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   1 /*
   2  * Helper functions for indirect PCM data transfer
   3  *
   4  *  Copyright (c) by Takashi Iwai <tiwai@suse.de>
   5  *                   Jaroslav Kysela <perex@perex.cz>
   6  *
   7  *   This program is free software; you can redistribute it and/or modify
   8  *   it under the terms of the GNU General Public License as published by
   9  *   the Free Software Foundation; either version 2 of the License, or
  10  *   (at your option) any later version.
  11  *
  12  *   This program is distributed in the hope that it will be useful,
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *   GNU General Public License for more details.
  16  *
  17  *   You should have received a copy of the GNU General Public License
  18  *   along with this program; if not, write to the Free Software
  19  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  */
  21
  22 #ifndef __SOUND_PCM_INDIRECT_H
  23 #define __SOUND_PCM_INDIRECT_H
  24
  25 #include <sound/pcm.h>
  26
  27 struct snd_pcm_indirect {
  28         unsigned int hw_buffer_size;    /* Byte size of hardware buffer */
  29         unsigned int hw_queue_size;     /* Max queue size of hw buffer (0 = buffer size) */
  30         unsigned int hw_data;   /* Offset to next dst (or src) in hw ring buffer */
  31         unsigned int hw_io;     /* Ring buffer hw pointer */
  32         int hw_ready;           /* Bytes ready for play (or captured) in hw ring buffer */
  33         unsigned int sw_buffer_size;    /* Byte size of software buffer */
  34         unsigned int sw_data;   /* Offset to next dst (or src) in sw ring buffer */
  35         unsigned int sw_io;     /* Current software pointer in bytes */
  36         int sw_ready;           /* Bytes ready to be transferred to/from hw */
  37         snd_pcm_uframes_t appl_ptr;     /* Last seen appl_ptr */
  38 };
  39
  40 typedef void (*snd_pcm_indirect_copy_t)(struct snd_pcm_substream *substream,
  41                                         struct snd_pcm_indirect *rec, size_t bytes);
  42
  43 /*
  44  * helper function for playback ack callback
  45  */
  46 static inline void
  47 snd_pcm_indirect_playback_transfer(struct snd_pcm_substream *substream,
  48                                    struct snd_pcm_indirect *rec,
  49                                    snd_pcm_indirect_copy_t copy)
  50 {
  51         struct snd_pcm_runtime *runtime = substream->runtime;
  52         snd_pcm_uframes_t appl_ptr = runtime->control->appl_ptr;
  53         snd_pcm_sframes_t diff = appl_ptr - rec->appl_ptr;
  54         int qsize;
  55
  56         if (diff) {
  57                 if (diff < -(snd_pcm_sframes_t) (runtime->boundary / 2))
  58                         diff += runtime->boundary;
  59                 rec->sw_ready += (int)frames_to_bytes(runtime, diff);
  60                 rec->appl_ptr = appl_ptr;
  61         }
  62         qsize = rec->hw_queue_size ? rec->hw_queue_size : rec->hw_buffer_size;
  63         while (rec->hw_ready < qsize && rec->sw_ready > 0) {
  64                 unsigned int hw_to_end = rec->hw_buffer_size - rec->hw_data;
  65                 unsigned int sw_to_end = rec->sw_buffer_size - rec->sw_data;
  66                 unsigned int bytes = qsize - rec->hw_ready;
  67                 if (rec->sw_ready < (int)bytes)
  68                         bytes = rec->sw_ready;
  69                 if (hw_to_end < bytes)
  70                         bytes = hw_to_end;
  71                 if (sw_to_end < bytes)
  72                         bytes = sw_to_end;
  73                 if (! bytes)
  74                         break;
  75                 copy(substream, rec, bytes);
  76                 rec->hw_data += bytes;
  77                 if (rec->hw_data == rec->hw_buffer_size)
  78                         rec->hw_data = 0;
  79                 rec->sw_data += bytes;
  80                 if (rec->sw_data == rec->sw_buffer_size)
  81                         rec->sw_data = 0;
  82                 rec->hw_ready += bytes;
  83                 rec->sw_ready -= bytes;
  84         }
  85 }
  86
  87 /*
  88  * helper function for playback pointer callback
  89  * ptr = current byte pointer
  90  */
  91 static inline snd_pcm_uframes_t
  92 snd_pcm_indirect_playback_pointer(struct snd_pcm_substream *substream,
  93                                   struct snd_pcm_indirect *rec, unsigned int ptr)
  94 {
  95         int bytes = ptr - rec->hw_io;
  96         if (bytes < 0)
  97                 bytes += rec->hw_buffer_size;
  98         rec->hw_io = ptr;
  99         rec->hw_ready -= bytes;
 100         rec->sw_io += bytes;
 101         if (rec->sw_io >= rec->sw_buffer_size)
 102                 rec->sw_io -= rec->sw_buffer_size;
 103         if (substream->ops->ack)
 104                 substream->ops->ack(substream);
 105         return bytes_to_frames(substream->runtime, rec->sw_io);
 106 }
 107
 108
 109 /*
 110  * helper function for capture ack callback
 111  */
 112 static inline void
 113 snd_pcm_indirect_capture_transfer(struct snd_pcm_substream *substream,
 114                                   struct snd_pcm_indirect *rec,
 115                                   snd_pcm_indirect_copy_t copy)
 116 {
 117         struct snd_pcm_runtime *runtime = substream->runtime;
 118         snd_pcm_uframes_t appl_ptr = runtime->control->appl_ptr;
 119         snd_pcm_sframes_t diff = appl_ptr - rec->appl_ptr;
 120
 121         if (diff) {
 122                 if (diff < -(snd_pcm_sframes_t) (runtime->boundary / 2))
 123                         diff += runtime->boundary;
 124                 rec->sw_ready -= frames_to_bytes(runtime, diff);
 125                 rec->appl_ptr = appl_ptr;
 126         }
 127         while (rec->hw_ready > 0 &&
 128                rec->sw_ready < (int)rec->sw_buffer_size) {
 129                 size_t hw_to_end = rec->hw_buffer_size - rec->hw_data;
 130                 size_t sw_to_end = rec->sw_buffer_size - rec->sw_data;
 131                 size_t bytes = rec->sw_buffer_size - rec->sw_ready;
 132                 if (rec->hw_ready < (int)bytes)
 133                         bytes = rec->hw_ready;
 134                 if (hw_to_end < bytes)
 135                         bytes = hw_to_end;
 136                 if (sw_to_end < bytes)
 137                         bytes = sw_to_end;
 138                 if (! bytes)
 139                         break;
 140                 copy(substream, rec, bytes);
 141                 rec->hw_data += bytes;
 142                 if ((int)rec->hw_data == rec->hw_buffer_size)
 143                         rec->hw_data = 0;
 144                 rec->sw_data += bytes;
 145                 if (rec->sw_data == rec->sw_buffer_size)
 146                         rec->sw_data = 0;
 147                 rec->hw_ready -= bytes;
 148                 rec->sw_ready += bytes;
 149         }
 150 }
 151
 152 /*
 153  * helper function for capture pointer callback,
 154  * ptr = current byte pointer
 155  */
 156 static inline snd_pcm_uframes_t
 157 snd_pcm_indirect_capture_pointer(struct snd_pcm_substream *substream,
 158                                  struct snd_pcm_indirect *rec, unsigned int ptr)
 159 {
 160         int qsize;
 161         int bytes = ptr - rec->hw_io;
 162         if (bytes < 0)
 163                 bytes += rec->hw_buffer_size;
 164         rec->hw_io = ptr;
 165         rec->hw_ready += bytes;
 166         qsize = rec->hw_queue_size ? rec->hw_queue_size : rec->hw_buffer_size;
 167         if (rec->hw_ready > qsize)
 168                 return SNDRV_PCM_POS_XRUN;
 169         rec->sw_io += bytes;
 170         if (rec->sw_io >= rec->sw_buffer_size)
 171                 rec->sw_io -= rec->sw_buffer_size;
 172         if (substream->ops->ack)
 173                 substream->ops->ack(substream);
 174         return bytes_to_frames(substream->runtime, rec->sw_io);
 175 }
 176
 177 #endif /* __SOUND_PCM_INDIRECT_H */