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Diffstat (limited to 'plugins/eg-synth.lv2/synth.c')
| -rw-r--r-- | plugins/eg-synth.lv2/synth.c | 173 |
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; + } +} |