/* This function tests, whether the ISO 10646/Unicode character code
 * ucs represents a nonspacing or enclosing combining character. Xterm
 * handles these characters by overstriking the previous glyph without
 * advancing the cursor. This function returns 1 for precisely all
 * characters with a general category code Mn or Me in the Unicode-3.0
 * database, and it returns 0 for anything else. */

int iscombining(int ucs)
{
  /* sorted list of non-overlapping intervals */
  static struct interval {
    unsigned short first;
    unsigned short last;
  } combining[] = {
    { 0x0300, 0x034E }, { 0x0360, 0x0362 }, { 0x0483, 0x0486 },
    { 0x0488, 0x0489 }, { 0x0591, 0x05A1 }, { 0x05A3, 0x05B9 },
    { 0x05BB, 0x05BD }, { 0x05BF, 0x05BF }, { 0x05C1, 0x05C2 },
    { 0x05C4, 0x05C4 }, { 0x064B, 0x0655 }, { 0x0670, 0x0670 },
    { 0x06D6, 0x06E4 }, { 0x06E7, 0x06E8 }, { 0x06EA, 0x06ED },
    { 0x0711, 0x0711 }, { 0x0730, 0x074A }, { 0x07A6, 0x07B0 },
    { 0x0901, 0x0902 }, { 0x093C, 0x093C }, { 0x0941, 0x0948 },
    { 0x094D, 0x094D }, { 0x0951, 0x0954 }, { 0x0962, 0x0963 },
    { 0x0981, 0x0981 }, { 0x09BC, 0x09BC }, { 0x09C1, 0x09C4 },
    { 0x09CD, 0x09CD }, { 0x09E2, 0x09E3 }, { 0x0A02, 0x0A02 },
    { 0x0A3C, 0x0A3C }, { 0x0A41, 0x0A42 }, { 0x0A47, 0x0A48 },
    { 0x0A4B, 0x0A4D }, { 0x0A70, 0x0A71 }, { 0x0A81, 0x0A82 },
    { 0x0ABC, 0x0ABC }, { 0x0AC1, 0x0AC5 }, { 0x0AC7, 0x0AC8 },
    { 0x0ACD, 0x0ACD }, { 0x0B01, 0x0B01 }, { 0x0B3C, 0x0B3C },
    { 0x0B3F, 0x0B3F }, { 0x0B41, 0x0B43 }, { 0x0B4D, 0x0B4D },
    { 0x0B56, 0x0B56 }, { 0x0B82, 0x0B82 }, { 0x0BC0, 0x0BC0 },
    { 0x0BCD, 0x0BCD }, { 0x0C3E, 0x0C40 }, { 0x0C46, 0x0C48 },
    { 0x0C4A, 0x0C4D }, { 0x0C55, 0x0C56 }, { 0x0CBF, 0x0CBF },
    { 0x0CC6, 0x0CC6 }, { 0x0CCC, 0x0CCD }, { 0x0D41, 0x0D43 },
    { 0x0D4D, 0x0D4D }, { 0x0DCA, 0x0DCA }, { 0x0DD2, 0x0DD4 },
    { 0x0DD6, 0x0DD6 }, { 0x0E31, 0x0E31 }, { 0x0E34, 0x0E3A },
    { 0x0E47, 0x0E4E }, { 0x0EB1, 0x0EB1 }, { 0x0EB4, 0x0EB9 },
    { 0x0EBB, 0x0EBC }, { 0x0EC8, 0x0ECD }, { 0x0F18, 0x0F19 },
    { 0x0F35, 0x0F35 }, { 0x0F37, 0x0F37 }, { 0x0F39, 0x0F39 },
    { 0x0F71, 0x0F7E }, { 0x0F80, 0x0F84 }, { 0x0F86, 0x0F87 },
    { 0x0F90, 0x0F97 }, { 0x0F99, 0x0FBC }, { 0x0FC6, 0x0FC6 },
    { 0x102D, 0x1030 }, { 0x1032, 0x1032 }, { 0x1036, 0x1037 },
    { 0x1039, 0x1039 }, { 0x1058, 0x1059 }, { 0x17B7, 0x17BD },
    { 0x17C6, 0x17C6 }, { 0x17C9, 0x17D3 }, { 0x18A9, 0x18A9 },
    { 0x20D0, 0x20E3 }, { 0x302A, 0x302F }, { 0x3099, 0x309A },
    { 0xFB1E, 0xFB1E }, { 0xFE20, 0xFE23 }
  };
  int min = 0;
  int max = sizeof(combining) / sizeof(struct interval) - 1;
  int mid;

  /* first quick check for Latin-1 etc. characters */
  if (ucs < combining[0].first)
    return 0;

  /* binary search in table */
  while (max >= min) {
    mid = (min + max) / 2;
    if (combining[mid].last < ucs)
      min = mid + 1;
    else if (combining[mid].first > ucs)
      max = mid - 1;
    else if (combining[mid].first <= ucs && combining[mid].last >= ucs)
      return 1;
  }

  return 0;
}