System.Globalization.FormatProvider.Number.FindSection C# (CSharp) Method

            private static unsafe int FindSection(string format, int section)
            {
                int src;
                char ch;

                if (section == 0)
                    return 0;

                fixed (char* pFormat = format)
                {
                    src = 0;
                    for (;;)
                    {
                        switch (ch = pFormat[src++])
                        {
                            case '\'':
                            case '"':
                                while (pFormat[src] != 0 && pFormat[src++] != ch)
                                    ;
                                break;
                            case '\\':
                                if (pFormat[src] != 0)
                                    src++;
                                break;
                            case ';':
                                if (--section != 0)
                                    break;
                                if (pFormat[src] != 0 && pFormat[src] != ';')
                                    return src;
                                goto case '\0';
                            case '\0':
                                return 0;
                        }
                    }
                }
            }