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 --- Changes since v1: * Use EXPORT_SYMBOL_GPL instead of EXPORT_SYMBOL --- include/sound/pcm.h | 2 ++ sound/core/pcm_misc.c | 39 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+)
diff --git a/include/sound/pcm.h b/include/sound/pcm.h index 84b10f9..d017091 100644 --- a/include/sound/pcm.h +++ b/include/sound/pcm.h @@ -901,6 +901,8 @@ extern const struct snd_pcm_hw_constraint_list snd_pcm_known_rates; int snd_pcm_limit_hw_rates(struct snd_pcm_runtime *runtime); unsigned int snd_pcm_rate_to_rate_bit(unsigned int rate); unsigned int snd_pcm_rate_bit_to_rate(unsigned int rate_bit); +unsigned int snd_pcm_rate_mask_intersect(unsigned int rates_a, + unsigned int rates_b);
static inline void snd_pcm_set_runtime_buffer(struct snd_pcm_substream *substream, struct snd_dma_buffer *bufp) diff --git a/sound/core/pcm_misc.c b/sound/core/pcm_misc.c index 43f24cc..4560ca0 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);