const char *tocode,
const char *fromcode, const char *tocode,
static size_t choose_block (char *d, size_t dlen, int col,			    const char *tocode,			    encoder_t *encoder, size_t *wlen){  size_t n, nn;  n = dlen;  for (;;)  {    assert (d + n > d);    nn = try_block (d, n, tocode, encoder, wlen);    if (!nn && col + *wlen <= ENCWORD_LEN_MAX + 1)      break;    nn = (nn ? nn : n) - 1;    while ((d[nn] & 0xc0) == 0x80)      --nn;    assert (d + nn >= d);    if (!nn)      break;    n = nn;  }  return n;}