1  typedef unsigned long sample;
       2  struct pam
       3  {
       4    sample maxval;
       5  };
       6  typedef sample *tuple;
       7  enum function
       8    {
       9      FN_MULTIPLY, FN_DIVIDE, FN_ADD, FN_SUBTRACT, FN_MIN, FN_MAX, FN_AND, FN_OR,
      10      FN_XOR, FN_NOT, FN_SHIFTLEFT, FN_SHIFTRIGHT
      11    };
      12  struct cmdlineInfo
      13  {
      14    enum function function;
      15    union
      16    {
      17      float divisor;
      18      unsigned int shiftCount;
      19    }
      20      u;
      21  };
      22  applyFunction (struct cmdlineInfo const cmdline, struct pam const inpam,
      23                 struct pam const outpam, tuple * const inputRow,
      24                 tuple * const outputRow)
      25  {
      26    float const oneOverDivisor = 1 / cmdline.u.divisor;
      27    int col;
      28    {
      29      int plane;
      30      {
      31        sample const inSample = inputRow[col][plane];
      32        sample outSample;
      33        switch (cmdline.function)
      34          {
      35          case FN_DIVIDE:
      36            outSample = ((unsigned int) ((inSample * oneOverDivisor) + 0.5));
      37            break;
      38          case FN_SHIFTLEFT:
      39            outSample = (inSample << cmdline.u.shiftCount) & outpam.maxval;
      40          }
      41        outputRow[col][plane] =
      42          ((outpam.maxval) < (outSample) ? (outpam.maxval) : (outSample));
      43      }
      44    }
      45  }