source code is at http://www.linux-vst.com
Code: Select all
#ifndef __SYNTH__
#define __SYNTH__
// simple synth class
class CSynth
{
protected:
int rate;
double vol;
double freq, phase;
bool playing;
public:
CSynth();
void midiInput(int data);
void process(float* p1, float* p2, int samples);
void setRate(int val) { rate = val; }
};
CSynth :: CSynth()
{
vol = 0.25;
playing = false;
rate = 44100;
}
// convert note to hertz
double noteToHz(int note)
{
return (440 / (float)32) * pow(2, ( (note - 9) / (float)12) );
}
// handle midi input
void CSynth :: midiInput(int data)
{
unsigned char status = data & 0xF0;
unsigned char byte1 = (data >> 8) & 0xFF;
unsigned char byte2 = (data >> 16) & 0xFF;
// note on
if (status == 0x90 && byte2 > 0)
{
phase = 0;
freq = 2 * noteToHz(byte1) / rate;
playing = true;
}
// note off
else if (status == 0x80 || (status == 0x90 && byte2 == 0))
{
playing = false;
}
// control change
else if (status == 0xB0)
{
// todo
}
}
// synthesize
void CSynth :: process(float* p1, float* p2, int samples)
{
int i;
if (playing)
{
for (i = 0; i < samples; i++)
{
*p1 = (float) (*p1 + phase * vol);
*p2 = (float) (*p2 + phase * vol);
p1++;
p2++;
phase = phase + freq;
if (phase > 1)
phase -= 2;
}
}
}
#endif
cheers
jorgen
& 0xFF" threw me off until I realised - hey he's done the work for me. Just drop it in the code and don't worry about it. 
