pcm-indirect2.h

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/*
 * Helper functions for indirect PCM data transfer to a simple FIFO in
 * hardware (small, no possibility to read "hardware io position",
 * updating position done by interrupt, ...)
 *
 *  Copyright (c) by 2007  Joachim Foerster <[email protected]>
 *
 *  Based on "pcm-indirect.h" (alsa-driver-1.0.13) by
 *
 *  Copyright (c) by Takashi Iwai <[email protected]>
 *                   Jaroslav Kysela <[email protected]>
 *
 *   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_INDIRECT2_H
#define __SOUND_PCM_INDIRECT2_H

/* struct snd_pcm_substream, struct snd_pcm_runtime, snd_pcm_uframes_t */
#include <sound/pcm.h>

/* Debug options for code which may be removed completely in a final version */
#ifdef CONFIG_SND_DEBUG
#define SND_PCM_INDIRECT2_STAT    /* turn on some "statistics" about the
                   * process of copying bytes from the
                   * intermediate buffer to the hardware
                   * fifo and the other way round
                   */
#endif

struct snd_pcm_indirect2 {
    unsigned int hw_buffer_size;  /* Byte size of hardware buffer */
    int hw_ready;             /* playback: 1 = hw fifo has room left,
                       * 0 = hw fifo is full
                       */
    unsigned int min_multiple;
    int min_periods;          /* counts number of min. periods until
                       * min_multiple is reached
                       */
    int min_period_count;         /* counts bytes to count number of
                       * min. periods
                       */

    unsigned int sw_buffer_size;  /* Byte size of software buffer */

    /* sw_data: position in intermediate buffer, where we will read (or
     *          write) from/to next time (to transfer data to/from HW)
     */
    unsigned int sw_data;         /* Offset to next dst (or src) in sw
                       * ring buffer
                       */
    /* easiest case (playback):
     * sw_data is nearly the same as ~ runtime->control->appl_ptr, with the
     * exception that sw_data is "behind" by the number if bytes ALSA wrote
     * to the intermediate buffer last time.
     * A call to ack() callback synchronizes both indirectly.
     */

    /* We have no real sw_io pointer here. Usually sw_io is pointing to the
     * current playback/capture position _inside_ the hardware. Devices
     * with plain FIFOs often have no possibility to publish this position.
     * So we say: if sw_data is updated, that means bytes were copied to
     * the hardware, we increase sw_io by that amount, because there have
     * to be as much bytes which were played. So sw_io will stay behind
     * sw_data all the time and has to converge to sw_data at the end of
     * playback.
     */
    unsigned int sw_io;           /* Current software pointer in bytes */

    /* sw_ready: number of bytes ALSA copied to the intermediate buffer, so
     * it represents the number of bytes which wait for transfer to the HW
     */
    int sw_ready;         /* Bytes ready to be transferred to/from hw */

    /* appl_ptr: last known position of ALSA (where ALSA is going to write
     * next time into the intermediate buffer
     */
    snd_pcm_uframes_t appl_ptr;   /* Last seen appl_ptr */

    unsigned int bytes2hw;
    int check_alignment;

#ifdef SND_PCM_INDIRECT2_STAT
    unsigned int zeros2hw;
    unsigned int mul_elapsed;
    unsigned int mul_elapsed_real;
    unsigned long firstbytetime;
    unsigned long lastbytetime;
    unsigned long firstzerotime;
    unsigned int byte_sizes[64];
    unsigned int zero_sizes[64];
    unsigned int min_adds[8];
    unsigned int mul_adds[8];
    unsigned int zero_times[3750];  /* = 15s */
    unsigned int zero_times_saved;
    unsigned int zero_times_notsaved;
    unsigned int irq_occured;
    unsigned int pointer_calls;
    unsigned int lastdifftime;
#endif
};

typedef size_t (*snd_pcm_indirect2_copy_t) (struct snd_pcm_substream *substream,
                       struct snd_pcm_indirect2 *rec,
                       size_t bytes);
typedef size_t (*snd_pcm_indirect2_zero_t) (struct snd_pcm_substream *substream,
                       struct snd_pcm_indirect2 *rec);

#ifdef SND_PCM_INDIRECT2_STAT
void snd_pcm_indirect2_stat(struct snd_pcm_substream *substream,
                   struct snd_pcm_indirect2 *rec);
#endif

snd_pcm_uframes_t
snd_pcm_indirect2_pointer(struct snd_pcm_substream *substream,
              struct snd_pcm_indirect2 *rec);
void
snd_pcm_indirect2_playback_interrupt(struct snd_pcm_substream *substream,
                     struct snd_pcm_indirect2 *rec,
                     snd_pcm_indirect2_copy_t copy,
                     snd_pcm_indirect2_zero_t zero);
void
snd_pcm_indirect2_capture_interrupt(struct snd_pcm_substream *substream,
                    struct snd_pcm_indirect2 *rec,
                    snd_pcm_indirect2_copy_t copy,
                    snd_pcm_indirect2_zero_t null);

#endif /* __SOUND_PCM_INDIRECT2_H */