alsa.c

/*
robot36 - encode and decode images using SSTV in Robot 36 mode
Written in 2011 by <Ahmet Inan> <xdsopl@googlemail.com>
To the extent possible under law, the author(s) have dedicated all copyright and related and neighboring rights to this software to the public domain worldwide. This software is distributed without any warranty.
You should have received a copy of the CC0 Public Domain Dedication along with this software. If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
*/


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

struct alsa {
	struct pcm base;
	snd_pcm_t *pcm;
	int index;
	int frames;
	int r;
	int c;
};

void close_alsa(struct pcm *pcm)
{
	struct alsa *alsa = (struct alsa *)(pcm->data);
	snd_pcm_drain(alsa->pcm);
	snd_pcm_close(alsa->pcm);
	free(alsa);
}

void info_alsa(struct pcm *pcm)
{
	struct alsa *alsa = (struct alsa *)(pcm->data);
	if (alsa->frames)
		fprintf(stderr, "%d channel(s), %d rate, %.2f seconds\n", alsa->c, alsa->r, (float)alsa->frames / (float)alsa->r);
	else
		fprintf(stderr, "%d channel(s), %d rate\n", alsa->c, alsa->r);
}
int rate_alsa(struct pcm *pcm)
{
	struct alsa *alsa = (struct alsa *)(pcm->data);
	return alsa->r;
}
int channels_alsa(struct pcm *pcm)
{
	struct alsa *alsa = (struct alsa *)(pcm->data);
	return alsa->c;
}
int read_alsa(struct pcm *pcm, short *buff, int frames)
{
	struct alsa *alsa = (struct alsa *)(pcm->data);
	int got = 0;
	while (0 < frames) {
		while ((got = snd_pcm_readi(alsa->pcm, buff, frames)) < 0)
			if (snd_pcm_prepare(alsa->pcm) < 0)
				return 0;
		buff += got * alsa->c;
		frames -= got;
	}
	return 1;
}

int write_alsa(struct pcm *pcm, short *buff, int frames)
{
	struct alsa *alsa = (struct alsa *)(pcm->data);
	if (alsa->frames && (alsa->index + frames) > alsa->frames)
		return 0;
	alsa->index += frames;
	int got = 0;
	while (0 < frames) {
		while ((got = snd_pcm_writei(alsa->pcm, buff, frames)) < 0)
			if (snd_pcm_prepare(alsa->pcm) < 0)
				return 0;
		buff += got * alsa->c;
		frames -= got;
	}
	return 1;
}

int open_alsa_read(struct pcm **p, char *name)
{
	snd_pcm_t *pcm;
	if (snd_pcm_open(&pcm, name, SND_PCM_STREAM_CAPTURE, 0) < 0) {
		fprintf(stderr, "Error opening PCM device %s\n", name);
		return 0;
	}

	snd_pcm_hw_params_t *params;
	snd_pcm_hw_params_alloca(&params);
	if (snd_pcm_hw_params_any(pcm, params) < 0) {
		fprintf(stderr, "Can not configure this PCM device.\n");
		snd_pcm_close(pcm);
		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(pcm);
		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(pcm);
		return 0;
	}

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

	unsigned rate_min = 8000;
	int dir_min = 0;
	if (snd_pcm_hw_params_set_rate_min(pcm, params, &rate_min, &dir_min) < 0 || rate_min < 8000) {
		fprintf(stderr, "Error setting min rate.\n");
		snd_pcm_close(pcm);
		return 0;
	}

	if (snd_pcm_hw_params(pcm, params) < 0) {
		fprintf(stderr, "Error setting HW params.\n");
		snd_pcm_close(pcm);
		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(pcm);
		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(pcm);
		return 0;
	}

	struct alsa *alsa = (struct alsa *)malloc(sizeof(struct alsa));
	alsa->base.close = close_alsa;
	alsa->base.info = info_alsa;
	alsa->base.rate = rate_alsa;
	alsa->base.channels = channels_alsa;
	alsa->base.rw = read_alsa;
	alsa->base.data = (void *)alsa;

	alsa->pcm = pcm;
	alsa->r = rate;
	alsa->c = channels;
	alsa->frames = 0;
	*p = &(alsa->base);
	return 1;
}

int open_alsa_write(struct pcm **p, char *name, int rate, int channels, float seconds)
{
	snd_pcm_t *pcm;
	if (snd_pcm_open(&pcm, name, SND_PCM_STREAM_PLAYBACK, 0) < 0) {
		fprintf(stderr, "Error opening PCM device %s\n", name);
		return 0;
	}

	snd_pcm_hw_params_t *params;
	snd_pcm_hw_params_alloca(&params);
	if (snd_pcm_hw_params_any(pcm, params) < 0) {
		fprintf(stderr, "Can not configure this PCM device.\n");
		snd_pcm_close(pcm);
		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(pcm);
		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(pcm);
		return 0;
	}

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

	if (snd_pcm_hw_params_set_rate_near(pcm, params, (unsigned int *)&rate, 0) < 0) {
		fprintf(stderr, "Error setting rate.\n");
		snd_pcm_close(pcm);
		return 0;
	}

	if (snd_pcm_hw_params_set_channels_near(pcm, params, (unsigned int *)&channels) < 0) {
		fprintf(stderr, "Error setting channels.\n");
		snd_pcm_close(pcm);
		return 0;
	}

	if (snd_pcm_hw_params(pcm, params) < 0) {
		fprintf(stderr, "Error setting HW params.\n");
		snd_pcm_close(pcm);
		return 0;
	}

	struct alsa *alsa = (struct alsa *)malloc(sizeof(struct alsa));
	alsa->base.close = close_alsa;
	alsa->base.info = info_alsa;
	alsa->base.rate = rate_alsa;
	alsa->base.channels = channels_alsa;
	alsa->base.rw = write_alsa;
	alsa->base.data = (void *)alsa;

	alsa->pcm = pcm;
	alsa->r = rate;
	alsa->c = channels;
	alsa->frames = seconds * rate;
	alsa->index = 0;
	*p = &(alsa->base);
	return 1;
}