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
snd_pcm_indirect_playback_transfer(struct snd_pcm_substream * substream,struct snd_pcm_indirect * rec,snd_pcm_indirect_copy_t copy)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
snd_pcm_indirect_playback_pointer(struct snd_pcm_substream * substream,struct snd_pcm_indirect * rec,unsigned int ptr)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
snd_pcm_indirect_capture_transfer(struct snd_pcm_substream * substream,struct snd_pcm_indirect * rec,snd_pcm_indirect_copy_t copy)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
snd_pcm_indirect_capture_pointer(struct snd_pcm_substream * substream,struct snd_pcm_indirect * rec,unsigned int ptr)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 */
178