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#define ALSA_PCM_NEW_HW_PARAMS_API
#include <alsa/asoundlib.h>
#include "audio.h"
#include "typedef.h"
#define TEMP_BUF_SZ (handle->frames * CHANNELS * 2)
#define HANDLE (*(snd_pcm_t**)(handle->h))
#define MIN(a,b) (((a)<(b))?(a):(b))
int audio_create(audio_handle *handle, audio_handle_types t)
{
handle->h = malloc(sizeof(snd_pcm_t *));
snd_pcm_stream_t type = (t == RECORD) ? SND_PCM_STREAM_CAPTURE : SND_PCM_STREAM_PLAYBACK;
int rc = snd_pcm_open(handle->h, "default", type, 0);
if (rc < 0) {
err("unable to open pcm device: %s\n", snd_strerror(rc));
return 1;
}
int dir;
snd_pcm_hw_params_t *params;
snd_pcm_hw_params_alloca(¶ms); // allocate params
snd_pcm_hw_params_any(HANDLE, params); // set params
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);
snd_pcm_hw_params_set_channels(HANDLE, params, CHANNELS);
unsigned int samp_rate = SAMPLING_RATE;
snd_pcm_hw_params_set_rate_near(HANDLE, params, &samp_rate, &dir);
snd_pcm_uframes_t frames = FRAMES;
snd_pcm_hw_params_set_period_size_near(HANDLE, params, &frames, &dir);
rc = snd_pcm_hw_params(HANDLE, params); // write params to handle
if (rc < 0) {
err("unable to set hw parameters: %s\n", snd_strerror(rc));
return 1;
}
snd_pcm_hw_params_get_period_size(params, &frames, &dir);
handle->frames = frames;
return 0;
}
int audio_play(audio_handle *handle, char *buf)
{
char t[TEMP_BUF_SZ];
for(int i = 0; ;)
{
if(i >= REC_CAP) break;;
memset(t, 0, TEMP_BUF_SZ);
memcpy(t, &(buf[i]), MIN(TEMP_BUF_SZ, REC_CAP - i));
int rc = snd_pcm_writei(HANDLE, t, FRAMES);
if (rc == -EPIPE) {
err("underrun occurred\n");
snd_pcm_prepare(HANDLE);
} else if (rc < 0) {
err("error from writei: %s\n", snd_strerror(rc));
} else if (rc != FRAMES) {
err("short write, write %d frames\n", rc);
}
i += TEMP_BUF_SZ;
}
return 0;
}
int audio_record(audio_handle *handle, char *buf)
{
char t[TEMP_BUF_SZ];
for(int i = 0; ;)
{
if(i >= REC_CAP) break;
memset(t, 0, TEMP_BUF_SZ);
int rc = snd_pcm_readi(HANDLE, t, FRAMES);
if (rc == -EPIPE) {
err("overrun occurred\n");
snd_pcm_prepare(HANDLE);
} else if (rc < 0) {
err("error from read: %s\n", snd_strerror(rc));
} else if (rc != FRAMES) {
err("short read, read %d frames\n", rc);
}
memcpy(&(buf[i]), t, MIN(TEMP_BUF_SZ, REC_CAP - i));
i += TEMP_BUF_SZ;
}
return 0;
}
void audio_destroy(audio_handle *handle)
{
snd_pcm_drain(HANDLE);
snd_pcm_close(HANDLE);
free(handle->h);
}
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