private void setupRandPartA() throws IOException {
        if (this.su_i2 <= this.last) {
            this.su_chPrev = this.su_ch2;
            int su_ch2Shadow = this.data.ll8[this.su_tPos] & 0xff;
            this.su_tPos = this.data.tt[this.su_tPos];
            if (this.su_rNToGo == 0) {
                this.su_rNToGo = Rand.rNums(this.su_rTPos) - 1;
                if (++this.su_rTPos == 512) {
                    this.su_rTPos = 0;
                }
            } else {
                this.su_rNToGo--;
            }
            this.su_ch2 = su_ch2Shadow ^= (this.su_rNToGo == 1) ? 1 : 0;
            this.su_i2++;
            this.currentChar = su_ch2Shadow;
            this.currentState = RAND_PART_B_STATE;
            this.crc.updateCRC(su_ch2Shadow);
        } else {
            endBlock();
            initBlock();
            setupBlock();
        }
    }