sound/drivers/pcm-indirect2.h

   1 /*
   2  * Helper functions for indirect PCM data transfer to a simple FIFO in
   3  * hardware (small, no possibility to read "hardware io position",
   4  * updating position done by interrupt, ...)
   5  *
   6  *  Copyright (c) by 2007  Joachim Foerster <JOFT@gmx.de>
   7  *
   8  *  Based on "pcm-indirect.h" (alsa-driver-1.0.13) by
   9  *
  10  *  Copyright (c) by Takashi Iwai <tiwai@suse.de>
  11  *                   Jaroslav Kysela <perex@suse.cz>
  12  *
  13  *   This program is free software; you can redistribute it and/or modify
  14  *   it under the terms of the GNU General Public License as published by
  15  *   the Free Software Foundation; either version 2 of the License, or
  16  *   (at your option) any later version.
  17  *
  18  *   This program is distributed in the hope that it will be useful,
  19  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  *   GNU General Public License for more details.
  22  *
  23  *   You should have received a copy of the GNU General Public License
  24  *   along with this program; if not, write to the Free Software
  25  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  26  */
  27
  28 #ifndef __SOUND_PCM_INDIRECT2_H
  29 #define __SOUND_PCM_INDIRECT2_H
  30
  31 /* struct snd_pcm_substream, struct snd_pcm_runtime, snd_pcm_uframes_t */
  32 #include <sound/pcm.h>
  33
  34 /* Debug options for code which may be removed completely in a final version */
  35 #ifdef CONFIG_SND_DEBUG
  36 #define SND_PCM_INDIRECT2_STAT    /* turn on some "statistics" about the
  37                                    * process of copying bytes from the
  38                                    * intermediate buffer to the hardware
  39                                    * fifo and the other way round
  40                                    */
  41 #endif
  42
  43 struct snd_pcm_indirect2 {
  44         unsigned int hw_buffer_size;  /* Byte size of hardware buffer */
  45         int hw_ready;                 /* playback: 1 = hw fifo has room left,
  46                                        * 0 = hw fifo is full
  47                                        */
  48         unsigned int min_multiple;
  49         int min_periods;              /* counts number of min. periods until
  50                                        * min_multiple is reached
  51                                        */
  52         int min_period_count;         /* counts bytes to count number of
  53                                        * min. periods
  54                                        */
  55
  56         unsigned int sw_buffer_size;  /* Byte size of software buffer */
  57
  58         /* sw_data: position in intermediate buffer, where we will read (or
  59          *          write) from/to next time (to transfer data to/from HW)
  60          */
  61         unsigned int sw_data;         /* Offset to next dst (or src) in sw
  62                                        * ring buffer
  63                                        */
  64         /* easiest case (playback):
  65          * sw_data is nearly the same as ~ runtime->control->appl_ptr, with the
  66          * exception that sw_data is "behind" by the number if bytes ALSA wrote
  67          * to the intermediate buffer last time.
  68          * A call to ack() callback synchronizes both indirectly.
  69          */
  70
  71         /* We have no real sw_io pointer here. Usually sw_io is pointing to the
  72          * current playback/capture position _inside_ the hardware. Devices
  73          * with plain FIFOs often have no possibility to publish this position.
  74          * So we say: if sw_data is updated, that means bytes were copied to
  75          * the hardware, we increase sw_io by that amount, because there have
  76          * to be as much bytes which were played. So sw_io will stay behind
  77          * sw_data all the time and has to converge to sw_data at the end of
  78          * playback.
  79          */
  80         unsigned int sw_io;           /* Current software pointer in bytes */
  81
  82         /* sw_ready: number of bytes ALSA copied to the intermediate buffer, so
  83          * it represents the number of bytes which wait for transfer to the HW
  84          */
  85         int sw_ready;             /* Bytes ready to be transferred to/from hw */
  86
  87         /* appl_ptr: last known position of ALSA (where ALSA is going to write
  88          * next time into the intermediate buffer
  89          */
  90         snd_pcm_uframes_t appl_ptr;   /* Last seen appl_ptr */
  91
  92         unsigned int bytes2hw;
  93         int check_alignment;
  94
  95 #ifdef SND_PCM_INDIRECT2_STAT
  96         unsigned int zeros2hw;
  97         unsigned int mul_elapsed;
  98         unsigned int mul_elapsed_real;
  99         unsigned long firstbytetime;
 100         unsigned long lastbytetime;
 101         unsigned long firstzerotime;
 102         unsigned int byte_sizes[64];
 103         unsigned int zero_sizes[64];
 104         unsigned int min_adds[8];
 105         unsigned int mul_adds[8];
 106         unsigned int zero_times[3750];  /* = 15s */
 107         unsigned int zero_times_saved;
 108         unsigned int zero_times_notsaved;
 109         unsigned int irq_occured;
 110         unsigned int pointer_calls;
 111         unsigned int lastdifftime;
 112 #endif
 113 };
 114
 115 typedef size_t (*snd_pcm_indirect2_copy_t) (struct snd_pcm_substream *substream,
 116                                            struct snd_pcm_indirect2 *rec,
 117                                            size_t bytes);
 118 typedef size_t (*snd_pcm_indirect2_zero_t) (struct snd_pcm_substream *substream,
 119                                            struct snd_pcm_indirect2 *rec);
 120
 121 #ifdef SND_PCM_INDIRECT2_STAT
 122 void snd_pcm_indirect2_stat(struct snd_pcm_substream *substream,
 123                                    struct snd_pcm_indirect2 *rec);
 124 #endif
 125
 126 snd_pcm_uframes_t
 127 snd_pcm_indirect2_pointer(struct snd_pcm_substream *substream,
 128                           struct snd_pcm_indirect2 *rec);
 129 void
 130 snd_pcm_indirect2_playback_interrupt(struct snd_pcm_substream *substream,
 131                                      struct snd_pcm_indirect2 *rec,
 132                                      snd_pcm_indirect2_copy_t copy,
 133                                      snd_pcm_indirect2_zero_t zero);
 134 void
 135 snd_pcm_indirect2_capture_interrupt(struct snd_pcm_substream *substream,
 136                                     struct snd_pcm_indirect2 *rec,
 137                                     snd_pcm_indirect2_copy_t copy,
 138                                     snd_pcm_indirect2_zero_t null);
 139
 140 #endif /* __SOUND_PCM_INDIRECT2_H */