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/*
* Copyright 2003-2019 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.
*/
#ifndef MPD_ALSA_PERIOD_BUFFER_HXX
#define MPD_ALSA_PERIOD_BUFFER_HXX
#include <alsa/asoundlib.h>
#include <algorithm>
#include <stdint.h>
namespace Alsa {
class PeriodBuffer {
size_t capacity, head, tail;
uint8_t *buffer;
public:
PeriodBuffer() = default;
PeriodBuffer(const PeriodBuffer &) = delete;
PeriodBuffer &operator=(const PeriodBuffer &) = delete;
void Allocate(size_t n_frames, size_t frame_size) noexcept {
capacity = n_frames * frame_size;
/* reserve space for one more (partial) frame,
to be able to fill the buffer with silence,
after moving an unfinished frame to the
end */
buffer = new uint8_t[capacity + frame_size - 1];
head = tail = 0;
}
void Free() noexcept {
delete[] buffer;
}
bool IsEmpty() const noexcept {
return head == tail;
}
bool IsFull() const noexcept {
return tail >= capacity;
}
uint8_t *GetTail() noexcept {
return buffer + tail;
}
size_t GetSpaceBytes() const noexcept {
assert(tail <= capacity);
return capacity - tail;
}
void AppendBytes(size_t n) noexcept {
assert(n <= capacity);
assert(tail <= capacity - n);
tail += n;
}
void FillWithSilence(const uint8_t *_silence,
const size_t frame_size) noexcept {
size_t partial_frame = tail % frame_size;
auto *dest = GetTail() - partial_frame;
/* move the partial frame to the end */
std::copy(dest, GetTail(), buffer + capacity);
size_t silence_size = capacity - tail - partial_frame;
std::copy_n(_silence, silence_size, dest);
tail = capacity + partial_frame;
}
const uint8_t *GetHead() const noexcept {
return buffer + head;
}
snd_pcm_uframes_t GetFrames(size_t frame_size) const noexcept {
return (tail - head) / frame_size;
}
void ConsumeBytes(size_t n) noexcept {
head += n;
assert(head <= capacity);
if (head >= capacity) {
tail -= head;
/* copy the partial frame (if any)
back to the beginning */
std::copy_n(GetHead(), tail, buffer);
head = 0;
}
}
void ConsumeFrames(snd_pcm_uframes_t n, size_t frame_size) noexcept {
ConsumeBytes(n * frame_size);
}
snd_pcm_uframes_t GetPeriodPosition(size_t frame_size) const noexcept {
return head / frame_size;
}
void Rewind() noexcept {
head = 0;
}
void Clear() noexcept {
head = tail = 0;
}
};
} // namespace Alsa
#endif