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+/*
+ LV2 - An audio plugin interface specification.
+ Copyright 2006-2011 Steve Harris, David Robillard.
+
+ Based on LADSPA, Copyright 2000-2002 Richard W.E. Furse,
+ Paul Barton-Davis, Stefan Westerfeld.
+
+ 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.
+*/
+
+/**
+ @file lv2.h
+ API for the LV2 specification <http://lv2plug.in/ns/lv2core>.
+ Revision: 4.1
+*/
+
+#ifndef LV2_H_INCLUDED
+#define LV2_H_INCLUDED
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ Plugin Instance Handle.
+
+ This is a handle for one particular instance of a plugin. It is valid to
+ compare to NULL (or 0 for C++) but otherwise the host MUST NOT attempt to
+ interpret it.
+*/
+typedef void * LV2_Handle;
+
+/**
+ Feature.
+
+ Features allow hosts to make additional functionality available to plugins
+ without requiring modification to the LV2 API. Extensions may define new
+ features and specify the @ref URI and @ref data to be used if necessary.
+ Some features, such as lv2:isLive, do not require the host to pass data.
+*/
+typedef struct _LV2_Feature {
+ /**
+ A globally unique, case-sensitive identifier (URI) for this feature.
+
+ This MUST be a valid URI string as defined by RFC 3986.
+ */
+ const char * URI;
+
+ /**
+ Pointer to arbitrary data.
+
+ The format of this data is defined by the extension which describes the
+ feature with the given @ref URI.
+ */
+ void * data;
+} LV2_Feature;
+
+/**
+ Plugin Descriptor.
+
+ This structure provides the core functions necessary to instantiate and use
+ a plugin.
+*/
+typedef struct _LV2_Descriptor {
+ /**
+ A globally unique, case-sensitive identifier for this plugin.
+
+ This MUST be a valid URI string as defined by RFC 3986. All plugins with
+ the same URI MUST be compatible to some degree, see
+ http://lv2plug.in/ns/lv2core for details.
+ */
+ const char * URI;
+
+ /**
+ Instantiate the plugin.
+
+ Note that instance initialisation should generally occur in activate()
+ rather than here. If a host calls instantiate(), it MUST call cleanup()
+ at some point in the future.
+
+ @param descriptor Descriptor of the plugin to instantiate.
+
+ @param sample_rate Sample rate, in Hz, for the new plugin instance.
+
+ @param bundle_path Path to the LV2 bundle which contains this plugin
+ binary. It MUST include the trailing directory separator (e.g. '/') so
+ that simply appending a filename will yield the path to that file in the
+ bundle.
+
+ @param features A NULL terminated array of LV2_Feature structs which
+ represent the features the host supports. Plugins may refuse to
+ instantiate if required features are not found here. However, hosts MUST
+ NOT use this as a discovery mechanism: instead, use the RDF data to
+ determine which features are required and do not attempt to instantiate
+ unsupported plugins at all. This parameter MUST NOT be NULL, i.e. a host
+ that supports no features MUST pass a single element array containing
+ NULL.
+
+ @return A handle for the new plugin instance, or NULL if instantiation
+ has failed.
+ */
+ LV2_Handle (*instantiate)(const struct _LV2_Descriptor * descriptor,
+ double sample_rate,
+ const char * bundle_path,
+ const LV2_Feature *const * features);
+
+ /**
+ Connect a port on a plugin instance to a memory location.
+
+ Plugin writers should be aware that the host may elect to use the same
+ buffer for more than one port and even use the same buffer for both
+ input and output (see lv2:inPlaceBroken in lv2.ttl).
+
+ If the plugin has the feature lv2:hardRTCapable then there are various
+ things that the plugin MUST NOT do within the connect_port() function;
+ see lv2.ttl for details.
+
+ connect_port() MUST be called at least once for each port before run()
+ is called, unless that port is lv2:connectionOptional. The plugin must
+ pay careful attention to the block size passed to run() since the block
+ allocated may only just be large enough to contain the data, and is not
+ guaranteed to remain constant between run() calls.
+
+ connect_port() may be called more than once for a plugin instance to
+ allow the host to change the buffers that the plugin is reading or
+ writing. These calls may be made before or after activate() or
+ deactivate() calls.
+
+ @param instance Plugin instance containing the port.
+
+ @param port Index of the port to connect. The host MUST NOT try to
+ connect a port index that is not defined in the plugin's RDF data. If
+ it does, the plugin's behaviour is undefined (a crash is likely).
+
+ @param data_location Pointer to data of the type defined by the port
+ type in the plugin's RDF data (e.g. an array of float for an
+ lv2:AudioPort). This pointer must be stored by the plugin instance and
+ used to read/write data when run() is called. Data present at the time
+ of the connect_port() call MUST NOT be considered meaningful.
+ */
+ void (*connect_port)(LV2_Handle instance,
+ uint32_t port,
+ void * data_location);
+
+ /**
+ Initialise a plugin instance and activate it for use.
+
+ This is separated from instantiate() to aid real-time support and so
+ that hosts can reinitialise a plugin instance by calling deactivate()
+ and then activate(). In this case the plugin instance MUST reset all
+ state information dependent on the history of the plugin instance except
+ for any data locations provided by connect_port(). If there is nothing
+ for activate() to do then this field may be NULL.
+
+ When present, hosts MUST call this function once before run() is called
+ for the first time. This call SHOULD be made as close to the run() call
+ as possible and indicates to real-time plugins that they are now live,
+ however plugins MUST NOT rely on a prompt call to run() after
+ activate().
+
+ The host MUST NOT call activate() again until deactivate() has been
+ called first. If a host calls activate(), it MUST call deactivate() at
+ some point in the future. Note that connect_port() may be called before
+ or after activate().
+ */
+ void (*activate)(LV2_Handle instance);
+
+ /**
+ Run a plugin instance for a block.
+
+ Note that if an activate() function exists then it must be called before
+ run(). If deactivate() is called for a plugin instance then run() may
+ not be called until activate() has been called again.
+
+ If the plugin has the feature lv2:hardRTCapable then there are various
+ things that the plugin MUST NOT do within the run() function (see
+ lv2.ttl for details).
+
+ As a special case, when @c sample_count == 0, the plugin should update
+ any output ports that represent a single instant in time (e.g. control
+ ports, but not audio ports). This is particularly useful for latent
+ plugins, which should update their latency output port so hosts can
+ pre-roll plugins to compute latency. Plugins MUST NOT crash when
+ @c sample_count == 0.
+
+ @param instance Instance to be run.
+
+ @param sample_count The block size (in samples) for which the plugin
+ instance must run.
+ */
+ void (*run)(LV2_Handle instance,
+ uint32_t sample_count);
+
+ /**
+ Deactivate a plugin instance (counterpart to activate()).
+
+ Hosts MUST deactivate all activated instances after they have been run()
+ for the last time. This call SHOULD be made as close to the last run()
+ call as possible and indicates to real-time plugins that they are no
+ longer live, however plugins MUST NOT rely on prompt deactivation. If
+ there is nothing for deactivate() to do then this field may be NULL
+
+ Deactivation is not similar to pausing since the plugin instance will be
+ reinitialised by activate(). However, deactivate() itself MUST NOT fully
+ reset plugin state. For example, the host may deactivate a plugin, then
+ store its state (using some extension to do so).
+
+ Hosts MUST NOT call deactivate() unless activate() was previously
+ called. Note that connect_port() may be called before or after
+ deactivate().
+ */
+ void (*deactivate)(LV2_Handle instance);
+
+ /**
+ Clean up a plugin instance (counterpart to instantiate()).
+
+ Once an instance of a plugin has been finished with it must be deleted
+ using this function. The instance handle passed ceases to be valid after
+ this call.
+
+ If activate() was called for a plugin instance then a corresponding call
+ to deactivate() MUST be made before cleanup() is called. Hosts MUST NOT
+ call cleanup() unless instantiate() was previously called.
+ */
+ void (*cleanup)(LV2_Handle instance);
+
+ /**
+ Return additional plugin data defined by some extenion.
+
+ A typical use of this facility is to return a struct containing function
+ pointers to extend the LV2_Descriptor API.
+
+ The actual type and meaning of the returned object MUST be specified
+ precisely by the extension. This function MUST return NULL for any
+ unsupported URI. If a plugin does not support any extension data, this
+ field may be NULL.
+
+ The host is never responsible for freeing the returned value.
+ */
+ const void * (*extension_data)(const char * uri);
+} LV2_Descriptor;
+
+/**
+ Prototype for plugin accessor function.
+
+ Plugins are discovered by hosts using RDF data (not by loading libraries).
+ See http://lv2plug.in for details on the discovery process, though most
+ hosts should use an existing library to implement this functionality.
+
+ A plugin library MUST include a function called "lv2_descriptor" with this
+ prototype. This function MUST have C-style linkage (if you are using C++
+ this is taken care of by the 'extern "C"' clause at the top of this file).
+
+ When it is time to load a plugin (designated by its URI), the host loads the
+ plugin's library, gets the lv2_descriptor() function from it, and uses this
+ function to find the LV2_Descriptor for the desired plugin. Plugins are
+ accessed by index using values from 0 upwards. This function MUST return
+ NULL for out of range indices, so the host can enumerate plugins by
+ increasing @c index until NULL is returned.
+
+ Note that @c index has no meaning, hosts MUST NOT depend on it remaining
+ consistent between loads of the plugin library.
+*/
+const LV2_Descriptor * lv2_descriptor(uint32_t index);
+
+/**
+ Type of the lv2_descriptor() function in a plugin library.
+*/
+typedef const LV2_Descriptor *
+(*LV2_Descriptor_Function)(uint32_t index);
+
+/**
+ Put this (LV2_SYMBOL_EXPORT) before any functions that are to be loaded
+ by the host as a symbol from the dynamic library.
+*/
+#ifdef WIN32
+#define LV2_SYMBOL_EXPORT __declspec(dllexport)
+#else
+#define LV2_SYMBOL_EXPORT
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* LV2_H_INCLUDED */