nextSymbol() — netty Function Reference

Source Code

codec-compression/src/main/java/io/netty/handler/codec/compression/Bzip2HuffmanStageDecoder.java lines 173–202

    int nextSymbol() {
        // Move to next group selector if required
        if (++groupPosition % HUFFMAN_GROUP_RUN_LENGTH == 0) {
            groupIndex++;
            if (groupIndex == selectors.length) {
                throw new DecompressionException("error decoding block");
            }
            currentTable = selectors[groupIndex] & 0xff;
        }

        final Bzip2BitReader reader = this.reader;
        final int currentTable = this.currentTable;
        final int[] tableLimits = codeLimits[currentTable];
        final int[] tableBases = codeBases[currentTable];
        final int[] tableSymbols = codeSymbols[currentTable];
        int codeLength = minimumLengths[currentTable];

        // Starting with the minimum bit length for the table, read additional bits one at a time
        // until a complete code is recognised
        int codeBits = reader.readBits(codeLength);
        for (; codeLength <= HUFFMAN_DECODE_MAX_CODE_LENGTH; codeLength++) {
            if (codeBits <= tableLimits[codeLength]) {
                // Convert the code to a symbol index and return
                return tableSymbols[codeBits - tableBases[codeLength]];
            }
            codeBits = codeBits << 1 | reader.readBits(1);
        }

        throw new DecompressionException("a valid code was not recognised");
    }