1 /* 2 Copyright 2008-2011 David Robillard <http://drobilla.net> 3 Copyright 2006-2007 Lars Luthman <lars.luthman@gmail.com> 4 5 Permission to use, copy, modify, and/or distribute this software for any 6 purpose with or without fee is hereby granted, provided that the above 7 copyright notice and this permission notice appear in all copies. 8 9 THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 /** 19 @file event.h 20 C API for the LV2 Event extension <http://lv2plug.in/ns/ext/event>. 21 22 This extension is a generic transport mechanism for time stamped events 23 of any type (e.g. MIDI, OSC, ramps, etc). Each port can transport mixed 24 events of any type; the type of events and timestamps are defined by a URI 25 which is mapped to an integer by the host for performance reasons. 26 27 This extension requires the host to support the LV2 URI Map extension. 28 Any host which supports this extension MUST guarantee that any call to 29 the LV2 URI Map uri_to_id function with the URI of this extension as the 30 'map' argument returns a value within the range of uint16_t. 31 */ 32 33 #ifndef LV2_EVENT_H 34 #define LV2_EVENT_H 35 36 #define LV2_EVENT_URI "http://lv2plug.in/ns/ext/event" 37 #define LV2_EVENT_PREFIX LV2_EVENT_URI "#" 38 39 #define LV2_EVENT__Event LV2_EVENT_PREFIX "Event" 40 #define LV2_EVENT__EventPort LV2_EVENT_PREFIX "EventPort" 41 #define LV2_EVENT__FrameStamp LV2_EVENT_PREFIX "FrameStamp" 42 #define LV2_EVENT__TimeStamp LV2_EVENT_PREFIX "TimeStamp" 43 #define LV2_EVENT__generatesTimeStamp LV2_EVENT_PREFIX "generatesTimeStamp" 44 #define LV2_EVENT__generic LV2_EVENT_PREFIX "generic" 45 #define LV2_EVENT__inheritsEvent LV2_EVENT_PREFIX "inheritsEvent" 46 #define LV2_EVENT__inheritsTimeStamp LV2_EVENT_PREFIX "inheritsTimeStamp" 47 #define LV2_EVENT__supportsEvent LV2_EVENT_PREFIX "supportsEvent" 48 #define LV2_EVENT__supportsTimeStamp LV2_EVENT_PREFIX "supportsTimeStamp" 49 50 #define LV2_EVENT_AUDIO_STAMP 0 51 52 #include <stdint.h> 53 54 #ifdef __cplusplus 55 extern "C" { 56 #endif 57 58 /** 59 The best Pulses Per Quarter Note for tempo-based uint32_t timestamps. 60 Equal to 2^12 * 5 * 7 * 9 * 11 * 13 * 17, which is evenly divisble 61 by all integers from 1 through 18 inclusive, and powers of 2 up to 2^12. 62 */ 63 static const uint32_t LV2_EVENT_PPQN = 3136573440U; 64 65 /** 66 An LV2 event (header only). 67 68 LV2 events are generic time-stamped containers for any type of event. 69 The type field defines the format of a given event's contents. 70 71 This struct defines the header of an LV2 event. An LV2 event is a single 72 chunk of POD (plain old data), usually contained in a flat buffer (see 73 LV2_EventBuffer below). Unless a required feature says otherwise, hosts may 74 assume a deep copy of an LV2 event can be created safely using a simple: 75 76 memcpy(ev_copy, ev, sizeof(LV2_Event) + ev->size); (or equivalent) 77 */ 78 typedef struct { 79 /** 80 The frames portion of timestamp. The units used here can optionally be 81 set for a port (with the lv2ev:timeUnits property), otherwise this is 82 audio frames, corresponding to the sample_count parameter of the LV2 run 83 method (e.g. frame 0 is the first frame for that call to run). 84 */ 85 uint32_t frames; 86 87 /** 88 The sub-frames portion of timestamp. The units used here can optionally 89 be set for a port (with the lv2ev:timeUnits property), otherwise this is 90 1/(2^32) of an audio frame. 91 */ 92 uint32_t subframes; 93 94 /** 95 The type of this event, as a number which represents some URI 96 defining an event type. This value MUST be some value previously 97 returned from a call to the uri_to_id function defined in the LV2 98 URI map extension (see lv2_uri_map.h). 99 There are special rules which must be followed depending on the type 100 of an event. If the plugin recognizes an event type, the definition 101 of that event type will describe how to interpret the event, and 102 any required behaviour. Otherwise, if the type is 0, this event is a 103 non-POD event and lv2_event_unref MUST be called if the event is 104 'dropped' (see above). Even if the plugin does not understand an event, 105 it may pass the event through to an output by simply copying (and NOT 106 calling lv2_event_unref). These rules are designed to allow for generic 107 event handling plugins and large non-POD events, but with minimal hassle 108 on simple plugins that "don't care" about these more advanced features. 109 */ 110 uint16_t type; 111 112 /** 113 The size of the data portion of this event in bytes, which immediately 114 follows. The header size (12 bytes) is not included in this value. 115 */ 116 uint16_t size; 117 118 /* size bytes of data follow here */ 119 } LV2_Event; 120 121 122 /** 123 A buffer of LV2 events (header only). 124 125 Like events (which this contains) an event buffer is a single chunk of POD: 126 the entire buffer (including contents) can be copied with a single memcpy. 127 The first contained event begins sizeof(LV2_EventBuffer) bytes after the 128 start of this struct. 129 130 After this header, the buffer contains an event header (defined by struct 131 LV2_Event), followed by that event's contents (padded to 64 bits), followed 132 by another header, etc: 133 134 | | | | | | | 135 | | | | | | | | | | | | | | | | | | | | | | | | | 136 |FRAMES |SUBFRMS|TYP|LEN|DATA..DATA..PAD|FRAMES | ... 137 */ 138 typedef struct { 139 /** 140 The contents of the event buffer. This may or may not reside in the 141 same block of memory as this header, plugins must not assume either. 142 The host guarantees this points to at least capacity bytes of allocated 143 memory (though only size bytes of that are valid events). 144 */ 145 uint8_t* data; 146 147 /** 148 The size of this event header in bytes (including everything). 149 150 This is to allow for extending this header in the future without 151 breaking binary compatibility. Whenever this header is copied, 152 it MUST be done using this field (and NOT the sizeof this struct). 153 */ 154 uint16_t header_size; 155 156 /** 157 The type of the time stamps for events in this buffer. 158 As a special exception, '0' always means audio frames and subframes 159 (1/UINT32_MAX'th of a frame) in the sample rate passed to instantiate. 160 161 INPUTS: The host must set this field to the numeric ID of some URI 162 defining the meaning of the frames/subframes fields of contained events 163 (obtained by the LV2 URI Map uri_to_id function with the URI of this 164 extension as the 'map' argument, see lv2_uri_map.h). The host must 165 never pass a plugin a buffer which uses a stamp type the plugin does not 166 'understand'. The value of this field must never change, except when 167 connect_port is called on the input port, at which time the host MUST 168 have set the stamp_type field to the value that will be used for all 169 subsequent run calls. 170 171 OUTPUTS: The plugin may set this to any value that has been returned 172 from uri_to_id with the URI of this extension for a 'map' argument. 173 When connected to a buffer with connect_port, output ports MUST set this 174 field to the type of time stamp they will be writing. On any call to 175 connect_port on an event input port, the plugin may change this field on 176 any output port, it is the responsibility of the host to check if any of 177 these values have changed and act accordingly. 178 */ 179 uint16_t stamp_type; 180 181 /** 182 The number of events in this buffer. 183 184 INPUTS: The host must set this field to the number of events contained 185 in the data buffer before calling run(). The plugin must not change 186 this field. 187 188 OUTPUTS: The plugin must set this field to the number of events it has 189 written to the buffer before returning from run(). Any initial value 190 should be ignored by the plugin. 191 */ 192 uint32_t event_count; 193 194 /** 195 The size of the data buffer in bytes. 196 This is set by the host and must not be changed by the plugin. 197 The host is allowed to change this between run() calls. 198 */ 199 uint32_t capacity; 200 201 /** 202 The size of the initial portion of the data buffer containing data. 203 204 INPUTS: The host must set this field to the number of bytes used 205 by all events it has written to the buffer (including headers) 206 before calling the plugin's run(). 207 The plugin must not change this field. 208 209 OUTPUTS: The plugin must set this field to the number of bytes 210 used by all events it has written to the buffer (including headers) 211 before returning from run(). 212 Any initial value should be ignored by the plugin. 213 */ 214 uint32_t size; 215 } LV2_Event_Buffer; 216 217 218 /** 219 Opaque pointer to host data. 220 */ 221 typedef void* LV2_Event_Callback_Data; 222 223 224 /** 225 Non-POD events feature. 226 227 To support this feature the host must pass an LV2_Feature struct to the 228 plugin's instantiate method with URI "http://lv2plug.in/ns/ext/event" 229 and data pointed to an instance of this struct. Note this feature 230 is not mandatory to support the event extension. 231 */ 232 typedef struct { 233 /** 234 Opaque pointer to host data. 235 236 The plugin MUST pass this to any call to functions in this struct. 237 Otherwise, it must not be interpreted in any way. 238 */ 239 LV2_Event_Callback_Data callback_data; 240 241 /** 242 Take a reference to a non-POD event. 243 244 If a plugin receives an event with type 0, it means the event is a 245 pointer to some object in memory and not a flat sequence of bytes 246 in the buffer. When receiving a non-POD event, the plugin already 247 has an implicit reference to the event. If the event is stored AND 248 passed to an output, lv2_event_ref MUST be called on that event. 249 If the event is only stored OR passed through, this is not necessary 250 (as the plugin already has 1 implicit reference). 251 252 @param event An event received at an input that will not be copied to 253 an output or stored in any way. 254 255 @param context The calling context. Like event types, this is a mapped 256 URI, see lv2_context.h. Simple plugin with just a run() method should 257 pass 0 here (the ID of the 'standard' LV2 run context). The host 258 guarantees that this function is realtime safe iff @a context is 259 realtime safe. 260 261 PLUGINS THAT VIOLATE THESE RULES MAY CAUSE CRASHES AND MEMORY LEAKS. 262 */ 263 uint32_t (*lv2_event_ref)(LV2_Event_Callback_Data callback_data, 264 LV2_Event* event); 265 266 /** 267 Drop a reference to a non-POD event. 268 269 If a plugin receives an event with type 0, it means the event is a 270 pointer to some object in memory and not a flat sequence of bytes 271 in the buffer. If the plugin does not pass the event through to 272 an output or store it internally somehow, it MUST call this function 273 on the event (more information on using non-POD events below). 274 275 @param event An event received at an input that will not be copied to an 276 output or stored in any way. 277 278 @param context The calling context. Like event types, this is a mapped 279 URI, see lv2_context.h. Simple plugin with just a run() method should 280 pass 0 here (the ID of the 'standard' LV2 run context). The host 281 guarantees that this function is realtime safe iff @a context is 282 realtime safe. 283 284 PLUGINS THAT VIOLATE THESE RULES MAY CAUSE CRASHES AND MEMORY LEAKS. 285 */ 286 uint32_t (*lv2_event_unref)(LV2_Event_Callback_Data callback_data, 287 LV2_Event* event); 288 } LV2_Event_Feature; 289 290 #ifdef __cplusplus 291 } /* extern "C" */ 292 #endif 293 294 #endif /* LV2_EVENT_H */ 295