Provided by:
linux-doc-2.6.15_2.6.15-23.39_all 
NAME
snd_pcm_hw_param_mask -
SYNOPSIS
int snd_pcm_hw_param_mask (snd_pcm_t * pcm,
snd_pcm_hw_params_t * params,
snd_pcm_hw_param_t var,
const snd_mask_t * val);
ARGUMENTS
pcm PCM instance
params the hw_params instance
var parameter to retrieve
val mask to apply
DESCRIPTION
Inside configuration space defined by PARAMS remove from PAR all values
not contained in MASK. Reduce configuration space accordingly. This
function can be called only for SNDRV_PCM_HW_PARAM_ACCESS,
SNDRV_PCM_HW_PARAM_FORMAT, SNDRV_PCM_HW_PARAM_SUBFORMAT. Return 0 on
success or -EINVAL if the configuration space is empty