alsaaudio.c

qemu虚拟机代码

/*
 * QEMU ALSA audio driver
 *
 * Copyright (c) 2005 Vassili Karpov (malc)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#include <alsa/asoundlib.h>
#include "vl.h"

#define AUDIO_CAP "alsa"
#include "audio_int.h"

typedef struct ALSAVoiceOut {
    HWVoiceOut hw;
    void *pcm_buf;
    snd_pcm_t *handle;
} ALSAVoiceOut;

typedef struct ALSAVoiceIn {
    HWVoiceIn hw;
    snd_pcm_t *handle;
    void *pcm_buf;
} ALSAVoiceIn;

static struct {
    int size_in_usec_in;
    int size_in_usec_out;
    const char *pcm_name_in;
    const char *pcm_name_out;
    unsigned int buffer_size_in;
    unsigned int period_size_in;
    unsigned int buffer_size_out;
    unsigned int period_size_out;
    unsigned int threshold;

    int buffer_size_in_overriden;
    int period_size_in_overriden;

    int buffer_size_out_overriden;
    int period_size_out_overriden;
    int verbose;
} conf = {
#ifdef HIGH_LATENCY
    .size_in_usec_in = 1,
    .size_in_usec_out = 1,
#endif
    .pcm_name_out = "hw:0,0",
    .pcm_name_in = "hw:0,0",
#ifdef HIGH_LATENCY
    .buffer_size_in = 400000,
    .period_size_in = 400000 / 4,
    .buffer_size_out = 400000,
    .period_size_out = 400000 / 4,
#else
#define DEFAULT_BUFFER_SIZE 1024
#define DEFAULT_PERIOD_SIZE 256
    .buffer_size_in = DEFAULT_BUFFER_SIZE * 4,
    .period_size_in = DEFAULT_PERIOD_SIZE * 4,
    .buffer_size_out = DEFAULT_BUFFER_SIZE,
    .period_size_out = DEFAULT_PERIOD_SIZE,
    .buffer_size_in_overriden = 0,
    .buffer_size_out_overriden = 0,
    .period_size_in_overriden = 0,
    .period_size_out_overriden = 0,
#endif
    .threshold = 0,
    .verbose = 0
};

struct alsa_params_req {
    int freq;
    audfmt_e fmt;
    int nchannels;
    unsigned int buffer_size;
    unsigned int period_size;
};

struct alsa_params_obt {
    int freq;
    audfmt_e fmt;
    int nchannels;
    snd_pcm_uframes_t samples;
};

static void GCC_FMT_ATTR (2, 3) alsa_logerr (int err, const char *fmt, ...)
{
    va_list ap;

    va_start (ap, fmt);
    AUD_vlog (AUDIO_CAP, fmt, ap);
    va_end (ap);

    AUD_log (AUDIO_CAP, "Reason: %s\n", snd_strerror (err));
}

static void GCC_FMT_ATTR (3, 4) alsa_logerr2 (
    int err,
    const char *typ,
    const char *fmt,
    ...
    )
{
    va_list ap;

    AUD_log (AUDIO_CAP, "Could not initialize %s\n", typ);

    va_start (ap, fmt);
    AUD_vlog (AUDIO_CAP, fmt, ap);
    va_end (ap);

    AUD_log (AUDIO_CAP, "Reason: %s\n", snd_strerror (err));
}

static void alsa_anal_close (snd_pcm_t **handlep)
{
    int err = snd_pcm_close (*handlep);
    if (err) {
        alsa_logerr (err, "Failed to close PCM handle %p\n", *handlep);
    }
    *handlep = NULL;
}

static int alsa_write (SWVoiceOut *sw, void *buf, int len)
{
    return audio_pcm_sw_write (sw, buf, len);
}

static int aud_to_alsafmt (audfmt_e fmt)
{
    switch (fmt) {
    case AUD_FMT_S8:
        return SND_PCM_FORMAT_S8;

    case AUD_FMT_U8:
        return SND_PCM_FORMAT_U8;

    case AUD_FMT_S16:
        return SND_PCM_FORMAT_S16_LE;

    case AUD_FMT_U16:
        return SND_PCM_FORMAT_U16_LE;

    default:
        dolog ("Internal logic error: Bad audio format %d\n", fmt);
#ifdef DEBUG_AUDIO
        abort ();
#endif
        return SND_PCM_FORMAT_U8;
    }
}

static int alsa_to_audfmt (int alsafmt, audfmt_e *fmt, int *endianness)
{
    switch (alsafmt) {
    case SND_PCM_FORMAT_S8:
        *endianness = 0;
        *fmt = AUD_FMT_S8;
        break;

    case SND_PCM_FORMAT_U8:
        *endianness = 0;
        *fmt = AUD_FMT_U8;
        break;

    case SND_PCM_FORMAT_S16_LE:
        *endianness = 0;
        *fmt = AUD_FMT_S16;
        break;

    case SND_PCM_FORMAT_U16_LE:
        *endianness = 0;
        *fmt = AUD_FMT_U16;
        break;

    case SND_PCM_FORMAT_S16_BE:
        *endianness = 1;
        *fmt = AUD_FMT_S16;
        break;

    case SND_PCM_FORMAT_U16_BE:
        *endianness = 1;
        *fmt = AUD_FMT_U16;
        break;

    default:
        dolog ("Unrecognized audio format %d\n", alsafmt);
        return -1;
    }

    return 0;
}

#if defined DEBUG_MISMATCHES || defined DEBUG
static void alsa_dump_info (struct alsa_params_req *req,
                            struct alsa_params_obt *obt)
{
    dolog ("parameter | requested value | obtained value\n");
    dolog ("format    |      %10d |     %10d\n", req->fmt, obt->fmt);
    dolog ("channels  |      %10d |     %10d\n",
           req->nchannels, obt->nchannels);
    dolog ("frequency |      %10d |     %10d\n", req->freq, obt->freq);
    dolog ("============================================\n");
    dolog ("requested: buffer size %d period size %d\n",
           req->buffer_size, req->period_size);
    dolog ("obtained: samples %ld\n", obt->samples);
}
#endif

static void alsa_set_threshold (snd_pcm_t *handle, snd_pcm_uframes_t threshold)
{
    int err;
    snd_pcm_sw_params_t *sw_params;

    snd_pcm_sw_params_alloca (&sw_params);

    err = snd_pcm_sw_params_current (handle, sw_params);
    if (err < 0) {
        dolog ("Could not fully initialize DAC\n");
        alsa_logerr (err, "Failed to get current software parameters\n");
        return;
    }

    err = snd_pcm_sw_params_set_start_threshold (handle, sw_params, threshold);
    if (err < 0) {
        dolog ("Could not fully initialize DAC\n");
        alsa_logerr (err, "Failed to set software threshold to %ld\n",
                     threshold);
        return;
    }

    err = snd_pcm_sw_params (handle, sw_params);
    if (err < 0) {
        dolog ("Could not fully initialize DAC\n");
        alsa_logerr (err, "Failed to set software parameters\n");
        return;
    }
}

static int alsa_open (int in, struct alsa_params_req *req,
                      struct alsa_params_obt *obt, snd_pcm_t **handlep)
{
    snd_pcm_t *handle;
    snd_pcm_hw_params_t *hw_params;
    int err, freq, nchannels;
    const char *pcm_name = in ? conf.pcm_name_in : conf.pcm_name_out;
    unsigned int period_size, buffer_size;
    snd_pcm_uframes_t obt_buffer_size;
    const char *typ = in ? "ADC" : "DAC";

    freq = req->freq;
    period_size = req->period_size;
    buffer_size = req->buffer_size;
    nchannels = req->nchannels;

    snd_pcm_hw_params_alloca (&hw_params);

    err = snd_pcm_open (
        &handle,
        pcm_name,
        in ? SND_PCM_STREAM_CAPTURE : SND_PCM_STREAM_PLAYBACK,
        SND_PCM_NONBLOCK
        );
    if (err < 0) {
        alsa_logerr2 (err, typ, "Failed to open `%s':\n", pcm_name);
        return -1;
    }

    err = snd_pcm_hw_params_any (handle, hw_params);
    if (err < 0) {
        alsa_logerr2 (err, typ, "Failed to initialize hardware parameters\n");
        goto err;
    }

    err = snd_pcm_hw_params_set_access (
        handle,
        hw_params,
        SND_PCM_ACCESS_RW_INTERLEAVED
        );
    if (err < 0) {
        alsa_logerr2 (err, typ, "Failed to set access type\n");
        goto err;
    }

    err = snd_pcm_hw_params_set_format (handle, hw_params, req->fmt);
    if (err < 0) {
        alsa_logerr2 (err, typ, "Failed to set format %d\n", req->fmt);
        goto err;
    }

    err = snd_pcm_hw_params_set_rate_near (handle, hw_params, &freq, 0);
    if (err < 0) {
        alsa_logerr2 (err, typ, "Failed to set frequency %d\n", req->freq);
        goto err;
    }

    err = snd_pcm_hw_params_set_channels_near (
        handle,
        hw_params,
        &nchannels
        );
    if (err < 0) {
        alsa_logerr2 (err, typ, "Failed to set number of channels %d\n",
                      req->nchannels);
        goto err;
    }

    if (nchannels != 1 && nchannels != 2) {
        alsa_logerr2 (err, typ,
                      "Can not handle obtained number of channels %d\n",
                      nchannels);
        goto err;
    }

    if (!((in && conf.size_in_usec_in) || (!in && conf.size_in_usec_out))) {
        if (!buffer_size) {
            buffer_size = DEFAULT_BUFFER_SIZE;
            period_size= DEFAULT_PERIOD_SIZE;
        }
    }

    if (buffer_size) {
        if ((in && conf.size_in_usec_in) || (!in && conf.size_in_usec_out)) {
            if (period_size) {
                err = snd_pcm_hw_params_set_period_time_near (
                    handle,
                    hw_params,
                    &period_size,
                    0
                    );
                if (err < 0) {
                    alsa_logerr2 (err, typ,
                                  "Failed to set period time %d\n",
                                  req->period_size);
                    goto err;
                }
            }

            err = snd_pcm_hw_params_set_buffer_time_near (
                handle,
                hw_params,
                &buffer_size,
                0
                );

            if (err < 0) {
                alsa_logerr2 (err, typ,
                              "Failed to set buffer time %d\n",
                              req->buffer_size);
                goto err;
            }
        }
        else {
            int dir;
            snd_pcm_uframes_t minval;

            if (period_size) {
                minval = period_size;
                dir = 0;

                err = snd_pcm_hw_params_get_period_size_min (
                    hw_params,
                    &minval,
                    &dir
                    );
                if (err < 0) {
                    alsa_logerr (
                        err,
                        "Could not get minmal period size for %s\n",
                        typ
                        );
                }
                else {
                    if (period_size < minval) {
                        if ((in && conf.period_size_in_overriden)
                            || (!in && conf.period_size_out_overriden)) {
                            dolog ("%s period size(%d) is less "
                                   "than minmal period size(%ld)\n",
                                   typ,
                                   period_size,
                                   minval);
                        }
                        period_size = minval;
                    }
                }

                err = snd_pcm_hw_params_set_period_size (
                    handle,
                    hw_params,
                    period_size,
                    0
                    );
                if (err < 0) {
                    alsa_logerr2 (err, typ, "Failed to set period size %d\n",
                                  req->period_size);
                    goto err;
                }
            }

            minval = buffer_size;
            err = snd_pcm_hw_params_get_buffer_size_min (
                hw_params,
                &minval
                );
            if (err < 0) {
                alsa_logerr (err, "Could not get minmal buffer size for %s\n",
                             typ);
            }
            else {
                if (buffer_size < minval) {
                    if ((in && conf.buffer_size_in_overriden)
                        || (!in && conf.buffer_size_out_overriden)) {
                        dolog (
                            "%s buffer size(%d) is less "
                            "than minimal buffer size(%ld)\n",
                            typ,
                            buffer_size,
                            minval
                            );
                    }
                    buffer_size = minval;
                }
            }

            err = snd_pcm_hw_params_set_buffer_size (
                handle,
                hw_params,
                buffer_size
                );
            if (err < 0) {
                alsa_logerr2 (err, typ, "Failed to set buffer size %d\n",
                              req->buffer_size);
                goto err;
            }
        }
    }
    else {
        dolog ("warning: Buffer size is not set\n");
    }

    err = snd_pcm_hw_params (handle, hw_params);
    if (err < 0) {
        alsa_logerr2 (err, typ, "Failed to apply audio parameters\n");
        goto err;
    }

    err = snd_pcm_hw_params_get_buffer_size (hw_params, &obt_buffer_size);
    if (err < 0) {
        alsa_logerr2 (err, typ, "Failed to get buffer size\n");
        goto err;
    }

    err = snd_pcm_prepare (handle);
    if (err < 0) {
        alsa_logerr2 (err, typ, "Could not prepare handle %p\n", handle);
        goto err;
    }

    if (!in && conf.threshold) {
        snd_pcm_uframes_t threshold;
        int bytes_per_sec;

        bytes_per_sec = freq
            << (nchannels == 2)
            << (req->fmt == AUD_FMT_S16 || req->fmt == AUD_FMT_U16);

        threshold = (conf.threshold * bytes_per_sec) / 1000;
        alsa_set_threshold (handle, threshold);
    }

    obt->fmt = req->fmt;
    obt->nchannels = nchannels;
    obt->freq = freq;
    obt->samples = obt_buffer_size;
    *handlep = handle;