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Small change to PCM recording API for low latency effects. Latency can be as low as 14 samples from input to output including the FIFOs (ColdFire) but 16 is more reasonable an expectation if only tranferring one sample per interrupt (\!). May convert PCM playback to use the same method as it can still be used in the old manner with some slight mods but has the potential to enable new features since it is more flexible.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@11668 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Michael Sevakis 2006-12-06 08:34:55 +00:00
parent 1ff7652adf
commit 51189b4cb4
6 changed files with 62 additions and 74 deletions
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42
firmware/pcm_record.c
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@ -55,13 +55,9 @@
be shared semi-privately **/
/* the registered callback function for when more data is available */
volatile pcm_more_callback_type pcm_callback_more_ready = NULL;
volatile pcm_more_callback_type2 pcm_callback_more_ready = NULL;
/* DMA transfer in is currently active */
volatile bool pcm_recording = false;
/* APIs implemented in the target-specific portion */
void pcm_rec_dma_start(const void *addr, size_t size);
void pcm_rec_dma_stop(void);
volatile bool pcm_recording = false;
/** General recording state **/
static bool is_recording; /* We are recording */
@ -225,16 +221,16 @@ static void pcm_thread_wait_for_stop(void)
/*******************************************************************/
/* Callback for when more data is ready */
static void pcm_rec_have_more(unsigned char **data, size_t *size)
static int pcm_rec_have_more(int status)
{
if (*size != 0)
if (status < 0)
{
/* some error condition */
if (*size == DMA_REC_ERROR_DMA)
if (status == DMA_REC_ERROR_DMA)
{
/* Flush recorded data to disk and stop recording */
queue_post(&pcmrec_queue, PCMREC_STOP, NULL);
return;
return -1;
}
/* else try again next transmission */
}
@ -243,9 +239,9 @@ static void pcm_rec_have_more(unsigned char **data, size_t *size)
/* advance write position */
dma_wr_pos = (dma_wr_pos + PCM_CHUNK_SIZE) & PCM_CHUNK_MASK;
}
*data = (unsigned char *)GET_PCM_CHUNK(dma_wr_pos);
*size = PCM_CHUNK_SIZE;
pcm_record_more(GET_PCM_CHUNK(dma_wr_pos), PCM_CHUNK_SIZE);
return 0;
} /* pcm_rec_have_more */
/** pcm_rec_* group **/
@ -423,9 +419,9 @@ void audio_set_recording_options(struct audio_recording_options *options)
if (audio_load_encoder(enc_config.afmt))
{
/* start DMA transfer */
pcm_record_data(pcm_rec_have_more, NULL, 0);
/* do unlock after starting to prevent preincrement of dma_wr_pos */
dma_lock = pre_record_ticks == 0;
pcm_record_data(pcm_rec_have_more, GET_PCM_CHUNK(dma_wr_pos),
PCM_CHUNK_SIZE);
}
else
{
@ -1621,20 +1617,14 @@ size_t enc_unget_pcm_data(size_t size)
* Functions that do not require targeted implementation but only a targeted
* interface
*/
void pcm_record_data(pcm_more_callback_type more_ready,
unsigned char *start, size_t size)
void pcm_record_data(pcm_more_callback_type2 more_ready,
void *start, size_t size)
{
pcm_callback_more_ready = more_ready;
if (!(start && size))
{
size = 0;
if (more_ready)
more_ready(&start, &size);
}
return;
if (start && size)
pcm_rec_dma_start(start, size);
pcm_callback_more_ready = more_ready;
pcm_rec_dma_start(start, size);
} /* pcm_record_data */
void pcm_stop_recording(void)