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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 -EINVAL;
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 	if (bytes < 0)
87 		bytes += rec->hw_buffer_size;
88 	rec->hw_io = ptr;
89 	rec->hw_ready -= bytes;
90 	rec->sw_io += bytes;
91 	if (rec->sw_io >= rec->sw_buffer_size)
92 		rec->sw_io -= rec->sw_buffer_size;
93 	if (substream->ops->ack)
94 		substream->ops->ack(substream);
95 	return bytes_to_frames(substream->runtime, rec->sw_io);
96 }
97 
98 
99 /*
100  * helper function for capture ack callback
101  */
102 static inline int
snd_pcm_indirect_capture_transfer(struct snd_pcm_substream * substream,struct snd_pcm_indirect * rec,snd_pcm_indirect_copy_t copy)103 snd_pcm_indirect_capture_transfer(struct snd_pcm_substream *substream,
104 				  struct snd_pcm_indirect *rec,
105 				  snd_pcm_indirect_copy_t copy)
106 {
107 	struct snd_pcm_runtime *runtime = substream->runtime;
108 	snd_pcm_uframes_t appl_ptr = runtime->control->appl_ptr;
109 	snd_pcm_sframes_t diff = appl_ptr - rec->appl_ptr;
110 
111 	if (diff) {
112 		if (diff < -(snd_pcm_sframes_t) (runtime->boundary / 2))
113 			diff += runtime->boundary;
114 		if (diff < 0)
115 			return -EINVAL;
116 		rec->sw_ready -= frames_to_bytes(runtime, diff);
117 		rec->appl_ptr = appl_ptr;
118 	}
119 	while (rec->hw_ready > 0 &&
120 	       rec->sw_ready < (int)rec->sw_buffer_size) {
121 		size_t hw_to_end = rec->hw_buffer_size - rec->hw_data;
122 		size_t sw_to_end = rec->sw_buffer_size - rec->sw_data;
123 		size_t bytes = rec->sw_buffer_size - rec->sw_ready;
124 		if (rec->hw_ready < (int)bytes)
125 			bytes = rec->hw_ready;
126 		if (hw_to_end < bytes)
127 			bytes = hw_to_end;
128 		if (sw_to_end < bytes)
129 			bytes = sw_to_end;
130 		if (! bytes)
131 			break;
132 		copy(substream, rec, bytes);
133 		rec->hw_data += bytes;
134 		if ((int)rec->hw_data == rec->hw_buffer_size)
135 			rec->hw_data = 0;
136 		rec->sw_data += bytes;
137 		if (rec->sw_data == rec->sw_buffer_size)
138 			rec->sw_data = 0;
139 		rec->hw_ready -= bytes;
140 		rec->sw_ready += bytes;
141 	}
142 	return 0;
143 }
144 
145 /*
146  * helper function for capture pointer callback,
147  * ptr = current byte pointer
148  */
149 static inline snd_pcm_uframes_t
snd_pcm_indirect_capture_pointer(struct snd_pcm_substream * substream,struct snd_pcm_indirect * rec,unsigned int ptr)150 snd_pcm_indirect_capture_pointer(struct snd_pcm_substream *substream,
151 				 struct snd_pcm_indirect *rec, unsigned int ptr)
152 {
153 	int qsize;
154 	int bytes = ptr - rec->hw_io;
155 	if (bytes < 0)
156 		bytes += rec->hw_buffer_size;
157 	rec->hw_io = ptr;
158 	rec->hw_ready += bytes;
159 	qsize = rec->hw_queue_size ? rec->hw_queue_size : rec->hw_buffer_size;
160 	if (rec->hw_ready > qsize)
161 		return SNDRV_PCM_POS_XRUN;
162 	rec->sw_io += bytes;
163 	if (rec->sw_io >= rec->sw_buffer_size)
164 		rec->sw_io -= rec->sw_buffer_size;
165 	if (substream->ops->ack)
166 		substream->ops->ack(substream);
167 	return bytes_to_frames(substream->runtime, rec->sw_io);
168 }
169 
170 #endif /* __SOUND_PCM_INDIRECT_H */
171