Order examples in a sensible progression for the book.

1 files changed, 225 insertions, 0 deletions

diff --git a/plugins/eg01-amp.lv2/amp.c b/plugins/eg01-amp.lv2/amp.c
new file mode 100644
index 0000000..8dd7b4f
--- /dev/null
+++ b/plugins/eg01-amp.lv2/amp.c
@@ -0,0 +1,225 @@
+/*
+  Copyright 2006-2011 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.
+*/
+
+/** Include standard C headers */
+#include <math.h>
+#include <stdlib.h>
+
+/**
+   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/lv2plug.in/ns/lv2core/lv2.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*)malloc(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)
+
+/** Process a block of audio (audio thread, must be RT safe). */
+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() 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;
+}
+
+/**
+   Define the LV2_Descriptor for this plugin.  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)
+{
+	switch (index) {
+	case 0:
+		return &descriptor;
+	default:
+		return NULL;
+	}
+}