1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3 * Helper functions for indirect PCM data transfer
4 *
5 * Copyright (c) by Takashi Iwai <tiwai@suse.de>
6 * Jaroslav Kysela <perex@perex.cz>
7 */
8
9 #ifndef __SOUND_PCM_INDIRECT_H
10 #define __SOUND_PCM_INDIRECT_H
11
12 #include <sound/pcm.h>
13
14 struct snd_pcm_indirect {
15 unsigned int hw_buffer_size; /* Byte size of hardware buffer */
16 unsigned int hw_queue_size; /* Max queue size of hw buffer (0 = buffer size) */
17 unsigned int hw_data; /* Offset to next dst (or src) in hw ring buffer */
18 unsigned int hw_io; /* Ring buffer hw pointer */
19 int hw_ready; /* Bytes ready for play (or captured) in hw ring buffer */
20 unsigned int sw_buffer_size; /* Byte size of software buffer */
21 unsigned int sw_data; /* Offset to next dst (or src) in sw ring buffer */
22 unsigned int sw_io; /* Current software pointer in bytes */
23 int sw_ready; /* Bytes ready to be transferred to/from hw */
24 snd_pcm_uframes_t appl_ptr; /* Last seen appl_ptr */
25 };
26
27 typedef void (*snd_pcm_indirect_copy_t)(struct snd_pcm_substream *substream,
28 struct snd_pcm_indirect *rec, size_t bytes);
29
30 /*
31 * helper function for playback ack callback
32 */
33 static inline int
snd_pcm_indirect_playback_transfer(struct snd_pcm_substream * substream,struct snd_pcm_indirect * rec,snd_pcm_indirect_copy_t copy)34 snd_pcm_indirect_playback_transfer(struct snd_pcm_substream *substream,
35 struct snd_pcm_indirect *rec,
36 snd_pcm_indirect_copy_t copy)
37 {
38 struct snd_pcm_runtime *runtime = substream->runtime;
39 snd_pcm_uframes_t appl_ptr = runtime->control->appl_ptr;
40 snd_pcm_sframes_t diff = appl_ptr - rec->appl_ptr;
41 int qsize;
42
43 if (diff) {
44 if (diff < -(snd_pcm_sframes_t) (runtime->boundary / 2))
45 diff += runtime->boundary;
46 if (diff < 0)
47 return -EPIPE;
48 rec->sw_ready += (int)frames_to_bytes(runtime, diff);
49 rec->appl_ptr = appl_ptr;
50 }
51 qsize = rec->hw_queue_size ? rec->hw_queue_size : rec->hw_buffer_size;
52 while (rec->hw_ready < qsize && rec->sw_ready > 0) {
53 unsigned int hw_to_end = rec->hw_buffer_size - rec->hw_data;
54 unsigned int sw_to_end = rec->sw_buffer_size - rec->sw_data;
55 unsigned int bytes = qsize - rec->hw_ready;
56 if (rec->sw_ready < (int)bytes)
57 bytes = rec->sw_ready;
58 if (hw_to_end < bytes)
59 bytes = hw_to_end;
60 if (sw_to_end < bytes)
61 bytes = sw_to_end;
62 if (! bytes)
63 break;
64 copy(substream, rec, bytes);
65 rec->hw_data += bytes;
66 if (rec->hw_data == rec->hw_buffer_size)
67 rec->hw_data = 0;
68 rec->sw_data += bytes;
69 if (rec->sw_data == rec->sw_buffer_size)
70 rec->sw_data = 0;
71 rec->hw_ready += bytes;
72 rec->sw_ready -= bytes;
73 }
74 return 0;
75 }
76
77 /*
78 * helper function for playback pointer callback
79 * ptr = current byte pointer
80 */
81 static inline snd_pcm_uframes_t
snd_pcm_indirect_playback_pointer(struct snd_pcm_substream * substream,struct snd_pcm_indirect * rec,unsigned int ptr)82 snd_pcm_indirect_playback_pointer(struct snd_pcm_substream *substream,
83 struct snd_pcm_indirect *rec, unsigned int ptr)
84 {
85 int bytes = ptr - rec->hw_io;
86 int err;
87
88 if (bytes < 0)
89 bytes += rec->hw_buffer_size;
90 rec->hw_io = ptr;
91 rec->hw_ready -= bytes;
92 rec->sw_io += bytes;
93 if (rec->sw_io >= rec->sw_buffer_size)
94 rec->sw_io -= rec->sw_buffer_size;
95 if (substream->ops->ack) {
96 err = substream->ops->ack(substream);
97 if (err == -EPIPE)
98 return SNDRV_PCM_POS_XRUN;
99 }
100 return bytes_to_frames(substream->runtime, rec->sw_io);
101 }
102
103
104 /*
105 * helper function for capture ack callback
106 */
107 static inline int
snd_pcm_indirect_capture_transfer(struct snd_pcm_substream * substream,struct snd_pcm_indirect * rec,snd_pcm_indirect_copy_t copy)108 snd_pcm_indirect_capture_transfer(struct snd_pcm_substream *substream,
109 struct snd_pcm_indirect *rec,
110 snd_pcm_indirect_copy_t copy)
111 {
112 struct snd_pcm_runtime *runtime = substream->runtime;
113 snd_pcm_uframes_t appl_ptr = runtime->control->appl_ptr;
114 snd_pcm_sframes_t diff = appl_ptr - rec->appl_ptr;
115
116 if (diff) {
117 if (diff < -(snd_pcm_sframes_t) (runtime->boundary / 2))
118 diff += runtime->boundary;
119 if (diff < 0)
120 return -EPIPE;
121 rec->sw_ready -= frames_to_bytes(runtime, diff);
122 rec->appl_ptr = appl_ptr;
123 }
124 while (rec->hw_ready > 0 &&
125 rec->sw_ready < (int)rec->sw_buffer_size) {
126 size_t hw_to_end = rec->hw_buffer_size - rec->hw_data;
127 size_t sw_to_end = rec->sw_buffer_size - rec->sw_data;
128 size_t bytes = rec->sw_buffer_size - rec->sw_ready;
129 if (rec->hw_ready < (int)bytes)
130 bytes = rec->hw_ready;
131 if (hw_to_end < bytes)
132 bytes = hw_to_end;
133 if (sw_to_end < bytes)
134 bytes = sw_to_end;
135 if (! bytes)
136 break;
137 copy(substream, rec, bytes);
138 rec->hw_data += bytes;
139 if ((int)rec->hw_data == rec->hw_buffer_size)
140 rec->hw_data = 0;
141 rec->sw_data += bytes;
142 if (rec->sw_data == rec->sw_buffer_size)
143 rec->sw_data = 0;
144 rec->hw_ready -= bytes;
145 rec->sw_ready += bytes;
146 }
147 return 0;
148 }
149
150 /*
151 * helper function for capture pointer callback,
152 * ptr = current byte pointer
153 */
154 static inline snd_pcm_uframes_t
snd_pcm_indirect_capture_pointer(struct snd_pcm_substream * substream,struct snd_pcm_indirect * rec,unsigned int ptr)155 snd_pcm_indirect_capture_pointer(struct snd_pcm_substream *substream,
156 struct snd_pcm_indirect *rec, unsigned int ptr)
157 {
158 int qsize;
159 int bytes = ptr - rec->hw_io;
160 int err;
161
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 err = substream->ops->ack(substream);
174 if (err == -EPIPE)
175 return SNDRV_PCM_POS_XRUN;
176 }
177 return bytes_to_frames(substream->runtime, rec->sw_io);
178 }
179
180 #endif /* __SOUND_PCM_INDIRECT_H */
181
