LZSS

void Decode(void)   /* Just the reverse of Encode(). */
{
    int  i, j, k, r, c;
    unsigned int  flags;

    for (i = 0; i < N - F; i++) text_buf[i] = ' ';
    r = N - F;  flags = 0;
    for ( ; ; ) {
        if (((flags >>= 1) & 256) == 0) {
            if ((c = getc(infile)) == EOF) break;
            flags = c | 0xff00;     /* uses higher byte cleverly */
        }                           /* to count eight */
        if (flags & 1) {
            if ((c = getc(infile)) == EOF) break;
            putc(c, outfile);  text_buf[r++] = c;  r &= (N - 1);
        } else {
            if ((i = getc(infile)) == EOF) break;
            if ((j = getc(infile)) == EOF) break;
            i |= ((j & 0xf0) << 4);  j = (j & 0x0f) + THRESHOLD;
            for (k = 0; k <= j; k++) {
                c = text_buf[(i + k) & (N - 1)];
                putc(c, outfile);  text_buf[r++] = c;  r &= (N - 1);
            }
        }
    }
}