80 lines
2.1 KiB
C++
80 lines
2.1 KiB
C++
|
#include "pcmdma.h"
|
||
|
|
#include <pthread.h>
|
||
|
|
#include <alsa/asoundlib.h>
|
||
|
|
#include <signal.h>
|
||
|
|
|
||
|
|
struct Sample {
|
||
|
|
short l;
|
||
|
|
short r;
|
||
|
|
}__attribute__((packed));
|
||
|
|
|
||
|
|
static constexpr unsigned BufLen = FULL_LEN;
|
||
|
|
|
||
|
|
static const char *device = "default";
|
||
|
|
static snd_pcm_t *handle;
|
||
|
|
|
||
|
|
static int open_alsa_device (int channels, int srate) {
|
||
|
|
int err;
|
||
|
|
if ((err = snd_pcm_open(&handle, device, SND_PCM_STREAM_PLAYBACK, 0)) < 0) {
|
||
|
|
printf("Playback open error: %s\n", snd_strerror(err));
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
if ((err = snd_pcm_set_params(handle,
|
||
|
|
SND_PCM_FORMAT_S16_LE,
|
||
|
|
SND_PCM_ACCESS_RW_INTERLEAVED,
|
||
|
|
channels,
|
||
|
|
srate,
|
||
|
|
1,
|
||
|
|
500000)) < 0) { /* 0.5sec */
|
||
|
|
printf("Playback open error: %s\n", snd_strerror(err));
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
return 1;
|
||
|
|
}
|
||
|
|
int alsa_write (const void * buf, int len) {
|
||
|
|
snd_pcm_sframes_t frames;
|
||
|
|
int err = 0;
|
||
|
|
frames = snd_pcm_writei(handle, buf, len);
|
||
|
|
if (frames < 0)
|
||
|
|
frames = snd_pcm_recover(handle, frames, 0);
|
||
|
|
if (frames < 0) {
|
||
|
|
printf("snd_pcm_writei failed: %s\n", snd_strerror(err));
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
if (frames > 0 && frames < (long)sizeof(buf))
|
||
|
|
printf("Short write (expected %i, wrote %li)\n", len, frames);
|
||
|
|
return len;
|
||
|
|
}
|
||
|
|
void sig_handler (int signum) {
|
||
|
|
printf(" - Received signal %d\n", signum);
|
||
|
|
::exit (0);
|
||
|
|
}
|
||
|
|
|
||
|
|
static constexpr int CC = MAXPWM / 2;
|
||
|
|
|
||
|
|
static pthread_t rc;
|
||
|
|
|
||
|
|
void * WriteHandler (void * data) {
|
||
|
|
printf ("Start thread\n");
|
||
|
|
PcmDma * pA = (PcmDma *) data;
|
||
|
|
Sample buf [BufLen];
|
||
|
|
uint16_t * pbuf = pA->getBuff();
|
||
|
|
for (;;) {
|
||
|
|
pA->send (false);
|
||
|
|
pA->send (true);
|
||
|
|
//printf ("pass\n");
|
||
|
|
for (unsigned i=0; i<BufLen; i++) {
|
||
|
|
const short s = (pbuf [i] - CC) * 32;
|
||
|
|
buf[i].l = s; buf[i].r = s;
|
||
|
|
}
|
||
|
|
alsa_write (buf, BufLen);
|
||
|
|
}
|
||
|
|
return NULL;
|
||
|
|
}
|
||
|
|
|
||
|
|
PcmDma::PcmDma() noexcept : pL(buffer), pH(buffer + HALF_LEN), src(nullptr) {
|
||
|
|
signal (SIGINT, sig_handler);
|
||
|
|
open_alsa_device(2, 24000);
|
||
|
|
pthread_create (&rc, NULL, WriteHandler, this);
|
||
|
|
}
|