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+/*
+ 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 */