[mce] Make tristate_t type generally available. JB#22475

Generic "extended boolean" type supporting als "unknown" in
addition to "true" and "false" is useful for dealing with
state data where neither true nor false is suitable for
use as initial value. There already is tristate_t type
that fits the requirement, but it is internal to the
buttonbacklight plugin.

Move tristate_t from plugin to mce core modules so that
it can be utilized anywhere within mce.

Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

datapipe.c

@@ -1533,6 +1533,7 @@ const char *orientation_state_repr(orientation_state_t state)
 	return name;
 }
 
+/** Translate key state to human readable form */
 const char *key_state_repr(key_state_t state)
 {
 	const char *repr = "UNKNOWN";
@@ -1545,6 +1546,19 @@ const char *key_state_repr(key_state_t state)
 	return repr;
 }
 
+/** Translate tristate to human readable form */
+const char *tristate_repr(tristate_t state)
+{
+	const char *repr = "invalid";
+	switch( state ) {
+	case TRISTATE_UNKNOWN: repr = "unknown"; break;
+	case TRISTATE_FALSE:   repr = "false";   break;
+	case TRISTATE_TRUE:    repr = "true";    break;
+	default: break;
+	}
+	return repr;
+}
+
 /** Lookup table for fpstate_t <--> string */
 static const mce_translation_t fpstate_lut[] =
 {

mce.h

@@ -404,6 +404,16 @@ typedef enum {
 
 const char *key_state_repr(key_state_t state);
 
+/** Generic "extended boolean" type */
+typedef enum
+{
+  TRISTATE_UNKNOWN = -1,
+  TRISTATE_FALSE   =  0,
+  TRISTATE_TRUE    =  1,
+} tristate_t;
+
+const char *tristate_repr(tristate_t state);
+
 /** Fingerprint daemon state */
 typedef enum fpstate_t
 {

modules/buttonbacklight.c

@@ -44,31 +44,10 @@
 /** Maximum number of concurrent button backlight enabler clients */
 #define BBL_MAX_CLIENTS 15
 
-/* ========================================================================= *
- * TYPES
- * ========================================================================= */
-
-/* ------------------------------------------------------------------------- *
- * TRISTATE
- * ------------------------------------------------------------------------- */
-
-typedef enum
-{
-    TRISTATE_UNKNOWN = -1,
-    TRISTATE_FALSE   =  0,
-    TRISTATE_TRUE    =  1,
-} tristate_t;
-
 /* ========================================================================= *
  * PROTOTYPES
  * ========================================================================= */
 
-/* ------------------------------------------------------------------------- *
- * TRISTATE
- * ------------------------------------------------------------------------- */
-
-static const char *tristate_repr                (tristate_t state);
-
 /* ------------------------------------------------------------------------- *
  * GENRIC_UTILS
  * ------------------------------------------------------------------------- */
@@ -182,24 +161,6 @@ bbl_write_sysfs(const char *path, const char *data)
         TEMP_FAILURE_RETRY(close(fd));
 }
 
-/* ========================================================================= *
- * TRISTATE
- * ========================================================================= */
-
-static const char *
-tristate_repr(tristate_t state)
-{
-    const char *repr = "invalid";
-
-    switch( state ) {
-    case TRISTATE_UNKNOWN: repr = "unknown"; break;
-    case TRISTATE_FALSE:   repr = "false";   break;
-    case TRISTATE_TRUE:    repr = "true";    break;
-    default: break;
-    }
-    return repr;
-}
-
 /* ========================================================================= *
  * BACKLIGHT_STATE
  * ========================================================================= */