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(2)ToneIIRLP02rt.c

extern void InitC5402(void); extern void OpenMcBSP(void); extern void CloseMcBSP(void); extern void READAD50(void); extern void WRITEAD50(void);

/*********************************************************************** ** Main Function Program

***********************************************************************/ #include \ #include \ #define pi 3.1415926

double fs,nlpass,nlstop,nhpass,nhstop,a[3],b[3],x,y;

void biir2lpdes(double fs, double nlpass, double nlstop, double a[], double b[]);

void biir2lpdes(double fs, double nlpass, double nlstop, double a[], double b[])

{

int i,u,v; double wp,omp,gsa,t; wp=nlpass*2*pi;

omp=tan(wp/2.0); gsa=omp*omp; for (i=0; i<=2; i++) { u=i%2; }

for (i=0; i<=2; i++) { u=i%2;

b[i]=gsa*pow(2,u); } t=a[0];

for (i=0; i<=2; i++) { a[i]=a[i]/t;

v=i-1;

a[i]=gsa*pow(2,u)-sqrt(2)*omp*v+pow(-2,u);

b[i]=b[i]/t; } }

void main(void) { int i,j; int x_ad,y_da;

InitC5402(); /* initialize C5402 DSP */ OpenMcBSP();

fs=16000;

int *px = (int*)0x3000; int *py = (int*)0x3100; double w2,w1,w0; w2=w1=w0=0.0;

for ( ; ; )

{ /* IIR LP filter */ for (i=0; i<=1; i++) {

nlpass = 0.11-(i/10.0);

nlstop = 0.31-(i/10.0); biir2lpdes(fs,nlpass,nlstop,a,b);

for (j=-32000; j<=32000; j++) {

READAD50(); px = (int*)(0x3000);

x_ad = *px;

x = x_ad/32768.0; w2=x-a[1]*w1-a[2]*w0; y=b[0]*w2+b[1]*w1+b[2]*w0; w0=w1; w1=w2;

y_da=(int)(y*32768.0); py = (int*)(0x3100); *py = y_da;

WRITEAD50(); }

}

}

}

/*void PROCESSING(void) {

do the necessery operations here!*/

/*********************************************************************** ** End of File –– exp08.c

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