robot36/alsa.c

#include <stdio.h>
#include <malloc.h>
#include <alsa/asoundlib.h> 
#include "alsa.h"

typedef struct {
	void (*close)(pcm_t *);
	void (*info)(pcm_t *);
	int (*rate)(pcm_t *);
	int (*channels)(pcm_t *);
	int (*read)(struct pcm *, short *, int);
	snd_pcm_t *pcm;
	int r;
	int c;
} alsa_t;

void close_alsa(pcm_t *pcm)
{
	alsa_t *alsa = (alsa_t *)pcm;
	snd_pcm_close(alsa->pcm);
}

void info_alsa(pcm_t *pcm)
{
	alsa_t *alsa = (alsa_t *)pcm;
	fprintf(stderr, "%d channel(s), %d rate\n", alsa->c, alsa->r);
}
int rate_alsa(pcm_t *pcm)
{
	alsa_t *alsa = (alsa_t *)pcm;
	return alsa->r;
}
int channels_alsa(pcm_t *pcm)
{
	alsa_t *alsa = (alsa_t *)pcm;
	return alsa->c;
}
int read_alsa(pcm_t *pcm, short *buff, int frames)
{
	alsa_t *alsa = (alsa_t *)pcm;
	int got = 0;
	while (0 < frames) {
		while ((got = snd_pcm_readi(alsa->pcm, buff, frames)) < 0) {
			snd_pcm_prepare(alsa->pcm);
			fprintf(stderr, "<<<<<<<<<<<<<<< Buffer Overrun >>>>>>>>>>>>>>>\n");
		}
		buff += got * alsa->c;
		frames -= got;
	}
	return 1;
}

int open_alsa(pcm_t **p, char *name)
{
	alsa_t *alsa = (alsa_t *)malloc(sizeof(alsa_t));
	alsa->close = close_alsa;
	alsa->info = info_alsa;
	alsa->rate = rate_alsa;
	alsa->channels = channels_alsa;
	alsa->read = read_alsa;

	snd_pcm_t *pcm;
	snd_pcm_hw_params_t *params;
	snd_pcm_hw_params_alloca(&params);

	if (snd_pcm_open(&pcm, name, SND_PCM_STREAM_CAPTURE, 0) < 0) {
		fprintf(stderr, "Error opening PCM device %s\n", name);
		free(alsa);
		return 0;
	}
  
	if (snd_pcm_hw_params_any(pcm, params) < 0) {
		fprintf(stderr, "Can not configure this PCM device.\n");
		snd_pcm_close(alsa->pcm);
		free(alsa);
		return 0;
	}
  
	if (snd_pcm_hw_params_set_access(pcm, params, SND_PCM_ACCESS_RW_INTERLEAVED) < 0) {
		fprintf(stderr, "Error setting access.\n");
		snd_pcm_close(alsa->pcm);
		free(alsa);
		return 0;
	}

	if (snd_pcm_hw_params_set_format(pcm, params, SND_PCM_FORMAT_S16_LE) < 0) {
		fprintf(stderr, "Error setting S16_LE format.\n");
		snd_pcm_close(alsa->pcm);
		free(alsa);
		return 0;
	}

	if (snd_pcm_hw_params_set_rate_resample(pcm, params, 0) < 0) {
		fprintf(stderr, "Error disabling resampling.\n");
		snd_pcm_close(alsa->pcm);
		free(alsa);
		return 0;
	}

	if (snd_pcm_hw_params(pcm, params) < 0) {
		fprintf(stderr, "Error setting HW params.\n");
		snd_pcm_close(alsa->pcm);
		free(alsa);
		return 0;
	}
	unsigned int rate = 0;
	if (snd_pcm_hw_params_get_rate(params, &rate, 0) < 0) {
		fprintf(stderr, "Error getting rate.\n");
		snd_pcm_close(alsa->pcm);
		free(alsa);
		return 0;
	}
	unsigned int channels = 0;
	if (snd_pcm_hw_params_get_channels(params, &channels) < 0) {
		fprintf(stderr, "Error getting channels.\n");
		snd_pcm_close(alsa->pcm);
		free(alsa);
		return 0;
	}
	alsa->pcm = pcm;
	alsa->r = rate;
	alsa->c = channels;
	*p = (pcm_t *)alsa;
	return 1;
}