pcm: Introduce snd_pcm_subformat_value()

Allow userspace applications to select subformats easily just like in
snd_pcm_format_t case - by string conversion.

Closes: #342
Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

include/pcm.h

@@ -282,6 +282,8 @@ typedef enum _snd_pcm_format {
 
 /** PCM sample subformat */
 typedef enum _snd_pcm_subformat {
+	/** Unknown */
+	SND_PCM_SUBFORMAT_UNKNOWN = -1,
 	/** Standard */
 	SND_PCM_SUBFORMAT_STD = 0,
 	SND_PCM_SUBFORMAT_LAST = SND_PCM_SUBFORMAT_STD
@@ -1092,6 +1094,7 @@ const char *snd_pcm_format_name(const snd_pcm_format_t format);
 const char *snd_pcm_format_description(const snd_pcm_format_t format);
 const char *snd_pcm_subformat_name(const snd_pcm_subformat_t subformat);
 const char *snd_pcm_subformat_description(const snd_pcm_subformat_t subformat);
+snd_pcm_subformat_t snd_pcm_subformat_value(const char* name);
 snd_pcm_format_t snd_pcm_format_value(const char* name);
 const char *snd_pcm_tstamp_mode_name(const snd_pcm_tstamp_t mode);
 const char *snd_pcm_state_name(const snd_pcm_state_t state);

src/pcm/pcm.c

@@ -2197,6 +2197,30 @@ const char *snd_pcm_subformat_description(const snd_pcm_subformat_t subformat)
 	return snd_pcm_subformat_descriptions[subformat];
 }
 
+/**
+ * \brief get PCM sample subformat from name
+ * \param name PCM sample subformat name (case insensitive)
+ * \return PCM sample subformat
+ */
+snd_pcm_subformat_t snd_pcm_subformat_value(const char* name)
+{
+	snd_pcm_subformat_t subformat;
+
+	for (subformat = 0; subformat <= SND_PCM_SUBFORMAT_LAST; subformat++) {
+		if (snd_pcm_subformat_names[subformat] &&
+		    !strcasecmp(name, snd_pcm_subformat_names[subformat]))
+			return subformat;
+	}
+
+	for (subformat = 0; subformat <= SND_PCM_SUBFORMAT_LAST; subformat++) {
+		if (snd_pcm_subformat_descriptions[subformat] &&
+		    !strcasecmp(name, snd_pcm_subformat_descriptions[subformat]))
+			return subformat;
+	}
+
+	return SND_PCM_SUBFORMAT_UNKNOWN;
+}
+
 /**
  * \brief (DEPRECATED) get name of PCM start mode setting
  * \param mode PCM start mode