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| -rw-r--r-- | lv2/lv2_event.h | 281 |
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diff --git a/lv2/lv2_event.h b/lv2/lv2_event.h index e69de29..2c340ba 100644 --- a/lv2/lv2_event.h +++ b/lv2/lv2_event.h @@ -0,0 +1,281 @@ +/* + LV2 Event Extension + Copyright 2008-2011 David Robillard <http://drobilla.net> + Copyright 2006-2007 Lars Luthman <lars.luthman@gmail.com> + + Permission to use, copy, modify, and/or distribute this software for any + purpose with or without fee is hereby granted, provided that the above + copyright notice and this permission notice appear in all copies. + + THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. +*/ + +#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 event.h + C API 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 timestamps. + 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; + + +/** + Non-POD events feature. + + 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. Note this feature + is not mandatory to support the event extension. +*/ +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 */ |