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/*

 * Helper functions for indirect PCM data transfer

 *

 *  Copyright (c) by Takashi Iwai <tiwai@suse.de>

 *                   Jaroslav Kysela <perex@perex.cz>

 *

 *   This program is free software; you can redistribute it and/or modify

 *   it under the terms of the GNU General Public License as published by

 *   the Free Software Foundation; either version 2 of the License, or

 *   (at your option) any later version.

 *

 *   This program is distributed in the hope that it will be useful,

 *   but WITHOUT ANY WARRANTY; without even the implied warranty of

 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *   GNU General Public License for more details.

 *

 *   You should have received a copy of the GNU General Public License

 *   along with this program; if not, write to the Free Software

 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 */

#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 void

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;

                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;

        }

}

/*

 * 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;

        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)

                substream->ops->ack(substream);

        return bytes_to_frames(substream->runtime, rec->sw_io);

}

/*

 * helper function for capture ack callback

 */

static inline void

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;

                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;

        }

}

/*

 * 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;

        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)

                substream->ops->ack(substream);

        return bytes_to_frames(substream->runtime, rec->sw_io);

}

#endif /* __SOUND_PCM_INDIRECT_H */