how to create C-mex function

How to create suitable mex gateway function coresponduing to the following C function (decimal to binary conversion)?

void deci2bin( int x, int n, double* output){
double *temp;
int i;
temp = (double *)mxMalloc(sizeof(double)*n);

i=0;
while(x>=0 && i<n){
  temp[i] = x%2;
  i++;
}
for(i=0;i<n;i++)
  output[i] = temp[n-1-i];
}

Thanks in advance for any help.

[Walter Roberson]

Have you considered looking at the source of dec2bin() and removing the char() and the +'0' from the algorithm given there?