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-rw-r--r--plugins/eg03-metro.lv2/metro.c352
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diff --git a/plugins/eg03-metro.lv2/metro.c b/plugins/eg03-metro.lv2/metro.c
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--- a/plugins/eg03-metro.lv2/metro.c
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-/*
- LV2 Metronome Example Plugin
- 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.
-*/
-
-#include <math.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#ifndef __cplusplus
-# include <stdbool.h>
-#endif
-
-#include "lv2/lv2plug.in/ns/ext/atom/atom.h"
-#include "lv2/lv2plug.in/ns/ext/atom/util.h"
-#include "lv2/lv2plug.in/ns/ext/time/time.h"
-#include "lv2/lv2plug.in/ns/ext/urid/urid.h"
-#include "lv2/lv2plug.in/ns/lv2core/lv2.h"
-
-#ifndef M_PI
-# define M_PI 3.14159265
-#endif
-
-#define EG_METRO_URI "http://lv2plug.in/plugins/eg-metro"
-
-typedef struct {
- LV2_URID atom_Blank;
- LV2_URID atom_Float;
- LV2_URID atom_Object;
- LV2_URID atom_Path;
- LV2_URID atom_Resource;
- LV2_URID atom_Sequence;
- LV2_URID time_Position;
- LV2_URID time_barBeat;
- LV2_URID time_beatsPerMinute;
- LV2_URID time_speed;
-} MetroURIs;
-
-static const double attack_s = 0.005;
-static const double decay_s = 0.075;
-
-enum {
- METRO_CONTROL = 0,
- METRO_OUT = 1
-};
-
-/** During execution this plugin can be in one of 3 states: */
-typedef enum {
- STATE_ATTACK, // Envelope rising
- STATE_DECAY, // Envelope lowering
- STATE_OFF // Silent
-} State;
-
-/**
- This plugin must keep track of more state than previous examples to be able
- to render audio. The basic idea is to generate a single cycle of a sine
- wave which is conceptually played continuously. The 'tick' is generated by
- enveloping the amplitude so there is a short attack/decay peak around a
- tick, and silence the rest of the time.
-
- This example uses a simple AD envelope with fixed parameters. A more
- sophisticated implementation might use a more advanced envelope and allow
- the user to modify these parameters, the frequency of the wave, and so on.
- */
-typedef struct {
- LV2_URID_Map* map; // URID map feature
- MetroURIs uris; // Cache of mapped URIDs
-
- struct {
- LV2_Atom_Sequence* control;
- float* output;
- } ports;
-
- // Variables to keep track of the tempo information sent by the host
- double rate; // Sample rate
- float bpm; // Beats per minute (tempo)
- float speed; // Transport speed (usually 0=stop, 1=play)
-
- uint32_t elapsed_len; // Frames since the start of the last click
- uint32_t wave_offset; // Current play offset in the wave
- State state; // Current play state
-
- // One cycle of a sine wave
- float* wave;
- uint32_t wave_len;
-
- // Envelope parameters
- uint32_t attack_len;
- uint32_t decay_len;
-} Metro;
-
-static void
-connect_port(LV2_Handle instance,
- uint32_t port,
- void* data)
-{
- Metro* self = (Metro*)instance;
-
- switch (port) {
- case METRO_CONTROL:
- self->ports.control = (LV2_Atom_Sequence*)data;
- break;
- case METRO_OUT:
- self->ports.output = (float*)data;
- break;
- default:
- break;
- }
-}
-
-/**
- The activate() method resets the state completely, so the wave offset is
- zero and the envelope is off.
-*/
-static void
-activate(LV2_Handle instance)
-{
- Metro* self = (Metro*)instance;
-
- self->elapsed_len = 0;
- self->wave_offset = 0;
- self->state = STATE_OFF;
-}
-
-/**
- This plugin does a bit more work in instantiate() than the previous
- examples. The tempo updates from the host contain several URIs, so those
- are mapped, and the sine wave to be played needs to be generated based on
- the current sample rate.
-*/
-static LV2_Handle
-instantiate(const LV2_Descriptor* descriptor,
- double rate,
- const char* path,
- const LV2_Feature* const* features)
-{
- Metro* self = (Metro*)calloc(1, sizeof(Metro));
- if (!self) {
- return NULL;
- }
-
- // Scan host features for URID map
- LV2_URID_Map* map = NULL;
- for (int i = 0; features[i]; ++i) {
- if (!strcmp(features[i]->URI, LV2_URID_URI "#map")) {
- map = (LV2_URID_Map*)features[i]->data;
- }
- }
- if (!map) {
- fprintf(stderr, "Host does not support urid:map.\n");
- free(self);
- return NULL;
- }
-
- // Map URIS
- MetroURIs* const uris = &self->uris;
- self->map = map;
- uris->atom_Blank = map->map(map->handle, LV2_ATOM__Blank);
- uris->atom_Float = map->map(map->handle, LV2_ATOM__Float);
- uris->atom_Object = map->map(map->handle, LV2_ATOM__Object);
- uris->atom_Path = map->map(map->handle, LV2_ATOM__Path);
- uris->atom_Resource = map->map(map->handle, LV2_ATOM__Resource);
- uris->atom_Sequence = map->map(map->handle, LV2_ATOM__Sequence);
- uris->time_Position = map->map(map->handle, LV2_TIME__Position);
- uris->time_barBeat = map->map(map->handle, LV2_TIME__barBeat);
- uris->time_beatsPerMinute = map->map(map->handle, LV2_TIME__beatsPerMinute);
- uris->time_speed = map->map(map->handle, LV2_TIME__speed);
-
- // Initialise instance fields
- self->rate = rate;
- self->bpm = 120.0f;
- self->attack_len = (uint32_t)(attack_s * rate);
- self->decay_len = (uint32_t)(decay_s * rate);
- self->state = STATE_OFF;
-
- // Generate one cycle of a sine wave at the desired frequency
- const double freq = 440.0 * 2.0;
- const double amp = 0.5;
- self->wave_len = (uint32_t)(rate / freq);
- self->wave = (float*)malloc(self->wave_len * sizeof(float));
- for (uint32_t i = 0; i < self->wave_len; ++i) {
- self->wave[i] = (float)(sin(i * 2 * M_PI * freq / rate) * amp);
- }
-
- return (LV2_Handle)self;
-}
-
-static void
-cleanup(LV2_Handle instance)
-{
- free(instance);
-}
-
-/**
- Play back audio for the range [begin..end) relative to this cycle. This is
- called by run() in-between events to output audio up until the current time.
-*/
-static void
-play(Metro* self, uint32_t begin, uint32_t end)
-{
- float* const output = self->ports.output;
- const uint32_t frames_per_beat = 60.0f / self->bpm * self->rate;
-
- if (self->speed == 0.0f) {
- memset(output, 0, (end - begin) * sizeof(float));
- return;
- }
-
- for (uint32_t i = begin; i < end; ++i) {
- switch (self->state) {
- case STATE_ATTACK:
- // Amplitude increases from 0..1 until attack_len
- output[i] = self->wave[self->wave_offset] *
- self->elapsed_len / (float)self->attack_len;
- if (self->elapsed_len >= self->attack_len) {
- self->state = STATE_DECAY;
- }
- break;
- case STATE_DECAY:
- // Amplitude decreases from 1..0 until attack_len + decay_len
- output[i] = 0.0f;
- output[i] = self->wave[self->wave_offset] *
- (1 - ((self->elapsed_len - self->attack_len) /
- (float)self->decay_len));
- if (self->elapsed_len >= self->attack_len + self->decay_len) {
- self->state = STATE_OFF;
- }
- break;
- case STATE_OFF:
- output[i] = 0.0f;
- }
-
- // We continuously play the sine wave regardless of envelope
- self->wave_offset = (self->wave_offset + 1) % self->wave_len;
-
- // Update elapsed time and start attack if necessary
- if (++self->elapsed_len == frames_per_beat) {
- self->state = STATE_ATTACK;
- self->elapsed_len = 0;
- }
- }
-}
-
-/**
- Update the current position based on a host message. This is called by
- run() when a time:Position is received.
-*/
-static void
-update_position(Metro* self, const LV2_Atom_Object* obj)
-{
- const MetroURIs* uris = &self->uris;
-
- // Received new transport position/speed
- LV2_Atom *beat = NULL, *bpm = NULL, *speed = NULL;
- lv2_atom_object_get(obj,
- uris->time_barBeat, &beat,
- uris->time_beatsPerMinute, &bpm,
- uris->time_speed, &speed,
- NULL);
- if (bpm && bpm->type == uris->atom_Float) {
- // Tempo changed, update BPM
- self->bpm = ((LV2_Atom_Float*)bpm)->body;
- }
- if (speed && speed->type == uris->atom_Float) {
- // Speed changed, e.g. 0 (stop) to 1 (play)
- self->speed = ((LV2_Atom_Float*)speed)->body;
- }
- if (beat && beat->type == uris->atom_Float) {
- // Received a beat position, synchronise
- // This hard sync may cause clicks, a real plugin would be more graceful
- const float frames_per_beat = 60.0f / self->bpm * self->rate;
- const float bar_beats = ((LV2_Atom_Float*)beat)->body;
- const float beat_beats = bar_beats - floorf(bar_beats);
- self->elapsed_len = beat_beats * frames_per_beat;
- if (self->elapsed_len < self->attack_len) {
- self->state = STATE_ATTACK;
- } else if (self->elapsed_len < self->attack_len + self->decay_len) {
- self->state = STATE_DECAY;
- } else {
- self->state = STATE_OFF;
- }
- }
-}
-
-static void
-run(LV2_Handle instance, uint32_t sample_count)
-{
- Metro* self = (Metro*)instance;
- const MetroURIs* uris = &self->uris;
-
- // Work forwards in time frame by frame, handling events as we go
- const LV2_Atom_Sequence* in = self->ports.control;
- uint32_t last_t = 0;
- for (const LV2_Atom_Event* ev = lv2_atom_sequence_begin(&in->body);
- !lv2_atom_sequence_is_end(&in->body, in->atom.size, ev);
- ev = lv2_atom_sequence_next(ev)) {
-
- // Play the click for the time slice from last_t until now
- play(self, last_t, ev->time.frames);
-
- // Check if this event is an Object
- // (or deprecated Blank to tolerate old hosts)
- if (ev->body.type == uris->atom_Object ||
- ev->body.type == uris->atom_Blank) {
- const LV2_Atom_Object* obj = (const LV2_Atom_Object*)&ev->body;
- if (obj->body.otype == uris->time_Position) {
- // Received position information, update
- update_position(self, obj);
- }
- }
-
- // Update time for next iteration and move to next event
- last_t = ev->time.frames;
- }
-
- // Play for remainder of cycle
- play(self, last_t, sample_count);
-}
-
-static const LV2_Descriptor descriptor = {
- EG_METRO_URI,
- instantiate,
- connect_port,
- activate,
- run,
- NULL, // deactivate,
- cleanup,
- NULL, // extension_data
-};
-
-LV2_SYMBOL_EXPORT const LV2_Descriptor*
-lv2_descriptor(uint32_t index)
-{
- switch (index) {
- case 0:
- return &descriptor;
- default:
- return NULL;
- }
-}
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