LV2 subproject with meson
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/*
Copyright 2006-2016 David Robillard <d@drobilla.net>
Copyright 2006 Steve Harris <steve@plugin.org.uk>
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.
*/
/**
LV2 headers are based on the URI of the specification they come from, so a
consistent convention can be used even for unofficial extensions. The URI
of the core LV2 specification is <http://lv2plug.in/ns/lv2core>, by
replacing `http:/` with `lv2` any header in the specification bundle can be
included, in this case `lv2.h`.
*/
#include "lv2/core/lv2.h"
/** Include standard C headers */
#include <math.h>
#include <stdint.h>
#include <stdlib.h>
/**
The URI is the identifier for a plugin, and how the host associates this
implementation in code with its description in data. In this plugin it is
only used once in the code, but defining the plugin URI at the top of the
file is a good convention to follow. If this URI does not match that used
in the data files, the host will fail to load the plugin.
*/
#define AMP_URI "http://lv2plug.in/plugins/eg-amp"
/**
In code, ports are referred to by index. An enumeration of port indices
should be defined for readability.
*/
typedef enum { AMP_GAIN = 0, AMP_INPUT = 1, AMP_OUTPUT = 2 } PortIndex;
/**
Every plugin defines a private structure for the plugin instance. All data
associated with a plugin instance is stored here, and is available to
every instance method. In this simple plugin, only port buffers need to be
stored, since there is no additional instance data.
*/
typedef struct {
// Port buffers
const float* gain;
const float* input;
float* output;
} Amp;
/**
The `instantiate()` function is called by the host to create a new plugin
instance. The host passes the plugin descriptor, sample rate, and bundle
path for plugins that need to load additional resources (e.g. waveforms).
The features parameter contains host-provided features defined in LV2
extensions, but this simple plugin does not use any.
This function is in the ``instantiation'' threading class, so no other
methods on this instance will be called concurrently with it.
*/
static LV2_Handle
instantiate(const LV2_Descriptor* descriptor,
double rate,
const char* bundle_path,
const LV2_Feature* const* features)
{
Amp* amp = (Amp*)calloc(1, sizeof(Amp));
return (LV2_Handle)amp;
}
/**
The `connect_port()` method is called by the host to connect a particular
port to a buffer. The plugin must store the data location, but data may not
be accessed except in run().
This method is in the ``audio'' threading class, and is called in the same
context as run().
*/
static void
connect_port(LV2_Handle instance, uint32_t port, void* data)
{
Amp* amp = (Amp*)instance;
switch ((PortIndex)port) {
case AMP_GAIN:
amp->gain = (const float*)data;
break;
case AMP_INPUT:
amp->input = (const float*)data;
break;
case AMP_OUTPUT:
amp->output = (float*)data;
break;
}
}
/**
The `activate()` method is called by the host to initialise and prepare the
plugin instance for running. The plugin must reset all internal state
except for buffer locations set by `connect_port()`. Since this plugin has
no other internal state, this method does nothing.
This method is in the ``instantiation'' threading class, so no other
methods on this instance will be called concurrently with it.
*/
static void
activate(LV2_Handle instance)
{}
/** Define a macro for converting a gain in dB to a coefficient. */
#define DB_CO(g) ((g) > -90.0f ? powf(10.0f, (g)*0.05f) : 0.0f)
/**
The `run()` method is the main process function of the plugin. It processes
a block of audio in the audio context. Since this plugin is
`lv2:hardRTCapable`, `run()` must be real-time safe, so blocking (e.g. with
a mutex) or memory allocation are not allowed.
*/
static void
run(LV2_Handle instance, uint32_t n_samples)
{
const Amp* amp = (const Amp*)instance;
const float gain = *(amp->gain);
const float* const input = amp->input;
float* const output = amp->output;
const float coef = DB_CO(gain);
for (uint32_t pos = 0; pos < n_samples; pos++) {
output[pos] = input[pos] * coef;
}
}
/**
The `deactivate()` method is the counterpart to `activate()`, and is called
by the host after running the plugin. It indicates that the host will not
call `run()` again until another call to `activate()` and is mainly useful
for more advanced plugins with ``live'' characteristics such as those with
auxiliary processing threads. As with `activate()`, this plugin has no use
for this information so this method does nothing.
This method is in the ``instantiation'' threading class, so no other
methods on this instance will be called concurrently with it.
*/
static void
deactivate(LV2_Handle instance)
{}
/**
Destroy a plugin instance (counterpart to `instantiate()`).
This method is in the ``instantiation'' threading class, so no other
methods on this instance will be called concurrently with it.
*/
static void
cleanup(LV2_Handle instance)
{
free(instance);
}
/**
The `extension_data()` function returns any extension data supported by the
plugin. Note that this is not an instance method, but a function on the
plugin descriptor. It is usually used by plugins to implement additional
interfaces. This plugin does not have any extension data, so this function
returns NULL.
This method is in the ``discovery'' threading class, so no other functions
or methods in this plugin library will be called concurrently with it.
*/
static const void*
extension_data(const char* uri)
{
return NULL;
}
/**
Every plugin must define an `LV2_Descriptor`. It is best to define
descriptors statically to avoid leaking memory and non-portable shared
library constructors and destructors to clean up properly.
*/
static const LV2_Descriptor descriptor = {AMP_URI,
instantiate,
connect_port,
activate,
run,
deactivate,
cleanup,
extension_data};
/**
The `lv2_descriptor()` function is the entry point to the plugin library. The
host will load the library and call this function repeatedly with increasing
indices to find all the plugins defined in the library. The index is not an
indentifier, the URI of the returned descriptor is used to determine the
identify of the plugin.
This method is in the ``discovery'' threading class, so no other functions
or methods in this plugin library will be called concurrently with it.
*/
LV2_SYMBOL_EXPORT
const LV2_Descriptor*
lv2_descriptor(uint32_t index)
{
return index == 0 ? &descriptor : NULL;
}