aq.c

MIDI解码程序(用VC编写)

static void alloc_soft_queue(void)
{
    int i;
    char *base;

    if(base_buckets)
    {
	free(base_buckets[0].data);
	free(base_buckets);
	base_buckets = NULL;
    }

    base_buckets = (AudioBucket *)safe_malloc(nbuckets * sizeof(AudioBucket));
    base = (char *)safe_malloc(nbuckets * bucket_size);
    for(i = 0; i < nbuckets; i++)
	base_buckets[i].data = base + i * bucket_size;
    flush_buckets();
}

/* aq_fill_one() transfers one audio bucket to device. */
static int aq_fill_one(void)
{
    AudioBucket *tmp;

    if(head == NULL)
	return 0;
    if(aq_output_data(head->data, bucket_size) == -1)
	return -1;
    tmp = head;
    head = head->next;
    reuse_audio_bucket(tmp);
    return 0;
}

/* aq_fill_nonblocking() transfers some audio buckets to device.
 * This function is non-blocking.  But it is possible to block because
 * of miss-estimated aq_fillable() calculation.
 */
int aq_fill_nonblocking(void)
{
    int32 i, nfills;
    AudioBucket *tmp;

    if(head == NULL || head->len != bucket_size || !IS_STREAM_TRACE)
	return 0;

    nfills = (aq_fillable() * Bps) / bucket_size;
    for(i = 0; i < nfills; i++)
    {
	if(head == NULL || head->len != bucket_size)
	    break;
	if(aq_output_data(head->data, bucket_size) == -1)
	    return RC_ERROR;
	tmp = head;
	head = head->next;
	reuse_audio_bucket(tmp);
    }
    return 0;
}

int32 aq_samples(void)
{
    double realtime, es;
    int s;

    if(play_mode->acntl(PM_REQ_GETSAMPLES, &s) != -1)
    {
	/* Reset counter & timer */
	if(play_counter)
	{
	    play_start_time = get_current_calender_time();
	    play_offset_counter = s;
	    play_counter = 0;
	}
	return s;
    }

    if(!IS_STREAM_TRACE)
	return -1;

    realtime = get_current_calender_time();
    if(play_counter == 0)
    {
	play_start_time = realtime;
	return play_offset_counter;
    }
    es = play_mode->rate * (realtime - play_start_time);
    if(es >= play_counter)
    {
	/* Ouch!
	 * Audio device queue may be empty!
	 * Reset counters.
	 */

	play_offset_counter += play_counter;
	play_counter = 0;
	play_start_time = realtime;
	return play_offset_counter;
    }

    return (int32)es + play_offset_counter;
}

int32 aq_filled(void)
{
    double realtime, es;
    int filled;

    if(!IS_STREAM_TRACE)
	return 0;

    if(play_mode->acntl(PM_REQ_GETFILLED, &filled) != -1)
      return filled;

    realtime = get_current_calender_time();
    if(play_counter == 0)
    {
	play_start_time = realtime;
	return 0;
    }
    es = play_mode->rate * (realtime - play_start_time);
    if(es >= play_counter)
    {
	/* out of play counter */
	play_offset_counter += play_counter;
	play_counter = 0;
	play_start_time = realtime;
	return 0;
    }
    return play_counter - (int32)es;
}

int32 aq_soft_filled(void)
{
    int32 bytes;
    AudioBucket *cur;

    bytes = 0;
    for(cur = head; cur != NULL; cur = cur->next)
	bytes += cur->len;
    return bytes / Bps;
}

int32 aq_fillable(void)
{
    int fillable;
    if(!IS_STREAM_TRACE)
	return 0;
    if(play_mode->acntl(PM_REQ_GETFILLABLE, &fillable) != -1)
	return fillable;
    return device_qsize / Bps - aq_filled();
}

double aq_filled_ratio(void)
{
    double ratio;

    if(!IS_STREAM_TRACE)
	return 1.0;
    ratio = (double)aq_filled() * Bps / device_qsize;
    if(ratio > 1.0)
	return 1.0; /* for safety */
    return ratio;
}

int aq_get_dev_queuesize(void)
{
    if(!IS_STREAM_TRACE)
	return 0;
    return device_qsize / Bps;
}

int aq_soft_flush(void)
{
    int rc;

    while(head)
    {
	if(head->len < bucket_size)
	{
	    /* Add silence code */
	    memset (head->data + head->len, 0, bucket_size - head->len);
	    head->len = bucket_size;
	}
	if(aq_fill_one() == -1)
	    return RC_ERROR;
	trace_loop();
	rc = check_apply_control();
	if(RC_IS_SKIP_FILE(rc))
	{
	    play_mode->acntl(PM_REQ_DISCARD, NULL);
	    flush_buckets();
	    return rc;
	}
    }
    play_mode->acntl(PM_REQ_OUTPUT_FINISH, NULL);
    return RC_NONE;
}

int aq_flush(int discard)
{
    int rc;
    int more_trace;

    /* to avoid infinite loop */
    double t, timeout_expect;

    aq_add_count = 0;
    init_effect();

    if(discard)
    {
	trace_flush();
	if(play_mode->acntl(PM_REQ_DISCARD, NULL) != -1)
	{
	    flush_buckets();
	    return RC_NONE;
	}
	ctl->cmsg(CMSG_ERROR, VERB_NORMAL,
		  "ERROR: Can't discard audio buffer");
    }

    if(!IS_STREAM_TRACE)
    {
	play_mode->acntl(PM_REQ_FLUSH, NULL);
	play_counter = play_offset_counter = 0;
	return RC_NONE;
    }

    rc = aq_soft_flush();
    if(RC_IS_SKIP_FILE(rc))
	return rc;

    more_trace = 1;
    t = get_current_calender_time();
    timeout_expect = t + (double)aq_filled() / play_mode->rate;

    while(more_trace || aq_filled() > 0)
    {
	rc = check_apply_control();
	if(RC_IS_SKIP_FILE(rc))
	{
	    play_mode->acntl(PM_REQ_DISCARD, NULL);
	    flush_buckets();
	    return rc;
	}
	more_trace = trace_loop();

	t = get_current_calender_time();
	if(t >= timeout_expect - 0.1)
	  break;

	if(!more_trace)
	  usleep((unsigned long)((timeout_expect - t) * 1000000));
	else
	  aq_wait_ticks();
    }

    trace_flush();
    play_mode->acntl(PM_REQ_FLUSH, NULL);
    flush_buckets();
    return RC_NONE;
}

/* Wait a moment */
static void aq_wait_ticks(void)
{
    int32 trace_wait, wait_samples;

    if(device_qsize == 0 ||
       (trace_wait = trace_wait_samples()) == 0)
	return; /* No wait */
    wait_samples = (device_qsize / Bps) / 5; /* 20% */
    if(trace_wait != -1 && /* There are more trace events */
       trace_wait < wait_samples)
	wait_samples = trace_wait;
    usleep((unsigned int)((double)wait_samples / play_mode->rate * 1000000.0));
}

/* add_play_bucket() attempts to add buf to audio bucket.
 * It returns actually added bytes.
 */
static int add_play_bucket(const char *buf, int n)
{
    int total;

    if(n == 0)
	return 0;

    if(!nbuckets) {
      play_mode->output_data((char *)buf, n);
      return n;
    }

    if(head == NULL)
	head = tail = next_allocated_bucket();

    total = 0;
    while(n > 0)
    {
	int i;

	if(tail->len == bucket_size)
	{
	    AudioBucket *b;
	    if((b = next_allocated_bucket()) == NULL)
		break;
	    if(head == NULL)
		head = tail = b;
	    else
		tail = tail->next = b;
	}

	i = bucket_size - tail->len;
	if(i > n)
	    i = n;
	memcpy(tail->data + tail->len, buf + total, i);
	total += i;
	n     -= i;
	tail->len += i;
    }

    return total;
}

/* Flush and clear audio bucket */
static void flush_buckets(void)
{
    int i;

    allocated_bucket_list = NULL;
    for(i = 0; i < nbuckets; i++)
	reuse_audio_bucket(&base_buckets[i]);
    head = tail = NULL;
    aq_fill_buffer_flag = (aq_start_count > 0);
    play_counter = play_offset_counter = 0;
}

/* next_allocated_bucket() gets free bucket.  If all buckets is used, it
 * returns NULL.
 */
static AudioBucket *next_allocated_bucket(void)
{
    AudioBucket *b;

    if(allocated_bucket_list == NULL)
	return NULL;
    b = allocated_bucket_list;
    allocated_bucket_list = allocated_bucket_list->next;
    b->len = 0;
    b->next = NULL;
    return b;
}

/* Reuse specified bucket */
static void reuse_audio_bucket(AudioBucket *bucket)
{
    bucket->next = allocated_bucket_list;
    allocated_bucket_list = bucket;
}