[pulseaudio-discuss] [PATCH 17/23] core-format: Add pa_format_info_negotiate()

[Tanu Kaskinen]

Currently format negotiation is done in
pa_sink_input_new_data_set_sink(), but the new data won't be available
when a router module needs to connect a sink input node to some other
node, so a different function is needed.

It would probably otherwise be possible to convert also
pa_sink_input_new_data_set_sink() to use pa_format_info_negotiate()
internally, but pa_sink_input_new_data_set_sink() doesn't currently
choose the final format, which pa_format_info_negotiate() does. The
reason is probably to allow policy modules to choose the format if
there are multiple alternatives, but I don't know if we really need
that possibility (AFAIK the possibility is not currently used), so
perhaps that conversion should be done to get rid of the duplicated
code?
---
 src/Makefile.am             |  1 +
 src/pulsecore/core-format.c | 51 +++++++++++++++++++++++++++++++++++++++++++++
 src/pulsecore/core-format.h | 44 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 96 insertions(+)
 create mode 100644 src/pulsecore/core-format.c
 create mode 100644 src/pulsecore/core-format.h

diff --git a/src/Makefile.am b/src/Makefile.am
index 4efd4c4..168415e 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -871,6 +871,7 @@ libpulsecore_ at PA_MAJORMINOR@_la_SOURCES = \
 		pulsecore/cli-text.c pulsecore/cli-text.h \
 		pulsecore/client.c pulsecore/client.h \
 		pulsecore/card.c pulsecore/card.h \
+		pulsecore/core-format.c pulsecore/core-format.h \
 		pulsecore/core-scache.c pulsecore/core-scache.h \
 		pulsecore/core-subscribe.c pulsecore/core-subscribe.h \
 		pulsecore/core.c pulsecore/core.h \
diff --git a/src/pulsecore/core-format.c b/src/pulsecore/core-format.c
new file mode 100644
index 0000000..6e534f4
--- /dev/null
+++ b/src/pulsecore/core-format.c
@@ -0,0 +1,51 @@
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2013 Intel Corporation
+
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as published
+  by the Free Software Foundation; either version 2.1 of the License,
+  or (at your option) any later version.
+
+  PulseAudio 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 Lesser General Public License
+  along with PulseAudio; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "core-format.h"
+
+int pa_format_info_negotiate(pa_idxset *formats_a, pa_idxset *formats_b, const pa_format_info **format) {
+    pa_format_info *a;
+    uint32_t idx_a;
+    pa_format_info *b;
+    uint32_t idx_b;
+
+    pa_assert(formats_a);
+    pa_assert(formats_b);
+    pa_assert(format);
+
+    PA_IDXSET_FOREACH(a, formats_a, idx_a) {
+        PA_IDXSET_FOREACH(b, formats_b, idx_b) {
+            /* pa_format_info_is_compatible() succeeds if the first parameter
+             * is a subset of the second parameter, so b must be the first
+             * parameter. */
+            if (pa_format_info_is_compatible(b, a)) {
+                *format = a;
+                return 0;
+            }
+        }
+    }
+
+    return -PA_ERR_NOTSUPPORTED;
+}
diff --git a/src/pulsecore/core-format.h b/src/pulsecore/core-format.h
new file mode 100644
index 0000000..f492c19
--- /dev/null
+++ b/src/pulsecore/core-format.h
@@ -0,0 +1,44 @@
+#ifndef foocoreformathfoo
+#define foocoreformathfoo
+
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2013 Intel Corporation
+
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as published
+  by the Free Software Foundation; either version 2.1 of the License,
+  or (at your option) any later version.
+
+  PulseAudio 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 Lesser General Public License
+  along with PulseAudio; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#include <pulse/format.h>
+
+#include <pulsecore/idxset.h>
+
+/* Selects the first format in formats_a that is compatible with some format in
+ * formats_b, and stores the result in format. Returns a negative error code if
+ * no compatible format can be found.
+ *
+ * Being "compatible" means that format a is a superset of format b (internally
+ * this function uses pa_format_info_compatible(), which defines what
+ * "compatible" means). If you have two format sets, how do you know which one
+ * is going to contain supersets of the other? Currently (as of 2013-11-17)
+ * things are designed so that formats_a should represent stream formats and
+ * formats_b should represent device formats. Hopefully the definition of
+ * "compatible" will change at some point so that it would actually mean that
+ * there's a valid intersection of a and b, because then it wouldn't matter if
+ * the formats are stream or device formats. */
+int pa_format_info_negotiate(pa_idxset *formats_a, pa_idxset *formats_b, const pa_format_info **format);
+
+#endif
-- 
1.8.3.1