Add preliminary C++ work.

1 files changed, 256 insertions, 0 deletions

diff --git a/lv2/lv2plug.in/ns/lv2core/Plugin.hpp b/lv2/lv2plug.in/ns/lv2core/Plugin.hpp
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+++ b/lv2/lv2plug.in/ns/lv2core/Plugin.hpp
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+/*
+  Copyright 2015 David Robillard <http://drobilla.net>
+
+  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_PLUGIN_HPP
+#define LV2_PLUGIN_HPP
+
+#include "lv2/lv2plug.in/ns/lv2core/lv2.h"
+
+namespace lv2 {
+
+/**
+   C++ wrapper for an LV2 plugin.
+
+   This interface is a convenience for plugin authors only, and is not an ABI
+   used by hosts.  Plugin authors should inherit from this interface, and use
+   the resulting class as the template parameter to lv2::set_descriptor() to
+   initialise a descriptor for the plugin.
+
+   This class is a stateless interface and imposes no restrictions or overhead
+   compared to a plugin implemented using the underlying C interface.  Note
+   that this is not a virtual class, so calling methods from a Plugin* base
+   pointer will not work.  Instead, anything that must dispatch on Plugin
+   methods takes a template parameter for static dispatch.
+*/
+class Plugin
+{
+public:
+	/**
+	   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 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.
+	*/
+	Plugin(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 lv2core.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 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(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() {}
+
+	/**
+	   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
+	   lv2core.ttl for details).
+
+	   As a special case, when `sample_count` is 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
+	   `sample_count` is 0.
+
+	   @param sample_count The block size (in samples) for which the plugin
+	   instance must run.
+	*/
+	void run(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() {}
+
+	/**
+	   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.
+	*/
+	static const void* extension_data(const char* uri) { return NULL; }
+};
+
+template<typename Plugin>
+static LV2_Handle s_instantiate(const LV2_Descriptor*     descriptor,
+                                double                    sample_rate,
+                                const char*               bundle_path,
+                                const LV2_Feature* const* features) {
+	Plugin* t = new Plugin(sample_rate, bundle_path, features);
+	if (!t) {
+		delete t;
+		return nullptr;
+	}
+
+	return reinterpret_cast<LV2_Handle>(t);
+}
+
+template<typename Plugin>
+static void s_connect_port(LV2_Handle instance, uint32_t port, void* buf)
+{
+	reinterpret_cast<Plugin*>(instance)->connect_port(port, buf);
+}
+
+template<typename Plugin>
+static void s_activate(LV2_Handle instance)
+{
+	reinterpret_cast<Plugin*>(instance)->activate();
+}
+
+template<typename Plugin>
+static void s_run(LV2_Handle instance, uint32_t sample_count)
+{
+	reinterpret_cast<Plugin*>(instance)->run(sample_count);
+}
+
+template<typename Plugin>
+static void s_deactivate(LV2_Handle instance)
+{
+	reinterpret_cast<Plugin*>(instance)->deactivate();
+}
+
+template<typename Plugin>
+static void s_cleanup(LV2_Handle instance)
+{
+	delete reinterpret_cast<Plugin*>(instance);
+}
+
+/**
+   Get an LV2_Descriptor for a plugin class.
+
+   @code
+   static const LV2_Descriptor a = lv2::descriptor<Amp>("http://example.org/amp");
+   @endcode
+*/
+template<typename Plugin>
+static LV2_Descriptor
+descriptor(const char* uri)
+{
+	const LV2_Descriptor desc = { uri,
+	                              &s_instantiate<Plugin>,
+	                              &s_connect_port<Plugin>,
+	                              &s_activate<Plugin>,
+	                              &s_run<Plugin>,
+	                              &s_deactivate<Plugin>,
+	                              &s_cleanup<Plugin>,
+	                              &Plugin::extension_data };
+	return desc;
+}
+
+} /* namespace lv2 */
+
+#endif /* LV2_PLUGIN_HPP */