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/*******************************************************************************
* Copyright 2009-2016 Jörg Müller
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
******************************************************************************/
#include "fx/ReverseReader.h"
#include "Exception.h"
#include <cstring>
AUD_NAMESPACE_BEGIN
ReverseReader::ReverseReader(std::shared_ptr<IReader> reader) :
EffectReader(reader),
m_length(reader->getLength()),
m_position(0)
{
if(m_length < 0 || !reader->isSeekable())
AUD_THROW(StateException, "A reader has to be seekable and have finite length to be reversible.");
}
void ReverseReader::seek(int position)
{
m_position = position;
}
int ReverseReader::getLength() const
{
return m_length;
}
int ReverseReader::getPosition() const
{
return m_position;
}
void ReverseReader::read(int& length, bool& eos, sample_t* buffer)
{
// first correct the length
if(m_position + length > m_length)
length = m_length - m_position;
if(length <= 0)
{
length = 0;
eos = true;
return;
}
const Specs specs = getSpecs();
const int samplesize = AUD_SAMPLE_SIZE(specs);
sample_t temp[CHANNEL_MAX];
int len = length;
// read from reader
m_reader->seek(m_length - m_position - len);
m_reader->read(len, eos, buffer);
// set null if reader didn't give enough data
if(len < length)
std::memset(buffer, 0, (length - len) * samplesize);
// copy the samples reverted
for(int i = 0; i < length / 2; i++)
{
std::memcpy(temp, buffer + (len - 1 - i) * specs.channels, samplesize);
std::memcpy(buffer + (len - 1 - i) * specs.channels, buffer + i * specs.channels, samplesize);
std::memcpy(buffer + i * specs.channels, temp, samplesize);
}
m_position += length;
eos = false;
}
AUD_NAMESPACE_END
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