浅析alsa声卡驱动snd_pcm_lib_write函数

snd_pcm_sframes_t snd_pcm_lib_write(struct snd_pcm_substream *substream, const void __user *buf, snd_pcm_uframes_t size)
{
    struct snd_pcm_runtime *runtime;
    int nonblock;
    int err;

    err = pcm_sanity_check(substream);
    if (err < 0)
        return err;
    runtime = substream->runtime;
    nonblock = !!(substream->f_flags & O_NONBLOCK);

    if (runtime->access != SNDRV_PCM_ACCESS_RW_INTERLEAVED &&
        runtime->channels > 1)
        return -EINVAL;
    // 调用snd_pcm_lib_write_transfer将buf中的size大小音频数据发送到外围音频硬件[luther.gliethttp]
    return snd_pcm_lib_write1(substream, (unsigned long)buf, size, nonblock,
                  snd_pcm_lib_write_transfer); 《浅析alsa声卡驱动snd_pcm_lib_write1函数》
}