1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3 * Helper functions for indirect PCM data transfer to a simple FIFO in
4 * hardware (small, no possibility to read "hardware io position",
5 * updating position done by interrupt, ...)
6 *
7 * Copyright (c) by 2007 Joachim Foerster <JOFT@gmx.de>
8 *
9 * Based on "pcm-indirect.h" (alsa-driver-1.0.13) by
10 *
11 * Copyright (c) by Takashi Iwai <tiwai@suse.de>
12 * Jaroslav Kysela <perex@suse.cz>
13 */
14
15 #ifndef __SOUND_PCM_INDIRECT2_H
16 #define __SOUND_PCM_INDIRECT2_H
17
18 /* struct snd_pcm_substream, struct snd_pcm_runtime, snd_pcm_uframes_t */
19 #include <sound/pcm.h>
20
21 /* Debug options for code which may be removed completely in a final version */
22 #ifdef CONFIG_SND_DEBUG
23 #define SND_PCM_INDIRECT2_STAT /* turn on some "statistics" about the
24 * process of copying bytes from the
25 * intermediate buffer to the hardware
26 * fifo and the other way round
27 */
28 #endif
29
30 struct snd_pcm_indirect2 {
31 unsigned int hw_buffer_size; /* Byte size of hardware buffer */
32 int hw_ready; /* playback: 1 = hw fifo has room left,
33 * 0 = hw fifo is full
34 */
35 unsigned int min_multiple;
36 int min_periods; /* counts number of min. periods until
37 * min_multiple is reached
38 */
39 int min_period_count; /* counts bytes to count number of
40 * min. periods
41 */
42
43 unsigned int sw_buffer_size; /* Byte size of software buffer */
44
45 /* sw_data: position in intermediate buffer, where we will read (or
46 * write) from/to next time (to transfer data to/from HW)
47 */
48 unsigned int sw_data; /* Offset to next dst (or src) in sw
49 * ring buffer
50 */
51 /* easiest case (playback):
52 * sw_data is nearly the same as ~ runtime->control->appl_ptr, with the
53 * exception that sw_data is "behind" by the number if bytes ALSA wrote
54 * to the intermediate buffer last time.
55 * A call to ack() callback synchronizes both indirectly.
56 */
57
58 /* We have no real sw_io pointer here. Usually sw_io is pointing to the
59 * current playback/capture position _inside_ the hardware. Devices
60 * with plain FIFOs often have no possibility to publish this position.
61 * So we say: if sw_data is updated, that means bytes were copied to
62 * the hardware, we increase sw_io by that amount, because there have
63 * to be as much bytes which were played. So sw_io will stay behind
64 * sw_data all the time and has to converge to sw_data at the end of
65 * playback.
66 */
67 unsigned int sw_io; /* Current software pointer in bytes */
68
69 /* sw_ready: number of bytes ALSA copied to the intermediate buffer, so
70 * it represents the number of bytes which wait for transfer to the HW
71 */
72 int sw_ready; /* Bytes ready to be transferred to/from hw */
73
74 /* appl_ptr: last known position of ALSA (where ALSA is going to write
75 * next time into the intermediate buffer
76 */
77 snd_pcm_uframes_t appl_ptr; /* Last seen appl_ptr */
78
79 unsigned int bytes2hw;
80 int check_alignment;
81
82 #ifdef SND_PCM_INDIRECT2_STAT
83 unsigned int zeros2hw;
84 unsigned int mul_elapsed;
85 unsigned int mul_elapsed_real;
86 unsigned long firstbytetime;
87 unsigned long lastbytetime;
88 unsigned long firstzerotime;
89 unsigned int byte_sizes[64];
90 unsigned int zero_sizes[64];
91 unsigned int min_adds[8];
92 unsigned int mul_adds[8];
93 unsigned int zero_times[3750]; /* = 15s */
94 unsigned int zero_times_saved;
95 unsigned int zero_times_notsaved;
96 unsigned int irq_occured;
97 unsigned int pointer_calls;
98 unsigned int lastdifftime;
99 #endif
100 };
101
102 typedef size_t (*snd_pcm_indirect2_copy_t) (struct snd_pcm_substream *substream,
103 struct snd_pcm_indirect2 *rec,
104 size_t bytes);
105 typedef size_t (*snd_pcm_indirect2_zero_t) (struct snd_pcm_substream *substream,
106 struct snd_pcm_indirect2 *rec);
107
108 #ifdef SND_PCM_INDIRECT2_STAT
109 void snd_pcm_indirect2_stat(struct snd_pcm_substream *substream,
110 struct snd_pcm_indirect2 *rec);
111 #endif
112
113 snd_pcm_uframes_t
114 snd_pcm_indirect2_pointer(struct snd_pcm_substream *substream,
115 struct snd_pcm_indirect2 *rec);
116 void
117 snd_pcm_indirect2_playback_interrupt(struct snd_pcm_substream *substream,
118 struct snd_pcm_indirect2 *rec,
119 snd_pcm_indirect2_copy_t copy,
120 snd_pcm_indirect2_zero_t zero);
121 void
122 snd_pcm_indirect2_capture_interrupt(struct snd_pcm_substream *substream,
123 struct snd_pcm_indirect2 *rec,
124 snd_pcm_indirect2_copy_t copy,
125 snd_pcm_indirect2_zero_t null);
126
127 #endif /* __SOUND_PCM_INDIRECT2_H */
128
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