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authorLars-Peter Clausen <lars@metafoo.de>2014-01-11 10:24:43 +0100
committerMark Brown <broonie@linaro.org>2014-01-14 20:42:34 +0000
commite3a9269f874067fcefc5eb8037466161fb0fe3f4 (patch)
tree5d5d71d96c19cd786fd14e2ccfe50d22ab962c3a /sound/core/pcm_misc.c
parentbf103eb4af73596edbab5faab67e29ea1e87c769 (diff)
downloadlinux-e3a9269f874067fcefc5eb8037466161fb0fe3f4.tar.bz2
ALSA: Add helper function for intersecting two rate masks
A bit of special care is necessary when creating the intersection of two rate masks. This comes from the special meaning of the SNDRV_PCM_RATE_CONTINUOUS and SNDRV_PCM_RATE_KNOT bits, which needs special handling when intersecting two rate masks. SNDRV_PCM_RATE_CONTINUOUS means the hardware supports all rates in a specific interval. SNDRV_PCM_RATE_KNOT means the hardware supports a set of discrete rates specified by a list constraint. For all other cases the supported rates are specified directly in the rate mask. Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Reviewed-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Mark Brown <broonie@linaro.org>
Diffstat (limited to 'sound/core/pcm_misc.c')
-rw-r--r--sound/core/pcm_misc.c39
1 files changed, 39 insertions, 0 deletions
diff --git a/sound/core/pcm_misc.c b/sound/core/pcm_misc.c
index 43f24cce3dec..4560ca0e5651 100644
--- a/sound/core/pcm_misc.c
+++ b/sound/core/pcm_misc.c
@@ -514,3 +514,42 @@ unsigned int snd_pcm_rate_bit_to_rate(unsigned int rate_bit)
return 0;
}
EXPORT_SYMBOL(snd_pcm_rate_bit_to_rate);
+
+static unsigned int snd_pcm_rate_mask_sanitize(unsigned int rates)
+{
+ if (rates & SNDRV_PCM_RATE_CONTINUOUS)
+ return SNDRV_PCM_RATE_CONTINUOUS;
+ else if (rates & SNDRV_PCM_RATE_KNOT)
+ return SNDRV_PCM_RATE_KNOT;
+ return rates;
+}
+
+/**
+ * snd_pcm_rate_mask_intersect - computes the intersection between two rate masks
+ * @rates_a: The first rate mask
+ * @rates_b: The second rate mask
+ *
+ * This function computes the rates that are supported by both rate masks passed
+ * to the function. It will take care of the special handling of
+ * SNDRV_PCM_RATE_CONTINUOUS and SNDRV_PCM_RATE_KNOT.
+ *
+ * Return: A rate mask containing the rates that are supported by both rates_a
+ * and rates_b.
+ */
+unsigned int snd_pcm_rate_mask_intersect(unsigned int rates_a,
+ unsigned int rates_b)
+{
+ rates_a = snd_pcm_rate_mask_sanitize(rates_a);
+ rates_b = snd_pcm_rate_mask_sanitize(rates_b);
+
+ if (rates_a & SNDRV_PCM_RATE_CONTINUOUS)
+ return rates_b;
+ else if (rates_b & SNDRV_PCM_RATE_CONTINUOUS)
+ return rates_a;
+ else if (rates_a & SNDRV_PCM_RATE_KNOT)
+ return rates_b;
+ else if (rates_b & SNDRV_PCM_RATE_KNOT)
+ return rates_a;
+ return rates_a & rates_b;
+}
+EXPORT_SYMBOL_GPL(snd_pcm_rate_mask_intersect);