/*
* Copyright (C) 2003-2009 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef QUEUE_H
#define QUEUE_H
#include <glib.h>
#include <assert.h>
#include <stdbool.h>
#include <stdint.h>
enum {
/**
* reserve max_length * QUEUE_HASH_MULT elements in the id
* number space
*/
QUEUE_HASH_MULT = 4,
};
/**
* One element of the queue: basically a song plus some queue specific
* information attached.
*/
struct queue_item {
struct song *song;
/** the unique id of this item in the queue */
unsigned id;
/** when was this item last changed? */
uint32_t version;
};
/**
* A queue of songs. This is the backend of the playlist: it contains
* an ordered list of songs.
*
* Songs can be addressed in three possible ways:
*
* - the position in the queue
* - the unique id (which stays the same, regardless of moves)
* - the order number (which only differs from "position" in random mode)
*/
struct queue {
/** configured maximum length of the queue */
unsigned max_length;
/** number of songs in the queue */
unsigned length;
/** the current version number */
uint32_t version;
/** all songs in "position" order */
struct queue_item *items;
/** map order numbers to positions */
unsigned *order;
/** map song ids to posiitons */
int *idToPosition;
/** repeat playback when the end of the queue has been
reached? */
bool repeat;
/** play back songs in random order? */
bool random;
/** random number generator for shuffle and random mode */
GRand *rand;
};
static inline unsigned
queue_length(const struct queue *queue)
{
assert(queue->length <= queue->max_length);
return queue->length;
}
/**
* Determine if the queue is empty, i.e. there are no songs.
*/
static inline bool
queue_is_empty(const struct queue *queue)
{
return queue->length == 0;
}
/**
* Determine if the maximum number of songs has been reached.
*/
static inline bool
queue_is_full(const struct queue *queue)
{
assert(queue->length <= queue->max_length);
return queue->length >= queue->max_length;
}
/**
* Is that a valid position number?
*/
static inline bool
queue_valid_position(const struct queue *queue, unsigned position)
{
return position < queue->length;
}
/**
* Is that a valid order number?
*/
static inline bool
queue_valid_order(const struct queue *queue, unsigned order)
{
return order < queue->length;
}
static inline int
queue_id_to_position(const struct queue *queue, unsigned id)
{
if (id >= queue->max_length * QUEUE_HASH_MULT)
return -1;
assert(queue->idToPosition[id] >= -1);
assert(queue->idToPosition[id] < (int)queue->length);
return queue->idToPosition[id];
}
static inline int
queue_position_to_id(const struct queue *queue, unsigned position)
{
assert(position < queue->length);
return queue->items[position].id;
}
static inline unsigned
queue_order_to_position(const struct queue *queue, unsigned order)
{
assert(order < queue->length);
return queue->order[order];
}
static inline unsigned
queue_position_to_order(const struct queue *queue, unsigned position)
{
assert(position < queue->length);
for (unsigned i = 0;; ++i) {
assert(i < queue->length);
if (queue->order[i] == position)
return i;
}
}
/**
* Returns the song at the specified position.
*/
static inline struct song *
queue_get(const struct queue *queue, unsigned position)
{
assert(position < queue->length);
return queue->items[position].song;
}
/**
* Returns the song at the specified order number.
*/
static inline struct song *
queue_get_order(const struct queue *queue, unsigned order)
{
return queue_get(queue, queue_order_to_position(queue, order));
}
/**
* Is the song at the specified position newer than the specified
* version?
*/
static inline bool
queue_song_newer(const struct queue *queue, unsigned position,
uint32_t version)
{
assert(position < queue->length);
return version > queue->version ||
queue->items[position].version >= version ||
queue->items[position].version == 0;
}
/**
* Initialize a queue object.
*/
void
queue_init(struct queue *queue, unsigned max_length);
/**
* Deinitializes a queue object. It does not free the queue pointer
* itself.
*/
void
queue_finish(struct queue *queue);
/**
* Generate a non-existing id number.
*/
unsigned
queue_generate_id(const struct queue *queue);
/**
* Returns the order number following the specified one. This takes
* end of queue and "repeat" mode into account.
*
* @return the next order number, or -1 to stop playback
*/
int
queue_next_order(const struct queue *queue, unsigned order);
/**
* Increments the queue's version number. This handles integer
* overflow well.
*/
void
queue_increment_version(struct queue *queue);
/**
* Marks the specified song as "modified" and increments the version
* number.
*/
void
queue_modify(struct queue *queue, unsigned order);
/**
* Marks all songs as "modified" and increments the version number.
*/
void
queue_modify_all(struct queue *queue);
/**
* Appends a song to the queue and returns its position. Prior to
* that, the caller must check if the queue is already full.
*
* If a song is not in the database (determined by
* song_in_database()), it is freed when removed from the queue.
*/
unsigned
queue_append(struct queue *queue, struct song *song);
/**
* Swaps two songs, addressed by their position.
*/
void
queue_swap(struct queue *queue, unsigned position1, unsigned position2);
/**
* Swaps two songs, addressed by their order number.
*/
static inline void
queue_swap_order(struct queue *queue, unsigned order1, unsigned order2)
{
unsigned tmp = queue->order[order1];
queue->order[order1] = queue->order[order2];
queue->order[order2] = tmp;
}
/**
* Moves a song to a new position.
*/
void
queue_move(struct queue *queue, unsigned from, unsigned to);
/**
* Removes a song from the playlist.
*/
void
queue_delete(struct queue *queue, unsigned position);
/**
* Removes all songs from the playlist.
*/
void
queue_clear(struct queue *queue);
/**
* Initializes the "order" array, and restores "normal" order.
*/
static inline void
queue_restore_order(struct queue *queue)
{
for (unsigned i = 0; i < queue->length; ++i)
queue->order[i] = i;
}
/**
* Shuffles a (position) range in the queue. The songs are physically
* shuffled, not by using the "order" mapping.
*/
void
queue_shuffle_range(struct queue *queue, unsigned start, unsigned end);
#endif
