alsaaudio.c

qemu虚拟机代码

#if defined DEBUG_MISMATCHES || defined DEBUG
    if (obt->fmt != req->fmt ||
        obt->nchannels != req->nchannels ||
        obt->freq != req->freq) {
        dolog ("Audio paramters mismatch for %s\n", typ);
        alsa_dump_info (req, obt);
    }
#endif

#ifdef DEBUG
    alsa_dump_info (req, obt);
#endif
    return 0;

 err:
    alsa_anal_close (&handle);
    return -1;
}

static int alsa_recover (snd_pcm_t *handle)
{
    int err = snd_pcm_prepare (handle);
    if (err < 0) {
        alsa_logerr (err, "Failed to prepare handle %p\n", handle);
        return -1;
    }
    return 0;
}

static snd_pcm_sframes_t alsa_get_avail (snd_pcm_t *handle)
{
    snd_pcm_sframes_t avail;

    avail = snd_pcm_avail_update (handle);
    if (avail < 0) {
        if (avail == -EPIPE) {
            if (!alsa_recover (handle)) {
                avail = snd_pcm_avail_update (handle);
            }
        }

        if (avail < 0) {
            alsa_logerr (avail,
                         "Could not obtain number of available frames\n");
            return -1;
        }
    }

    return avail;
}

static int alsa_run_out (HWVoiceOut *hw)
{
    ALSAVoiceOut *alsa = (ALSAVoiceOut *) hw;
    int rpos, live, decr;
    int samples;
    uint8_t *dst;
    st_sample_t *src;
    snd_pcm_sframes_t avail;

    live = audio_pcm_hw_get_live_out (hw);
    if (!live) {
        return 0;
    }

    avail = alsa_get_avail (alsa->handle);
    if (avail < 0) {
        dolog ("Could not get number of available playback frames\n");
        return 0;
    }

    decr = audio_MIN (live, avail);
    samples = decr;
    rpos = hw->rpos;
    while (samples) {
        int left_till_end_samples = hw->samples - rpos;
        int len = audio_MIN (samples, left_till_end_samples);
        snd_pcm_sframes_t written;

        src = hw->mix_buf + rpos;
        dst = advance (alsa->pcm_buf, rpos << hw->info.shift);

        hw->clip (dst, src, len);

        while (len) {
            written = snd_pcm_writei (alsa->handle, dst, len);

            if (written <= 0) {
                switch (written) {
                case 0:
                    if (conf.verbose) {
                        dolog ("Failed to write %d frames (wrote zero)\n", len);
                    }
                    goto exit;

                case -EPIPE:
                    if (alsa_recover (alsa->handle)) {
                        alsa_logerr (written, "Failed to write %d frames\n",
                                     len);
                        goto exit;
                    }
                    if (conf.verbose) {
                        dolog ("Recovering from playback xrun\n");
                    }
                    continue;

                case -EAGAIN:
                    goto exit;

                default:
                    alsa_logerr (written, "Failed to write %d frames to %p\n",
                                 len, dst);
                    goto exit;
                }
            }

            mixeng_clear (src, written);
            rpos = (rpos + written) % hw->samples;
            samples -= written;
            len -= written;
            dst = advance (dst, written << hw->info.shift);
            src += written;
        }
    }

 exit:
    hw->rpos = rpos;
    return decr;
}

static void alsa_fini_out (HWVoiceOut *hw)
{
    ALSAVoiceOut *alsa = (ALSAVoiceOut *) hw;

    ldebug ("alsa_fini\n");
    alsa_anal_close (&alsa->handle);

    if (alsa->pcm_buf) {
        qemu_free (alsa->pcm_buf);
        alsa->pcm_buf = NULL;
    }
}

static int alsa_init_out (HWVoiceOut *hw, audsettings_t *as)
{
    ALSAVoiceOut *alsa = (ALSAVoiceOut *) hw;
    struct alsa_params_req req;
    struct alsa_params_obt obt;
    audfmt_e effective_fmt;
    int endianness;
    int err;
    snd_pcm_t *handle;
    audsettings_t obt_as;

    req.fmt = aud_to_alsafmt (as->fmt);
    req.freq = as->freq;
    req.nchannels = as->nchannels;
    req.period_size = conf.period_size_out;
    req.buffer_size = conf.buffer_size_out;

    if (alsa_open (0, &req, &obt, &handle)) {
        return -1;
    }

    err = alsa_to_audfmt (obt.fmt, &effective_fmt, &endianness);
    if (err) {
        alsa_anal_close (&handle);
        return -1;
    }

    obt_as.freq = obt.freq;
    obt_as.nchannels = obt.nchannels;
    obt_as.fmt = effective_fmt;

    audio_pcm_init_info (
        &hw->info,
        &obt_as,
        audio_need_to_swap_endian (endianness)
        );
    hw->samples = obt.samples;

    alsa->pcm_buf = audio_calloc (AUDIO_FUNC, obt.samples, 1 << hw->info.shift);
    if (!alsa->pcm_buf) {
        dolog ("Could not allocate DAC buffer (%d samples, each %d bytes)\n",
               hw->samples, 1 << hw->info.shift);
        alsa_anal_close (&handle);
        return -1;
    }

    alsa->handle = handle;
    return 0;
}

static int alsa_voice_ctl (snd_pcm_t *handle, const char *typ, int pause)
{
    int err;

    if (pause) {
        err = snd_pcm_drop (handle);
        if (err < 0) {
            alsa_logerr (err, "Could not stop %s\n", typ);
            return -1;
        }
    }
    else {
        err = snd_pcm_prepare (handle);
        if (err < 0) {
            alsa_logerr (err, "Could not prepare handle for %s\n", typ);
            return -1;
        }
    }

    return 0;
}

static int alsa_ctl_out (HWVoiceOut *hw, int cmd, ...)
{
    ALSAVoiceOut *alsa = (ALSAVoiceOut *) hw;

    switch (cmd) {
    case VOICE_ENABLE:
        ldebug ("enabling voice\n");
        return alsa_voice_ctl (alsa->handle, "playback", 0);

    case VOICE_DISABLE:
        ldebug ("disabling voice\n");
        return alsa_voice_ctl (alsa->handle, "playback", 1);
    }

    return -1;
}

static int alsa_init_in (HWVoiceIn *hw, audsettings_t *as)
{
    ALSAVoiceIn *alsa = (ALSAVoiceIn *) hw;
    struct alsa_params_req req;
    struct alsa_params_obt obt;
    int endianness;
    int err;
    audfmt_e effective_fmt;
    snd_pcm_t *handle;
    audsettings_t obt_as;

    req.fmt = aud_to_alsafmt (as->fmt);
    req.freq = as->freq;
    req.nchannels = as->nchannels;
    req.period_size = conf.period_size_in;
    req.buffer_size = conf.buffer_size_in;

    if (alsa_open (1, &req, &obt, &handle)) {
        return -1;
    }

    err = alsa_to_audfmt (obt.fmt, &effective_fmt, &endianness);
    if (err) {
        alsa_anal_close (&handle);
        return -1;
    }

    obt_as.freq = obt.freq;
    obt_as.nchannels = obt.nchannels;
    obt_as.fmt = effective_fmt;

    audio_pcm_init_info (
        &hw->info,
        &obt_as,
        audio_need_to_swap_endian (endianness)
        );
    hw->samples = obt.samples;

    alsa->pcm_buf = audio_calloc (AUDIO_FUNC, hw->samples, 1 << hw->info.shift);
    if (!alsa->pcm_buf) {
        dolog ("Could not allocate ADC buffer (%d samples, each %d bytes)\n",
               hw->samples, 1 << hw->info.shift);
        alsa_anal_close (&handle);
        return -1;
    }

    alsa->handle = handle;
    return 0;
}

static void alsa_fini_in (HWVoiceIn *hw)
{
    ALSAVoiceIn *alsa = (ALSAVoiceIn *) hw;

    alsa_anal_close (&alsa->handle);

    if (alsa->pcm_buf) {
        qemu_free (alsa->pcm_buf);
        alsa->pcm_buf = NULL;
    }
}

static int alsa_run_in (HWVoiceIn *hw)
{
    ALSAVoiceIn *alsa = (ALSAVoiceIn *) hw;
    int hwshift = hw->info.shift;
    int i;
    int live = audio_pcm_hw_get_live_in (hw);
    int dead = hw->samples - live;
    int decr;
    struct {
        int add;
        int len;
    } bufs[2] = {
        { hw->wpos, 0 },
        { 0, 0 }
    };
    snd_pcm_sframes_t avail;
    snd_pcm_uframes_t read_samples = 0;

    if (!dead) {
        return 0;
    }

    avail = alsa_get_avail (alsa->handle);
    if (avail < 0) {
        dolog ("Could not get number of captured frames\n");
        return 0;
    }

    if (!avail && (snd_pcm_state (alsa->handle) == SND_PCM_STATE_PREPARED)) {
        avail = hw->samples;
    }

    decr = audio_MIN (dead, avail);
    if (!decr) {
        return 0;
    }

    if (hw->wpos + decr > hw->samples) {
        bufs[0].len = (hw->samples - hw->wpos);
        bufs[1].len = (decr - (hw->samples - hw->wpos));
    }
    else {
        bufs[0].len = decr;
    }

    for (i = 0; i < 2; ++i) {
        void *src;
        st_sample_t *dst;
        snd_pcm_sframes_t nread;
        snd_pcm_uframes_t len;

        len = bufs[i].len;

        src = advance (alsa->pcm_buf, bufs[i].add << hwshift);
        dst = hw->conv_buf + bufs[i].add;

        while (len) {
            nread = snd_pcm_readi (alsa->handle, src, len);

            if (nread <= 0) {
                switch (nread) {
                case 0:
                    if (conf.verbose) {
                        dolog ("Failed to read %ld frames (read zero)\n", len);
                    }
                    goto exit;

                case -EPIPE:
                    if (alsa_recover (alsa->handle)) {
                        alsa_logerr (nread, "Failed to read %ld frames\n", len);
                        goto exit;
                    }
                    if (conf.verbose) {
                        dolog ("Recovering from capture xrun\n");
                    }
                    continue;

                case -EAGAIN:
                    goto exit;

                default:
                    alsa_logerr (
                        nread,
                        "Failed to read %ld frames from %p\n",
                        len,
                        src
                        );
                    goto exit;
                }
            }

            hw->conv (dst, src, nread, &nominal_volume);

            src = advance (src, nread << hwshift);
            dst += nread;

            read_samples += nread;
            len -= nread;
        }
    }

 exit:
    hw->wpos = (hw->wpos + read_samples) % hw->samples;
    return read_samples;
}

static int alsa_read (SWVoiceIn *sw, void *buf, int size)
{
    return audio_pcm_sw_read (sw, buf, size);
}

static int alsa_ctl_in (HWVoiceIn *hw, int cmd, ...)
{
    ALSAVoiceIn *alsa = (ALSAVoiceIn *) hw;

    switch (cmd) {
    case VOICE_ENABLE:
        ldebug ("enabling voice\n");
        return alsa_voice_ctl (alsa->handle, "capture", 0);

    case VOICE_DISABLE:
        ldebug ("disabling voice\n");
        return alsa_voice_ctl (alsa->handle, "capture", 1);
    }

    return -1;
}

static void *alsa_audio_init (void)
{
    return &conf;
}

static void alsa_audio_fini (void *opaque)
{
    (void) opaque;
}

static struct audio_option alsa_options[] = {
    {"DAC_SIZE_IN_USEC", AUD_OPT_BOOL, &conf.size_in_usec_out,
     "DAC period/buffer size in microseconds (otherwise in frames)", NULL, 0},
    {"DAC_PERIOD_SIZE", AUD_OPT_INT, &conf.period_size_out,
     "DAC period size", &conf.period_size_out_overriden, 0},
    {"DAC_BUFFER_SIZE", AUD_OPT_INT, &conf.buffer_size_out,
     "DAC buffer size", &conf.buffer_size_out_overriden, 0},

    {"ADC_SIZE_IN_USEC", AUD_OPT_BOOL, &conf.size_in_usec_in,
     "ADC period/buffer size in microseconds (otherwise in frames)", NULL, 0},
    {"ADC_PERIOD_SIZE", AUD_OPT_INT, &conf.period_size_in,
     "ADC period size", &conf.period_size_in_overriden, 0},
    {"ADC_BUFFER_SIZE", AUD_OPT_INT, &conf.buffer_size_in,
     "ADC buffer size", &conf.buffer_size_in_overriden, 0},

    {"THRESHOLD", AUD_OPT_INT, &conf.threshold,
     "(undocumented)", NULL, 0},

    {"DAC_DEV", AUD_OPT_STR, &conf.pcm_name_out,
     "DAC device name (for instance dmix)", NULL, 0},

    {"ADC_DEV", AUD_OPT_STR, &conf.pcm_name_in,
     "ADC device name", NULL, 0},

    {"VERBOSE", AUD_OPT_BOOL, &conf.verbose,
     "Behave in a more verbose way", NULL, 0},

    {NULL, 0, NULL, NULL, NULL, 0}
};

static struct audio_pcm_ops alsa_pcm_ops = {
    alsa_init_out,
    alsa_fini_out,
    alsa_run_out,
    alsa_write,
    alsa_ctl_out,

    alsa_init_in,
    alsa_fini_in,
    alsa_run_in,
    alsa_read,
    alsa_ctl_in
};

struct audio_driver alsa_audio_driver = {
    INIT_FIELD (name           = ) "alsa",
    INIT_FIELD (descr          = ) "ALSA http://www.alsa-project.org",
    INIT_FIELD (options        = ) alsa_options,
    INIT_FIELD (init           = ) alsa_audio_init,
    INIT_FIELD (fini           = ) alsa_audio_fini,
    INIT_FIELD (pcm_ops        = ) &alsa_pcm_ops,
    INIT_FIELD (can_be_default = ) 1,
    INIT_FIELD (max_voices_out = ) INT_MAX,
    INIT_FIELD (max_voices_in  = ) INT_MAX,
    INIT_FIELD (voice_size_out = ) sizeof (ALSAVoiceOut),
    INIT_FIELD (voice_size_in  = ) sizeof (ALSAVoiceIn)
};