BaseNcoding.Base32.Decode C# (CSharp) Method

        public override byte[] Decode(string data)
        {
            unchecked
            {
                if (string.IsNullOrEmpty(data))
                    return new byte[0];

                int additionalBytes = 0, diff = 0, tempLen = 0;

                int lastSpecialInd = data.Length;
                while (data[lastSpecialInd - 1] == Special)
                    lastSpecialInd--;
                int tailLength = data.Length - lastSpecialInd;

                switch (tailLength)
                {
                    case 6:
                        additionalBytes = 4;
                        break;
                    case 4:
                        additionalBytes = 3;
                        break;
                    case 3:
                        additionalBytes = 2;
                        break;
                    case 1:
                        additionalBytes = 1;
                        break;
                }

                diff = tailLength - additionalBytes;
                tailLength = additionalBytes;
                tempLen = data.Length - diff;

                byte[] result = new byte[(tempLen + 7) / 8 * 5 - tailLength];
                int length5 = result.Length / 5 * 5;
                int x1, x2, x3, x4, x5, x6, x7, x8;

                int i, srcInd = 0;
                for (i = 0; i < length5; i += 5)
                {
                    x1 = InvAlphabet[data[srcInd++]];
                    x2 = InvAlphabet[data[srcInd++]];
                    x3 = InvAlphabet[data[srcInd++]];
                    x4 = InvAlphabet[data[srcInd++]];
                    x5 = InvAlphabet[data[srcInd++]];
                    x6 = InvAlphabet[data[srcInd++]];
                    x7 = InvAlphabet[data[srcInd++]];
                    x8 = InvAlphabet[data[srcInd++]];

                    result[i] = (byte)((x1 << 3) | ((x2 >> 2) & 0x07));
                    result[i + 1] = (byte)((x2 << 6) | ((x3 << 1) & 0x3E) | ((x4 >> 4) & 0x01));
                    result[i + 2] = (byte)((x4 << 4) | ((x5 >> 1) & 0xF));
                    result[i + 3] = (byte)((x5 << 7) | ((x6 << 2) & 0x7C) | ((x7 >> 3) & 0x03));
                    result[i + 4] = (byte)((x7 << 5) | (x8 & 0x1F));
                }

                switch (tailLength)
                {
                    case 4:
                        x1 = InvAlphabet[data[srcInd++]];
                        x2 = InvAlphabet[data[srcInd++]];
                        result[i] = (byte)((x1 << 3) | ((x2 >> 2) & 0x07));
                        break;
                    case 3:
                        x1 = InvAlphabet[data[srcInd++]];
                        x2 = InvAlphabet[data[srcInd++]];
                        x3 = InvAlphabet[data[srcInd++]];
                        x4 = InvAlphabet[data[srcInd++]];

                        result[i] = (byte)((x1 << 3) | ((x2 >> 2) & 0x07));
                        result[i + 1] = (byte)((x2 << 6) | ((x3 << 1) & 0x3E) | ((x4 >> 4) & 0x01));
                        break;
                    case 2:
                        x1 = InvAlphabet[data[srcInd++]];
                        x2 = InvAlphabet[data[srcInd++]];
                        x3 = InvAlphabet[data[srcInd++]];
                        x4 = InvAlphabet[data[srcInd++]];
                        x5 = InvAlphabet[data[srcInd++]];

                        result[i] = (byte)((x1 << 3) | ((x2 >> 2) & 0x07));
                        result[i + 1] = (byte)((x2 << 6) | ((x3 << 1) & 0x3E) | ((x4 >> 4) & 0x01));
                        result[i + 2] = (byte)((x4 << 4) | ((x5 >> 1) & 0xF));
                        break;
                    case 1:
                        x1 = InvAlphabet[data[srcInd++]];
                        x2 = InvAlphabet[data[srcInd++]];
                        x3 = InvAlphabet[data[srcInd++]];
                        x4 = InvAlphabet[data[srcInd++]];
                        x5 = InvAlphabet[data[srcInd++]];
                        x6 = InvAlphabet[data[srcInd++]];
                        x7 = InvAlphabet[data[srcInd++]];

                        result[i] = (byte)((x1 << 3) | ((x2 >> 2) & 0x07));
                        result[i + 1] = (byte)((x2 << 6) | ((x3 << 1) & 0x3E) | ((x4 >> 4) & 0x01));
                        result[i + 2] = (byte)((x4 << 4) | ((x5 >> 1) & 0xF));
                        result[i + 3] = (byte)((x5 << 7) | ((x6 << 2) & 0x7C) | ((x7 >> 3) & 0x03));
                        break;
                }

                return result;
            }
        }