bufferUnaligned = NULL;
    buffer = NULL;
}


// Sets number of channels, 1 = mono, 2 = stereo
void FIFOSampleBuffer::setChannels(int numChannels)
{
    uint usedBytes;

    assert(numChannels > 0);
    usedBytes = channels * samplesInBuffer;
    channels = (uint)numChannels;
    samplesInBuffer = usedBytes / channels;
}


// if output location pointer 'bufferPos' isn't zero, 'rewinds' the buffer and
// zeroes this pointer by copying samples from the 'bufferPos' pointer 
// location on to the beginning of the buffer.
void FIFOSampleBuffer::rewind()
{
    if (buffer && bufferPos) 
    {
        memmove(buffer, ptrBegin(), sizeof(SAMPLETYPE) * channels * samplesInBuffer);
        bufferPos = 0;
    }
}


// Adds 'numSamples' pcs of samples from the 'samples' memory position to 
// the sample buffer.
void FIFOSampleBuffer::putSamples(const SAMPLETYPE *samples, uint nSamples)
{
    memcpy(ptrEnd(nSamples), samples, sizeof(SAMPLETYPE) * nSamples * channels);
    samplesInBuffer += nSamples;
}


// Increases the number of samples in the buffer without copying any actual
// samples.
//
// This function is used to update the number of samples in the sample buffer
// when accessing the buffer directly with 'ptrEnd' function. Please be 
// careful though!
void FIFOSampleBuffer::putSamples(uint nSamples)
{
    uint req;

    req = samplesInBuffer + nSamples;
    ensureCapacity(req);
    samplesInBuffer += nSamples;
}


// Returns a pointer to the end of the used part of the sample buffer (i.e. 
// where the new samples are to be inserted). This function may be used for 
// inserting new samples into the sample buffer directly. Please be careful! 
//
// Parameter 'slackCapacity' tells the function how much free capacity (in
// terms of samples) there _at least_ should be, in order to the caller to
// succesfully insert all the required samples to the buffer. When necessary, 
// the function grows the buffer size to comply with this requirement.
//
// When using this function as means for inserting new samples, also remember 
// to increase the sample count afterwards, by calling  the 
// 'putSamples(numSamples)' function.
SAMPLETYPE *FIFOSampleBuffer::ptrEnd(uint slackCapacity) 
{
    ensureCapacity(samplesInBuffer + slackCapacity);
    return buffer + samplesInBuffer * channels;
}


// Returns a pointer to the beginning of the currently non-outputted samples. 
// This function is provided for accessing the output samples directly. 
// Please be careful!
//
// When using this function to output samples, also remember to 'remove' the
// outputted samples from the buffer by calling the 
// 'receiveSamples(numSamples)' function
SAMPLETYPE *FIFOSampleBuffer::ptrBegin() const
{
    return buffer + bufferPos * channels;
}


// Ensures that the buffer has enought capacity, i.e. space for _at least_
// 'capacityRequirement' number of samples. The buffer is grown in steps of
// 4 kilobytes to eliminate the need for frequently growing up the buffer,
// as well as to round the buffer size up to the virtual memory page size.
void FIFOSampleBuffer::ensureCapacity(uint capacityRequirement)
{
    SAMPLETYPE *tempUnaligned, *temp;

    if (capacityRequirement > getCapacity()) 
    {
        // enlarge the buffer in 4kbyte steps (round up to next 4k boundary)
        sizeInBytes = (capacityRequirement * channels * sizeof(SAMPLETYPE) + 4095) & (uint)-4096;
        assert(sizeInBytes % 2 == 0);
        tempUnaligned = new SAMPLETYPE[sizeInBytes / sizeof(SAMPLETYPE) + 16 / sizeof(SAMPLETYPE)];
        if (tempUnaligned == NULL)
        {
            throw std::runtime_error("Couldn't allocate memory!\n");
        }
        temp = (SAMPLETYPE *)(((ulong)tempUnaligned + 15) & (ulong)-16);
        memcpy(temp, ptrBegin(), samplesInBuffer * channels * sizeof(SAMPLETYPE));
        delete[] bufferUnaligned;
        buffer = temp;
        bufferUnaligned = tempUnaligned;
        bufferPos = 0;
    } 
    else 
    {
        // simply rewind the buffer (if necessary)
        rewind();
    }
}


// Returns the current buffer capacity in terms of samples
uint FIFOSampleBuffer::getCapacity() const
{
    return sizeInBytes / (channels * sizeof(SAMPLETYPE));
}


// Returns the number of samples currently in the buffer
uint FIFOSampleBuffer::numSamples() const
{
    return samplesInBuffer;
}


// Output samples from beginning of the sample buffer. Copies demanded number
// of samples to output and removes them from the sample buffer. If there
// are less than 'numsample' samples in the buffer, returns all available.
//
// Returns number of samples copied.
uint FIFOSampleBuffer::receiveSamples(SAMPLETYPE *output, uint maxSamples)
{
    uint num;

    num = (maxSamples > samplesInBuffer) ? samplesInBuffer : maxSamples;

    memcpy(output, ptrBegin(), channels * sizeof(SAMPLETYPE) * num);
    return receiveSamples(num);
}


// Removes samples from the beginning of the sample buffer without copying them
// anywhere. Used to reduce the number of samples in the buffer, when accessing
// the sample buffer with the 'ptrBegin' function.
uint FIFOSampleBuffer::receiveSamples(uint maxSamples)
{
    if (maxSamples >= samplesInBuffer)
    {
        uint temp;

        temp = samplesInBuffer;
        samplesInBuffer = 0;
        return temp;
    }

    samplesInBuffer -= maxSamples;
    bufferPos += maxSamples;

    return maxSamples;
}


// Returns nonzero if the sample buffer is empty
int FIFOSampleBuffer::isEmpty() const
{
    return (samplesInBuffer == 0) ? 1 : 0;
}


// Clears the sample buffer
void FIFOSampleBuffer::clear()
{
    samplesInBuffer = 0;
    bufferPos = 0;
}