iir1.c

dsp6713开发板的许多例程.对入门特别有用

void iircas4_1(const int n, const short (* restrict c)[4], int (*d)[2], int *y)
{
    int k0, k1, i;
    int y0 = y[0];
    int y1 = y[1];

    _nassert(((int)(c) & 0x3) == 0);

    #pragma MUST_ITERATE(10) 
 
    for (i = 0; i < n; i++)
    {
        k0 = c[i][1] * (d[i][1] >> 16) + c[i][0] * (d[i][0] >> 16) + y0;
        y0 = c[i][3] * (d[i][1] >> 16) + c[i][2] * (d[i][0] >> 16) + k0;
        k1 = c[i][1] * (d[i][0] >> 16) + c[i][0] * (k0 >> 16) + y1;
        y1 = c[i][3] * (d[i][0] >> 16) + c[i][2] * (k0 >> 16) + k1;

        d[i][1] = k0;
        d[i][0] = k1; 
    }
 
    y[0] = y0;
    y[1] = y1;
}