private void getAndMoveToFrontDecode()

in lib-src/bzip2/org/apache/tools/bzip2r/CBZip2InputStream.java [626:826]
173 lines of code
30 McCabe index (conditional complexity)

    private void getAndMoveToFrontDecode() throws IOException {
        char[] yy = new char[256];
        int i, j, nextSym, limitLast;
        int EOB, groupNo, groupPos;

        limitLast = baseBlockSize * blockSize100k;
        origPtr = bsGetIntVS(24);

        recvDecodingTables();
        EOB = nInUse + 1;
        groupNo = -1;
        groupPos = 0;

        /*
          Setting up the unzftab entries here is not strictly
          necessary, but it does save having to do it later
          in a separate pass, and so saves a block's worth of
          cache misses.
        */
        for (i = 0; i <= 255; i++) {
            unzftab[i] = 0;
        }

        for (i = 0; i <= 255; i++) {
            yy[i] = (char) i;
        }

        last = -1;

        {
            int zt, zn, zvec, zj;
            if (groupPos == 0) {
                groupNo++;
                groupPos = G_SIZE;
            }
            groupPos--;
            zt = selector[groupNo];
            zn = minLens[zt];
            zvec = bsR(zn);
            while (zvec > limit[zt][zn]) {
                zn++;
                {
                    {
                        while (bsLive < 1) {
                            int zzi = 0;
                            try {
                                zzi = readBs();
                            } catch (IOException e) {
                                compressedStreamEOF();
                            }
                            if (zzi == -1) {
                                compressedStreamEOF();
                            }
                            bsBuff = (bsBuff << 8) | (zzi & 0xff);
                            bsLive += 8;
                        }
                    }
                    zj = (bsBuff >> (bsLive - 1)) & 1;
                    bsLive--;
                }
                zvec = (zvec << 1) | zj;
            }
            nextSym = perm[zt][zvec - base[zt][zn]];
        }

        while (true) {

            if (nextSym == EOB) {
                break;
            }

            if (nextSym == RUNA || nextSym == RUNB) {
                char ch;
                int s = -1;
                int N = 1;
                do {
                    if (nextSym == RUNA) {
                        s = s + (0 + 1) * N;
                    } else if (nextSym == RUNB) {
                        s = s + (1 + 1) * N;
                           }
                    N = N * 2;
                    {
                        int zt, zn, zvec, zj;
                        if (groupPos == 0) {
                            groupNo++;
                            groupPos = G_SIZE;
                        }
                        groupPos--;
                        zt = selector[groupNo];
                        zn = minLens[zt];
                        zvec = bsR(zn);
                        while (zvec > limit[zt][zn]) {
                            zn++;
                            {
                                {
                                    while (bsLive < 1) {
                                        int zzi = 0;
                                        try {
                                            zzi = readBs();
                                        } catch (IOException e) {
                                            compressedStreamEOF();
                                        }
                                        if (zzi == -1) {
                                            compressedStreamEOF();
                                        }
                                        bsBuff = (bsBuff << 8) | (zzi & 0xff);
                                        bsLive += 8;
                                    }
                                }
                                zj = (bsBuff >> (bsLive - 1)) & 1;
                                bsLive--;
                            }
                            zvec = (zvec << 1) | zj;
                        }
                        nextSym = perm[zt][zvec - base[zt][zn]];
                    }
                } while (nextSym == RUNA || nextSym == RUNB);

                s++;
                ch = seqToUnseq[yy[0]];
                unzftab[ch] += s;

                while (s > 0) {
                    last++;
                    ll8[last] = ch;
                    s--;
                }

                if (last >= limitLast) {
                    blockOverrun();
                }
                continue;
            } else {
                char tmp;
                last++;
                if (last >= limitLast) {
                    blockOverrun();
                }

                tmp = yy[nextSym - 1];
                unzftab[seqToUnseq[tmp]]++;
                ll8[last] = seqToUnseq[tmp];

                /*
                  This loop is hammered during decompression,
                  hence the unrolling.

                  for (j = nextSym-1; j > 0; j--) yy[j] = yy[j-1];
                */

                j = nextSym - 1;
                for (; j > 3; j -= 4) {
                    yy[j]     = yy[j - 1];
                    yy[j - 1] = yy[j - 2];
                    yy[j - 2] = yy[j - 3];
                    yy[j - 3] = yy[j - 4];
                }
                for (; j > 0; j--) {
                    yy[j] = yy[j - 1];
                }

                yy[0] = tmp;
                {
                    int zt, zn, zvec, zj;
                    if (groupPos == 0) {
                        groupNo++;
                        groupPos = G_SIZE;
                    }
                    groupPos--;
                    zt = selector[groupNo];
                    zn = minLens[zt];
                    zvec = bsR(zn);
                    while (zvec > limit[zt][zn]) {
                        zn++;
                        {
                            {
                                while (bsLive < 1) {
                                    int zzi;
                                    char thech = 0;
                                    try {
                                        thech = (char) readBs();
                                    } catch (IOException e) {
                                        compressedStreamEOF();
                                    }
                                    zzi = thech;
                                    bsBuff = (bsBuff << 8) | (zzi & 0xff);
                                    bsLive += 8;
                                }
                            }
                            zj = (bsBuff >> (bsLive - 1)) & 1;
                            bsLive--;
                        }
                        zvec = (zvec << 1) | zj;
                    }
                    nextSym = perm[zt][zvec - base[zt][zn]];
                }
                continue;
            }
        }
    }