From 335411422c5ca298ef3e2eee6b725284073a4353 Mon Sep 17 00:00:00 2001
From: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Date: Sun, 22 Dec 2019 11:05:29 +0900
Subject: [PATCH] ctl: elem_id: add an API to check whether two instances
 indicates the same element

It's convenient for users to check whether two instances of elem_id
indicates the same element. This commit adds an API to satisfy the
convenience.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
---
 src/ctl/alsactl.map   |  1 +
 src/ctl/elem-id.c     | 22 ++++++++++++++++++++++
 src/ctl/elem-id.h     |  3 +++
 tests/alsactl-elem-id |  1 +
 4 files changed, 27 insertions(+)

diff --git a/src/ctl/alsactl.map b/src/ctl/alsactl.map
index b88de55..37268cf 100644
--- a/src/ctl/alsactl.map
+++ b/src/ctl/alsactl.map
@@ -40,6 +40,7 @@ ALSA_GOBJECT_0_0_0 {
     "alsactl_elem_id_get_subdevice_id";
     "alsactl_elem_id_get_name";
     "alsactl_elem_id_get_index";
+    "alsactl_elem_id_equal";
 
     "alsactl_elem_info_get_type";
 
diff --git a/src/ctl/elem-id.c b/src/ctl/elem-id.c
index b598e91..79c7017 100644
--- a/src/ctl/elem-id.c
+++ b/src/ctl/elem-id.c
@@ -129,3 +129,25 @@ void alsactl_elem_id_get_index(const ALSACtlElemId *self, guint *index)
 {
     *index = self->index;
 }
+
+/**
+ * alsactl_elem_id_equal:
+ * @self: A #ALSACtlElemId.
+ * @target: A #ALSACtlElemId to compare.
+ *
+ * Returns: whether the given object indicates the same element.
+ */
+gboolean alsactl_elem_id_equal(const ALSACtlElemId *self,
+                               const ALSACtlElemId *target) {
+    const struct snd_ctl_elem_id *lhs, *rhs;
+
+    lhs = (const struct snd_ctl_elem_id *)self;
+    rhs = (const struct snd_ctl_elem_id *)target;
+
+    return lhs->numid == rhs->numid ||
+           (lhs->iface == rhs->iface &&
+            lhs->device == rhs->device &&
+            lhs->subdevice == rhs->subdevice &&
+            !strcmp((const char *)lhs->name, (const char *)rhs->name) &&
+            lhs->index == rhs->index);
+}
diff --git a/src/ctl/elem-id.h b/src/ctl/elem-id.h
index 7482348..b20f581 100644
--- a/src/ctl/elem-id.h
+++ b/src/ctl/elem-id.h
@@ -31,6 +31,9 @@ void alsactl_elem_id_get_subdevice_id(const ALSACtlElemId *self,
 void alsactl_elem_id_get_name(const ALSACtlElemId *self, const gchar **name);
 void alsactl_elem_id_get_index(const ALSACtlElemId *self, guint *index);
 
+gboolean alsactl_elem_id_equal(const ALSACtlElemId *self,
+                               const ALSACtlElemId *target);
+
 G_END_DECLS
 
 #endif
diff --git a/tests/alsactl-elem-id b/tests/alsactl-elem-id
index 454ff9d..08f6b1e 100644
--- a/tests/alsactl-elem-id
+++ b/tests/alsactl-elem-id
@@ -18,6 +18,7 @@ methods = (
     'get_subdevice',
     'get_name',
     'get_index',
+    'equals',
 )
 signals = ()
 
-- 
2.47.3