NKF ^(Module)

/*
 * Character code detection - Algorithm described in:
 * Ken Lunde. `Understanding Japanese Information Processing'
 * Sebastopol, CA: O'Reilly & Associates.
 */

static VALUE
rb_nkf_guess(obj, src)
     VALUE obj, src;
{
  unsigned char *p;
  unsigned char *pend;
  int sequence_counter = 0;

  StringValue(src);
  p = RSTRING(src)->ptr;
  pend = p + RSTRING(src)->len;
  if (p == pend) return INT2FIX(_UNKNOWN);

#define INCR do {\
    p++;\
    if (p==pend) return INT2FIX(_UNKNOWN);\
    sequence_counter++;\
    if (sequence_counter % 2 == 1 && *p != 0xa4)\
	sequence_counter = 0;\
    if (6 <= sequence_counter) {\
	sequence_counter = 0;\
	return INT2FIX(_EUC);\
    }\
}