The mapper library maps directory and song objects to file system
paths.  With this central library, the code mixture in path.c should
be cleaned up, and we will be able to add neat features like aliasing.

The runtime check suggests that the author has somehow thought
song_get_url(NULL) might be valid.  It should not be.  Replace it with
an assertion.

CamelCase is ugly...  rename all functions.

"bool" should be used in C99 programs for boolean values.

Again, a data type which can be forward-declared.

Why have a "_func" prefix on all method names?  Also don't typedef the
methods, there is no advantage in that.

There was a known deadlocking bug in the notify library: when the
other thread set notify->pending after the according check in
notify_wait(), the latter thread was deadlocked.  Resolve this by
synchronizing all accesses to notify->pending with the notify object's
mutex.  Since notify_signal_sync() was never used, we can remove it.
As a consequence, we don't need notify_enter() and notify_leave()
anymore; eliminate them, too.

Give player.c a better name, meaning that the code is used to control
the player thread.

It should be obvious in which thread or context a function is being
executed at runtime.  The code which was left in decode.c is for the
decoder thread itself; give the file a better name.

This is the last of the three variables.  Now we don't need
playerData.h anymore in most sources.

This flag is used internally; it is set by decoder_seek_where(), and
indicates that the decoder plugin has begun the seek process.  It is
used for the case that the decoder plugin has to read data during the
seek process.  Before this patch, that was impossible, because
decoder_read() would refuse to read data unless dc->command is NONE.
This patch is kind of a dirty workaround, and needs to be redesigned
later.

The flag "ready" indicates whether the input stream is ready and it
has parsed all meta data.  Previously, it was impossible for
decodeStart() to see the content type of HTTP input streams, because
at that time, the HTTP response wasn't parsed yet.

Move code which runs in the player thread to player_thread.c.  Having
a lot of player thread code in decode.c isn't easy to understand.

decode.c should be a lot smaller; start by moving all code which
handles cross-fading to crossfade.c.  Also includes camelCase
conversion.

Make the code more readable by hiding big formulas in an inline
function with a nice name.

Make calculateCrossFadeChunks() more generic and portable by
eliminating global variable access.

InputPlugin to decoder_plugin, and no camelCase.

"decoder plugin" is a better name than "input plugin", since the
plugin does not actually do the input - InputStream does.  Also don't
use typedef, so we can forward-declare it if required.

PlayerControl.command replaces the old attributes play, stop, pause,
closeAudio, lockQueue, unlockQueue, seek.  The main thread waits for
each command synchronously, so there can only be one command enabled
at a time anyway.

Some decoder commands are implemented in the decoder plugins, thus
they need to have an API call to signal that their current command has
been finished.  Let them use the new decoder_command_finished()
instead of the internal dc_command_finished().

We want to expose the AudioFormat structure to plugins; remove some
clutter by moving its declaration to a separate header file.

After the decoder has been initialized and the audio device has been
opened, don't sleep.  The decoder plugin won't do anything special nor
will it care to wake us up for some reason.

The decoder struct should later be made opaque to the decoder plugin,
because maintaining a stable struct ABI is quite difficult.  The ABI
should only consist of a small number of stable functions.

Don't use wrappers like player_wakeup_decoder_nb().  These have been
wrappers calling notify.c functions, for compatibility with the
existing code when we migrated to notify.c.

The "if" block breaked out of the loop.  That means we can move the
code out of the "else" block.

dc_command_finished() is invoked by the decoder thread when it has
finished a command (sent by the player thread).  It resets dc.command
and wakes up the player thread.  This combination was used at a lot of
places, and by introducing this function, the code will be more
readable.

Busy wait loops are a bad thing, especially when the response time can
be very long - busy waits eat a lot of CPU, and thus slow down the
other thread.  Since the other thread will notify us when it's ready,
we can use notify_wait() instead.

Much of the existing code queries all three variables sequentially.
Since only one of them can be set at a time, this can be optimized and
unified by merging all of them into one enum variable.  Later, the
"command" checks can be expressed in a "switch" statement.

pc->errored_song is already set by decodeParent() in the player thread
when we set dc->error; no need to set it in the decoder thread.

Since pc->current_song denotes the song which the decoder should use
next, we should move it to DecoderControl.  This removes one internal
PlayerControl struct access from the decoder code.

Also add pc.next_song, which is manipulated by the playlist code, and
gets copied to dc.next_song as soon as the decoder is started.

Streaming was broken, beacuse the stream URL was never copied to
path_max_fs.

[ew: replaced strcpy with pathcpy_trunc for ease of auditing]

git-svn-id: https://svn.musicpd.org/mpd/trunk@7371 09075e82-0dd4-0310-85a5-a0d7c8717e4f

git-svn-id: https://svn.musicpd.org/mpd/trunk@7367 09075e82-0dd4-0310-85a5-a0d7c8717e4f

During the decoder thread main loop, dc.state must be
DECODE_STATE_STOP.  Explicitly assigning it after the "dc.stop" check
is redundant.

git-svn-id: https://svn.musicpd.org/mpd/trunk@7366 09075e82-0dd4-0310-85a5-a0d7c8717e4f

In lazy mode (previously the default), outputBuffer.c only wakes up
the player when it was previously empty.  That caused a deadlock when
the player was waiting for buffered_before_play, since the decoder
wouldn't wake up the player when buffered_before_play was reached.  In
non-lazy mode, always wake up the player when a new chunk was decoded.

git-svn-id: https://svn.musicpd.org/mpd/trunk@7364 09075e82-0dd4-0310-85a5-a0d7c8717e4f

git-svn-id: https://svn.musicpd.org/mpd/trunk@7362 09075e82-0dd4-0310-85a5-a0d7c8717e4f

git-svn-id: https://svn.musicpd.org/mpd/trunk@7359 09075e82-0dd4-0310-85a5-a0d7c8717e4f

git-svn-id: https://svn.musicpd.org/mpd/trunk@7358 09075e82-0dd4-0310-85a5-a0d7c8717e4f