encode() — netty Function Reference

Source Code

codec-compression/src/main/java/io/netty/handler/codec/compression/Bzip2MTFAndRLE2StageEncoder.java lines 80–156

    void encode() {
        final int bwtLength = this.bwtLength;
        final boolean[] bwtValuesPresent = this.bwtValuesPresent;
        final int[] bwtBlock = this.bwtBlock;
        final char[] mtfBlock = this.mtfBlock;
        final int[] mtfSymbolFrequencies = this.mtfSymbolFrequencies;
        final byte[] huffmanSymbolMap = new byte[256];
        final Bzip2MoveToFrontTable symbolMTF = new Bzip2MoveToFrontTable();

        int totalUniqueValues = 0;
        for (int i = 0; i < huffmanSymbolMap.length; i++) {
            if (bwtValuesPresent[i]) {
                huffmanSymbolMap[i] = (byte) totalUniqueValues++;
            }
        }
        final int endOfBlockSymbol = totalUniqueValues + 1;

        int mtfIndex = 0;
        int repeatCount = 0;
        int totalRunAs = 0;
        int totalRunBs = 0;
        for (int i = 0; i < bwtLength; i++) {
            // Move To Front
            final int mtfPosition = symbolMTF.valueToFront(huffmanSymbolMap[bwtBlock[i] & 0xff]);
            // Run Length Encode
            if (mtfPosition == 0) {
                repeatCount++;
            } else {
                if (repeatCount > 0) {
                    repeatCount--;
                    while (true) {
                        if ((repeatCount & 1) == 0) {
                            mtfBlock[mtfIndex++] = HUFFMAN_SYMBOL_RUNA;
                            totalRunAs++;
                        } else {
                            mtfBlock[mtfIndex++] = HUFFMAN_SYMBOL_RUNB;
                            totalRunBs++;
                        }

                        if (repeatCount <= 1) {
                            break;
                        }
                        repeatCount = (repeatCount - 2) >>> 1;
                    }
                    repeatCount = 0;
                }
                mtfBlock[mtfIndex++] = (char) (mtfPosition + 1);
                mtfSymbolFrequencies[mtfPosition + 1]++;
            }
        }

        if (repeatCount > 0) {
            repeatCount--;
            while (true) {
                if ((repeatCount & 1) == 0) {
                    mtfBlock[mtfIndex++] = HUFFMAN_SYMBOL_RUNA;
                    totalRunAs++;
                } else {
                    mtfBlock[mtfIndex++] = HUFFMAN_SYMBOL_RUNB;
                    totalRunBs++;
                }

                if (repeatCount <= 1) {
                    break;
                }
                repeatCount = (repeatCount - 2) >>> 1;
            }
        }

        mtfBlock[mtfIndex] = (char) endOfBlockSymbol;
        mtfSymbolFrequencies[endOfBlockSymbol]++;
        mtfSymbolFrequencies[HUFFMAN_SYMBOL_RUNA] += totalRunAs;
        mtfSymbolFrequencies[HUFFMAN_SYMBOL_RUNB] += totalRunBs;

        mtfLength = mtfIndex + 1;
        alphabetSize = endOfBlockSymbol + 1;
    }