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rawmidi: Add rawmidi framing API

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Optionally, incoming rawmidi bytes can be put inside a frame of type
snd_rawmidi_framing_tstamp_t.
The main current benefit is that can enable in-kernel timestamping of
incoming bytes, and that timestamp is likely to be more precise than
what userspace can offer.

Tstamp type framing requires a kernel >= 5.14 and a buffer size that
is a multiple of sizeof(snd_rawmidi_framing_tstamp_t). It is only
available on input streams.

Signed-off-by: David Henningsson <coding@diwic.se>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
David Henningsson 2021-08-17 16:21:12 +02:00 • committed by Takashi Iwai
parent 23a191a82c
commit 95eb312fad
5 changed files with 153 additions and 2 deletions
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38
include/rawmidi.h
View file

@ -79,6 +79,39 @@ typedef enum _snd_rawmidi_type {
SND_RAWMIDI_TYPE_VIRTUAL
} snd_rawmidi_type_t;
/** Type of clock used with rawmidi tstamp framing */
typedef enum _snd_rawmidi_clock {
SND_RAWMIDI_CLOCK_NONE = 0,
SND_RAWMIDI_CLOCK_REALTIME = 1,
SND_RAWMIDI_CLOCK_MONOTONIC = 2,
SND_RAWMIDI_CLOCK_MONOTONIC_RAW = 3,
} snd_rawmidi_clock_t;
/** Enable or disable rawmidi framing */
typedef enum _snd_rawmidi_framing {
SND_RAWMIDI_FRAMING_NONE = 0,
SND_RAWMIDI_FRAMING_TSTAMP = 1,
} snd_rawmidi_framing_t;
#define SND_RAWMIDI_FRAME_TYPE_DEFAULT 0
#define SND_RAWMIDI_FRAMING_DATA_LENGTH 16
/** Incoming RawMidi bytes is put inside this container if tstamp type framing is enabled. */
typedef struct _snd_rawmidi_framing_tstamp {
/**
* For now, frame_type is always SND_RAWMIDI_FRAME_TYPE_DEFAULT.
* Midi 2.0 is expected to add new types here.
* Applications are expected to skip unknown frame types.
*/
__u8 frame_type;
__u8 length; /* number of valid bytes in data field */
__u8 reserved[2];
__u32 tv_nsec; /* nanoseconds */
__u64 tv_sec; /* seconds */
__u8 data[SND_RAWMIDI_FRAMING_DATA_LENGTH];
} snd_rawmidi_framing_tstamp_t;
int snd_rawmidi_open(snd_rawmidi_t **in_rmidi, snd_rawmidi_t **out_rmidi,
const char *name, int mode);
int snd_rawmidi_open_lconf(snd_rawmidi_t **in_rmidi, snd_rawmidi_t **out_rmidi,
@ -126,6 +159,11 @@ int snd_rawmidi_params_set_avail_min(snd_rawmidi_t *rmidi, snd_rawmidi_params_t
size_t snd_rawmidi_params_get_avail_min(const snd_rawmidi_params_t *params);
int snd_rawmidi_params_set_no_active_sensing(snd_rawmidi_t *rmidi, snd_rawmidi_params_t *params, int val);
int snd_rawmidi_params_get_no_active_sensing(const snd_rawmidi_params_t *params);
int snd_rawmidi_params_set_framing_type(const snd_rawmidi_t *rawmidi, snd_rawmidi_params_t *params, snd_rawmidi_framing_t val);
snd_rawmidi_framing_t snd_rawmidi_params_get_framing_type(const snd_rawmidi_params_t *params);
int snd_rawmidi_params_set_clock_type(const snd_rawmidi_t *rawmidi, snd_rawmidi_params_t *params, snd_rawmidi_clock_t val);
snd_rawmidi_clock_t snd_rawmidi_params_get_clock_type(const snd_rawmidi_params_t *params);
int snd_rawmidi_params(snd_rawmidi_t *rmidi, snd_rawmidi_params_t * params);
int snd_rawmidi_params_current(snd_rawmidi_t *rmidi, snd_rawmidi_params_t *params);
size_t snd_rawmidi_status_sizeof(void);

30
include/sound/uapi/asound.h
View file

@ -702,7 +702,7 @@ enum {
* Raw MIDI section - /dev/snd/midi??
*/
#define SNDRV_RAWMIDI_VERSION SNDRV_PROTOCOL_VERSION(2, 0, 1)
#define SNDRV_RAWMIDI_VERSION SNDRV_PROTOCOL_VERSION(2, 0, 2)
enum {
SNDRV_RAWMIDI_STREAM_OUTPUT = 0,
@ -728,12 +728,38 @@ struct snd_rawmidi_info {
unsigned char reserved[64]; /* reserved for future use */
};
#define SNDRV_RAWMIDI_MODE_FRAMING_MASK (7<<0)
#define SNDRV_RAWMIDI_MODE_FRAMING_SHIFT 0
#define SNDRV_RAWMIDI_MODE_FRAMING_NONE (0<<0)
#define SNDRV_RAWMIDI_MODE_FRAMING_TSTAMP (1<<0)
#define SNDRV_RAWMIDI_MODE_CLOCK_MASK (7<<3)
#define SNDRV_RAWMIDI_MODE_CLOCK_SHIFT 3
#define SNDRV_RAWMIDI_MODE_CLOCK_NONE (0<<3)
#define SNDRV_RAWMIDI_MODE_CLOCK_REALTIME (1<<3)
#define SNDRV_RAWMIDI_MODE_CLOCK_MONOTONIC (2<<3)
#define SNDRV_RAWMIDI_MODE_CLOCK_MONOTONIC_RAW (3<<3)
#define SNDRV_RAWMIDI_FRAMING_DATA_LENGTH 16
struct snd_rawmidi_framing_tstamp {
/* For now, frame_type is always 0. Midi 2.0 is expected to add new
* types here. Applications are expected to skip unknown frame types.
*/
__u8 frame_type;
__u8 length; /* number of valid bytes in data field */
__u8 reserved[2];
__u32 tv_nsec; /* nanoseconds */
__u64 tv_sec; /* seconds */
__u8 data[SNDRV_RAWMIDI_FRAMING_DATA_LENGTH];
} __packed;
struct snd_rawmidi_params {
int stream;
size_t buffer_size; /* queue size in bytes */
size_t avail_min; /* minimum avail bytes for wakeup */
unsigned int no_active_sensing: 1; /* do not send active sensing byte in close() */
unsigned char reserved[16]; /* reserved for future use */
unsigned int mode; /* For input data only, frame incoming data */
unsigned char reserved[12]; /* reserved for future use */
};
struct snd_rawmidi_status {