enum { TXT, BIN, WSPACE, UTF8, QUOT, ESC, SEP, CR, NL_EOLX, ..., NN };
enum { EXFIELD, INFIELD = 1*NN, INQUOT = 2*NN, CRSEEN = 3*NN } state;

while ((c = getc()) != EOF) {
    int ctype = cached->xlat[c];

    if () ... /* perhaps peel the most likely case(s) */
    switch (state + ctype) {
    case WSPACE: continue; /* nop: allow_whitespace test in xlat[] */
    case BIN: error(); /* again, resolved when constructing xlat[] */
    case TXT: state = INFIELD; putc(c); continue;
    case INFIELD+TXT: case INQUOT+TXT: case INQUOT+SEP: ... putc(c);
    ...
    case UTF8: case INFIELD+UTF8: ...accumulate/xlat...
    case CRSEEN+NL_EOLX: ...; state = 0; continue;
    case CRSEEN+...: error();
    default: error();
    }
    ...