Carla/source/native-plugins/midi-channel-filter.c

/*
 * Carla Native Plugins
 * Copyright (C) 2012-2019 Filipe Coelho <falktx@falktx.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * For a full copy of the GNU General Public License see the doc/GPL.txt file.
 */

#include "CarlaNative.h"
#include "CarlaMIDI.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

// -----------------------------------------------------------------------

typedef struct {
    const NativeHostDescriptor* host;
    bool channels[MAX_MIDI_CHANNELS];
} MidiGainHandle;

// -----------------------------------------------------------------------

static NativePluginHandle midichanfilter_instantiate(const NativeHostDescriptor* host)
{
    MidiGainHandle* const handle = (MidiGainHandle*)malloc(sizeof(MidiGainHandle));

    if (handle == NULL)
        return NULL;

    handle->host = host;

    for (int i=MAX_MIDI_CHANNELS; --i>=0;)
        handle->channels[i] = 1.0f;

    return handle;
}

#define handlePtr ((MidiGainHandle*)handle)

static void midichanfilter_cleanup(NativePluginHandle handle)
{
    free(handlePtr);
}

static uint32_t midichanfilter_get_parameter_count(NativePluginHandle handle)
{
    return MAX_MIDI_CHANNELS;

    // unused
    (void)handle;
}

static const NativeParameter* midichanfilter_get_parameter_info(NativePluginHandle handle, uint32_t index)
{
    if (index > MAX_MIDI_CHANNELS)
        return NULL;

    static NativeParameter param;
    static const NativeParameterScalePoint scalePoints[2] = { { "Off", 0.0f }, { "On", 1.0f } };
    static char paramName[24];

    param.hints = NATIVE_PARAMETER_IS_ENABLED|NATIVE_PARAMETER_IS_AUTOMABLE|NATIVE_PARAMETER_IS_BOOLEAN|NATIVE_PARAMETER_USES_SCALEPOINTS;
    param.name  = paramName;
    param.unit  = NULL;
    param.ranges.def       = 1.0f;
    param.ranges.min       = 0.0f;
    param.ranges.max       = 1.0f;
    param.ranges.step      = 1.0f;
    param.ranges.stepSmall = 1.0f;
    param.ranges.stepLarge = 1.0f;
    param.scalePointCount  = 2;
    param.scalePoints      = scalePoints;

    snprintf(paramName, 24, "%u", index+1);

    return &param;

    // unused
    (void)handle;
}

static float midichanfilter_get_parameter_value(NativePluginHandle handle, uint32_t index)
{
    if (index > MAX_MIDI_CHANNELS)
        return 0.0f;

    return handlePtr->channels[index] ? 1.0f : 0.0f;
}

static void midichanfilter_set_parameter_value(NativePluginHandle handle, uint32_t index, float value)
{
    if (index > MAX_MIDI_CHANNELS)
        return;

    handlePtr->channels[index] = (value >= 0.5f);
}

static void midichanfilter_process(NativePluginHandle handle,
                                   const float** inBuffer, float** outBuffer, uint32_t frames,
                                   const NativeMidiEvent* midiEvents, uint32_t midiEventCount)
{
    const NativeHostDescriptor* const host     = handlePtr->host;
    const bool*                 const channels = handlePtr->channels;

    for (uint32_t i=0; i < midiEventCount; ++i)
    {
        const NativeMidiEvent* const midiEvent = &midiEvents[i];

        const uint8_t status = (uint8_t)MIDI_GET_STATUS_FROM_DATA(midiEvent->data);

        if (MIDI_IS_CHANNEL_MESSAGE(status))
        {
            const uint8_t channel = (uint8_t)MIDI_GET_CHANNEL_FROM_DATA(midiEvent->data);

            if (channel >= MAX_MIDI_CHANNELS)
                continue;

            if (channels[channel])
                host->write_midi_event(host->handle, midiEvent);
        }
        else
        {
            // pass through all non-message events
            host->write_midi_event(host->handle, midiEvent);
        }
    }

    return;

    // unused
    (void)inBuffer;
    (void)outBuffer;
    (void)frames;
}

// -----------------------------------------------------------------------

static const NativePluginDescriptor midichanfilterDesc = {
    .category  = NATIVE_PLUGIN_CATEGORY_UTILITY,
    .hints     = NATIVE_PLUGIN_IS_RTSAFE,
    .supports  = NATIVE_PLUGIN_SUPPORTS_EVERYTHING,
    .audioIns  = 0,
    .audioOuts = 0,
    .cvIns     = 0,
    .cvOuts    = 0,
    .midiIns   = 1,
    .midiOuts  = 1,
    .paramIns  = 0,
    .paramOuts = 0,
    .name      = "MIDI Channel Filter",
    .label     = "midichanfilter",
    .maker     = "falkTX",
    .copyright = "GNU GPL v2+",

    .instantiate = midichanfilter_instantiate,
    .cleanup     = midichanfilter_cleanup,

    .get_parameter_count = midichanfilter_get_parameter_count,
    .get_parameter_info  = midichanfilter_get_parameter_info,
    .get_parameter_value = midichanfilter_get_parameter_value,

    .get_midi_program_count = NULL,
    .get_midi_program_info  = NULL,

    .set_parameter_value = midichanfilter_set_parameter_value,
    .set_midi_program    = NULL,
    .set_custom_data     = NULL,

    .ui_show = NULL,
    .ui_idle = NULL,

    .ui_set_parameter_value = NULL,
    .ui_set_midi_program    = NULL,
    .ui_set_custom_data     = NULL,

    .activate   = NULL,
    .deactivate = NULL,
    .process    = midichanfilter_process,

    .get_state = NULL,
    .set_state = NULL,

    .dispatcher = NULL,

    .render_inline_display = NULL
};

// -----------------------------------------------------------------------

void carla_register_native_plugin_midichanfilter(void);

void carla_register_native_plugin_midichanfilter(void)
{
    carla_register_native_plugin(&midichanfilterDesc);
}

// -----------------------------------------------------------------------