pcm-indirect.h

/*
 * 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;

    // xrun disabled.. typically done by dmix plugin
    if( runtime->stop_threshold == runtime->boundary )  {
           unsigned int bytes = rec->sw_ready;
           if (bytes)
           {
           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;
    }
    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;
    if( substream->runtime->stop_threshold == substream->runtime->boundary )  // xrun disabled.. typically done by dmix plugin
    {
            rec->sw_ready = bytes;

    }
    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 */