fragment.cpp

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/*
    Beatmup image and signal processing library
    Copyright (C) 2019, lnstadrum
 
    This program 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.
 
    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
*/
 
#include "fragment.h"
 
using namespace Beatmup::Fragments;
 
 
Fragment::Fragment() : referenceCount(0), sampleCount(0) {};
 
 
Fragment* Fragment::edit() {
    std::lock_guard<std::mutex> lock(access);
    if (referenceCount > 1) {
        --referenceCount;
        Fragment* copy = clone();
        copy->referenceCount = 1;
        return copy;
    }
    return this;
}
 
 
Fragment* Fragment::use() {
    std::lock_guard<std::mutex> lock(access);
    ++referenceCount;
    return this;
}
 
 
void Fragment::drop() {
    std::unique_lock<std::mutex> lock(access);
    if (referenceCount <= 1) {
        lock.unlock();
        delete this;
        return;
    }
    --referenceCount;
    lock.unlock();
}
 
 
void FragmentPtr::operator =(const FragmentPtr& src) {
    if (!isNull())
        fragment->drop();
    if (src.isNull())
        nullify();
    else {
        fragment = src.fragment->use();
        offset = src.offset;
        length = src.length;
    }
}
 
 
FragmentPtr::FragmentPtr() {
    fragment = NULL;
    offset = length = 0;
}
 
 
 
FragmentPtr::FragmentPtr(Fragment& fragment, int offset, int length):
    fragment(&fragment), offset(offset), length(length)
{
    fragment.use();
}
 
 
FragmentPtr::FragmentPtr(const FragmentPtr& src) {
    if (src.isNull()) {
        fragment = NULL;
        offset = length = 0;
    }
    else {
        fragment = src.fragment->use();
        offset = src.offset;
        length = src.length;
    }
}
 
 
FragmentPtr::FragmentPtr(FragmentPtr&& src) {
    fragment = src.fragment;
    offset = src.offset;
    length = src.length;
    // nullifying source
    src.fragment = NULL;
    src.offset = src.length = 0;
}
 
 
FragmentPtr::~FragmentPtr() {
    if (!isNull())
        fragment->drop();
}
 
 
void FragmentPtr::editData() {
    fragment = fragment->edit();
        // No need to check if the fragment is cloned or not and drop the original if it is.
        // If it is cloned, there is at least one reference to the original fragment.
        // So no dropping, just decrease ref counter in fragment->edit().
}
 
 
void FragmentPtr::nullify() {
    if (!isNull())
        fragment->drop();
    fragment = NULL;
    offset = length = 0;
}