ALSA: Introduce 'snd_interval_rate_bits'

Signed-off-by: Martin Povišer <povik+lin@cutebit.org>

Author: povik

include/sound/pcm.h

@@ -1066,6 +1066,7 @@ int snd_interval_ranges(struct snd_interval *i, unsigned int count,
 int snd_interval_ratnum(struct snd_interval *i,
 			unsigned int rats_count, const struct snd_ratnum *rats,
 			unsigned int *nump, unsigned int *denp);
+int snd_interval_rate_bits(struct snd_interval *i, unsigned int rate_bits);
 
 void _snd_pcm_hw_params_any(struct snd_pcm_hw_params *params);
 void _snd_pcm_hw_param_setempty(struct snd_pcm_hw_params *params, snd_pcm_hw_param_t var);

sound/core/pcm_lib.c

@@ -1146,6 +1146,43 @@ static int snd_interval_step(struct snd_interval *i, unsigned int step)
 	return changed;
 }
 
+/**
+ * snd_interval_rate_bits - refine the rate interval from a rate bitmask
+ * @i: the rate interval to refine
+ * @mask: the rate bitmask
+ *
+ * Refines the interval value, assumed to be the sample rate, according to
+ * a bitmask of available rates (an ORed combination of SNDRV_PCM_RATE_*).
+ *
+ * Return: Positive if the value is changed, zero if it's not changed, or a
+ * negative error code.
+ */
+int snd_interval_rate_bits(struct snd_interval *i, unsigned int mask)
+{
+	unsigned int k;
+	struct snd_interval mask_range;
+
+	if (!mask)
+		return -EINVAL;
+
+	snd_interval_any(&mask_range);
+	mask_range.min = UINT_MAX;
+	mask_range.max = 0;
+	for (k = 0; k < snd_pcm_known_rates.count; k++) {
+		unsigned int rate = snd_pcm_known_rates.list[k];
+		if (!(mask & (1 << k)))
+			continue;
+
+		if (rate > mask_range.max)
+			mask_range.max = rate;
+
+		if (rate < mask_range.min)
+			mask_range.min = rate;
+	}
+	return snd_interval_refine(i, &mask_range);
+}
+EXPORT_SYMBOL(snd_interval_rate_bits);
+
 /* Info constraints helpers */
 
 /**