control: rename snd_ctl_elem_id_compare() to snd_ctl_elem_id_compare_set()

- add asserts to check if the unsigned integers are in the valid range
- replace tuple with set in the id description
- add const prefix for id1

Signed-off-by: Jaroslav Kysela <perex@perex.cz>

diff --git a/include/control.h b/include/control.h
index 40ac2e97425c86365ecb2089388d2988a7c866f8..9e52f4c0a795ea961e2a0ec93ae30917f7ef95c8 100644 (file)
--- a/include/control.h
+++ b/include/control.h
@@ -424,7 +424,7 @@ int snd_ctl_elem_id_malloc(snd_ctl_elem_id_t **ptr);
 void snd_ctl_elem_id_free(snd_ctl_elem_id_t *obj);
 void snd_ctl_elem_id_clear(snd_ctl_elem_id_t *obj);
 void snd_ctl_elem_id_copy(snd_ctl_elem_id_t *dst, const snd_ctl_elem_id_t *src);
-int snd_ctl_elem_id_compare(snd_ctl_elem_id_t *id1, const snd_ctl_elem_id_t *id2);
+int snd_ctl_elem_id_compare_set(const snd_ctl_elem_id_t *id1, const snd_ctl_elem_id_t *id2);
 unsigned int snd_ctl_elem_id_get_numid(const snd_ctl_elem_id_t *obj);
 snd_ctl_elem_iface_t snd_ctl_elem_id_get_interface(const snd_ctl_elem_id_t *obj);
 unsigned int snd_ctl_elem_id_get_device(const snd_ctl_elem_id_t *obj);

diff --git a/src/control/control.c b/src/control/control.c
index 2e1125794177d04b19f549b1fe0d0bf57f7d447b..3f98817c7be860e3c2009761e7a882fb9401767c 100644 (file)
--- a/src/control/control.c
+++ b/src/control/control.c
@@ -77,12 +77,12 @@ Each element has the following identifying properties:
   - Its name
   - Its index
 
-An element can be identified either by its numid or by the tuple
-(interface type, device, subdevice, name, index). This tuple is always
-the same (driver updates can change it, but in practice this is
-rare). The numid can change on each boot. In case of an USB sound
-card, the numid can also change when it is reconnected.
-
+An element can be identified either by its short numid or by the full
+set of fields (interface type, device, subdevice, name, index).
+This set of fields is always the same (driver updates can change it,
+but in practice this is rare). The numid can change on each boot.
+In case of an USB sound card, the numid can also change when it
+is reconnected. The short numid is used to reduce the lookup time.
 
 \section element_lists Element Lists
 
@@ -153,6 +153,7 @@ against the original design.
 #include <signal.h>
 #include <poll.h>
 #include <stdbool.h>
+#include <limits.h>
 #include "control_local.h"
 
 /**
@@ -1827,17 +1828,21 @@ void snd_ctl_elem_id_copy(snd_ctl_elem_id_t *dst, const snd_ctl_elem_id_t *src)
  * This comparison ignores the numid part. The numid comparison can be easily
  * implemented using snd_ctl_elem_id_get_numid() calls.
  *
- * The identifier fields are compared in this order: interface, device,
+ * The identifier set fields are compared in this order: interface, device,
  * subdevice, name, index.
  *
  * The return value can be used for sorting like qsort(). It gives persistent
  * results.
  */
-int snd_ctl_elem_id_compare(snd_ctl_elem_id_t *id1, const snd_ctl_elem_id_t *id2)
+int snd_ctl_elem_id_compare_set(const snd_ctl_elem_id_t *id1, const snd_ctl_elem_id_t *id2)
 {
        int d;
 
        assert(id1 && id2);
+       /* although those values are unsigned integer, practically, */
+       /* the useable limit is really much lower */
+       assert((id1->iface | id1->device | id1->subdevice | id1->index) <= INT_MAX);
+       assert((id2->iface | id2->device | id2->subdevice | id1->index) <= INT_MAX);
        d = id1->iface - id2->iface;
        if (d != 0)
                return d;