diff options
| author | Lars-Peter Clausen <lars@metafoo.de> | 2014-01-11 13:24:43 +0400 |
|---|---|---|
| committer | Mark Brown <broonie@linaro.org> | 2014-01-15 00:42:34 +0400 |
| commit | e3a9269f874067fcefc5eb8037466161fb0fe3f4 (patch) | |
| tree | 5d5d71d96c19cd786fd14e2ccfe50d22ab962c3a /sound/core | |
| parent | bf103eb4af73596edbab5faab67e29ea1e87c769 (diff) | |
| download | linux-e3a9269f874067fcefc5eb8037466161fb0fe3f4.tar.xz | |
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')
| -rw-r--r-- | sound/core/pcm_misc.c | 39 |
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); |