fix ANSI C code generation

[wfg666]

This tool helped me a lot. But the generated ANSI C code is like this:

/* Digital filter designed by mkfilter/mkshape/gencode   A.J. Fisher
   Command line: /www/usr/fisher/helpers/mkfilter -Bu -Lp -o 4 -a 8.0000000000e-02 0.0000000000e+00 -l */

#define NZEROS 4
#define NPOLES 4
#define GAIN   4.474489752e+02

static float xv[NZEROS+1], yv[NPOLES+1];

static void filterloop()
  { for (;;)
      { xv[0] = xv[1]; xv[1] = xv[2]; xv[2] = xv[3]; xv[3] = xv[4]; 
        xv[4] = next input value / GAIN;
        yv[0] = yv[1]; yv[1] = yv[2]; yv[2] = yv[3]; yv[3] = yv[4]; 
        yv[4] =   (xv[0] + xv[4]) + 4 * (xv[1] + xv[3]) + 6 * xv[2]
                     + ( -0.2644548164 * yv[0]) + (  1.4034846714 * yv[1])
                     + ( -2.8673991091 * yv[2]) + (  2.6926109870 * yv[3]);
        next output value = yv[4];
      }
  }

which is not compilable. I edited the ANSI C generator and the code is like this:

/* Digital filter designed by mkfilter/mkshape/gencode   A.J. Fisher
   Command line: ./mkfilter -Bu -Lp -o 4 -a 8.0000000000e-02 0.0000000000e+00 -l */

static float filterloop(float next_input_value)
{
    const int NZEROS = 4;
    const int NPOLES = 4;
    const float GAIN = 4.474489752e+02;

    static float xv[NZEROS+1], yv[NPOLES+1];

    xv[0] = xv[1]; xv[1] = xv[2]; xv[2] = xv[3]; xv[3] = xv[4]; 
    xv[4] = next_input_value / GAIN;
    yv[0] = yv[1]; yv[1] = yv[2]; yv[2] = yv[3]; yv[3] = yv[4]; 
    yv[4] =   (xv[0] + xv[4]) + 4 * (xv[1] + xv[3]) + 6 * xv[2]
                     + ( -0.2644548164 * yv[0]) + (  1.4034846714 * yv[1])
                     + ( -2.8673991091 * yv[2]) + (  2.6926109870 * yv[3]);
    return yv[4];
}

[MikeCurrington]

Awesome, thanks for the fix - much appreciated.