SevenZip.Compression.LZMA.Base.GetLenToPosState C# (CSharp) Method

        public static uint GetLenToPosState(uint len)
        {
            len -= kMatchMinLen;
            if (len < kNumLenToPosStates)
                return len;
            return (uint)(kNumLenToPosStates - 1);
        }

        public void Code(
            Stream inStream,
            Stream outStream,
            long inSize,
            long outSize,
            ICodeProgress progress)
        {
            this.Init(inStream, outStream);
            Base.State state = new Base.State();
            state.Init();
            uint  distance = 0;
            uint  num1     = 0;
            uint  num2     = 0;
            uint  num3     = 0;
            ulong num4     = 0;
            ulong num5     = (ulong)outSize;

            if (num4 < num5)
            {
                if (this.m_IsMatchDecoders[(state.Index << 4)].Decode(this.m_RangeDecoder) != 0U)
                {
                    throw new DataErrorException();
                }
                state.UpdateChar();
                this.m_OutWindow.PutByte(this.m_LiteralDecoder.DecodeNormal(this.m_RangeDecoder, 0U, (byte)0));
                ++num4;
            }
            while (num4 < num5)
            {
                uint posState = (uint)num4 & this.m_PosStateMask;
                if (this.m_IsMatchDecoders[((state.Index << 4) + posState)].Decode(this.m_RangeDecoder) == 0U)
                {
                    byte prevByte = this.m_OutWindow.GetByte(0U);
                    this.m_OutWindow.PutByte(state.IsCharState() ? this.m_LiteralDecoder.DecodeNormal(this.m_RangeDecoder, (uint)num4, prevByte) : this.m_LiteralDecoder.DecodeWithMatchByte(this.m_RangeDecoder, (uint)num4, prevByte, this.m_OutWindow.GetByte(distance)));
                    state.UpdateChar();
                    ++num4;
                }
                else
                {
                    uint len;
                    if (this.m_IsRepDecoders[state.Index].Decode(this.m_RangeDecoder) == 1U)
                    {
                        if (this.m_IsRepG0Decoders[state.Index].Decode(this.m_RangeDecoder) == 0U)
                        {
                            if (this.m_IsRep0LongDecoders[((state.Index << 4) + posState)].Decode(this.m_RangeDecoder) == 0U)
                            {
                                state.UpdateShortRep();
                                this.m_OutWindow.PutByte(this.m_OutWindow.GetByte(distance));
                                ++num4;
                                continue;
                            }
                        }
                        else
                        {
                            uint num6;
                            if (this.m_IsRepG1Decoders[state.Index].Decode(this.m_RangeDecoder) == 0U)
                            {
                                num6 = num1;
                            }
                            else
                            {
                                if (this.m_IsRepG2Decoders[state.Index].Decode(this.m_RangeDecoder) == 0U)
                                {
                                    num6 = num2;
                                }
                                else
                                {
                                    num6 = num3;
                                    num3 = num2;
                                }
                                num2 = num1;
                            }
                            num1     = distance;
                            distance = num6;
                        }
                        len = this.m_RepLenDecoder.Decode(this.m_RangeDecoder, posState) + 2U;
                        state.UpdateRep();
                    }
                    else
                    {
                        num3 = num2;
                        num2 = num1;
                        num1 = distance;
                        len  = 2U + this.m_LenDecoder.Decode(this.m_RangeDecoder, posState);
                        state.UpdateMatch();
                        uint num6 = this.m_PosSlotDecoder[Base.GetLenToPosState(len)].Decode(this.m_RangeDecoder);
                        if (num6 >= 4U)
                        {
                            int  NumBitLevels = (int)(num6 >> 1) - 1;
                            uint num7         = (uint)((2 | (int)num6 & 1) << NumBitLevels);
                            distance = num6 >= 14U ? num7 + (this.m_RangeDecoder.DecodeDirectBits(NumBitLevels - 4) << 4) + this.m_PosAlignDecoder.ReverseDecode(this.m_RangeDecoder) : num7 + BitTreeDecoder.ReverseDecode(this.m_PosDecoders, (uint)((int)num7 - (int)num6 - 1), this.m_RangeDecoder, NumBitLevels);
                        }
                        else
                        {
                            distance = num6;
                        }
                    }
                    if ((ulong)distance >= (ulong)this.m_OutWindow.TrainSize + num4 || distance >= this.m_DictionarySizeCheck)
                    {
                        if (distance != uint.MaxValue)
                        {
                            throw new DataErrorException();
                        }
                        break;
                    }
                    this.m_OutWindow.CopyBlock(distance, len);
                    num4 += (ulong)len;
                }
            }
            this.m_OutWindow.Flush();
            this.m_OutWindow.ReleaseStream();
            this.m_RangeDecoder.ReleaseStream();
        }