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pcm-indirect.h
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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Helper functions for indirect PCM data transfer
*
* Copyright (c) by Takashi Iwai <[email protected]>
* Jaroslav Kysela <[email protected]>
*/
#ifndef __SOUND_PCM_INDIRECT_H
#define __SOUND_PCM_INDIRECT_H
#include <sound/pcm.h>
struct snd_pcm_indirect {
unsigned int hw_buffer_size; /* Byte size of hardware buffer */
unsigned int hw_queue_size; /* Max queue size of hw buffer (0 = buffer size) */
unsigned int hw_data; /* Offset to next dst (or src) in hw ring buffer */
unsigned int hw_io; /* Ring buffer hw pointer */
int hw_ready; /* Bytes ready for play (or captured) in hw ring buffer */
unsigned int sw_buffer_size; /* Byte size of software buffer */
unsigned int sw_data; /* Offset to next dst (or src) in sw ring buffer */
unsigned int sw_io; /* Current software pointer in bytes */
int sw_ready; /* Bytes ready to be transferred to/from hw */
snd_pcm_uframes_t appl_ptr; /* Last seen appl_ptr */
};
typedef void (*snd_pcm_indirect_copy_t)(struct snd_pcm_substream *substream,
struct snd_pcm_indirect *rec, size_t bytes);
/*
* helper function for playback ack callback
*/
static inline int
snd_pcm_indirect_playback_transfer(struct snd_pcm_substream *substream,
struct snd_pcm_indirect *rec,
snd_pcm_indirect_copy_t copy)
{
struct snd_pcm_runtime *runtime = substream->runtime;
snd_pcm_uframes_t appl_ptr = runtime->control->appl_ptr;
snd_pcm_sframes_t diff = appl_ptr - rec->appl_ptr;
int qsize;
if (diff) {
if (diff < -(snd_pcm_sframes_t) (runtime->boundary / 2))
diff += runtime->boundary;
if (diff < 0)
return -EPIPE;
rec->sw_ready += (int)frames_to_bytes(runtime, diff);
rec->appl_ptr = appl_ptr;
}
qsize = rec->hw_queue_size ? rec->hw_queue_size : rec->hw_buffer_size;
while (rec->hw_ready < qsize && rec->sw_ready > 0) {
unsigned int hw_to_end = rec->hw_buffer_size - rec->hw_data;
unsigned int sw_to_end = rec->sw_buffer_size - rec->sw_data;
unsigned int bytes = qsize - rec->hw_ready;
if (rec->sw_ready < (int)bytes)
bytes = rec->sw_ready;
if (hw_to_end < bytes)
bytes = hw_to_end;
if (sw_to_end < bytes)
bytes = sw_to_end;
if (! bytes)
break;
copy(substream, rec, bytes);
rec->hw_data += bytes;
if (rec->hw_data == rec->hw_buffer_size)
rec->hw_data = 0;
rec->sw_data += bytes;
if (rec->sw_data == rec->sw_buffer_size)
rec->sw_data = 0;
rec->hw_ready += bytes;
rec->sw_ready -= bytes;
}
return 0;
}
/*
* helper function for playback pointer callback
* ptr = current byte pointer
*/
static inline snd_pcm_uframes_t
snd_pcm_indirect_playback_pointer(struct snd_pcm_substream *substream,
struct snd_pcm_indirect *rec, unsigned int ptr)
{
int bytes = ptr - rec->hw_io;
int err;
if (bytes < 0)
bytes += rec->hw_buffer_size;
rec->hw_io = ptr;
rec->hw_ready -= bytes;
rec->sw_io += bytes;
if (rec->sw_io >= rec->sw_buffer_size)
rec->sw_io -= rec->sw_buffer_size;
if (substream->ops->ack) {
err = substream->ops->ack(substream);
if (err == -EPIPE)
return SNDRV_PCM_POS_XRUN;
}
return bytes_to_frames(substream->runtime, rec->sw_io);
}
/*
* helper function for capture ack callback
*/
static inline int
snd_pcm_indirect_capture_transfer(struct snd_pcm_substream *substream,
struct snd_pcm_indirect *rec,
snd_pcm_indirect_copy_t copy)
{
struct snd_pcm_runtime *runtime = substream->runtime;
snd_pcm_uframes_t appl_ptr = runtime->control->appl_ptr;
snd_pcm_sframes_t diff = appl_ptr - rec->appl_ptr;
if (diff) {
if (diff < -(snd_pcm_sframes_t) (runtime->boundary / 2))
diff += runtime->boundary;
if (diff < 0)
return -EPIPE;
rec->sw_ready -= frames_to_bytes(runtime, diff);
rec->appl_ptr = appl_ptr;
}
while (rec->hw_ready > 0 &&
rec->sw_ready < (int)rec->sw_buffer_size) {
size_t hw_to_end = rec->hw_buffer_size - rec->hw_data;
size_t sw_to_end = rec->sw_buffer_size - rec->sw_data;
size_t bytes = rec->sw_buffer_size - rec->sw_ready;
if (rec->hw_ready < (int)bytes)
bytes = rec->hw_ready;
if (hw_to_end < bytes)
bytes = hw_to_end;
if (sw_to_end < bytes)
bytes = sw_to_end;
if (! bytes)
break;
copy(substream, rec, bytes);
rec->hw_data += bytes;
if ((int)rec->hw_data == rec->hw_buffer_size)
rec->hw_data = 0;
rec->sw_data += bytes;
if (rec->sw_data == rec->sw_buffer_size)
rec->sw_data = 0;
rec->hw_ready -= bytes;
rec->sw_ready += bytes;
}
return 0;
}
/*
* helper function for capture pointer callback,
* ptr = current byte pointer
*/
static inline snd_pcm_uframes_t
snd_pcm_indirect_capture_pointer(struct snd_pcm_substream *substream,
struct snd_pcm_indirect *rec, unsigned int ptr)
{
int qsize;
int bytes = ptr - rec->hw_io;
int err;
if (bytes < 0)
bytes += rec->hw_buffer_size;
rec->hw_io = ptr;
rec->hw_ready += bytes;
qsize = rec->hw_queue_size ? rec->hw_queue_size : rec->hw_buffer_size;
if (rec->hw_ready > qsize)
return SNDRV_PCM_POS_XRUN;
rec->sw_io += bytes;
if (rec->sw_io >= rec->sw_buffer_size)
rec->sw_io -= rec->sw_buffer_size;
if (substream->ops->ack) {
err = substream->ops->ack(substream);
if (err == -EPIPE)
return SNDRV_PCM_POS_XRUN;
}
return bytes_to_frames(substream->runtime, rec->sw_io);
}
#endif /* __SOUND_PCM_INDIRECT_H */