vst.h

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/* An attempt at an untained clean room reimplementation of the widely popular VST 2.x SDK.
 * Copyright (c) 2020 Xaymar Dirks <info@xaymar.com> (previously known as Michael Fabian Dirks)
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
 * following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
 *    disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
 *    following disclaimer in the documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
// Please refer to README.md and LICENSE for further information.
 
// Protect against double inclusion in practically every compiler available.
#pragma once
#ifndef VST2SDK_VST_H
/** @private */
#define VST2SDK_VST_H
 
/* The VST 2.x alignment appears to be 8 for both 32 and 64-bit. This alignment is ignored by some earlier Windows
 * platforms and compilers, but we don't care about those.
 */
#pragma pack(push, 8)
 
#ifdef __cplusplus
#include <cinttypes>
extern "C" {
#else
#include <inttypes.h>
#endif
 
/** Standard calling convention across plug-ins and hosts.
 * On some older Windows platforms this is not __cdecl but something similar to __stdcall. We don't really care about
 * those old platforms anyway so __cdecl it is.
 */
#define VST_FUNCTION_INTERFACE __cdecl
 
/** Maximum number of channels/streams/inputs/outputs supported by VST 2.x
 */
#define VST_MAX_CHANNELS 32 // Couldn't find any audio editing software which would attempt to add more channels.
 
/** Convert four numbers into a FourCC
 */
#define VST_FOURCC(a,b,c,d) ((((uint32_t)a) << 24) | (((uint32_t)b) << 16) | (((uint32_t)c) << 8) | (((uint32_t)d) << 0))
 
/** Known Status Codes
 */
enum VST_STATUS {
    /** Unknown / False
     * We either don't know the answer or we can't handle the data/notification.
     *
     * @sa VST_HOST_OPCODE
     * @sa VST_EFFECT_OPCODE
     */
    VST_STATUS_0 = 0,
    /** @sa VST_STATUS_0 */
    VST_STATUS_FALSE = 0,
    /** @sa VST_STATUS_0 */
    VST_STATUS_ERROR = 0,
    /** @sa VST_STATUS_0 */
    VST_STATUS_UNKNOWN = 0,
 
    /** Yes / True
     * We've handled the data/notification.
     *
     * @sa VST_HOST_OPCODE
     * @sa VST_EFFECT_OPCODE
     */
    VST_STATUS_1 = 1,
    /** @sa VST_STATUS_1 */
    VST_STATUS_TRUE = 1,
    /** @sa VST_STATUS_1 */
    VST_STATUS_SUCCESS = 1,
    /** @sa VST_STATUS_1 */
    VST_STATUS_YES = 1,
 
    /** No
     * We're unable to handle the data/notification.
     *
     * @sa VST_HOST_OPCODE
     * @sa VST_EFFECT_OPCODE
     */
    VST_STATUS_m1 = -1,
    /** @sa VST_STATUS_m1 */
    VST_STATUS_NO = -1,
 
    _VST_STATUS_PAD = 0xFFFFFFFFul,
};
 
/** Known Buffer Sizes
 */
enum VST_BUFFER_SIZE {
    VST_BUFFER_SIZE_PARAM_LABEL = 8,
    VST_BUFFER_SIZE_PARAM_NAME = 8,
    VST_BUFFER_SIZE_PARAM_VALUE = 8,
    VST_BUFFER_SIZE_STREAM_LABEL = 8,
    VST_BUFFER_SIZE_CATEGORY_LABEL = 24,
    VST_BUFFER_SIZE_PROGRAM_NAME = 24,
    VST_BUFFER_SIZE_EFFECT_NAME = 32,
    VST_BUFFER_SIZE_PARAM_LONG_NAME = 64,
    VST_BUFFER_SIZE_PRODUCT_NAME = 64,
    VST_BUFFER_SIZE_SPEAKER_NAME = 64,
    VST_BUFFER_SIZE_STREAM_NAME = 64,
    VST_BUFFER_SIZE_VENDOR_NAME = 64,
}; // This is an enum because I started to dislike macros.
 
/** Valid VST 1.x and 2.x versions
 * The format is either a single digit or four digits in Base10 format.
 *
 * @code{.c}
 * // Converts a Base10 VST version to a uint8_t[4] representation of the version.
 * uint32_t expand_vst_version(uint32_t v) {
 *   if (v < 10) { //
 *     return v << 24;
 *   }
 *   uint8_t major = v / 1000;
 *   uint8_t minor = (v / 100) % 10;
 *   uint8_t revision = (v / 10) % 10;
 *   uint8_t patch = v % 10;
 *   return (major << 24) | (minor << 16) | (revision << 8) | patch;
 * }
 * @endcode
 */
enum VST_VERSION {
    VST_VERSION_1       = 0, // Anything before 2.0, used by official plug-ins.
    VST_VERSION_1_0_0_0 = 1000, // 1.0, used by some third-party plug-ins.
    VST_VERSION_1_1_0_0 = 1100, // 1.1, used by some third-party plug-ins.
    VST_VERSION_2       = 2, // 2.0, used by official plug-ins.
    VST_VERSION_2_0_0_0 = 2000, // 2.0, used by some third-party plug-ins.
    VST_VERSION_2_1_0_0 = 2100, // 2.1
    VST_VERSION_2_2_0_0 = 2200, // 2.2
    VST_VERSION_2_3_0_0 = 2300, // 2.3
    VST_VERSION_2_4_0_0 = 2400, // 2.4
 
    // Pad to force 32-bit number.
    _VST_VERSION_PAD = 0xFFFFFFFFul,
};
 
/** Window/Editor Rectangle.
 * The order is counter-clockwise starting from the top.
 */
struct vst_rect_t {
    int16_t top;
    int16_t left;
    int16_t bottom;
    int16_t right;
};
 
/** Flags for parameters.
 * @sa vst_parameter_properties_t
 */
enum VST_PARAMETER_FLAG {
    /** Parameter is an on/off switch.
     *
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    VST_PARAMETER_FLAG_1ls0 = 1 << 0,
    /** @sa VST_PARAMETER_FLAG_1ls0 */
    VST_PARAMETER_FLAG_SWITCH = 1,
 
    /** Parameter limits are set as integers.
     *
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    VST_PARAMETER_FLAG_1ls1 = 1 << 1,
    /** @sa VST_PARAMETER_FLAG_1ls1 */
    VST_PARAMETER_FLAG_INTEGER_LIMITS = 1 << 1,
 
    /** Parameter uses float steps.
     *
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    VST_PARAMETER_FLAG_1ls2 = 1 << 2,
    /** @sa VST_PARAMETER_FLAG_1ls2 */
    VST_PARAMETER_FLAG_STEP_FLOAT = 1 << 2,
 
    /** Parameter uses integer steps.
     *
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    VST_PARAMETER_FLAG_1ls3 = 1 << 3,
    /** @sa VST_PARAMETER_FLAG_1ls3 */
    VST_PARAMETER_FLAG_STEP_INT = 1 << 3,
 
    /** Parameter has an display order index for the default editor.
     *
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    VST_PARAMETER_FLAG_1ls4 = 1 << 4,
    /** @sa VST_PARAMETER_FLAG_1ls4 */
    VST_PARAMETER_FLAG_INDEX = 1 << 4,
 
    /** Parameter has a category for the default editor.
     *
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    VST_PARAMETER_FLAG_1ls5 = 1 << 5,
    /** @sa VST_PARAMETER_FLAG_1ls5 */
    VST_PARAMETER_FLAG_CATEGORY = 1 << 5,
 
    /** Parameter can be gradually increased/decreased.
     *
     * @sa VST_EFFECT_OPCODE_PARAM_IS_AUTOMATABLE
     */
    VST_PARAMETER_FLAG_1ls6 = 1 << 6,
    /** @sa VST_PARAMETER_FLAG_1ls6 */
    VST_PARAMETER_FLAG_RAMPING = 1 << 6,
 
    _VST_PARAMETER_FLAG_PAD     = 0xFFFFFFFFul,
};
 
/** Information about a parameter.
 *
 * @important Many VST hosts and plug-ins expect their parameters to be normalized within 0.0 and 1.0.
 */
struct vst_parameter_properties_t {
    /** Float Step value
     *
     * Some hosts and plug-ins expect this to be within 0 and 1.0.
     *
     * @note Requires @ref VST_PARAMETER_FLAG_STEP_FLOAT to be set.
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    float step_f32;
 
    /** Float small step value
     * This is used for "tiny" changes.
     *
     * Some hosts and plug-ins expect this to be within 0 and 1.0.
     *
     * @note Requires @ref VST_PARAMETER_FLAG_STEP_FLOAT to be set.
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    float step_small_f32;
 
    /** Float large step value
     * This is used for "huge" changes.
     *
     * Some hosts and plug-ins expect this to be within 0 and 1.0.
     *
     * @note Requires @ref VST_PARAMETER_FLAG_STEP_FLOAT to be set.
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    float step_large_f32;
 
    /** Human-readable name for this parameter.
     *
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    char name[VST_BUFFER_SIZE_PARAM_LONG_NAME];
 
    /** Parameter Flags
     *
     * Any combination of @ref VST_PARAMETER_FLAG.
     */
    uint32_t flags;
 
    /** Minimum Integer value
     *
     * @note Requires @ref VST_PARAMETER_FLAG_INTEGER_LIMITS to be set.
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    int32_t  min_value_i32;
 
    /** Maximum Integer value
     *
     * @note Requires @ref VST_PARAMETER_FLAG_INTEGER_LIMITS to be set.
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    int32_t  max_value_i32;
 
    /** Integer Step value
     *
     * @note Requires @ref VST_PARAMETER_FLAG_STEP_INT to be set.
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    int32_t  step_i32;
 
    /** Short Human-readable label for this parameter.
     *
     * I have no idea why this exists?
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    char label[VST_BUFFER_SIZE_PARAM_LABEL];
 
    /** Display order index.
     *
     * @note Requires @ref VST_PARAMETER_FLAG_INDEX to be set.
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    uint16_t index;
 
    /** Category index
     *
     * Must either be 0 for no category, or any number increasing from 1 onwards.
     *
     * @note Requires @ref VST_PARAMETER_FLAG_CATEGORY to be set.
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    uint16_t category;
 
    /** How many parameters are in this category?
     * This allows the plug-in to specify the same category multiple times.
     *
     * @note Requires @ref VST_PARAMETER_FLAG_CATEGORY to be set.
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    uint16_t num_parameters_in_category;
 
    uint16_t _unknown_00; // Must be set to 0.
 
    /** Human-readable name for the category this parameter is in.
     *
     * @note Requires @ref VST_PARAMETER_FLAG_CATEGORY to be set.
     * @note Ignored if @ref VST_EFFECT_FLAG_EDITOR is set.
     */
    char category_label[VST_BUFFER_SIZE_CATEGORY_LABEL];
 
    char _reserved[16]; // Reserved for future expansions?
};
 
enum VST_SPEAKER_TYPE {
    // Default Types
    VST_SPEAKER_TYPE_MONO       = 0,
    VST_SPEAKER_TYPE_LEFT       = 1,
    VST_SPEAKER_TYPE_RIGHT      = 2,
    VST_SPEAKER_TYPE_CENTER     = 3,
    VST_SPEAKER_TYPE_LFE        = 4,
    VST_SPEAKER_TYPE_LEFT_REAR  = 5, // Rear/Surround Left
    VST_SPEAKER_TYPE_RIGHT_REAR = 6, // Rear/Surround Right
    // 7
    // 8
    // 9
    VST_SPEAKER_TYPE_LEFT_SIDE  = 10, // Side Left
    VST_SPEAKER_TYPE_RIGHT_SIDE = 11, // Side Right
    // 12
    // 13
    // 14
    // 15
    // ...
 
    // User Types (seen rarely, but never exceeds -32)
    VST_SPEAKER_TYPE_USER_32 = -32,
    VST_SPEAKER_TYPE_USER_31,
    VST_SPEAKER_TYPE_USER_30,
    VST_SPEAKER_TYPE_USER_29,
    VST_SPEAKER_TYPE_USER_28,
    VST_SPEAKER_TYPE_USER_27,
    VST_SPEAKER_TYPE_USER_26,
    VST_SPEAKER_TYPE_USER_25,
    VST_SPEAKER_TYPE_USER_24,
    VST_SPEAKER_TYPE_USER_23,
    VST_SPEAKER_TYPE_USER_22,
    VST_SPEAKER_TYPE_USER_21,
    VST_SPEAKER_TYPE_USER_20,
    VST_SPEAKER_TYPE_USER_19,
    VST_SPEAKER_TYPE_USER_18,
    VST_SPEAKER_TYPE_USER_17,
    VST_SPEAKER_TYPE_USER_16,
    VST_SPEAKER_TYPE_USER_15,
    VST_SPEAKER_TYPE_USER_14,
    VST_SPEAKER_TYPE_USER_13,
    VST_SPEAKER_TYPE_USER_12,
    VST_SPEAKER_TYPE_USER_11,
    VST_SPEAKER_TYPE_USER_10,
    VST_SPEAKER_TYPE_USER_09,
    VST_SPEAKER_TYPE_USER_08,
    VST_SPEAKER_TYPE_USER_07,
    VST_SPEAKER_TYPE_USER_06,
    VST_SPEAKER_TYPE_USER_05,
    VST_SPEAKER_TYPE_USER_04,
    VST_SPEAKER_TYPE_USER_03,
    VST_SPEAKER_TYPE_USER_02,
    VST_SPEAKER_TYPE_USER_01,
 
 
    // Pad to force 32-bit number.
    _VST_SPEAKER_TYPE_PAD = 0xFFFFFFFFul,
};
 
struct vst_speaker_properties_t {
    /** Azimuth in Radians
     * Range: -PI (Left) through 0.0 (Right) to PI (Left)
     *
     * @note Must be 10.0 if this is a LFE.
     */
    float azimuth;
 
    /** Altitude in Radians
     * Range: -PI/2 (Bottom) to PI/2 (Top)
     *
     * @note Must be 10.0 if this is a LFE.
     */
    float altitude;
 
    /** Distance in Meters
     * range: 0 to +-Infinity
     *
     * @note Must be 0.0 if this is a LFE.
     */
    float distance;
 
    float _unknown_00; // Must be set to 0
 
    /** Human readable name for this speaker.
     *
     * Some hosts will behave weird if you use "L", "R", "C", "Ls", "Rs", "Lc", "Rc", "LFE", "Lfe", "Sl", "Sr", "Cs",
     * and other 2 to 3 letter short codes. Best not to use those if you like your plug-in in a not-crashy state.
     */
    char name[VST_BUFFER_SIZE_SPEAKER_NAME];
 
    /** The type of the speaker
     *
     * See VST_SPEAKER_TYPE
     *
     * If the above is one of those short codes some host seems to overwrite this with their own. Memory safety is
     * optional apparently.
     */
    int32_t type;
 
    uint8_t _reserved[28]; // Reserved for future expansions?
};
 
enum VST_SPEAKER_ARRANGEMENT_TYPE {
    /** Custom speaker arrangement.
     *
     * Accidentally discovered through random testing.
     */
    VST_SPEAKER_ARRANGEMENT_TYPE_CUSTOM = -2,
 
    /** Unknown/Empty speaker layout.
     */
    VST_SPEAKER_ARRANGEMENT_TYPE_UNKNOWN = -1,
 
    /** Mono
     */
    VST_SPEAKER_ARRANGEMENT_TYPE_MONO = 0x00,
 
    /** Stereo
     */
    VST_SPEAKER_ARRANGEMENT_TYPE_STEREO = 0x01,
 
    /** Quadraphonic
     */
    VST_SPEAKER_ARRANGEMENT_TYPE_4_0 = 0x0B,
 
    /** 5.0 (Old Surround)
     *
     * L, R, C, RL, RR
     */
    VST_SPEAKER_ARRANGEMENT_TYPE_5_0 = 0x0E,
 
    /** 5.1 (Old Surround)
     *
     * L, R, C, LFE, RL, RR
     */
    VST_SPEAKER_ARRANGEMENT_TYPE_5_1 = 0x0F,
 
    /** 7.1 (Full Surround)
     *
     * L, R, C, LFE, SL, SR, RL, RR
     */
    VST_SPEAKER_ARRANGEMENT_TYPE_7_1 = 0x17,
 
    // Pad to force 32-bit number.
    _VST_SPEAKER_ARRANGEMENT_TYPE_PAD = 0xFFFFFFFFul,
};
 
struct vst_speaker_arrangement_t {
    int32_t type; // See VST_SPEAKER_ARRANGEMENT_TYPE
    int32_t channels; // Number of channels in this arrangement.
    struct vst_speaker_properties_t speakers[VST_MAX_CHANNELS]; // Array of speaker properties, actual size defined by channels.
};
 
enum VST_STREAM_FLAG {
    /** Ignored?
     */
    VST_STREAM_FLAG_1ls0 = 1 << 0,
 
    /** Stream is in Stereo
     *
     * Can't be used with VST_STREAM_FLAG_USE_TYPE.
     */
    VST_STREAM_FLAG_1ls1 = 1 << 1,
    VST_STREAM_FLAG_STEREO = 1 << 1,
 
    /** Stream is defined by VST_SPEAKER_ARRANGEMENT_TYPE
     *
     * Can't be used with VST_STREAM_FLAG_STEREO.
     */
    VST_STREAM_FLAG_1ls2 = 1 << 2,
    VST_STREAM_FLAG_USE_TYPE = 1 << 2,
};
 
struct vst_stream_properties_t {
    /** Human-readable name for this stream.
     */
    char name[VST_BUFFER_SIZE_STREAM_NAME];
 
    /** Stream flags
     * Any combination of VST_STREAM_FLAG
     */
    int32_t flags;
 
    /** Stream arrangement (optional)
     * See VST_SPEAKER_ARRANGEMENT_TYPE
     */
    int32_t type;
 
    /** Human-readable label for this stream.
     */
    char label[VST_BUFFER_SIZE_STREAM_LABEL];
 
    uint8_t _reserved[48]; // 48 bytes of uninitialized data, always.
};
 
//------------------------------------------------------------------------------------------------------------------------
// VST Host related Things
//------------------------------------------------------------------------------------------------------------------------
 
struct vst_effect_t; // Pre-define vst_effect_t so we can use it below.
 
/** Plug-in to Host Op-Codes
 * These Op-Codes are emitted by the plug-in and the host _may_ handle them or return 0 (false).
 * We have no guarantees about anything actually happening.
 */
enum VST_HOST_OPCODE {
    /** Update automation for a given Parameter
     *
     * Must be used to notify the host that the parameter was changed by the user if a custom editor is used.
     *
     * @param p_int1 Parameter Index
     * @param p_float Parameter Value
     * @return Expected to return... something.
     */
    VST_HOST_OPCODE_00 = 0x00, // cb(vst, 0x00, ?, 0, 0);
    /** @sa VST_HOST_OPCODE_00 */
    VST_HOST_OPCODE_AUTOMATE = 0x00,
    /** @sa VST_HOST_OPCODE_00 */
    VST_HOST_OPCODE_PARAM_UPDATE = 0x00,
 
    /** Retrieve the Hosts VST Version.
     *
     * @return See VST_VERSION enumeration.
     */
    VST_HOST_OPCODE_01 = 0x01,
    /** @sa VST_HOST_OPCODE_01 */
    VST_HOST_OPCODE_VST_VERSION = 0x01,
 
    /** Get the currently selected effect id in container plug-ins.
     *
     * Used in combination with @ref VST_EFFECT_CATEGORY_CONTAINER.
     *
     * @return The currently selected unique effect id in this container.
     */
    VST_HOST_OPCODE_02 = 0x02, // bool cb(0, 0x02, 0, 0, 0);
    /** @sa VST_HOST_OPCODE_02 */
    VST_HOST_OPCODE_CURRENT_EFFECT_ID = 0x02,
 
    /** Some sort of idle keep-alive?
     *
     * Seems to be called only in editor windows when a modal popup is present.
     */
    VST_HOST_OPCODE_03 = 0x03,
    /** @sa VST_HOST_OPCODE_03 */
    VST_HOST_OPCODE_KEEPALIVE_OR_IDLE = 0x03,
 
    VST_HOST_OPCODE_04 = 0x04,
 
    //--------------------------------------------------------------------------------
    // VST 2.x starts here.
    //--------------------------------------------------------------------------------
 
    VST_HOST_OPCODE_05 = 0x05,
 
    VST_HOST_OPCODE_06 = 0x06,
 
    VST_HOST_OPCODE_07 = 0x07,
 
    VST_HOST_OPCODE_08 = 0x08,
 
    VST_HOST_OPCODE_09 = 0x09,
 
    VST_HOST_OPCODE_0A = 0x0A,
 
    VST_HOST_OPCODE_0B = 0x0B,
 
    VST_HOST_OPCODE_0C = 0x0C,
 
    /** Notify the host that numInputs/numOutputs/delay/numParams has changed.
     * Only supported if the host replies @ref VST_STATUS_TRUE to @ref VST_HOST_OPCODE_SUPPORTS query for
     * @ref vst_host_supports_t.acceptIOChanges.
     *
     * @note In VST 2.3 and earlier calling this outside of @ref VST_EFFECT_OPCODE_IDLE may result in a crash.
     * @note In VST 2.3 and later this may only be called while between @ref VST_EFFECT_OPCODE_PROCESS_END and
     *       @ref VST_EFFECT_OPCODE_PROCESS_BEGIN.
     *
     * @return @ref VST_STATUS_TRUE if supported and handled otherwise @ref VST_STATUS_FALSE.
     */
    VST_HOST_OPCODE_0D = 0x0D,
    /** @sa VST_HOST_OPCODE_0D */
    VST_HOST_OPCODE_IO_MODIFIED = 0x0D,
 
    VST_HOST_OPCODE_0E = 0x0E,
 
    VST_HOST_OPCODE_0F = 0x0F,
 
    VST_HOST_OPCODE_10 = 0x10,
 
    VST_HOST_OPCODE_11 = 0x11,
 
    VST_HOST_OPCODE_12 = 0x12,
 
    VST_HOST_OPCODE_13 = 0x13,
 
    VST_HOST_OPCODE_14 = 0x14,
 
    VST_HOST_OPCODE_15 = 0x15,
 
    VST_HOST_OPCODE_16 = 0x16,
 
    VST_HOST_OPCODE_17 = 0x17,
 
    VST_HOST_OPCODE_18 = 0x18,
 
    VST_HOST_OPCODE_19 = 0x19,
 
    VST_HOST_OPCODE_1A = 0x1A,
 
    VST_HOST_OPCODE_1B = 0x1B,
 
    VST_HOST_OPCODE_1C = 0x1C,
 
    VST_HOST_OPCODE_1D = 0x1D,
 
    VST_HOST_OPCODE_1E = 0x1E,
 
    VST_HOST_OPCODE_1F = 0x1F,
 
    /** Retrieve the vendor name into the ptr buffer.
     *
     * @param p_ptr A zero terminated char buffer of size @ref VST_BUFFER_SIZE_VENDOR_NAME.
     */
    VST_HOST_OPCODE_20 = 0x20,
    /** @sa VST_HOST_OPCODE_20 */
    VST_HOST_OPCODE_VENDOR_NAME = 0x20,
 
    /** Retrieve the product name into the ptr buffer.
     *
     * @param p_ptr A zero terminated char buffer of size @ref VST_BUFFER_SIZE_PRODUCT_NAME.
     */
    VST_HOST_OPCODE_21 = 0x21,
    /** @sa VST_HOST_OPCODE_21 */
    VST_HOST_OPCODE_PRODUCT_NAME = 0x21,
 
    /** Retrieve the vendor version in return value.
     *
     * @return Version.
     */
    VST_HOST_OPCODE_22 = 0x22,
    /** @sa VST_HOST_OPCODE_22 */
    VST_HOST_OPCODE_VENDOR_VERSION = 0x22,
 
    /** User defined OP Code, for custom interaction.
     *
     */
    VST_HOST_OPCODE_23 = 0x23,
    /** @sa VST_HOST_OPCODE_23 */
    VST_HOST_OPCODE_CUSTOM = 0x23,
 
    VST_HOST_OPCODE_24 = 0x24,
 
    /** Check if the host supports a certain feature.
     *
     * @param p_ptr `char[...]` Zero terminated string for which feature we want to support.
     * @return @ref VST_STATUS_TRUE if the feature is supported otherwise @ref VST_STATUS_FALSE.
     */
    VST_HOST_OPCODE_25 = 0x25,
    /** @sa VST_HOST_OPCODE_25 */
    VST_HOST_OPCODE_SUPPORTS = 0x25,
 
    VST_HOST_OPCODE_26 = 0x26,
 
    /** Crash the host if p_ptr isn't nullptr. */
    VST_HOST_OPCODE_27 = 0x27,
 
    /** Crash the host if p_ptr isn't nullptr. */
    VST_HOST_OPCODE_28 = 0x28,
 
    VST_HOST_OPCODE_29 = 0x29,
 
    /** Request an update of the editor window.
     * 
     */
    VST_HOST_OPCODE_2A = 0x2A,
    /** @sa VST_HOST_OPCODE_2A */
    VST_HOST_OPCODE_EDITOR_UPDATE = 0x2A,
 
    /** Notify host that a parameter is being edited.
     *
     * @param p_int1 Parameter index.
     */
    VST_HOST_OPCODE_2B = 0x2B,
    /** @sa VST_HOST_OPCODE_2B */
    VST_HOST_OPCODE_PARAM_START_EDIT = 0x2B,
 
    /** Notify host that parameter is no longer being edited.
     *
     * @param p_int1 Parameter index.
     */
    VST_HOST_OPCODE_2C = 0x2C,
    /** @sa VST_HOST_OPCODE_2C */
    VST_HOST_OPCODE_PARAM_STOP_EDIT = 0x2C,
 
    VST_HOST_OPCODE_2D = 0x2D,
    VST_HOST_OPCODE_2E = 0x2E,
    VST_HOST_OPCODE_2F = 0x2F,
 
    // Highest number of known OPCODE.
    VST_HOST_OPCODE_MAX,
 
    // Pad to force 32-bit number.
    _VST_HOST_OPCODE_PAD = 0xFFFFFFFFul,
};
 
/** Plug-in to Host support checks
 *
 * Provided as `char* p_ptr` in the VST_EFFECT_OPCODE_SUPPORTS op code.
 *
 * Harvested via strings command and just checking what hosts actually responded to.
 */
struct vst_host_supports_t {
    /** Does the host support modifying input/output/params/delay when programs, banks or parameters are changed?
     * This only means that the host supports this inside of @ref VST_EFFECT_OPCODE_IDLE (VST 2.3 or earlier) or outside
     * of a @ref VST_EFFECT_OPCODE_PROCESS_BEGIN and @ref VST_EFFECT_OPCODE_PROCESS_END group.
     *
     * Signals that the host supports the following:
     * - @ref VST_HOST_OPCODE_IO_MODIFIED
     *
     * @return @ref VST_STATUS_TRUE if it supports it.
     */
    const char* acceptIOChanges;
 
    /** Is the host using process begin/end instead of idle?
     * The host may opt to emit @ref VST_EFFECT_OPCODE_IDLE or @ref VST_EFFECT_OPCODE_PROCESS_BEGIN and
     * @ref VST_EFFECT_OPCODE_PROCESS_END when running in VST 2.3 compatibility mode.
     *
     * @sa VST_EFFECT_OPCODE_PROCESS_BEGIN
     * @sa VST_EFFECT_OPCODE_PROCESS_END
     * @sa VST_EFFECT_OPCODE_IDLE
     * @deprecated (VST 2.4) This behavior is the default in VST 2.4 and later.
     * @return @ref VST_STATUS_TRUE if it supports it.
     */
    const char* startStopProcess;
 
    /** Does the host support container plug-ins?
     *
     * Signals that the host and plug-in support the following:
     * - @ref VST_HOST_OPCODE_CURRENT_EFFECT_ID
     * - @ref VST_EFFECT_OPCODE_CONTAINER_NEXT_EFFECT_ID
     *
     * @note Is shell a reference to Windows shell menus?
     *
     * @return @ref VST_STATUS_TRUE if the host supports it _and_ the current plug-in is a container plug-in.
     */
    const char* shellCategory;
 
    const char* sendVstEvents;
    const char* receiveVstEvents;
 
    const char* sendVstMidiEvent;
    const char* receiveVstMidiEvent;
    const char* sendVstMidiEventFlagIsRealtime;
 
    const char* sendVstTimeInfo;
    const char* reportConnectionChanges; // Seems related to speakers?
    const char* sizeWindow;
    const char* offline;
 
    const char* openFileSelector;
    const char* closeFileSelector;
} /** @private */ vst_host_supports = {
    .acceptIOChanges = "acceptIOChanges",
    .startStopProcess = "startStopProcess",
    .shellCategory = "shellCategory",
    .sendVstEvents = "sendVstEvents",
    .receiveVstEvents = "receiveVstEvents",
    .sendVstMidiEvent = "sendVstMidiEvent",
    .receiveVstMidiEvent = "receiveVstMidiEvent",
    .sendVstMidiEventFlagIsRealtime = "sendVstMidiEventFlagIsRealtime",
    .sendVstTimeInfo = "sendVstTimeInfo",
    .reportConnectionChanges = "reportConnectionChanges",
    .sizeWindow = "sizeWindow",
    .offline = "offline",
    .openFileSelector = "openFileSelector",
    .closeFileSelector = "closeFileSelector",
};
 
/** Plug-in to Host callback
 *
 * The plug-in may call this to attempt to change things on the host side. The host side is free to ignore all requests, annoyingly enough.
 *
 * @param opcode See VST_HOST_OPCODE
 * @param p_str Zero terminated string or null on call.
 * @return ?
 */
typedef intptr_t (VST_FUNCTION_INTERFACE *vst_host_callback_t)(struct vst_effect_t* plugin, int32_t opcode, int32_t p_int1, int64_t p_int2, const char* p_str, float p_float);
 
//------------------------------------------------------------------------------------------------------------------------
// VST Plug-in/Effect related Things
//------------------------------------------------------------------------------------------------------------------------
 
/** Magic Number identifying a VST 2.x plug-in structure
 *
 * @sa vst_effect_t.magic_numer
 */
#define VST_MAGICNUMBER VST_FOURCC('V', 's', 't', 'P')
 
/** Default VST 2.x Sample Rate
 * All VST 2.x hosts expect you to initialize your plug-in to these default values.
 *
 * @sa VST_EFFECT_OPCODE_SET_SAMPLE_RATE
 */
#define VST_DEFAULT_SAMPLE_RATE 44100.0f
 
/** Default VST 2.x Block Size
 * All VST 2.x hosts expect you to initialize your plug-in to these default values.
 *
 * @sa VST_EFFECT_OPCODE_SET_BLOCK_SIZE
 */
#define VST_DEFAULT_BLOCK_SIZE 1024
 
/** Plug-in Categories
 * Pre-defined category grouping that also affect host behavior when handling the plug-in. This is not just a UI/UX
 * thing, it actually affects what plug-ins can do, so place your plug-in into the correct category.
 *
 */
enum VST_EFFECT_CATEGORY {
    VST_EFFECT_CATEGORY_UNCATEGORIZED = 0x00,
 
    /** Generic Effects
     * Examples: Distortion, Pitch Shift, ...
     *
     * Supports: Delay (Optional), Tail Samples, MIDI
     */
    VST_EFFECT_CATEGORY_01            = 0x01,
    /** @sa VST_EFFECT_CATEGORY_01 */
    VST_EFFECT_CATEGORY_EFFECT        = 0x01,
 
    /** Instruments
     * Examples: Instruments, Synths, Samplers, ...
     *
     * Supports: Delay (Optional), Tail Samples, MIDI
     */
    VST_EFFECT_CATEGORY_02            = 0x02,
    /** @sa VST_EFFECT_CATEGORY_02 */
    VST_EFFECT_CATEGORY_INSTRUMENT    = 0x02,
 
    /** Metering
     * Examples: Loudness Meters, Volume Analysis, ...
     *
     * Supports: Tail Samples, MIDI
     * @note Delay causes crashes in some hosts. Fun.
     */
    VST_EFFECT_CATEGORY_03            = 0x03,
    /** @sa VST_EFFECT_CATEGORY_03 */
    VST_EFFECT_CATEGORY_METERING      = 0x03,
 
    /** Mastering
     * Examples: Compressors, Limiters, ...
     *
     * Supports: Delay, Tail Samples (optional), MIDI
     */
    VST_EFFECT_CATEGORY_04            = 0x04,
    /** @sa VST_EFFECT_CATEGORY_04 */
    VST_EFFECT_CATEGORY_MASTERING     = 0x04,
 
    /** Spatializers
     * Examples: Channel Panning, Expanders, ...
     *
     * Supports: Tail Samples (optional), MIDI
     */
    VST_EFFECT_CATEGORY_05            = 0x05,
    /** @sa VST_EFFECT_CATEGORY_05 */
    VST_EFFECT_CATEGORY_SPATIAL       = 0x05,
 
    /** Delay/Echo
     * Examples: Echo, Reverb, Room Simulation, Delay, ...
     *
     * Supports: Delay, Tail Samples, MIDI
     */
    VST_EFFECT_CATEGORY_06            = 0x06,
    /** @sa VST_EFFECT_CATEGORY_06 */
    VST_EFFECT_CATEGORY_DELAY_OR_ECHO = 0x06,
 
    VST_EFFECT_CATEGORY_07            = 0x07,
 
    /** Restoration
     * Examples: Noise Filtering, Upsamplers, ...
     *
     * Supports: Delay, Tail Samples, MIDI
     * @note Some DAWs allocate additional processing time to these.
     */
    VST_EFFECT_CATEGORY_08            = 0x08,
    /** @sa VST_EFFECT_CATEGORY_08 */
    VST_EFFECT_CATEGORY_RESTORATION   = 0x08,
 
    /** Offline Processing
     * Examples: Nothing
     * Supports: Nothing
     */
    VST_EFFECT_CATEGORY_09            = 0x09,
    /** @sa VST_EFFECT_CATEGORY_09 */
    VST_EFFECT_CATEGORY_OFFLINE       = 0x09, // Offline Processing VST? Seems to receive all audio data prior to playback.
 
    /** Container Plug-in
     * This plug-in contains multiple effects in one and requires special handling on both sides.
     *
     * Host handling:
     * @code{.c}
     * uint32_t current_select_id;
     *
     * // ... in intptr_t vst_host_callback(vst_effect_t* plugin, VST_HOST_OPCODE opcode, ...)
     *     case VST_HOST_OPCODE_SUPPORTS: {
     *       char* text = (char*)p_ptr;
     *       // The plug-in may ask the host if it even supports containers at all and changes behavior if we don't.
     *       if (text && strcmp(text, vst_host_supports.shellCategory) == 0) {
     *         return VST_STATUS_TRUE;
     *       }
     *     }
     *     case VST_HOST_OPCODE_CURRENT_EFFECT_ID:
     *       return current_selected_id;
     * // ...
     *
     * // ... in whatever you use to load plug-ins ...
     *   current_select_id;
     *   vst_effect_t* plugin = plugin_main(&vst_host_callback);
     *   int32_t plugin_category = plugin->control(plugin, VST_EFFECT_OPCODE_CATEGORY, 0, 0, 0, 0)
     *   if (plugin_category == VST_EFFECT_CATEGORY_CONTAINER) {
     *     char effect_name[VST_BUFFER_SIZE_EFFECT_NAME] effect_name;
     *     int32_t effect_id;
     *     // Iterate over all contained effects.
     *     while ((effect_id = plugin->control(plugin, VST_EFFECT_OPCODE_CONTAINER_NEXT_EFFECT_ID, 0, 0, effect_name, 0)) != 0) {
     *       // Contained effects must be named as far as I can tell.
     *       if (effect_name[0] != 0) {
     *          // Do some logic that does the necessary things to list these in the host.
     *       }
     *     }
     *   } else {
     *     // Do things to list only this plugin in the host.
     *   }
     * // ...
     * @endcode
     *
     * Plug-in handling:
     * @code{.c}
     * // ... in vst_effect for the container
     *   size_t current_effect_idx;
     *   int32_t effect_list[] = {
     *     // ... list of effect ids.
     *   }
     * // ... in control(...)
     *     case VST_EFFECT_OPCODE_CONTAINER_NEXT_EFFECT_ID:
     *       // Make sure current_effect_idx doesn't exceed the maximum.
     *       if (current_effect_idx > ARRAYSIZEOF(effect_list)) {
     *         current_effect_idx;
     *         return 0;
     *       }
     *       // Some code that turns effect indices into names to store into p_ptr.
     *       return effect_list[current_effect_idx++]; // Return the effect id.
     * // ...
     *
     * VST_ENTRYPOINT {
     *   // Ensure the host VST 2.x compatible.
     *   int32_t vst_version = callback(nullptr, VST_HOST_OPCODE_VST_VERSION, 0, 0, 0, 0);
     *   if (vst_version == 0) {
     *     return 0; // It's not so we exit early.
     *   }
     *
     *   // Check if the host wants
     *   int32_t effect_id = callback(nullptr, VST_HOST_OPCODE_CURRENT_EFFECT_ID, 0, 0, 0);
     *   if (effect_id == 0) {
     *     // ... logic specific to making the container.
     *     return new vst_container_effect();
     *   } else {
     *     // ... logic specific to make sub effects
     *     return new vst_sub_effect();
     *   }
     * }
     *
     * // ...
     * @endcode
     */
    VST_EFFECT_CATEGORY_0A            = 0x0A,
    /** @sa VST_EFFECT_CATEGORY_0A */
    VST_EFFECT_CATEGORY_CONTAINER     = 0x0A,
 
    /** Waveform Generators
     * Examples: Sine Wave Generator, ...
     * Supports: Delay, Tail Samples
     *
     * I don't know why this exists, there's only one plug-in that has it and all it does is generate a 400hz sine wave.
     *
     * @sa VST_EFFECT_CATEGORY_INSTRUMENT
     */
    VST_EFFECT_CATEGORY_0B            = 0x0B,
    /** @sa VST_EFFECT_CATEGORY_0B */
    VST_EFFECT_CATEGORY_WAVEGENERATOR = 0x0B,
 
    /** @private */
    VST_EFFECT_CATEGORY_MAX, // Not part of specification, marks maximum category.
 
    /** @private */
    _VST_EFFECT_CATEGORY_PAD = 0xFFFFFFFFul,
};
 
/** Effect Flags
 */
enum VST_EFFECT_FLAG {
    /** Effect provides a custom editor.
     * The host will not provide a generic editor interface and expects @ref VST_EFFECT_OPCODE_EDITOR_OPEN and
     * @ref VST_EFFECT_OPCODE_EDITOR_CLOSE to work as expected. We are in charge of notifying the host about various
     * things like which parameter is in focus and stuff.
     *
     * @sa VST_EFFECT_OPCODE_EDITOR_GET_RECT
     * @sa VST_EFFECT_OPCODE_EDITOR_OPEN
     * @sa VST_EFFECT_OPCODE_EDITOR_CLOSE
     * @sa VST_EFFECT_OPCODE_EDITOR_DRAW
     * @sa VST_EFFECT_OPCODE_EDITOR_MOUSE
     * @sa VST_EFFECT_OPCODE_EDITOR_KEYBOARD
     * @sa VST_EFFECT_OPCODE_EDITOR_KEEP_ALIVE
     * @sa VST_EFFECT_OPCODE_EDITOR_VKEY_DOWN
     * @sa VST_EFFECT_OPCODE_EDITOR_VKEY_UP
     * @sa VST_HOST_OPCODE_EDITOR_UPDATE
     * @sa VST_HOST_OPCODE_PARAM_START_EDIT
     * @sa VST_HOST_OPCODE_PARAM_STOP_EDIT
     * @sa VST_HOST_OPCODE_PARAM_UPDATE
     */
    VST_EFFECT_FLAG_1ls0 = 1 << 0,
    /** @sa VST_EFFECT_FLAG_1ls0 */
    VST_EFFECT_FLAG_EDITOR = 1 << 0,
 
    //1 << 1,
    //1 << 2, // Only seen when the plug-in responds to VST_EFFECT_OPCODE_09. Seems to be ignored by hosts entirely.
    //1 << 3, // Only seen when the plug-in behaves differently in mono mode. Seems to be ignored by hosts entirely.
 
    /** Effect uses process_float.
     *
     * @sa vst_effect_t.process_float
     * @sa vst_effect_process_float_t
     * @deprecated (VST 2.4) Must be set in VST 2.4 and later or the host should fail to load the plug-in.
     */
    VST_EFFECT_FLAG_1ls4 = 1 << 4,
    /** @sa VST_EFFECT_FLAG_1ls4 */
    VST_EFFECT_FLAG_SUPPORTS_FLOAT = 1 << 4,
 
    /** Effect supports saving/loading programs/banks from unformatted chunk data.
     * When not set some sort of format is expected that I've yet to decipher.
     *
     * @sa VST_EFFECT_OPCODE_GET_CHUNK_DATA
     * @sa VST_EFFECT_OPCODE_SET_CHUNK_DATA
     */
    VST_EFFECT_FLAG_1ls5 = 1 << 5,
    /** @sa VST_EFFECT_FLAG_1ls5 */
    VST_EFFECT_FLAG_CHUNKS = 1 << 5,
 
    //1 << 6,
    //1 << 7,
 
    /** Effect is an Instrument/Generator
     *
     * This must be set in addition to @ref VST_EFFECT_CATEGORY_INSTRUMENT otherwise instruments don't work right.
     * @note (VST 2.x) Flag is new to VST 2.x and later.
     */
    VST_EFFECT_FLAG_1ls8 = 1 << 8,
    /** @sa VST_EFFECT_FLAG_1ls8 */
    VST_EFFECT_FLAG_INSTRUMENT = 1 << 8,
 
    /** Effect does not produce tail samples when the input is silent.
     *
     * Not to be confused with choosing to tell the host there is no tail.
     * @sa VST_EFFECT_OPCODE_GET_TAIL_SAMPLES
     * @note (VST 2.x) Flag is new to VST 2.x and later.
     */
    VST_EFFECT_FLAG_1ls9 = 1 << 9,
    /** @sa VST_EFFECT_FLAG_1ls9 */
    VST_EFFECT_FLAG_SILENT_TAIL = 1 << 9,
 
    //1 << 10,
    //1 << 11,
 
    /** Effect supports process_double.
     * The host can freely choose between process_float and process_double as required.
     *
     * @note (VST 2.4) Available in VST 2.4 and later only.
     * @sa vst_effect_t.process_double
     * @sa vst_effect_process_double_t
     */
    VST_EFFECT_FLAG_1ls12 = 1 << 12,
    /** @sa VST_EFFECT_FLAG_1ls12 */
    VST_EFFECT_FLAG_SUPPORTS_DOUBLE = 1 << 12,
};
 
/** Host to Plug-in Op-Codes
 * These Op-Codes are emitted by the host and we must either handle them or return 0 (false).
 */
enum VST_EFFECT_OPCODE {
    /** Create/Initialize the effect (if it has not been created already).
     *
     * @return Always 0.
     */
    VST_EFFECT_OPCODE_00         = 0x00,
    /** @sa VST_EFFECT_OPCODE_00 */
    VST_EFFECT_OPCODE_CREATE     = 0x00,
    /** @sa VST_EFFECT_OPCODE_00 */
    VST_EFFECT_OPCODE_INITIALIZE = 0x00,
 
    /** Destroy the effect (if there is any) and free its memory.
     *
     * This should destroy the actual object created by VST_ENTRYPOINT.
     *
     * @return Always 0.
     */
    VST_EFFECT_OPCODE_01      = 0x01,
    /** @sa VST_EFFECT_OPCODE_01 */
    VST_EFFECT_OPCODE_DESTROY = 0x01,
 
    /** Set which program number is currently select.
     *
     * @param p_int2 The program number to set. Can be negative for some reason.
     */
    VST_EFFECT_OPCODE_02 = 0x02,
    /** @sa VST_EFFECT_OPCODE_02 */
    VST_EFFECT_OPCODE_SET_PROGRAM = 0x02,
    /** @sa VST_EFFECT_OPCODE_02 */
    VST_EFFECT_OPCODE_PROGRAM_SET = 0x02,
 
    /** Get currently selected program number.
     *
     * @return The currently set program number. Can be negative for some reason.
     */
    VST_EFFECT_OPCODE_03 = 0x03,
    /** @sa VST_EFFECT_OPCODE_03 */
    VST_EFFECT_OPCODE_GET_PROGRAM = 0x03,
    /** @sa VST_EFFECT_OPCODE_03 */
    VST_EFFECT_OPCODE_PROGRAM_GET = 0x03,
 
    /** Set the name of the currently selected program.
     *
     * @param p_ptr `const char[VST_BUFFER_SIZE_PROGRAM_NAME]` Zero terminated string.
     */
    VST_EFFECT_OPCODE_04 = 0x04,
    /** @sa VST_EFFECT_OPCODE_04 */
    VST_EFFECT_OPCODE_SET_PROGRAM_NAME = 0x04,
    /** @sa VST_EFFECT_OPCODE_04 */
    VST_EFFECT_OPCODE_PROGRAM_SET_NAME = 0x04,
 
    /** Get the name of the currently selected program.
     *
     * @param p_ptr `char[VST_BUFFER_SIZE_PROGRAM_NAME]` Zero terminated string.
     */
    VST_EFFECT_OPCODE_05 = 0x05,
    /** @sa VST_EFFECT_OPCODE_05 */
    VST_EFFECT_OPCODE_GET_PROGRAM_NAME = 0x05,
    /** @sa VST_EFFECT_OPCODE_05 */
    VST_EFFECT_OPCODE_PROGRAM_GET_NAME = 0x05,
 
    /** Get the value? label for the parameter.
     *
     * @param p_int1 Parameter index.
     * @param p_ptr 'char[VST_BUFFER_SIZE_PARAM_LABEL]' Zero terminated string.
     * @return 0 on success, 1 on failure.
     */
    VST_EFFECT_OPCODE_06             = 0x06,
    /** @sa VST_EFFECT_OPCODE_06 */
    VST_EFFECT_OPCODE_PARAM_GETLABEL = 0x06,
    /** @sa VST_EFFECT_OPCODE_06 */
    VST_EFFECT_OPCODE_PARAM_GET_LABEL = 0x06,
    /** @sa VST_EFFECT_OPCODE_06 */
    VST_EFFECT_OPCODE_PARAM_LABEL = 0x06,
 
    /** Get the string representing the value for the parameter.
     *
     * @param p_int1 Parameter index.
     * @param p_ptr 'char[VST_BUFFER_SIZE_PARAM_VALUE]' Zero terminated string.
     * @return 0 on success, 1 on failure.
     */
    VST_EFFECT_OPCODE_07             = 0x07,
    /** @sa VST_EFFECT_OPCODE_07 */
    VST_EFFECT_OPCODE_PARAM_GETVALUE = 0x07,
    /** @sa VST_EFFECT_OPCODE_07 */
    VST_EFFECT_OPCODE_PARAM_GET_VALUE = 0x07,
    /** @sa VST_EFFECT_OPCODE_07 */
    VST_EFFECT_OPCODE_PARAM_VALUE = 0x07,
    /** @sa VST_EFFECT_OPCODE_07 */
    VST_EFFECT_OPCODE_PARAM_VALUE_TO_STRING = 0x07,
 
    /** Get the name for the parameter.
     *
     * @param p_int1 Parameter index.
     * @param p_ptr 'char[VST_BUFFER_SIZE_PARAM_NAME]' Zero terminated string.
     * @return 0 on success, 1 on failure.
     */
    VST_EFFECT_OPCODE_08            = 0x08,
    /** @sa VST_EFFECT_OPCODE_08 */
    VST_EFFECT_OPCODE_PARAM_GETNAME = 0x08,
    /** @sa VST_EFFECT_OPCODE_08 */
    VST_EFFECT_OPCODE_PARAM_GET_NAME = 0x08,
    /** @sa VST_EFFECT_OPCODE_08 */
    VST_EFFECT_OPCODE_PARAM_NAME = 0x08,
 
    /**
     *
     * @deprecated: (VST 2.3+) Not used in VST 2.3 or later.
     */
    VST_EFFECT_OPCODE_09 = 0x09,
 
    /** Set the new sample rate for the plugin to use.
     *
     * @param p_float New sample rate as a float (double on 64-bit because register upgrades).
     */
    VST_EFFECT_OPCODE_0A              = 0x0A,
    /** @sa VST_EFFECT_OPCODE_0A */
    VST_EFFECT_OPCODE_SETSAMPLERATE   = 0x0A,
    /** @sa VST_EFFECT_OPCODE_0A */
    VST_EFFECT_OPCODE_SET_SAMPLE_RATE = 0x0A,
 
    /** Sets the block size, which is the maximum number of samples passed into the effect via process calls.
     *
     * @param p_int2 The maximum number of samples to be passed in.
     */
    VST_EFFECT_OPCODE_0B             = 0x0B,
    /** @sa VST_EFFECT_OPCODE_0B */
    VST_EFFECT_OPCODE_SETBLOCKSIZE   = 0x0B,
    /** @sa VST_EFFECT_OPCODE_0B */
    VST_EFFECT_OPCODE_SET_BLOCK_SIZE = 0x0B,
 
    /** Effect processing should be suspended/paused or resumed/unpaused.
     *
     * Unclear if this is should result in a flush of buffers. In VST 2.3+ this is quite clear as we get process
     * begin/end.
     *
     * @param p_int2 @ref VST_STATUS_FALSE if the effect should suspend processing, @ref VST_STATUS_TRUE if it should
     *               resume.
     */
    VST_EFFECT_OPCODE_0C      = 0x0C,
    /** @sa VST_EFFECT_OPCODE_0C */
    VST_EFFECT_OPCODE_PAUSE_UNPAUSE = 0x0C,
    /** @sa VST_EFFECT_OPCODE_0C */
    VST_EFFECT_OPCODE_SUSPEND_RESUME = 0x0C,
    /** @sa VST_EFFECT_OPCODE_0C */
    VST_EFFECT_OPCODE_SUSPEND = 0x0C,
 
    /** Retrieve the client rect size of the plugins window.
     * If no window has been created, returns the default rect.
     *
     * @param p_ptr Pointer of type 'struct vst_rect_t*'.
     * @return On success, returns 1 and updates p_ptr to the rect. On failure, returns 0.
     */
    VST_EFFECT_OPCODE_0D             = 0x0D,
    /** @sa VST_EFFECT_OPCODE_0D */
    VST_EFFECT_OPCODE_WINDOW_GETRECT = 0x0D,
    /** @sa VST_EFFECT_OPCODE_0D */
    VST_EFFECT_OPCODE_EDITOR_RECT = 0x0D,
    /** @sa VST_EFFECT_OPCODE_0D */
    VST_EFFECT_OPCODE_EDITOR_GET_RECT = 0x0D,
 
    /** Create the window for the plugin.
     *
     * @param p_ptr HWND of the parent window.
     * @return 0 on failure, or HWND on success.
     */
    VST_EFFECT_OPCODE_0E            = 0x0E,
    /** @sa VST_EFFECT_OPCODE_0E */
    VST_EFFECT_OPCODE_WINDOW_CREATE = 0x0E,
    /** @sa VST_EFFECT_OPCODE_0E */
    VST_EFFECT_OPCODE_EDITOR_OPEN = 0x0E,
 
    /** Destroy the plugins window.
     *
     * @return Always 0.
     */
    VST_EFFECT_OPCODE_0F             = 0x0F,
    /** @sa VST_EFFECT_OPCODE_0F */
    VST_EFFECT_OPCODE_WINDOW_DESTROY = 0x0F,
    /** @sa VST_EFFECT_OPCODE_0F */
    VST_EFFECT_OPCODE_EDITOR_CLOSE = 0x0F,
 
    /** Window Draw Event?
     *
     * Ocasionally called simultaneously as WM_DRAW on windows.
     *
     * @note Present in some VST 2.1 or earlier plugins.
     *
     * @note Appears to be Mac OS exclusive.
     *
     * @deprecated (VST 2.4+) Likely deprecated in VST 2.4 and later.
     */
    VST_EFFECT_OPCODE_10 = 0x10,
    /** @sa VST_EFFECT_OPCODE_10 */
    VST_EFFECT_OPCODE_WINDOW_DRAW = 0x10,
    /** @sa VST_EFFECT_OPCODE_10 */
    VST_EFFECT_OPCODE_EDITOR_DRAW = 0x10,
 
    /** Window Mouse Event?
     *
     * Called at the same time mouse events happen.
     *
     * @note Present in some VST 2.1 or earlier plugins.
     *
     * @note Appears to be Mac OS exclusive.
     *
     * @deprecated (VST 2.4+) Likely deprecated in VST 2.4 and later.
     */
    VST_EFFECT_OPCODE_11 = 0x11,
    /** @sa VST_EFFECT_OPCODE_11 */
    VST_EFFECT_OPCODE_WINDOW_MOUSE = 0x11,
    /** @sa VST_EFFECT_OPCODE_11 */
    VST_EFFECT_OPCODE_EDITOR_MOUSE = 0x11,
 
    /** Window Keyboard Event?
     *
     * Called at the same time keyboard events happen.
     *
     * @note Present in some VST 2.1 or earlier plugins.
     *
     * @note Appears to be Mac OS exclusive.
     *
     * @deprecated (VST 2.4+) Likely deprecated in VST 2.4 and later.
     */
    VST_EFFECT_OPCODE_12 = 0x12,
    /** @sa VST_EFFECT_OPCODE_12 */
    VST_EFFECT_OPCODE_WINDOW_KEYBOARD = 0x12,
    /** @sa VST_EFFECT_OPCODE_12 */
    VST_EFFECT_OPCODE_EDITOR_KEYBOARD = 0x12,
 
    /** Window/Editor Idle/Keep-Alive Callback?
     *
     * Does not receive any parameters. Randomly called when nothing happens? Idle/Keep-Alive callback?
     */
    VST_EFFECT_OPCODE_13 = 0x13,
    /** @sa VST_EFFECT_OPCODE_13 */
    VST_EFFECT_OPCODE_EDITOR_KEEP_ALIVE = 0x13,
 
    /** Window Focus Event?
     *
     * Sometimes called when the editor window goes back into focus.
     *
     * @note Present in some VST 2.1 or earlier plugins.
     * @note Appears to be Mac OS exclusive.
     * @deprecated (VST 2.4+) Likely deprecated in VST 2.4 and later.
     */
    VST_EFFECT_OPCODE_14 = 0x14,
 
    /** Window Unfocus Event?
     *
     * Sometimes called when the editor window goes out of focus.
     *
     * @note Present in some VST 2.1 or earlier plugins.
     * @note Appears to be Mac OS exclusive.
     * @deprecated (VST 2.4+) Likely deprecated in VST 2.4 and later.
     */
    VST_EFFECT_OPCODE_15 = 0x15,
 
    /**
     *
     * @note Present in some VST 2.1 or earlier plugins.
     * @important Almost all plug-ins return the @ref VST_FOURCC 'NvEf' (0x4E764566) here.
     * @deprecated (VST 2.4+) Likely deprecated in VST 2.4 and later.
     */
    VST_EFFECT_OPCODE_16 = 0x16,
    /** @sa VST_EFFECT_OPCODE_16 */
    VST_EFFECT_OPCODE_FOURCC = 0x16,
 
    /** Get Chunk Data
     *
     * Save current program or bank state to a buffer.
     * Behavior is different based on the @ref VST_EFFECT_FLAG_CHUNKS flag.
     *
     * @sa VST_EFFECT_FLAG_CHUNKS
     * @param p_int1    0 means Bank, 1 means Program, nothing else used?
     * @param p_ptr     `void**` Pointer to a potential pointer containing your own chunk data.
     * @return          Size of the Chunk Data in bytes.
     */
    VST_EFFECT_OPCODE_17 = 0x17,
    /** @sa VST_EFFECT_OPCODE_17 */
    VST_EFFECT_OPCODE_GET_CHUNK_DATA = 0x17,
 
    /** Set Chunk Data
     *
     * Restore current program or bank state from a buffer.
     * Behavior is different based on the @ref VST_EFFECT_FLAG_CHUNKS flag.
     *
     * @sa VST_EFFECT_FLAG_CHUNKS
     * @param p_int1    0 means Bank, 1 means Program, nothing else used?
     * @param p_int2    Size of the Chunk Data in bytes.
     * @param p_ptr     `void*` Pointer to a buffer containing chunk data.
     */
    VST_EFFECT_OPCODE_18 = 0x18,
    /** @sa VST_EFFECT_OPCODE_18 */
    VST_EFFECT_OPCODE_SET_CHUNK_DATA = 0x18,
 
    //--------------------------------------------------------------------------------
    // VST 2.x starts here.
    //--------------------------------------------------------------------------------
 
    /**
     *
     * Appears to be related to midi and audio events.
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     */
    VST_EFFECT_OPCODE_19 = 0x19,
 
    /** Can the parameter be automated?
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @param p_int1 Index of the parameter.
     * @return 1 if the parameter can be automated, otherwise 0.
     */
    VST_EFFECT_OPCODE_1A                   = 0x1A,
    /** @sa VST_EFFECT_OPCODE_1A */
    VST_EFFECT_OPCODE_PARAM_ISAUTOMATABLE  = 0x1A,
    /** @sa VST_EFFECT_OPCODE_1A */
    VST_EFFECT_OPCODE_PARAM_IS_AUTOMATABLE = 0x1A,
    /** @sa VST_EFFECT_OPCODE_1A */
    VST_EFFECT_OPCODE_PARAM_AUTOMATABLE = 0x1A,
 
    /** Set Parameter value from string representation.
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @param p_int1 Index of the parameter.
     * @param p_ptr `const char*` Zero terminated string representation of the value to set.
     * @return 1 if it worked, otherwise 0.
     */
    VST_EFFECT_OPCODE_1B = 0x1B,
    /** @sa VST_EFFECT_OPCODE_1B */
    VST_EFFECT_OPCODE_PARAM_SET_VALUE = 0x1B,
    /** @sa VST_EFFECT_OPCODE_1B */
    VST_EFFECT_OPCODE_PARAM_VALUE_FROM_STRING = 0x1B,
 
    /**
     *
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     */
    VST_EFFECT_OPCODE_1C = 0x1C,
 
    /**
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @sa VST_EFFECT_OPCODE_05
     */
    VST_EFFECT_OPCODE_1D = 0x1D,
 
    /**
     *
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     */
    VST_EFFECT_OPCODE_1E = 0x1E,
 
    /** Input connected.
     *
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     */
    VST_EFFECT_OPCODE_1F = 0x1F,
 
    /** Input disconnected.
     *
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     */
    VST_EFFECT_OPCODE_20 = 0x20,
 
    /** Retrieve properties for the given input index.
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @param p_int1 Index of the input to get the properties for.
     * @param p_ptr Pointer to @ref vst_stream_properties_t for the selected input provided by the host.
     * @return @ref VST_STATUS_TRUE if p_ptr is updated, @ref VST_STATUS_FALSE otherwise.
     */
    VST_EFFECT_OPCODE_21                   = 0x21,
    /** @sa VST_EFFECT_OPCODE_21 */
    VST_EFFECT_OPCODE_INPUT_GET_PROPERTIES = 0x21,
 
    /** Retrieve properties for the given output index.
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @param p_int1 Index of the output to get the properties for.
     * @param p_ptr Pointer to @ref vst_stream_properties_t for the selected output provided by the host.
     * @return @ref VST_STATUS_TRUE if p_ptr is updated, @ref VST_STATUS_FALSE otherwise.
     */
    VST_EFFECT_OPCODE_22                    = 0x22,
    /** @sa VST_EFFECT_OPCODE_22 */
    VST_EFFECT_OPCODE_OUTPUT_GET_PROPERTIES = 0x22,
 
    /** Retrieve category of this effect.
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @return The category that this effect is in, see @ref VST_EFFECT_CATEGORY.
     */
    VST_EFFECT_OPCODE_23              = 0x23,
    /** @sa VST_EFFECT_OPCODE_23 */
    VST_EFFECT_OPCODE_EFFECT_CATEGORY = 0x23,
    /** @sa VST_EFFECT_OPCODE_23 */
    VST_EFFECT_OPCODE_CATEGORY = 0x23,
 
    /**
     *
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     */
    VST_EFFECT_OPCODE_24 = 0x24,
 
    /**
     *
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     */
    VST_EFFECT_OPCODE_25 = 0x25,
 
    /**
     *
     * Seen in plug-ins with @ref VST_EFFECT_CATEGORY_OFFLINE.
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     */
    VST_EFFECT_OPCODE_26 = 0x26,
 
    /**
     *
     * Seen in plug-ins with @ref VST_EFFECT_CATEGORY_OFFLINE.
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     */
    VST_EFFECT_OPCODE_27 = 0x27,
 
    /**
     *
     * Seen in plug-ins with @ref VST_EFFECT_CATEGORY_OFFLINE.
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     */
    VST_EFFECT_OPCODE_28 = 0x28,
 
    /**
     *
     * Seen in plug-ins with @ref VST_EFFECT_CATEGORY_OFFLINE.
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     */
    VST_EFFECT_OPCODE_29 = 0x29,
 
    /** Host wants to change the speaker arrangement.
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @param p_int2 Pointer to a @ref vst_speaker_arrangement_t for the input.
     * @param p_ptr Pointer to a @ref vst_speaker_arrangement_t for the output.
     * @return @ref VST_STATUS_TRUE if we accept the new arrangement, @ref VST_STATUS_FALSE if we don't in which case
     *         the host is required to ask for the speaker arrangement via @ref VST_EFFECT_OPCODE_GET_SPEAKER_ARRANGEMENT
     *         and may retry this op-code with different values.
     * @sa vst_effect_t.num_inputs
     * @sa vst_effect_t.num_outputs
     * @sa VST_EFFECT_OPCODE_GET_SPEAKER_ARRANGEMENT
     */
    VST_EFFECT_OPCODE_2A                      = 0x2A,
    /** @sa VST_EFFECT_OPCODE_2A */
    VST_EFFECT_OPCODE_SET_SPEAKER_ARRANGEMENT = 0x2A,
 
    /**
     *
     *
     */
    VST_EFFECT_OPCODE_2B = 0x2B,
 
    /** Enable/Disable bypassing the effect.
     *
     * See @ref VST_EFFECT_OPCODE_SUPPORTS with @ref vst_effect_supports_t.bypass for more information.
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @param p_int2 Zero if bypassing the effect is disabled, otherwise 1.
     */
    VST_EFFECT_OPCODE_2C     = 0x2C,
    /** @sa VST_EFFECT_OPCODE_2C */
    VST_EFFECT_OPCODE_BYPASS = 0x2C,
 
    /** Retrieve the effect name into the ptr buffer.
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @bug Various hosts only provide a buffer that is 32 bytes long.
     * @param p_ptr A zero terminated char buffer of size @ref VST_BUFFER_SIZE_EFFECT_NAME.
     * @return Always 0, even on failure.
     */
    VST_EFFECT_OPCODE_2D          = 0x2D,
    /** @sa VST_EFFECT_OPCODE_2D */
    VST_EFFECT_OPCODE_GETNAME     = 0x2D,
    /** @sa VST_EFFECT_OPCODE_2D */
    VST_EFFECT_OPCODE_EFFECT_NAME = 0x2D,
    /** @sa VST_EFFECT_OPCODE_2D */
    VST_EFFECT_OPCODE_NAME = 0x2D,
 
    /** Translate an error code to a string.
     *
     * @bug Some hosts provide unexpected data in p_ptr.
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @deprecated (VST 2.4+) Fairly sure this is deprecated in VST 2.4 and later.
     * @param p_ptr A zero terminated char buffer with undefined size.
     * @return @ref VST_STATUS_TRUE if we could translate the error, @ref VST_STATUS_FALSE if not.
     */
    VST_EFFECT_OPCODE_2E              = 0x2E,
    /** @sa VST_EFFECT_OPCODE_2E */
    VST_EFFECT_OPCODE_TRANSLATE_ERROR = 0x2E,
 
    /** Retrieve the vendor name into the ptr buffer.
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @param p_ptr A zero terminated char buffer of size @ref VST_BUFFER_SIZE_VENDOR_NAME.
     */
    VST_EFFECT_OPCODE_2F          = 0x2F,
    /** @sa VST_EFFECT_OPCODE_2F */
    VST_EFFECT_OPCODE_GETVENDOR   = 0x2F,
    /** @sa VST_EFFECT_OPCODE_2F */
    VST_EFFECT_OPCODE_VENDOR_NAME = 0x2F,
 
    /** Retrieve the product name into the ptr buffer.
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @param p_ptr A zero terminated char buffer of size @ref VST_BUFFER_SIZE_PRODUCT_NAME.
     */
    VST_EFFECT_OPCODE_30           = 0x30,
    /** @sa VST_EFFECT_OPCODE_30 */
    VST_EFFECT_OPCODE_GETNAME2     = 0x30,
    /** @sa VST_EFFECT_OPCODE_30 */
    VST_EFFECT_OPCODE_PRODUCT_NAME = 0x30,
 
    /** Retrieve the vendor version in return value.
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @return Version.
     */
    VST_EFFECT_OPCODE_31               = 0x31,
    /** @sa VST_EFFECT_OPCODE_31 */
    VST_EFFECT_OPCODE_GETVENDORVERSION = 0x31,
    /** @sa VST_EFFECT_OPCODE_31 */
    VST_EFFECT_OPCODE_VENDOR_VERSION   = 0x31,
 
    /** User-defined Op-Code for VST extensions.
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * All parameters are undefined by the standard and left up to the host/plug-in. Use @ref VST_EFFECT_OPCODE_SUPPORTS
     * and @ref VST_EFFECT_OPCODE_VENDOR_NAME + @ref VST_EFFECT_OPCODE_VENDOR_VERSION to check if the plug-in is
     * compatible with your expected format.
     */
    VST_EFFECT_OPCODE_32     = 0x32,
    /** @sa VST_EFFECT_OPCODE_32 */
    VST_EFFECT_OPCODE_CUSTOM = 0x32,
 
    /** Test for support of a specific named feature.
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @param p_ptr A zero terminated char buffer of undefined size containing the feature name.
     * @return @ref VST_STATUS_YES if the feature is supported, @ref VST_STATUS_NO if the feature is not supported,
     *         @ref VST_STATUS_UNKNOWN in all other cases.
     */
    VST_EFFECT_OPCODE_33       = 0x33,
    /** @sa VST_EFFECT_OPCODE_33 */
    VST_EFFECT_OPCODE_SUPPORTS = 0x33,
 
    /** Number of samples that are at the tail at the end of playback.
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @return @ref VST_STATUS_UNKNOWN for automatic tail size, @ref VST_STATUS_TRUE for no tail, any other number above
     *         1 for the number of samples the tail has.
     */
    VST_EFFECT_OPCODE_34             = 0x34,
    /** @sa VST_EFFECT_OPCODE_34 */
    VST_EFFECT_OPCODE_GETTAILSAMPLES = 0x34,
    /** @sa VST_EFFECT_OPCODE_34 */
    VST_EFFECT_OPCODE_TAIL_SAMPLES   = 0x34,
 
    /** Notify effect that it is idle?
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @deprecated (VST 2.4+) As of VST 2.4 the default behavior is @ref VST_EFFECT_OPCODE_PROCESS_BEGIN and
     *             @ref VST_EFFECT_OPCODE_PROCESS_END which allows cleaner control flows.
     * @sa vst_host_supports.startStopProcess
     */
    VST_EFFECT_OPCODE_35 = 0x35,
    /** @sa VST_EFFECT_OPCODE_35 */
    VST_EFFECT_OPCODE_IDLE = 0x35,
 
    /**
     *
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @deprecated (VST 2.4) Invalid in all VST 2.4 and later hosts.
     */
    VST_EFFECT_OPCODE_36 = 0x36,
 
    /**
     *
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @deprecated (VST 2.4) Invalid in all VST 2.4 and later hosts.
     */
    VST_EFFECT_OPCODE_37 = 0x37,
 
    /** Parameter Properties
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @param p_int1 Parameter index to get properties for.
     * @param p_ptr Pointer to @ref vst_parameter_properties_t for the given parameter.
     * @return @ref VST_STATUS_YES if supported, otherwise @ref VST_STATUS_NO.
     */
    VST_EFFECT_OPCODE_38 = 0x38,
    /** @sa VST_EFFECT_OPCODE_38 */
    VST_EFFECT_OPCODE_GET_PARAMETER_PROPERTIES = 0x38,
    /** @sa VST_EFFECT_OPCODE_38 */
    VST_EFFECT_OPCODE_PARAM_PROPERTIES = 0x38,
 
    /**
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @deprecated (VST 2.4) Invalid in all VST 2.4 and later hosts.
     */
    VST_EFFECT_OPCODE_39                       = 0x39,
 
    /** Retrieve the VST Version supported.
     *
     * @note (VST 2.0+) Available from VST 2.0 onwards.
     * @sa VST_VERSION
     * @return One of the valid enums in @ref VST_VERSION
     */
    VST_EFFECT_OPCODE_3A          = 0x3A,
    /** @sa VST_EFFECT_OPCODE_3A */
    VST_EFFECT_OPCODE_VST_VERSION = 0x3A,
 
    //--------------------------------------------------------------------------------
    // VST 2.1
    //--------------------------------------------------------------------------------
 
    /** Editor Virtual Key Down Input
     *
     * @note (VST 2.1+) Available from VST 2.1 onwards.
     * @param p_int1 ASCII character that represents the virtual key code.
     * @param p_int2 Virtual Key Code
     * @param p_float Modifiers being held down (bitfield)
     * @return @ref VST_STATUS_TRUE if we used the input, otherwise @ref VST_STATUS_FALSE
     */
    VST_EFFECT_OPCODE_3B = 0x3B,
    /** @sa VST_EFFECT_OPCODE_3B */
    VST_EFFECT_OPCODE_EDITOR_VKEY_DOWN = 0x3B,
 
    /** Editor Virtual Key Up Event
     *
     * @note (VST 2.1+) Available from VST 2.1 onwards.
     * @param p_int1 ASCII character that represents the virtual key code.
     * @param p_int2 Virtual Key Code
     * @param p_float Modifiers being held down (bitfield)
     * @return @ref VST_STATUS_TRUE if we used the input, otherwise @ref VST_STATUS_FALSE
     */
    VST_EFFECT_OPCODE_3C = 0x3C,
    /** @sa VST_EFFECT_OPCODE_3C */
    VST_EFFECT_OPCODE_EDITOR_VKEY_UP = 0x3C,
 
    /**
     *
     * @note (VST 2.1+) Available from VST 2.1 onwards.
     * @param p_int2 A value between 0 and 2.
     */
    VST_EFFECT_OPCODE_3D = 0x3D,
 
    /**
     *
     * Midi related
     * @note (VST 2.1+) Available from VST 2.1 onwards.
     */
    VST_EFFECT_OPCODE_3E = 0x3E,
 
    /**
     *
     * Midi related
     * @note (VST 2.1+) Available from VST 2.1 onwards.
     */
    VST_EFFECT_OPCODE_3F = 0x3F,
 
    /**
     *
     * Midi related
     * @note (VST 2.1+) Available from VST 2.1 onwards.
     */
    VST_EFFECT_OPCODE_40 = 0x40,
 
    /**
     *
     * Midi related
     * @note (VST 2.1+) Available from VST 2.1 onwards.
     */
    VST_EFFECT_OPCODE_41 = 0x41,
 
    /**
     *
     * Midi related
     * @note (VST 2.1+) Available from VST 2.1 onwards.
     */
    VST_EFFECT_OPCODE_42 = 0x42,
 
    /** Host is starting to set up a program.
     * Emitted prior to the host loading a program.
     *
     * @note (VST 2.1+) Available from VST 2.1 onwards.
     * @return @ref VST_STATUS_TRUE if we understood the notification, or @ref VST_STATUS_FALSE if not.
     */
    VST_EFFECT_OPCODE_43 = 0x43,
    /** @sa VST_EFFECT_OPCODE_43 */
    VST_EFFECT_OPCODE_PROGRAM_SET_BEGIN = 0x43,
 
    /** Host is done setting up a program.
     * Emitted after the host finished loading a program.
     *
     * @note (VST 2.1+) Available from VST 2.1 onwards.
     * @return @ref VST_STATUS_TRUE if we understood the notification, or @ref VST_STATUS_FALSE if not.
     */
    VST_EFFECT_OPCODE_44 = 0x44,
    /** @sa VST_EFFECT_OPCODE_44 */
    VST_EFFECT_OPCODE_PROGRAM_SET_END = 0x44,
 
    //--------------------------------------------------------------------------------
    // VST 2.3
    //--------------------------------------------------------------------------------
 
    /** Host wants to know the current speaker arrangement.
     *
     * @note (VST 2.3+) Available from VST 2.3 onwards.
     * @param p_int2 Pointer to @ref vst_speaker_arrangement_t for the input.
     * @param p_ptr Pointer to @ref vst_speaker_arrangement_t for the output.
     * @return @ref VST_STATUS_TRUE if we were successful, otherwise @ref VST_STATUS_FALSE.
     */
    VST_EFFECT_OPCODE_45                      = 0x45,
    /** @sa VST_EFFECT_OPCODE_45 */
    VST_EFFECT_OPCODE_GET_SPEAKER_ARRANGEMENT = 0x45,
 
    /** Get the next effect contained in this effect.
     * This returns the next effect based on an effect internal counter, the host does not provide any index.
     *
     * Used in combination with @ref VST_EFFECT_CATEGORY_CONTAINER.
     *
     * @note (VST 2.3+) Available from VST 2.3 onwards.
     * @param p_ptr Pointer to a char buffer of size @ref VST_BUFFER_SIZE_EFFECT_NAME to store the name of the next effect.
     * @return Next effects unique_id
     */
    VST_EFFECT_OPCODE_46 = 0x46,
    /** @sa VST_EFFECT_OPCODE_46 */
    VST_EFFECT_OPCODE_CONTAINER_NEXT_EFFECT_ID = 0x46,
 
    /** Begin processing of audio.
     *
     * Host is requesting that we prepare for a new section of audio separate from the previous section.
     * @note (VST 2.3+) Available from VST 2.3 onwards.
     */
    VST_EFFECT_OPCODE_47 = 0x47,
    /** @sa VST_EFFECT_OPCODE_47 */
    VST_EFFECT_OPCODE_PROCESS_BEGIN = 0x47,
 
    /** End processing of audio.
     *
     * Host is requesting that we stop processing audio and go into idle instead.
     * @note (VST 2.3+) Available from VST 2.3 onwards.
     */
    VST_EFFECT_OPCODE_48 = 0x48,
    /** @sa VST_EFFECT_OPCODE_48 */
    VST_EFFECT_OPCODE_PROCESS_END = 0x48,
 
    /**
     *
     *
     * @note (VST 2.3+) Available from VST 2.3 onwards.
     */
    VST_EFFECT_OPCODE_49 = 0x49,
 
    /**
     *
     * @note (VST 2.3+) Available from VST 2.3 onwards.
     * @sa VST_EFFECT_CATEGORY_SPATIAL
     * @param p_int2 Unknown meaning.
     * @param p_float Unknown meaning, usually 1.0
     */
    VST_EFFECT_OPCODE_4A = 0x4A,
 
    /** Host wants to know if we can load the provided bank data.
     * Should be emitted prior to @ref VST_EFFECT_OPCODE_SET_CHUNK_DATA by the host.
     *
     * @note (VST 2.3+) Available from VST 2.3 onwards.
     * @param p_ptr Unknown structured data.
     * @return @ref VST_STATUS_NO if we can't load the data, @ref VST_STATUS_YES if we can load the data,
     *         @ref VST_STATUS_UNKNOWN if this isn't supported.
     */
    VST_EFFECT_OPCODE_4B = 0x4B,
    /** @sa VST_EFFECT_OPCODE_4B */
    VST_EFFECT_OPCODE_BANK_LOAD = 0x4B,
 
    /** Host wants to know if we can load the provided program data.
     * Should be emitted prior to @ref VST_EFFECT_OPCODE_PROGRAM_SET_BEGIN by the host.
     *
     * @note (VST 2.3+) Available from VST 2.3 onwards.
     * @param p_ptr Unknown structured data.
     * @return @ref VST_STATUS_NO if we can't load the data, @ref VST_STATUS_YES if we can load the data,
     *         @ref VST_STATUS_UNKNOWN if this isn't supported.
     */
    VST_EFFECT_OPCODE_4C = 0x4C,
    /** @sa VST_EFFECT_OPCODE_4C */
    VST_EFFECT_OPCODE_PROGRAM_LOAD = 0x4C,
 
    //--------------------------------------------------------------------------------
    // VST 2.4
    //--------------------------------------------------------------------------------
 
    /**
     *
     *
     * @note (VST 2.4+) Available from VST 2.4 onwards.
     */
    VST_EFFECT_OPCODE_4D = 0x4D,
 
    /**
     *
     *
     * @note (VST 2.4+) Available from VST 2.4 onwards.
     */
    VST_EFFECT_OPCODE_4E = 0x4E,
 
    /**
     *
     *
     * @note (VST 2.4+) Available from VST 2.4 onwards.
     */
    VST_EFFECT_OPCODE_4F = 0x4F,
 
    /** @private */
    VST_EFFECT_OPCODE_MAX,
 
    /** @private */
    _VST_EFFECT_OPCODE_PAD = 0xFFFFFFFFul,
};
 
/** Host to Plug-in support checks
 *
 * Provided as `char* p_ptr` in the VST_EFFECT_OPCODE_SUPPORTS op code.
 *
 * Harvested via strings command and just checking what plug-ins actually responded to.
 */
struct vst_effect_supports_t {
    /** Effect supports alternative bypass.
     * The alternative bypass still has the host call process/process_float/process_double and expects us to compensate
     * for our delay/latency, copy inputs to outputs, and do minimal work. If we don't support it the host will not call
     * process/process_float/process_double at all while bypass is enabled.
     *
     * @note VST 2.3 or later only.
     * @return VST_STATUS_TRUE if we support this, otherwise VST_STATUS_FALSE.
     */
    const char* bypass;
 
    const char* sendVstEvents;
    const char* receiveVstEvents;
    const char* sendVstMidiEvent;
    const char* receiveVstMidiEvent;
    const char* midiProgramNames; // VST 2.1 or later.
    const char* receiveVstTimeInfo;
    const char* offline;
    // The following were only found in VST 2.3 plug-ins
    const char* plugAsChannelInsert;
    const char* conformsToWindowRules; // Mac OS only, invalid in VST 2.4. Seems related to vst_host_supports.sizeWindow
    const char* plugAsSend;
    const char* mixDryWet;
    const char* noRealTime;
    const char* multipass;
    const char* metapass;
    const char* _1in1out;
    const char* _1in2out;
    const char* _2in1out;
    const char* _2in2out;
    const char* _2in4out;
    const char* _4in2out;
    const char* _4in4out;
    const char* _4in8out;
    const char* _8in4out;
    const char* _8in8out;
} /** @private */ vst_effect_supports = {
    .bypass = "bypass",
    .sendVstEvents = "sendVstEvents",
    .receiveVstEvents = "receiveVstEvents",
    .sendVstMidiEvent = "sendVstMidiEvent",
    .receiveVstMidiEvent = "receiveVstMidiEvent",
    .midiProgramNames = "midiProgramNames",
    .receiveVstTimeInfo = "receiveVstTimeInfo",
    .offline = "offline",
    .plugAsChannelInsert = "plugAsChannelInsert",
    .conformsToWindowRules = "conformsToWindowRules",
    .plugAsSend = "plugAsSend",
    .mixDryWet = "mixDryWet",
    .noRealTime = "noRealTime",
    .multipass = "multipass",
    .metapass = "metapass",
    ._1in1out = "1in1out",
    ._1in2out = "1in2out",
    ._2in1out = "2in1out",
    ._2in2out = "2in2out",
    ._2in4out = "2in4out",
    ._4in2out = "4in2out",
    ._4in4out = "4in4out",
    ._4in8out = "4in8out",
    ._8in4out = "8in4out",
    ._8in8out = "8in8out",
};
 
/** Control the VST through an opcode and up to four parameters.
 *
 * @sa VST_EFFECT_OPCODE
 *
 * @param self Pointer to the effect itself.
 * @param opcode The opcode to run, see @ref VST_EFFECT_OPCODE.
 * @param p_int1 Parameter, see @ref VST_EFFECT_OPCODE.
 * @param p_int2 Parameter, see @ref VST_EFFECT_OPCODE.
 * @param p_ptr Parameter, see @ref VST_EFFECT_OPCODE.
 * @param p_float Parameter, see @ref VST_EFFECT_OPCODE.
 */
typedef intptr_t (VST_FUNCTION_INTERFACE* vst_effect_control_t)(struct vst_effect_t* self, int32_t opcode, int32_t p_int1, intptr_t p_int2, void* p_ptr, float p_float);
 
/** Process the given number of samples in inputs and outputs.
 *
 * Used to handle input data and provides output data. We seem to be the ones that provide the output buffer?
 *
 * @param self Pointer to the effect itself.
 * @param inputs Pointer to an array of 'const float[samples]' with size @ref vst_effect_t.num_inputs.
 * @param outputs Pointer to an array of 'float[samples]' with size @ref vst_effect_t.num_outputs.
 * @param samples Number of samples per channel in inputs and outputs.
 */
typedef void (VST_FUNCTION_INTERFACE* vst_effect_process_t) (struct vst_effect_t* self, const float* const* inputs, float** outputs, int32_t samples);
 
/** Updates the value for the parameter at the given index, or does nothing if out of bounds.
 *
 * @param self Pointer to the effect itself.
 * @param index Parameter index.
 * @param value New value for the parameter.
 */
typedef void(VST_FUNCTION_INTERFACE* vst_effect_set_parameter_t)(struct vst_effect_t* self, uint32_t index, float value);
 
/** Retrieve the current value of the parameter at the given index, or do nothing if out of bounds.
 *
 * @param self Pointer to the effect itself.
 * @param index Parameter index.
 * @return Current value of the parameter.
 */
typedef float(VST_FUNCTION_INTERFACE* vst_effect_get_parameter_t)(struct vst_effect_t* self, uint32_t index);
 
/** Process the given number of single samples in inputs and outputs.
 *
 * Process input and overwrite the output in place. Host provides output buffers.
 *
 * @important Not thread-safe on MacOS for some reason or another.
 *
 * @param self Pointer to the effect itself.
 * @param inputs Pointer to an array of 'const float[samples]' with size numInputs.
 * @param outputs Pointer to an array of 'float[samples]' with size numOutputs.
 * @param samples Number of samples per channel in inputs.
 */
typedef void(VST_FUNCTION_INTERFACE* vst_effect_process_float_t)(struct vst_effect_t* self, const float* const* inputs, float** outputs, int32_t samples);
 
/** Process the given number of double samples in inputs and outputs.
 *
 * Process input and overwrite the output in place. Host provides output buffers.
 *
 * @note (VST 2.4+) Available from VST 2.4 and later.
 *
 * @param self Pointer to the effect itself.
 * @param inputs Pointer to an array of 'const double[samples]' with size numInputs.
 * @param outputs Pointer to an array of 'double[samples]' with size numOutputs.
 * @param samples Number of samples per channel in inputs.
 */
typedef void (VST_FUNCTION_INTERFACE* vst_effect_process_double_t)(struct vst_effect_t* self, const double* const* inputs, double** outputs, int32_t samples);
 
/** Plug-in Effect definition
 */
struct vst_effect_t {
    /** VST Magic Number
     *
     * Should always be VST_FOURCC('VstP')
     *
     * @sa VST_MAGICNUMBER
     */
    int32_t magic_number;
 
    /** Control Function
     * @sa vst_effect_control_t
     * @sa VST_EFFECT_OPCODE
     */
    vst_effect_control_t control;
 
    /** Process Function
     * @sa vst_effect_process_t
     * @deprecated (VST 2.4+) Deprecated and practically unsupported in all VST 2.4 compatible hosts and may treat it
     *             as just another @ref vst_effect_t.process_float.
     */
    vst_effect_process_t process;
 
    /** Set Parameter Function
     * @sa vst_effect_set_parameter_t
     */
    vst_effect_set_parameter_t set_parameter;
 
    /** Get Parameter Function
     * @sa vst_effect_get_parameter_t
     */
    vst_effect_get_parameter_t get_parameter;
 
    /** Number of available pre-defined programs.
     *
     * @sa VST_EFFECT_OPCODE_PROGRAM_LOAD
     * @sa VST_EFFECT_OPCODE_PROGRAM_SET_BEGIN
     * @sa VST_EFFECT_OPCODE_PROGRAM_SET
     * @sa VST_EFFECT_OPCODE_PROGRAM_SET_NAME
     * @sa VST_EFFECT_OPCODE_PROGRAM_SET_END
     * @sa VST_EFFECT_OPCODE_PROGRAM_GET
     * @sa VST_EFFECT_OPCODE_PROGRAM_GET_NAME
     * @sa VST_EFFECT_FLAG_CHUNKS
     * @sa VST_EFFECT_OPCODE_SET_CHUNK_DATA
     * @sa VST_EFFECT_OPCODE_GET_CHUNK_DATA
     */
    int32_t num_programs;
 
    /** Number of available parameters.
     * All programs must have at least this many parameters.
     *
     * @sa VST_HOST_OPCODE_IO_MODIFIED
     */
    int32_t num_params;
 
    /** Number of available input streams.
     *
     *
     * @sa VST_EFFECT_OPCODE_GET_SPEAKER_ARRANGEMENT
     * @sa VST_EFFECT_OPCODE_INPUT_GET_PROPERTIES
     * @sa VST_HOST_OPCODE_IO_MODIFIED
     */
    int32_t num_inputs;
 
    /** Number of available output streams.
     *
     * @sa VST_EFFECT_OPCODE_GET_SPEAKER_ARRANGEMENT
     * @sa VST_EFFECT_OPCODE_OUTPUT_GET_PROPERTIES
     * @sa VST_HOST_OPCODE_IO_MODIFIED
     */
    int32_t num_outputs;
 
    /** Effect Flags
     *
     * @sa VST_EFFECT_FLAGS
     */
    int32_t flags;
 
    void* _unknown_00; // Must be zero when created. Reserved for host?
    void* _unknown_01; // Must be zero when created. Reserved for host?
 
    /** Initial delay before processing of samples can actually begin in Samples.
     *
     * @note The host can modify this at runtime so it is not safe.
     * @note Should be reinitialized when the effect is resumed.
     *
     * @sa VST_HOST_OPCODE_IO_MODIFIED
     */
    int32_t delay;
 
    int32_t _unknown_02; // Unknown int32_t values.
    int32_t _unknown_03;
 
    /** Ratio of Input to Output production
     * Defines how much output data is produced relative to input data when using 'process' instead of 'processFloat'.
     * Example: A ratio of 2.0 means we produce twice as much output as we receive input.
     *
     * Range: >0.0 to Infinity
     * Default: 1.0
     * @note Ignored in VST 2.4 or with VST_EFFECT_FLAG_SUPPORTS_FLOAT.
     */
    float input_output_ratio;
 
    /** Effect Internal Pointer
     *
     * You can freely set this to point at some sort of class or similar for use in your own effect. The host must
     * never modify this or the data available through this.
     */
    void* effect_internal;
 
    /** Host Internal Pointer
     *
     * The host may set this to point at data related to your effect instance that the host needs. The effect must
     * never modify this or the data available through this.
     */
    void* host_internal; // Pointer to Host internal data.
 
    /** Id of the plugin.
     *
     * Due to this not being enough for uniqueness, it should not be used alone for indexing.
     * Ideally you want to index like this:
     *     [unique_id][module_name][version][flags]
     * If any of the checks after unique_id fail, you default to the first possible choice.
     *
     * Used in combination with @ref VST_EFFECT_CATEGORY_CONTAINER.
     *
     * BUG: Some broken hosts rely on this alone to save information about VST plug-ins.
     */
    int32_t unique_id;
 
    /** Plugin version
     *
     * Unrelated to the minimum VST Version, but often the same.
     */
    int32_t version;
 
    //--------------------------------------------------------------------------------
    // VST 2.x starts here.
    //--------------------------------------------------------------------------------
 
    /** Process function for in-place single (32-bit float) processiong.
     * @sa vst_effect_process_single_t
     * @note (VST 2.0+) Available from VST 2.0 and later.
     */
    vst_effect_process_float_t process_float;
 
    //--------------------------------------------------------------------------------
    // VST 2.4 starts here.
    //--------------------------------------------------------------------------------
 
    /** Process function for in-place double (64-bit float) processiong.
     * @sa vst_effect_process_double_t
     * @note (VST 2.4+) Available from VST 2.4 and later.
     */
    vst_effect_process_double_t process_double;
 
    // Everything after this is unknown and was present in reacomp-standalone.dll.
    uint8_t _unknown[56]; // 56-bytes of something. Could also just be 52-bytes.
};
 
/** VST 2.x Entry Point for all platforms
 *
 * Must be present in VST 2.x plug-ins but must not be present in VST 1.x plug-ins.
 *
 * @return A new instance of the VST 2.x effect.
 */
#define VST_ENTRYPOINT
    vst_effect_t* VSTPluginMain(vst_host_callback_t callback)
 
/** [DEPRECATED] VST 1.x Entry Point for Windows
 *
 * Do not implement in VST 2.1 or later plug-ins!
 *
 * @return A new instance of the VST 1.x effect.
 */
#define VST_ENTRYPOINT_WINDOWS
    vst_effect_t* MAIN(vst_host_callback_t callback) { return VSTPluginMain(callback); }
 
/** [DEPRECATED] VST 1.x Entry Point for MacOS
 *
 * Do not implement in VST 2.1 or later plug-ins!
 *
 * @return A new instance of the VST 1.x effect.
 */
#define VST_ENTRYPOINT_MACOS
    vst_effect_t* main_macho(vst_host_callback_t callback) { return VSTPluginMain(callback); }
 
/** [DEPRECATED] VST 2.3 Entry Point for PowerPC
 *
 * Present in some VST 2.3 and earlier compatible plug-ins that support MacOS.
 *
 * @return A new instance of the VST 2.x effect.
 */
#define VST_ENTRYPOINT_MACOS_POWERPC
    vst_effect_t* main(vst_host_callback_t callback) { return VSTPluginMain(callback); }
 
#ifdef __cplusplus
}
#endif
#pragma pack(pop)
#endif