Root/include/sound/pcm-indirect.h

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
27struct 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
40typedef 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 */
46static inline void
47snd_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 */
91static inline snd_pcm_uframes_t
92snd_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 */
112static inline void
113snd_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 */
156static inline snd_pcm_uframes_t
157snd_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

Archive Download this file



interactive