C++: VstIntPtr function dispatcher(AEffect* e, VstInt32 opcode, VstInt32 index, VstIntPtr value, void* ptr, float opt);
Delphi: function dispatcher(e: PAEffect; opcode, index: VstInt32; value: VstIntPtr; ptr: pointer; opt: Single): VstIntPtr; cdecl;
always returns 0, unless otherwise defined.
all string-pointers points to zero terminated strings.
e[ ]: = plugin receives as entry parameter
x[ ]: = plugin returns to host

dispatcher() function using opcode 56:
56. effGetParameterProperties 56. effGetParameterProperties   >= VST2.0   @see AudioEffectX::getParameterProperties()
e[index]: index of parameter
e[ptr]: pointer to VstParameterProperties* structure
x[return]: 1 = successful

C++ method:

 bool AudioEffectX::getParameterProperties(VstInt32 index, VstParameterProperties* p)

Delphi method:

 function AudioEffectX.getParameterProperties(index: VstInt32; p: PVstParameterProperties): boolean;

VstParameterProperties structure:

struct VstParameterProperties
 {
  float stepFloat;              // float step
  float smallStepFloat;         // small float step
  float largeStepFloat;         // large float step
  char label[kVstMaxLabelLen];  // parameter label
  VstInt32 flags;               // @see VstParameterFlags
  VstInt32 minInteger;          // integer minimum
  VstInt32 maxInteger;          // integer maximum
  VstInt32 stepInteger;         // integer step
  VstInt32 largeStepInteger;    // large integer step
  char shortLabel[kVstMaxShortLabelLen]; // short label, recommended: 6 + delimiter

  The following are for remote controller display purposes.
  Note that the kVstParameterSupportsDisplayIndex flag must be set.
  Host can scan all parameters, and find out in what order to display them:

  VstInt16 displayIndex;        // index where this parameter should be displayed (starting with 0)

  Host can also possibly display the parameter group (category), such as...
  -------------------------------------
  Osc 1
  Wave   Detune   Octave   Mod
  -------------------------------------
  ...if the plug-in supports it (flag #kVstParameterSupportsDisplayCategory)

  VstInt16 category;            // 0: no category, else group index + 1
  VstInt16 numParametersInCategory; // number of parameters in category
  VstInt16 reserved;            // zero
  char categoryLabel[kVstMaxCategLabelLen]; // category label, e.g. "Osc 1" 
  char future[16];              // reserved for future use
 };

VstParameterFlags constants:

 enum VstParameterFlags
 {
  kVstParameterIsSwitch                = 1 << 0,  // parameter is a switch (on/off)
  kVstParameterUsesIntegerMinMax       = 1 << 1,  // minInteger, maxInteger valid
  kVstParameterUsesFloatStep           = 1 << 2,  // stepFloat, smallStepFloat, largeStepFloat valid
  kVstParameterUsesIntStep             = 1 << 3,  // stepInteger, largeStepInteger valid
  kVstParameterSupportsDisplayIndex    = 1 << 4,  // displayIndex valid
  kVstParameterSupportsDisplayCategory = 1 << 5,  // category, etc. valid
  kVstParameterCanRamp                 = 1 << 6   // set if parameter value can ramp up/down
 };

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