[linux-audio-dev] select() ?? before snd_pcm_writei(handle, buffer, frames);

Hi Developers. I have write my small _alsa_test_program_. [C code ckunkz see below] It works good but now i wanna before call rc = snd_pcm_writei(handle, buffer, frames); somehow check - is sound device free for this call or not. For OSS i have such problem solve with select() : fdo = open("/dev/dsp", O_WRONLY ); ..... FD_ZERO(&wfds); FD_SET( fdo , &wfds); Zeit.tv_sec=0; Zeit.tv_usec=1; response=select(fdo+1, NULL, &wfds, NULL, & Zeit ); Tnx in advance Alf int alsa_snd_pcm_open_write(unsigned int sample_rate__, unsigned int chan__ , snd_pcm_uframes_t * frames_p , snd_pcm_t ** handle) { int dir; // snd_pcm_t *handle; snd_pcm_hw_params_t *params; unsigned int val; int ret_fun; int chan_nr; snd_pcm_uframes_t frames; /* Open PCM device for playback. */ ret_fun = snd_pcm_open(* &handle, "default", SND_PCM_STREAM_PLAYBACK, 0); if (ret_fun < 0){ fprintf(stderr, "unable to open pcm device: %s\n", snd_strerror(ret_fun) ); exit(1); } /* Allocate a hardware parameters object. */ snd_pcm_hw_params_alloca(&params); /* Fill it in with default values. */ snd_pcm_hw_params_any(* handle, params); /* Set the desired hardware parameters. */ snd_pcm_hw_params_set_access(* handle, params, SND_PCM_ACCESS_RW_INTERLEAVED); /* Interleaved mode */ snd_pcm_hw_params_set_format(* handle, params, SND_PCM_FORMAT_S16_LE); /* Signed 16-bit little-endian format */ //snd_pcm_hw_params_set_format(handle, params, SND_PCM_FORMAT_S16_BE); chan_nr = chan__; snd_pcm_hw_params_set_channels(* handle, params, chan_nr); val = sample_rate__; snd_pcm_hw_params_set_rate_near(* handle, params, &val, &dir ); frames = * frames_p; //frames = 2048; /* Set period size to __nr__ frames. */ snd_pcm_hw_params_set_period_size_near(* handle, params, &frames, &dir); * frames_p = frames; /* Write the parameters to the driver */ ret_fun = snd_pcm_hw_params(* handle, params); if (ret_fun < 0) { fprintf(stderr, "unable to set hw parameters: %s\n", snd_strerror(ret_fun)); exit(1); } /* Use a buffer large enough to hold one period */ snd_pcm_hw_params_get_period_size(params, &frames, &dir); snd_pcm_hw_params_get_period_time(params, &val, &dir); } int main(int argc, char **argv) { ........ snd_pcm_uframes_t frames; unsigned int sample_rate; unsigned int chan; snd_pcm_t *handle; //---- sample_rate=44100; chan=2; frames=1023; // 4096 // frames=2047; // 8192 // frames=4095; // 16384 // frames=8191; // 32768 alsa_snd_pcm_open_write( sample_rate , chan , & frames , & handle); ....... while (1) { ....... rc = snd_pcm_writei(handle, buffer, frames); if (rc == -EPIPE) { /* EPIPE means underrun */ fprintf(stderr, "underrun occurred\n"); snd_pcm_prepare(handle); } else if (rc < 0) { fprintf(stderr, "error from writei: %s\n", snd_strerror(rc)); } else if (rc != (int)frames) { fprintf(stderr,"short write, write %d frames\n", rc); } ....... } snd_pcm_drain(handle); snd_pcm_close(handle); }// main ------