fixing alsa step 2: complete rewrite of data transfer. The whole stuff is clean enough to go from there now.

Original commit message from CVS:
fixing alsa step 2: complete rewrite of data transfer. The whole stuff is clean enough to go from there now.
License change to LGPL, since no copied code is left now.
Missing:
- alsasrc
- resetting format
- corner cases
- testsuite

ext/alsa/README

@@ -3,7 +3,8 @@
 
 This plugin was originally written by Thomas Nyberg <thomas@codefactory.se> for
 ALSA 0.5.x. It was updated and changed quite a bit in September 2001 by Andy
-Wingo for use with ALSA 0.9.x.
+Wingo for use with ALSA 0.9.x. It was rewritten in great part again by Benjamin 
+Otte in January/February 2003.
 
 1.0 Introduction
 ----------------
@@ -44,21 +45,18 @@ My particular card has 4 channel out and 2 channel in. As you can see, each of
 these devices are stereo. The alsasink and alsasrc elements correspond to the
 default alsa devices.
 
-3.0 License
+3.0 Where to look for other ALSA drivers
+----------------------------------------
+
+ALSA 0.9 isn't very well documented, so we had to rely on a number of different
+sources for guidance. Sources of inspiration include JACK's alsa driver 
+(available in jack's cvs tree, http://jack.sourceforge.net/), the alsa2 driver 
+of mplayer (http://www.mplayerhq.hu) and the pcm.c example from the ALSA library
+itself.
+(http://www.alsa-project.org/alsa-doc/alsa-lib/_2test_2pcm_8c-example.html)
+
+4.0 License
 -----------
 
-ALSA 0.9.x isn't very well documented, so I had to rely on a number of different
+This plugin is licensed under the Lesser General Public License (LGPL). See the
-sources for guidance. One of the main sources of inspiration was Paul Davis'
+file COPYING in the top source directory.
-audioengine (available in quasimodo's cvs tree,
-http://quasimodo.sourceforge.net/), from which I took a large amount of code.
-Since that project is licensed under the GPL, it was only right that I license
-the updated version of this plugin under the GPL as well. What, in my
-understanding, this means for the end user is that you cannot use the ALSA
-plugin with a non-GPL program. If in doubt, please refer to the COPYING file
-located in this directory.
-
-
-
-
-
-

ext/alsa/gstalsa.h

@@ -2,6 +2,7 @@
  * Copyright (C) 2001 CodeFactory AB
  * Copyright (C) 2001 Thomas Nyberg <thomas@codefactory.se>
  * Copyright (C) 2001-2002 Andy Wingo <apwingo@eos.ncsu.edu>
+ * Copyright (C) 2003 Benjamin Otte <in7y118@public.uni-hamburg.de>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ -21,11 +22,16 @@
 #ifndef __GST_ALSA_H__
 #define __GST_ALSA_H__
 
+#define ALSA_PCM_NEW_HW_PARAMS_API
+#define ALSA_PCM_NEW_SW_PARAMS_API
+
 #include <alsa/asoundlib.h>
 #include <gst/gst.h>
 #include <gst/bytestream/bytestream.h>
 #include <glib.h>
 
+#define GST_ALSA_MAX_CHANNELS 64 /* we don't support more than 64 channels */
+
 #define GST_ALSA(obj) G_TYPE_CHECK_INSTANCE_CAST(obj, GST_TYPE_ALSA, GstAlsa)
 #define GST_ALSA_CLASS(klass) G_TYPE_CHECK_CLASS_CAST(klass, GST_TYPE_ALSA, GstAlsaClass)
 #define GST_IS_ALSA(obj) G_TYPE_CHECK_INSTANCE_TYPE(obj, GST_TYPE_ALSA)
@@ -44,8 +50,6 @@
 #define GST_IS_ALSA_SRC_CLASS(klass) G_TYPE_CHECK_CLASS_TYPE(klass, GST_TYPE_ALSA_SRC)
 #define GST_TYPE_ALSA_SRC gst_alsa_src_get_type()
 
-#define GST_ALSA_PAD(obj) ((GstAlsaPad*)obj->data) /* obj is a GList */
-
 /* I would have preferred to avoid this variety of trickery, but without it i
  * can't tell whether I'm a source or a sink upon creation. */
 
@@ -62,59 +66,32 @@ enum {
   GST_ALSA_FLAG_LAST = GST_ELEMENT_FLAG_LAST + 3,
 };
 
-typedef gboolean (*GstAlsaProcessFunc) (GstAlsa *, snd_pcm_uframes_t frames);
-
 typedef struct {
-  gint channel;
   GstPad *pad;
   GstByteStream *bs;
-
+  guint8 *data;
-  /* buf and offset are only used for src elements to hold data from the sound
-     card, while we're waiting for an entire period_frames data. */
-  char *buf;
-  snd_pcm_uframes_t offset;
 } GstAlsaPad;
 
 struct _GstAlsa {
   GstElement parent;
 
-  /* list of GstAlsaPads */
+  /* array of GstAlsaPads */
-  GList *pads;
+  GstAlsaPad pads[GST_ALSA_MAX_CHANNELS];
 
   gchar *device;
   snd_pcm_stream_t stream;
   snd_pcm_t *handle;
   snd_output_t *out;
 
-  /* our mmap'd data areas */
-  gboolean mmap_open;
-  const snd_pcm_channel_area_t *mmap_areas;
-  char **access_addr;
-  snd_pcm_uframes_t offset;
-  snd_pcm_sframes_t avail;
-
-  GstAlsaProcessFunc process;
-
   snd_pcm_format_t format;
   guint rate;
   gint channels;
-  guint32 mute; /* bitmask. */
 
-  /* the gstreamer data */
+  /* latency / performance parameters */
-  gboolean data_interleaved;
+  snd_pcm_uframes_t period_size;
+  unsigned int period_count;
+
   gboolean autorecover; 
-
-  /* access to the hardware */
-  gboolean access_interleaved;
-  guint sample_bytes;
-  guint interleave_unit;
-  guint interleave_skip;
-
-  guint buffer_frames;
-  guint period_count; /* 'number of fragments' in oss-speak */
-  guint period_frames;
-
-  gboolean debug;
 };
 
 struct _GstAlsaClass {