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
14struct 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
27typedef 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 */
33static inline int
34snd_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 */
81static inline snd_pcm_uframes_t
82snd_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 */
102static inline int
103snd_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 */
149static inline snd_pcm_uframes_t
150snd_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