path: root/src/alsa_pcm.cxx

#include "alsa_pcm.h"
#include <iostream>
#include <iomanip>
#include <sstream>

extern int verbosity;

// note that if the error code is -999,
// we exit with non-error status (0)
void alsa_pcm::error(const char* msg,
        const int ecode, snd_pcm_hw_params_t* hwparams) {
  using namespace std;
  if (ecode != -999) {
    cerr << "Device won't accept parameter '" << msg << "'"
         << "  ecode '" << ecode << "'" << endl;
  }
  else {
    cerr << msg << " for " << moniker << endl;
  }
  snd_pcm_hw_params_dump(hwparams, errlog);
  int sync = snd_pcm_hw_params_can_sync_start(hwparams);
  cout << "sync_start: " << sync << endl;
  int sbits = snd_pcm_hw_params_get_sbits(hwparams);
  if (sbits <= 0) try_formats(hwparams);        // ignore errors from here
  sbits = snd_pcm_hw_params_get_sbits(hwparams);        // try again
  if (sbits > 0) {
    cerr << "Allegedly can do "
            << sbits << " significant bits per sample." << endl;
  } else {
// Can't determine sigbits if the card is capable of
// multiple sample-sizes and we haven't chosen one yet.
    cerr << "Can't (yet) determine sigbits per sample.  Result was: "
        << sbits << " == "
        << snd_strerror(sbits) << endl;
    sbits = 0;
  }

  snd_pcm_close(phndl);
  snd_output_close(errlog);
  if (ecode == -999) exit(0);     // weird code for non-error
  exit(1);
}

// Try various sample formats.
int alsa_pcm::try_formats(snd_pcm_hw_params_t* hwparams){
    int err;
    format = SND_PCM_FORMAT_S32_LE;
    err = snd_pcm_hw_params_set_format(phndl, hwparams, format);
    if (err >= 0) return 0;

    format = SND_PCM_FORMAT_S16_LE;
    err = snd_pcm_hw_params_set_format(phndl, hwparams, format);
    if (err >= 0) return 0;

    format = SND_PCM_FORMAT_S8;
    err = snd_pcm_hw_params_set_format(phndl, hwparams, format);
    if (err >= 0) return 0;

    return -999;
}

int alsa_pcm::getrate(const std::string carddev,
        snd_pcm_stream_t stream_dir,
        const int dump_flag){
  int err;

  direction = stream_dir;
// Connect error reporting to stderr
  if (!errlog) snd_output_stdio_attach(&errlog, stderr, 0);

  int mode = 0;         // could have been SND_PCM_NONBLOCK;
  err = snd_pcm_open(&phndl, carddev.c_str(), direction, mode);
  if (err < 0){
    fprintf(stderr, "Error opening soundcard %s for %s: %s\n",
        carddev.c_str(), moniker, snd_strerror(err));
    snd_output_close(errlog);
    return 1;
  }

// now that we've grabbed the device, possibly without blocking
// if it was busy, we now switch to blocking mode for all I/O:
  err = snd_pcm_nonblock(phndl, 0);

// Allocate a hwparams struct...
  snd_pcm_hw_params_t* hwparams;
  snd_pcm_hw_params_alloca(&hwparams);

// ... and initialize it to the "wide open" ranges
// allowed by phndl:
  err = snd_pcm_hw_params_any(phndl, hwparams);
  if (err < 0) error("Initialization error", -999, hwparams);

// User can force a dump of parameters,
// here at a nice early stage:
  if (dump_flag < 0) error("Possibilities are:", -999, hwparams);

  snd_pcm_hw_params_get_rate_max(hwparams, &max_rate, 0);
  return 0;
}

int alsa_pcm::setup(const int _rate){
  rate = _rate;
  int err;

// Allocate a hwparams struct...
  snd_pcm_hw_params_t* hwparams;
  snd_pcm_hw_params_alloca(&hwparams);

// ... and initialize it to the "wide open" ranges
// allowed by phndl:
  err = snd_pcm_hw_params_any(phndl, hwparams);
  if (err < 0) error("Initialization error", -999, hwparams);

// Access method, interleaved or non-interleaved
  err = snd_pcm_hw_params_set_access(phndl, hwparams,
      SND_PCM_ACCESS_RW_INTERLEAVED);
  if (err < 0) error("access method", SND_PCM_ACCESS_RW_INTERLEAVED,
                hwparams);

// Try various sample formats:
  int rslt = try_formats(hwparams);
  if (rslt < 0)
    error("DSP error: format not S32_LE nor S16_LE nor S8", rslt,
        hwparams);

  if (!phndl) return -998;
  err = snd_pcm_hw_params_set_rate(phndl, hwparams, rate, 0);
  if (err < 0) error("rate", rate, hwparams);

// Number of channels we want, stereo = 2
  unsigned int nchan_max;
  snd_pcm_hw_params_get_channels_max(hwparams, &nchan_max);
  nchan = nchan_max;
  if (direction == SND_PCM_STREAM_PLAYBACK && nchan_max > 2){
    nchan = 2;  // calibrator doesn't need more than 2 channels
  }
  err = snd_pcm_hw_params_set_channels(phndl, hwparams, nchan);
  if (err < 0) error("Cannot set number of channels: ", nchan, hwparams);

// The period size. For all practical purposes this is synonymous
// to OSS/Free's fragment size.
// Note that this in frames (frame = nr_channels * sample_width)
// For example, a setup using FPP=1024, stereo, 16-bit format
// gives a period size of 4096 bytes (1024 x 2 x 2 bytes).
  if (1) {
    err = snd_pcm_hw_params_set_period_size(phndl, hwparams, FPP, 0);
    if (err < 0) error("period-size", FPP, hwparams);
  }

// The number of periods we want to allocate
  {
    unsigned int periods = 4;   // reasonable guess
    unsigned int minper, maxper;
    if (snd_pcm_hw_params_get_periods_min(hwparams, &minper, 0)==0
          && periods < minper) periods = minper;
    if (snd_pcm_hw_params_get_periods_max(hwparams, &maxper, 0)==0
          && periods > maxper) periods = maxper;
    err = snd_pcm_hw_params_set_periods(phndl, hwparams, periods, 0);
#ifdef testing
    fprintf(stderr, "periods: %d (%d -- %d) \n",
           periods, minper, maxper);
#endif
    if (periods <= 1) {
      fprintf(stderr, "Warning: %d periods is not really enough;  "
        "we should have at least 2 for double buffering\n", periods);
      if (periods==0) exit(1);
      fprintf(stderr, "Continuing anyway....\n");
    }
    if (err < 0) error("#-of-periods", periods, hwparams);
  }

// Finally set up our hardware with the selected values
  err = snd_pcm_hw_params(phndl, hwparams);
  if (err < 0) {
    fprintf(stderr, "Unable to set hardware parameter:\n");
    snd_pcm_hw_params_dump(hwparams, errlog);
    return 2;
  }

  err = sbits = snd_pcm_hw_params_get_sbits(hwparams);
  if (sbits <= 0 || sbits > 32) {
// if driver won't tell us how many are significant,
// assume they all are:
    sbits = snd_pcm_samples_to_bytes(phndl, 8);
    fprintf(stderr, "Trouble %d determining sig bits; assuming %d\n",
        err, sbits);
  }

  if (verbosity >= 2) {
    fprintf(stderr, ">>>>>> After setup (%s)\n", moniker);
    snd_pcm_hw_params_dump(hwparams, errlog);
  }

// At this point you can start sending PCM data to the device
  return 0;
}

// the last time the stream was started or stopped
snd_htimestamp_t alsa_pcm::ss_time(){
    snd_pcm_status_t* sts(0);
    snd_pcm_status_alloca(&sts);
    snd_htimestamp_t tstamp;      // this is a struct timespec
    int err = snd_pcm_status(phndl, sts);
    if (err < 0) {
      fprintf(stderr, "Setup: can't get status?\n");
      tstamp.tv_sec = 0;
      tstamp.tv_nsec = 0;
      return tstamp;
    }
    snd_pcm_status_get_trigger_htstamp(sts, &tstamp);
    return tstamp;
}

// same as above, but returns current time
snd_htimestamp_t alsa_pcm::now(){
    snd_pcm_status_t* sts(0);
    snd_pcm_status_alloca(&sts);
    snd_htimestamp_t tstamp;      // this is a struct timespec
    int err = snd_pcm_status(phndl, sts);
    if (err < 0) {
      fprintf(stderr, "Setup: can't get status?\n");
      tstamp.tv_sec = 0;
      tstamp.tv_nsec = 0;
      return tstamp;
    }
    snd_pcm_status_get_htstamp(sts, &tstamp);
    return tstamp;
}

std::string alsa_pcm::alsa_state_name() {

  snd_pcm_state_t state = snd_pcm_state(phndl);

#define checkit(XX) if (state == XX) return #XX

  checkit(SND_PCM_STATE_OPEN);
  checkit(SND_PCM_STATE_SETUP);
  checkit(SND_PCM_STATE_PREPARED);
  checkit(SND_PCM_STATE_RUNNING);
  checkit(SND_PCM_STATE_XRUN);
  checkit(SND_PCM_STATE_DRAINING);
  checkit(SND_PCM_STATE_PAUSED);
  checkit(SND_PCM_STATE_SUSPENDED);
  checkit(SND_PCM_STATE_DISCONNECTED);
  return "??unknown state??";
}

#define command "whatever"
#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95)
#define error(...) do {\
	fprintf(stderr, "%s: %s:%d: ", command, __FUNCTION__, __LINE__); \
	fprintf(stderr, __VA_ARGS__); \
	putc('\n', stderr); \
} while (0)
#else
#define error(args...) do {\
	fprintf(stderr, "%s: %s:%d: ", command, __FUNCTION__, __LINE__); \
	fprintf(stderr, ##args); \
	putc('\n', stderr); \
} while (0)
#endif

int dummy(int const xx);

void device_list(const snd_pcm_stream_t direction){
#define _(XX) XX
    snd_ctl_t *handle;
    int card, err, dev, idx;
    snd_ctl_card_info_t *info;
    snd_pcm_info_t *pcminfo;
    snd_ctl_card_info_alloca(&info);
    snd_pcm_info_alloca(&pcminfo);

    card = -1;
    if (snd_card_next(&card) < 0 || card < 0) {
        error(_("no soundcards found..."));
        return;
    }
    printf(_("**** List of %s Hardware Devices ****\n"),
           snd_pcm_stream_name(direction));

// loop over all cards:
    for (int ii=0;; ii++) {
    using namespace std;
        if (card < 0) break;
// use dummy to defend against false compiler warning,
// and possibly wrong code generation:
// "assuming signed overflow does not occur when simplifying conditional to constant"
        if (dummy(ii)) fprintf(stdout, "\n");
        stringstream name;
        name << "hw:" << card;
        if ((err = snd_ctl_open(&handle, name.str().c_str(), 0)) < 0) {
            error("control open (%i): %s", card, snd_strerror(err));
            goto next_card;
        }
        if ((err = snd_ctl_card_info(handle, info)) < 0) {
            error("control hardware info (%i): %s", card, snd_strerror(err));
            snd_ctl_close(handle);
            goto next_card;
        }
        cout << "card " << setw(2) << card
                << " ID: " << snd_ctl_card_info_get_id(info)
                << " ... name: " << snd_ctl_card_info_get_name(info)
                << endl;

        cout << "  driver:   " << snd_ctl_card_info_get_driver(info)
                << endl;
        cout << "  mixer:    " << snd_ctl_card_info_get_mixername(info)
                << endl;
        dev = -1;
// loop over all devices on the card
        for (int ndev=0; ; ndev++) {
            unsigned int count;
            if (snd_ctl_pcm_next_device(handle, &dev)<0)
                error("snd_ctl_pcm_next_device");
            if (dev < 0)
                break;
            snd_pcm_info_set_device(pcminfo, dev);
            snd_pcm_info_set_subdevice(pcminfo, 0);
            snd_pcm_info_set_stream(pcminfo, direction);
            if ((err = snd_ctl_pcm_info(handle, pcminfo)) < 0) {
                if (err != -ENOENT)
                    error("control digital audio info (%i): %s", card, snd_strerror(err));
                continue;
            }
            cout << "  device " << setw(2) << dev
                << " ID: " << snd_pcm_info_get_id(pcminfo)
                << " ... name: " << snd_pcm_info_get_name(pcminfo)
                << endl;
            count = snd_pcm_info_get_subdevices_count(pcminfo);
            int avail = snd_pcm_info_get_subdevices_avail(pcminfo);
            cout << "    subdevices available: " << setw(2) << avail
                << " total: " << count
                << endl;
            for (idx = 0; idx < (int)count; idx++) {
                snd_pcm_info_set_subdevice(pcminfo, idx);
                if ((err = snd_ctl_pcm_info(handle, pcminfo)) < 0) {
                    error("control digital audio playback info (%i): %s",
                        card, snd_strerror(err));
                } else {
                    cout << "    subdevice " << setw(2) << idx
                        << " ... name: "
                           << snd_pcm_info_get_subdevice_name(pcminfo)
                        << endl;
                }
            }
        }
        snd_ctl_close(handle);
    next_card:
        if (snd_card_next(&card) < 0) {
            error("snd_card_next");
            break;
        }
    }
}