How to emulate PSG and SCC in Windows applications.

there is also msxplug, a plugin for winamp and some other media player. It has scc, fmpac, music module, psg. I am not sure whether it is open source or whatever.

I am currently trying to make a sort of Vortex Tracker II clone using my limited C and windowsAPI knowledge.

The plan is simple: Reimplement the VTII functionalities and expand them with 5 new SCC channels without the PSG specific attributes (envelope etc.). So that we can finally produce real 8 channel music in our projects.Erhm, would it be possible to do it in Java and add FM-PAC and Music Moulde support? (Java for cross-platformness so I could use it on my maccie )

I need help in PSG emulation. The major problems are in emulating the psg noise
Mixing tones and noise is a sort of mistery...
I cannot find a clear explanation in docs on how real HW works
Can anyone have a look to the following code and tell me where I am wrong?

SHORT R01 = 0;
SHORT R23 = 0;
SHORT R45 = 0;

char R6 = 31;
char R7 = 0;

char R8 = 15;
char R9 = 15;
char R10= 15;

char R15 =0;

#define playback_frequency     44100.0
#define psg_master_frequency   (1.7897725e6/16.0)

unsigned char volume_table[] = {0,2,3,4,6,8,11,16,23,32,45,64,90,128,180,255};

void psg_generator(LPSTR data, int size)
{
    static float PhaseA,PhaseB,PhaseC;    // state counters for ch A, B and C
    static SHORT LA,LB,LC;                // output state for ch A, B and C

    static float PhaseN;                 // state counters for Noise Generator
    static SHORT LN;                     // state for Noise Generator

    SHORT VA = volume_table[R8 & 15] * !(R7 & 0x01);     // output volume for ch A, B and C
    SHORT VB = volume_table[R9 & 15] * !(R7 & 0x02);
    SHORT VC = volume_table[R10& 15] * !(R7 & 0x04);

    float hPeriodA = ((R01 & 0x0FFF)+0)*128.0*playback_frequency/psg_master_frequency;
    float hPeriodB = ((R23 & 0x0FFF)+0)*128.0*playback_frequency/psg_master_frequency;
    float hPeriodC = ((R45 & 0x0FFF)+0)*128.0*playback_frequency/psg_master_frequency;

    float PeriodN = ((R6 & 0x1F)+0)*256.0*playback_frequency/psg_master_frequency;

    PSHORT b = (PSHORT) data;

    for (int i=0;i<(int)size/sizeof(SHORT);i++)
    {
        SHORT Level = 0;

        PhaseN-=256;
        if (PhaseN<=0)
        {
            PhaseN += PeriodN;			// 8 bit of fractional part
//            LN = ((rand()+1)>>1) & 1;
            LN = AY8910_NoiseGenerator();   // 17 bit random generator
        }

		PhaseA-=256;					// 8 bit of fractional part
		if (PhaseA<=0)
        {
            PhaseA += hPeriodA;			// 8 bit of fractional part
            LA = (LA>=0) ? (-VA):(VA);
        }
		PhaseB-=256;					// 8 bit of fractional part
		if (PhaseB<=0)
        {
            PhaseB += hPeriodB;			// 8 bit of fractional part
            LB = (LB>=0) ? (-VB):(VB);
        }
		PhaseC-=256;					// 8 bit of fractional part
		if (PhaseC<=0)
        {
            PhaseC += hPeriodC;			// 8 bit of fractional part
            LC = (LC>=0) ? (-VC):(VC);
        }


        if (!(R7 & 0x08) && (LN==0))
			Level += -VA;
        else
            Level += LA;

        if (!(R7 & 0x10) && (LN==0))
			Level += -VB;
        else
            Level += LB;

        if (!(R7 & 0x20) && (LN==0))
			Level += -VC;
        else
            Level += LC;

        b[i] = Level*16;
    }
}

what is a vsti ?

VSTi are plug-ins for use in trackers etc.

@ wouter_: that seems like some very valuable info, thanks!