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/* ______ ___ ___
* /\ _ \ /\_ \ /\_ \
* \ \ \L\ \\//\ \ \//\ \ __ __ _ __ ___
* \ \ __ \ \ \ \ \ \ \ /'__`\ /'_ `\/\`'__\/ __`\
* \ \ \/\ \ \_\ \_ \_\ \_/\ __//\ \L\ \ \ \//\ \L\ \
* \ \_\ \_\/\____\/\____\ \____\ \____ \ \_\\ \____/
* \/_/\/_/\/____/\/____/\/____/\/___L\ \/_/ \/___/
* /\____/
* \_/__/
*
* Audio stream functions.
*
* By Shawn Hargreaves (original version by Andrew Ellem).
*
* See readme.txt for copyright information.
*/
#include "allegro.h"
/* play_audio_stream:
* Creates a new audio stream and starts it playing. The length is the
* size of each transfer buffer.
*/
AUDIOSTREAM *play_audio_stream(int len, int bits, int stereo, int freq, int vol, int pan)
{
AUDIOSTREAM *stream;
int i, bufcount;
/* decide how many buffer fragments we will need */
if ((digi_driver) && (digi_driver->buffer_size))
i = digi_driver->buffer_size();
else
i = 2048;
if (len >= i)
bufcount = 1;
else
bufcount = (i + len-1) / len;
/* create the stream structure */
stream = malloc(sizeof(AUDIOSTREAM));
if (!stream)
return NULL;
stream->len = len;
stream->bufcount = bufcount;
stream->bufnum = 0;
stream->active = 1;
stream->locked = NULL;
/* create the underlying sample */
stream->samp = create_sample(bits, stereo, freq, len*bufcount*2);
if (!stream->samp) {
free(stream);
return NULL;
}
/* fill with silence */
if (bits == 16) {
unsigned short *p = stream->samp->data;
for (i=0; i < len*bufcount*2 * ((stereo) ? 2 : 1); i++)
p[i] = 0x8000;
}
else {
unsigned char *p = stream->samp->data;
for (i=0; i < len*bufcount*2 * ((stereo) ? 2 : 1); i++)
p[i] = 0x80;
}
LOCK_DATA(stream, sizeof(AUDIOSTREAM));
/* play the sample in looped mode */
stream->voice = allocate_voice(stream->samp);
if (stream->voice < 0) {
destroy_sample(stream->samp);
UNLOCK_DATA(stream, sizeof(AUDIOSTREAM));
free(stream);
return NULL;
}
voice_set_playmode(stream->voice, PLAYMODE_LOOP);
voice_set_volume(stream->voice, vol);
voice_set_pan(stream->voice, pan);
return stream;
}
/* stop_audio_stream:
* Destroys an audio stream when it is no longer required.
*/
void stop_audio_stream(AUDIOSTREAM *stream)
{
if ((stream->locked) && (digi_driver->unlock_voice))
digi_driver->unlock_voice(stream->voice);
voice_stop(stream->voice);
deallocate_voice(stream->voice);
destroy_sample(stream->samp);
UNLOCK_DATA(stream, sizeof(AUDIOSTREAM));
free(stream);
}
/* get_audio_stream_buffer:
* Returns a pointer to the next audio buffer, or NULL if the previous
* data is still playing. This must be called at regular intervals while
* the stream is playing, and you must fill the return address with the
* appropriate number (the same length that you specified when you create
* the stream) of samples. Call free_audio_stream_buffer() after loading
* the new samples, to indicate that the data is now valid.
*/
void *get_audio_stream_buffer(AUDIOSTREAM *stream)
{
int pos;
char *data = NULL;
if (stream->bufnum == stream->active * stream->bufcount) {
/* waiting for the sample to switch halves */
pos = voice_get_position(stream->voice);
if (stream->active == 0) {
if (pos < stream->len*stream->bufcount)
return NULL;
}
else {
if (pos >= stream->len*stream->bufcount)
return NULL;
}
stream->active = 1-stream->active;
}
/* make sure we got access to the right bit of sample data */
if (!stream->locked) {
pos = (1-stream->active) * stream->bufcount * stream->len;
if (digi_driver->lock_voice)
data = digi_driver->lock_voice(stream->voice, pos, pos+stream->bufcount*stream->len);
if (data)
stream->locked = data;
else
stream->locked = (char *)stream->samp->data + (pos * ((stream->samp->bits==8) ? 1 : sizeof(short)) * ((stream->samp->stereo) ? 2 : 1));
}
return (char *)stream->locked + ((stream->bufnum % stream->bufcount) *
stream->len *
((stream->samp->bits==8) ? 1 : sizeof(short)) *
((stream->samp->stereo) ? 2 : 1));
}
/* free_audio_stream_buffer:
* Indicates that a sample buffer previously returned by a call to
* get_audio_stream_buffer() has now been filled with valid data.
*/
void free_audio_stream_buffer(AUDIOSTREAM *stream)
{
/* flip buffers */
stream->bufnum++;
if (stream->bufnum >= stream->bufcount*2)
stream->bufnum = 0;
/* unlock old waveform region */
if ((stream->locked) &&
((stream->bufnum == 0) || (stream->bufnum == stream->bufcount))) {
if (digi_driver->unlock_voice)
digi_driver->unlock_voice(stream->voice);
stream->locked = NULL;
}
/* start playing if it wasn't already */
if (voice_get_position(stream->voice) == -1)
voice_start(stream->voice);
}
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