gistfile1.c

int scoreMatrixRead(ScoreMatrix *sm, char x, char y) {
  int idx, jdx;

  switch (tolower(x)) {
    case 'a': idx = 0; break;
    case 'c': idx = 1; break;
    case 'g': idx = 2; break;
    case 't': idx = 3; break;
  }

  switch (tolower(y)) {
    case 'a': jdx = 0; break;
    case 'c': jdx = 1; break;
    case 'g': jdx = 2; break;
    case 't': jdx = 3; break;
  }

  return sm->matrix[idx][jdx];
}