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 int
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 if (diff < 0)
60 return -EINVAL;
61 rec->sw_ready += (int)frames_to_bytes(runtime, diff);
62 rec->appl_ptr = appl_ptr;
63 }
64 qsize = rec->hw_queue_size ? rec->hw_queue_size : rec->hw_buffer_size;
65 while (rec->hw_ready < qsize && rec->sw_ready > 0) {
66 unsigned int hw_to_end = rec->hw_buffer_size - rec->hw_data;
67 unsigned int sw_to_end = rec->sw_buffer_size - rec->sw_data;
68 unsigned int bytes = qsize - rec->hw_ready;
69 if (rec->sw_ready < (int)bytes)
70 bytes = rec->sw_ready;
71 if (hw_to_end < bytes)
72 bytes = hw_to_end;
73 if (sw_to_end < bytes)
74 bytes = sw_to_end;
75 if (! bytes)
76 break;
77 copy(substream, rec, bytes);
78 rec->hw_data += bytes;
79 if (rec->hw_data == rec->hw_buffer_size)
80 rec->hw_data = 0;
81 rec->sw_data += bytes;
82 if (rec->sw_data == rec->sw_buffer_size)
83 rec->sw_data = 0;
84 rec->hw_ready += bytes;
85 rec->sw_ready -= bytes;
86 }
87 return 0;
88 }
89
90 /*
91 * helper function for playback pointer callback
92 * ptr = current byte pointer
93 */
94 static inline snd_pcm_uframes_t
snd_pcm_indirect_playback_pointer(struct snd_pcm_substream * substream,struct snd_pcm_indirect * rec,unsigned int ptr)95 snd_pcm_indirect_playback_pointer(struct snd_pcm_substream *substream,
96 struct snd_pcm_indirect *rec, unsigned int ptr)
97 {
98 int bytes = ptr - rec->hw_io;
99 if (bytes < 0)
100 bytes += rec->hw_buffer_size;
101 rec->hw_io = ptr;
102 rec->hw_ready -= bytes;
103 rec->sw_io += bytes;
104 if (rec->sw_io >= rec->sw_buffer_size)
105 rec->sw_io -= rec->sw_buffer_size;
106 if (substream->ops->ack)
107 substream->ops->ack(substream);
108 return bytes_to_frames(substream->runtime, rec->sw_io);
109 }
110
111
112 /*
113 * helper function for capture ack callback
114 */
115 static inline int
snd_pcm_indirect_capture_transfer(struct snd_pcm_substream * substream,struct snd_pcm_indirect * rec,snd_pcm_indirect_copy_t copy)116 snd_pcm_indirect_capture_transfer(struct snd_pcm_substream *substream,
117 struct snd_pcm_indirect *rec,
118 snd_pcm_indirect_copy_t copy)
119 {
120 struct snd_pcm_runtime *runtime = substream->runtime;
121 snd_pcm_uframes_t appl_ptr = runtime->control->appl_ptr;
122 snd_pcm_sframes_t diff = appl_ptr - rec->appl_ptr;
123
124 if (diff) {
125 if (diff < -(snd_pcm_sframes_t) (runtime->boundary / 2))
126 diff += runtime->boundary;
127 if (diff < 0)
128 return -EINVAL;
129 rec->sw_ready -= frames_to_bytes(runtime, diff);
130 rec->appl_ptr = appl_ptr;
131 }
132 while (rec->hw_ready > 0 &&
133 rec->sw_ready < (int)rec->sw_buffer_size) {
134 size_t hw_to_end = rec->hw_buffer_size - rec->hw_data;
135 size_t sw_to_end = rec->sw_buffer_size - rec->sw_data;
136 size_t bytes = rec->sw_buffer_size - rec->sw_ready;
137 if (rec->hw_ready < (int)bytes)
138 bytes = rec->hw_ready;
139 if (hw_to_end < bytes)
140 bytes = hw_to_end;
141 if (sw_to_end < bytes)
142 bytes = sw_to_end;
143 if (! bytes)
144 break;
145 copy(substream, rec, bytes);
146 rec->hw_data += bytes;
147 if ((int)rec->hw_data == rec->hw_buffer_size)
148 rec->hw_data = 0;
149 rec->sw_data += bytes;
150 if (rec->sw_data == rec->sw_buffer_size)
151 rec->sw_data = 0;
152 rec->hw_ready -= bytes;
153 rec->sw_ready += bytes;
154 }
155 return 0;
156 }
157
158 /*
159 * helper function for capture pointer callback,
160 * ptr = current byte pointer
161 */
162 static inline snd_pcm_uframes_t
snd_pcm_indirect_capture_pointer(struct snd_pcm_substream * substream,struct snd_pcm_indirect * rec,unsigned int ptr)163 snd_pcm_indirect_capture_pointer(struct snd_pcm_substream *substream,
164 struct snd_pcm_indirect *rec, unsigned int ptr)
165 {
166 int qsize;
167 int bytes = ptr - rec->hw_io;
168 if (bytes < 0)
169 bytes += rec->hw_buffer_size;
170 rec->hw_io = ptr;
171 rec->hw_ready += bytes;
172 qsize = rec->hw_queue_size ? rec->hw_queue_size : rec->hw_buffer_size;
173 if (rec->hw_ready > qsize)
174 return SNDRV_PCM_POS_XRUN;
175 rec->sw_io += bytes;
176 if (rec->sw_io >= rec->sw_buffer_size)
177 rec->sw_io -= rec->sw_buffer_size;
178 if (substream->ops->ack)
179 substream->ops->ack(substream);
180 return bytes_to_frames(substream->runtime, rec->sw_io);
181 }
182
183 #endif /* __SOUND_PCM_INDIRECT_H */
184