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//-------------------------------------------------------------------------------------------------------
// VST Plug-Ins SDK
// Version 2.4 $Date: 2006/11/13 09:08:27 $
//
// Category : VST 2.x SDK Samples
// Filename : vstxsynthproc.cpp
// Created by : Steinberg Media Technologies
// Description : Example VstXSynth
//
// A simple 2 oscillators test 'synth',
// Each oscillator has waveform, frequency, and volume
//
// *very* basic monophonic 'synth' example. you should not attempt to use this
// example 'algorithm' to start a serious virtual instrument; it is intended to demonstrate
// how VstEvents ('MIDI') are handled, but not how a virtual analog synth works.
// there are numerous much better examples on the web which show how to deal with
// bandlimited waveforms etc.
//
// � 2006, Steinberg Media Technologies, All Rights Reserved
//-------------------------------------------------------------------------------------------------------
#include "vstxsynth.h"
enum
{
kNumFrequencies = 128, // 128 midi notes
kWaveSize = 4096 // samples (must be power of 2 here)
};
const double midiScaler = (1. / 127.);
static float sawtooth[kWaveSize];
static float pulse[kWaveSize];
static float freqtab[kNumFrequencies];
//-----------------------------------------------------------------------------------------
// VstXSynth
//-----------------------------------------------------------------------------------------
void VstXSynth::setSampleRate (float sampleRate)
{
AudioEffectX::setSampleRate (sampleRate);
fScaler = (float)((double)kWaveSize / (double)sampleRate);
}
//-----------------------------------------------------------------------------------------
void VstXSynth::setBlockSize (VstInt32 blockSize)
{
AudioEffectX::setBlockSize (blockSize);
// you may need to have to do something here...
}
//-----------------------------------------------------------------------------------------
void VstXSynth::initProcess ()
{
fPhase1 = fPhase2 = 0.f;
fScaler = (float)((double)kWaveSize / 44100.); // we don't know the sample rate yet
noteIsOn = false;
currentDelta = currentNote = currentDelta = 0;
VstInt32 i;
// make waveforms
VstInt32 wh = kWaveSize / 4; // 1:3 pulse
for (i = 0; i < kWaveSize; i++)
{
sawtooth[i] = (float)(-1. + (2. * ((double)i / (double)kWaveSize)));
pulse[i] = (i < wh) ? -1.f : 1.f;
}
// make frequency (Hz) table
double k = 1.059463094359; // 12th root of 2
double a = 6.875; // a
a *= k; // b
a *= k; // bb
a *= k; // c, frequency of midi note 0
for (i = 0; i < kNumFrequencies; i++) // 128 midi notes
{
freqtab[i] = (float)a;
a *= k;
}
}
//-----------------------------------------------------------------------------------------
void VstXSynth::processReplacing (float** inputs, float** outputs, VstInt32 sampleFrames)
{
float* out1 = outputs[0];
float* out2 = outputs[1];
if (noteIsOn)
{
float baseFreq = freqtab[currentNote & 0x7f] * fScaler;
float freq1 = baseFreq + fFreq1; // not really linear...
float freq2 = baseFreq + fFreq2;
float* wave1 = (fWaveform1 < .5) ? sawtooth : pulse;
float* wave2 = (fWaveform2 < .5) ? sawtooth : pulse;
float wsf = (float)kWaveSize;
float vol = (float)(fVolume * (double)currentVelocity * midiScaler);
VstInt32 mask = kWaveSize - 1;
if (currentDelta > 0)
{
if (currentDelta >= sampleFrames) // future
{
currentDelta -= sampleFrames;
return;
}
memset (out1, 0, currentDelta * sizeof (float));
memset (out2, 0, currentDelta * sizeof (float));
out1 += currentDelta;
out2 += currentDelta;
sampleFrames -= currentDelta;
currentDelta = 0;
}
// loop
while (--sampleFrames >= 0)
{
// this is all very raw, there is no means of interpolation,
// and we will certainly get aliasing due to non-bandlimited
// waveforms. don't use this for serious projects...
(*out1++) = wave1[(VstInt32)fPhase1 & mask] * fVolume1 * vol;
(*out2++) = wave2[(VstInt32)fPhase2 & mask] * fVolume2 * vol;
fPhase1 += freq1;
fPhase2 += freq2;
}
}
else
{
memset (out1, 0, sampleFrames * sizeof (float));
memset (out2, 0, sampleFrames * sizeof (float));
}
}
//-----------------------------------------------------------------------------------------
VstInt32 VstXSynth::processEvents (VstEvents* ev)
{
for (VstInt32 i = 0; i < ev->numEvents; i++)
{
if ((ev->events[i])->type != kVstMidiType)
continue;
VstMidiEvent* event = (VstMidiEvent*)ev->events[i];
char* midiData = event->midiData;
VstInt32 status = midiData[0] & 0xf0; // ignoring channel
if (status == 0x90 || status == 0x80) // we only look at notes
{
VstInt32 note = midiData[1] & 0x7f;
VstInt32 velocity = midiData[2] & 0x7f;
if (status == 0x80)
velocity = 0; // note off by velocity 0
if (!velocity && (note == currentNote))
noteOff ();
else
noteOn (note, velocity, event->deltaFrames);
}
else if (status == 0xb0)
{
if (midiData[1] == 0x7e || midiData[1] == 0x7b) // all notes off
noteOff ();
}
event++;
}
return 1;
}
//-----------------------------------------------------------------------------------------
void VstXSynth::noteOn (VstInt32 note, VstInt32 velocity, VstInt32 delta)
{
currentNote = note;
currentVelocity = velocity;
currentDelta = delta;
noteIsOn = true;
fPhase1 = fPhase2 = 0;
}
//-----------------------------------------------------------------------------------------
void VstXSynth::noteOff ()
{
noteIsOn = false;
}
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