Add synth example from Harry van Haaren.

1 files changed, 173 insertions, 0 deletions

diff --git a/plugins/eg-synth.lv2/synth.c b/plugins/eg-synth.lv2/synth.c
new file mode 100644
index 0000000..c607daa
--- /dev/null
+++ b/plugins/eg-synth.lv2/synth.c
@@ -0,0 +1,173 @@
+/*
+  Copyright 2012 Harry van Haaren <harryhaaren@gmail.com>
+  Copyright 2012 David Robillard <d@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.
+*/
+
+/**
+   @file synth.c Implementation of the LV2 Sin Synth example plugin.
+
+   This is a simple LV2 synthesis plugin that demonstrates how to receive MIDI
+   events and render audio in response to them.
+*/
+
+#include <math.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "lv2/lv2plug.in/ns/lv2core/lv2.h"
+
+#define SYNTH_URI "http://lv2plug.in/plugins/eg-synth"
+
+/** Port indices. */
+typedef enum {
+	SYNTH_FREQ = 0,
+	SYNTH_OUTPUT,
+} PortIndex;
+
+/** Plugin instance. */
+typedef struct {
+	// Sample rate, necessary to generate sin wave in run()
+	double sample_rate;
+  
+	// Current wave phase
+	float phase;
+
+	// Port buffers
+	float* freq;
+	float* input;
+	float* output;
+} Synth;
+
+/** Create a new plugin instance. */
+static LV2_Handle
+instantiate(const LV2_Descriptor*     descriptor,
+            double                    rate,
+            const char*               bundle_path,
+            const LV2_Feature* const* features)
+{
+	Synth* self = (Synth*)malloc(sizeof(Synth));
+  
+	// Store the sample rate so it is available in run()
+	self->sample_rate = rate;
+  
+	return (LV2_Handle)self;
+}
+
+/** Connect a port to a buffer (audio thread, must be RT safe). */
+static void
+connect_port(LV2_Handle instance,
+             uint32_t   port,
+             void*      data)
+{
+	Synth* self = (Synth*)instance;
+
+	switch ((PortIndex)port) {
+	case SYNTH_FREQ:
+		self->freq = (float*)data;
+		break;
+	case SYNTH_OUTPUT:
+		self->output = (float*)data;
+		break;
+	}
+}
+
+/** Initialise and prepare the plugin instance for running. */
+static void
+activate(LV2_Handle instance)
+{
+	Synth* self = (Synth*)instance;
+
+	// Initialize phase so we start at the beginning of the wave
+	self->phase = 0.0f;
+}
+
+/** Process a block of audio (audio thread, must be RT safe). */
+static void
+run(LV2_Handle instance, uint32_t n_samples)
+{
+	Synth* self = (Synth*)instance;
+  
+	const float  PI     = 3.1415;
+	const float  volume = 0.3;
+	const float  freq   = *(self->freq);
+	float* const output = self->output;
+  
+	float samples_per_cycle = self->sample_rate / freq;
+  
+	/* Calculate the phase offset per sample.  Phase ranges from 0..1, so
+	   phase_increment is a floating point number such that we get "freq"
+	   number of cycles in "sample_rate" amount of samples. */
+	float phase_increment = (1.f / samples_per_cycle);
+  
+	for (uint32_t pos = 0; pos < n_samples; pos++) {
+    
+		/* Calculate the next sample.  Phase ranges from 0..1, but sin()
+		   expects its input in radians, so we multiply by 2 PI to convert it.
+		   We also multiply by volume so it's not extremely loud. */
+		output[pos] = sin(self->phase * 2 * PI) * volume;
+    
+		/* Increment the phase so we generate the next sample */
+		self->phase += phase_increment;
+		if (self->phase > 1.0f) {
+			self->phase = 0.0f;
+		}
+	}
+}
+
+/** Finish running (counterpart to activate()). */
+static void
+deactivate(LV2_Handle instance)
+{
+	/* Nothing to do here in this trivial mostly stateless plugin. */
+}
+
+/** Destroy a plugin instance (counterpart to instantiate()). */
+static void
+cleanup(LV2_Handle instance)
+{
+	free(instance);
+}
+
+/** Return extension data provided by the plugin. */
+const void*
+extension_data(const char* uri)
+{
+	return NULL;  /* This plugin has no extension data. */
+}
+
+/** The LV2_Descriptor for this plugin. */
+static const LV2_Descriptor descriptor = {
+	SYNTH_URI,
+	instantiate,
+	connect_port,
+	activate,
+	run,
+	deactivate,
+	cleanup,
+	extension_data
+};
+
+/** Entry point, the host will call this function to access descriptors. */
+LV2_SYMBOL_EXPORT
+const LV2_Descriptor*
+lv2_descriptor(uint32_t index)
+{
+	switch (index) {
+	case 0:
+		return &descriptor;
+	default:
+		return NULL;
+	}
+}