Skip to content
This repository

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

file 258 lines (224 sloc) 11.262 kb
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258
/* lv2_event.h - C header file for the LV2 events extension.
*
* Copyright (C) 2006-2007 Lars Luthman <lars.luthman@gmail.com>
* Copyright (C) 2008-2009 David Robillard <http://drobilla.net>
*
* This header is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This header is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this header; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place, Suite 330, Boston, MA 01222-1307 USA
*/

#ifndef LV2_EVENT_H
#define LV2_EVENT_H

#define LV2_EVENT_URI "http://lv2plug.in/ns/ext/event"
#define LV2_EVENT_AUDIO_STAMP 0

#include <stdint.h>

/** @file
* C header for the LV2 Event extension <http://lv2plug.in/ns/ext/event>.
*
* This extension is a generic transport mechanism for time stamped events
* of any type (e.g. MIDI, OSC, ramps, etc). Each port can transport mixed
* events of any type; the type of events and timestamps are defined by a URI
* which is mapped to an integer by the host for performance reasons.
*
* This extension requires the host to support the LV2 URI Map extension.
* Any host which supports this extension MUST guarantee that any call to
* the LV2 URI Map uri_to_id function with the URI of this extension as the
* 'map' argument returns a value within the range of uint16_t.
*/


/** The best Pulses Per Quarter Note for tempo-based uint32_t timestmaps.
* Equal to 2^12 * 5 * 7 * 9 * 11 * 13 * 17, which is evenly divisble
* by all integers from 1 through 18 inclusive, and powers of 2 up to 2^12.
*/
static const uint32_t LV2_EVENT_PPQN = 3136573440U;


/** An LV2 event (header only).
*
* LV2 events are generic time-stamped containers for any type of event.
* The type field defines the format of a given event's contents.
*
* This struct defines the header of an LV2 event. An LV2 event is a single
* chunk of POD (plain old data), usually contained in a flat buffer
* (see LV2_EventBuffer below). Unless a required feature says otherwise,
* hosts may assume a deep copy of an LV2 event can be created safely
* using a simple:
*
* memcpy(ev_copy, ev, sizeof(LV2_Event) + ev->size); (or equivalent)
*/
typedef struct {

/** The frames portion of timestamp. The units used here can optionally be
* set for a port (with the lv2ev:timeUnits property), otherwise this
* is audio frames, corresponding to the sample_count parameter of the
* LV2 run method (e.g. frame 0 is the first frame for that call to run).
*/
uint32_t frames;

/** The sub-frames portion of timestamp. The units used here can
* optionally be set for a port (with the lv2ev:timeUnits property),
* otherwise this is 1/(2^32) of an audio frame.
*/
uint32_t subframes;

/** The type of this event, as a number which represents some URI
* defining an event type. This value MUST be some value previously
* returned from a call to the uri_to_id function defined in the LV2
* URI map extension (see lv2_uri_map.h).
* There are special rules which must be followed depending on the type
* of an event. If the plugin recognizes an event type, the definition
* of that event type will describe how to interpret the event, and
* any required behaviour. Otherwise, if the type is 0, this event is a
* non-POD event and lv2_event_unref MUST be called if the event is
* 'dropped' (see above). Even if the plugin does not understand an event,
* it may pass the event through to an output by simply copying (and NOT
* calling lv2_event_unref). These rules are designed to allow for generic
* event handling plugins and large non-POD events, but with minimal hassle
* on simple plugins that "don't care" about these more advanced features.
*/
uint16_t type;

/** The size of the data portion of this event in bytes, which immediately
* follows. The header size (12 bytes) is not included in this value.
*/
uint16_t size;

/* size bytes of data follow here */

} LV2_Event;



/** A buffer of LV2 events (header only).
*
* Like events (which this contains) an event buffer is a single chunk of POD:
* the entire buffer (including contents) can be copied with a single memcpy.
* The first contained event begins sizeof(LV2_EventBuffer) bytes after
* the start of this struct.
*
* After this header, the buffer contains an event header (defined by struct
* LV2_Event), followed by that event's contents (padded to 64 bits), followed by
* another header, etc:
*
* | | | | | | |
* | | | | | | | | | | | | | | | | | | | | | | | | |
* |FRAMES |SUBFRMS|TYP|LEN|DATA..DATA..PAD|FRAMES | ...
*/
typedef struct {

/** The contents of the event buffer. This may or may not reside in the
* same block of memory as this header, plugins must not assume either.
* The host guarantees this points to at least capacity bytes of allocated
* memory (though only size bytes of that are valid events).
*/
uint8_t* data;

/** The size of this event header in bytes (including everything).
*
* This is to allow for extending this header in the future without
* breaking binary compatibility. Whenever this header is copied,
* it MUST be done using this field (and NOT the sizeof this struct).
*/
uint16_t header_size;

/** The type of the time stamps for events in this buffer.
* As a special exception, '0' always means audio frames and subframes
* (1/UINT32_MAX'th of a frame) in the sample rate passed to instantiate.
* INPUTS: The host must set this field to the numeric ID of some URI
* defining the meaning of the frames/subframes fields of contained
* events (obtained by the LV2 URI Map uri_to_id function with the URI
* of this extension as the 'map' argument, see lv2_uri_map.h).
* The host must never pass a plugin a buffer which uses a stamp type
* the plugin does not 'understand'. The value of this field must
* never change, except when connect_port is called on the input
* port, at which time the host MUST have set the stamp_type field to
* the value that will be used for all subsequent run calls.
* OUTPUTS: The plugin may set this to any value that has been returned
* from uri_to_id with the URI of this extension for a 'map' argument.
* When connected to a buffer with connect_port, output ports MUST set
* this field to the type of time stamp they will be writing. On any
* call to connect_port on an event input port, the plugin may change
* this field on any output port, it is the responsibility of the host
* to check if any of these values have changed and act accordingly.
*/
uint16_t stamp_type;

/** The number of events in this buffer.
* INPUTS: The host must set this field to the number of events
* contained in the data buffer before calling run().
* The plugin must not change this field.
* OUTPUTS: The plugin must set this field to the number of events it
* has written to the buffer before returning from run().
* Any initial value should be ignored by the plugin.
*/
uint32_t event_count;

/** The size of the data buffer in bytes.
* This is set by the host and must not be changed by the plugin.
* The host is allowed to change this between run() calls.
*/
uint32_t capacity;

/** The size of the initial portion of the data buffer containing data.
* INPUTS: The host must set this field to the number of bytes used
* by all events it has written to the buffer (including headers)
* before calling the plugin's run().
* The plugin must not change this field.
* OUTPUTS: The plugin must set this field to the number of bytes
* used by all events it has written to the buffer (including headers)
* before returning from run().
* Any initial value should be ignored by the plugin.
*/
uint32_t size;

} LV2_Event_Buffer;


/** Opaque pointer to host data. */
typedef void* LV2_Event_Callback_Data;


/** The data field of the LV2_Feature for this extension.
*
* To support this feature the host must pass an LV2_Feature struct to the
* plugin's instantiate method with URI "http://lv2plug.in/ns/ext/event"
* and data pointed to an instance of this struct.
*/
typedef struct {

/** Opaque pointer to host data.
*
* The plugin MUST pass this to any call to functions in this struct.
* Otherwise, it must not be interpreted in any way.
*/
LV2_Event_Callback_Data callback_data;

/** Take a reference to a non-POD event.
*
* If a plugin receives an event with type 0, it means the event is a
* pointer to some object in memory and not a flat sequence of bytes
* in the buffer. When receiving a non-POD event, the plugin already
* has an implicit reference to the event. If the event is stored AND
* passed to an output, lv2_event_ref MUST be called on that event.
* If the event is only stored OR passed through, this is not necessary
* (as the plugin already has 1 implicit reference).
*
* @param event An event received at an input that will not be copied to
* an output or stored in any way.
* @param context The calling context. (Like event types) this is a mapped
* URI, see lv2_context.h. Simple plugin with just a run()
* method should pass 0 here (the ID of the 'standard' LV2
* run context). The host guarantees that this function is
* realtime safe iff @a context is realtime safe.
*
* PLUGINS THAT VIOLATE THESE RULES MAY CAUSE CRASHES AND MEMORY LEAKS.
*/
uint32_t (*lv2_event_ref)(LV2_Event_Callback_Data callback_data,
LV2_Event* event);

/** Drop a reference to a non-POD event.
*
* If a plugin receives an event with type 0, it means the event is a
* pointer to some object in memory and not a flat sequence of bytes
* in the buffer. If the plugin does not pass the event through to
* an output or store it internally somehow, it MUST call this function
* on the event (more information on using non-POD events below).
*
* @param event An event received at an input that will not be copied to
* an output or stored in any way.
* @param context The calling context. (Like event types) this is a mapped
* URI, see lv2_context.h. Simple plugin with just a run()
* method should pass 0 here (the ID of the 'standard' LV2
* run context). The host guarantees that this function is
* realtime safe iff @a context is realtime safe.
*
* PLUGINS THAT VIOLATE THESE RULES MAY CAUSE CRASHES AND MEMORY LEAKS.
*/
uint32_t (*lv2_event_unref)(LV2_Event_Callback_Data callback_data,
LV2_Event* event);

} LV2_Event_Feature;


#endif /* LV2_EVENT_H */
Something went wrong with that request. Please try again.