mpd/src/util/PeakBuffer.cxx

131 lines
2.9 KiB
C++

/*
* Copyright 2003-2021 The Music Player Daemon Project
* http://www.musicpd.org
*
* 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 2 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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "PeakBuffer.hxx"
#include "DynamicFifoBuffer.hxx"
#include <algorithm>
#include <cassert>
PeakBuffer::~PeakBuffer() noexcept
{
delete normal_buffer;
delete peak_buffer;
}
bool
PeakBuffer::empty() const noexcept
{
return (normal_buffer == nullptr || normal_buffer->empty()) &&
(peak_buffer == nullptr || peak_buffer->empty());
}
std::span<std::byte>
PeakBuffer::Read() const noexcept
{
if (normal_buffer != nullptr) {
const auto p = normal_buffer->Read();
if (!p.empty())
return p;
}
if (peak_buffer != nullptr) {
const auto p = peak_buffer->Read();
if (!p.empty())
return p;
}
return {};
}
void
PeakBuffer::Consume(std::size_t length) noexcept
{
if (normal_buffer != nullptr && !normal_buffer->empty()) {
normal_buffer->Consume(length);
return;
}
if (peak_buffer != nullptr && !peak_buffer->empty()) {
peak_buffer->Consume(length);
if (peak_buffer->empty()) {
delete peak_buffer;
peak_buffer = nullptr;
}
return;
}
}
static std::size_t
AppendTo(DynamicFifoBuffer<std::byte> &buffer,
std::span<const std::byte> src) noexcept
{
assert(!src.empty());
std::size_t total = 0;
do {
const auto p = buffer.Write();
if (p.empty())
break;
const std::size_t nbytes = std::min(src.size(), p.size());
std::copy_n(src.begin(), nbytes, p.begin());
buffer.Append(nbytes);
src = src.subspan(nbytes);
total += nbytes;
} while (!src.empty());
return total;
}
bool
PeakBuffer::Append(std::span<const std::byte> src)
{
if (src.empty())
return true;
if (peak_buffer != nullptr && !peak_buffer->empty()) {
std::size_t nbytes = AppendTo(*peak_buffer, src);
return nbytes == src.size();
}
if (normal_buffer == nullptr)
normal_buffer = new DynamicFifoBuffer<std::byte>(normal_size);
std::size_t nbytes = AppendTo(*normal_buffer, src);
if (nbytes > 0) {
src = src.subspan(nbytes);
if (src.empty())
return true;
}
if (peak_buffer == nullptr) {
if (peak_size > 0)
peak_buffer = new DynamicFifoBuffer<std::byte>(peak_size);
if (peak_buffer == nullptr)
return false;
}
nbytes = AppendTo(*peak_buffer, src);
return nbytes == src.size();
}