Anyone please help me. I do not understand how to code the reverse code for CRC64. I know that reversal is possible and there exists Algorithm for reversing the CRC. The CRC
can be reversed when we input same number of characters as the size of the CRC in bytes.
CRC32 = 4 Bytes, CRC64 = 8 Bytes. If anyone knows how the coding and the logic, please help
me. Below is the CRC64 C# coding I converted from C++ project:

Code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CRC64
{
    public class cCRC64
    {


    public UInt64[] crc64_table = { 
	                0x0000000000000000, 0x42F0E1EBA9EA3693,
	                0x85E1C3D753D46D26, 0xC711223CFA3E5BB5,
	                0x493366450E42ECDF, 0x0BC387AEA7A8DA4C,
	                0xCCD2A5925D9681F9, 0x8E224479F47CB76A,
	                0x9266CC8A1C85D9BE, 0xD0962D61B56FEF2D,
	                0x17870F5D4F51B498, 0x5577EEB6E6BB820B,
	                0xDB55AACF12C73561, 0x99A54B24BB2D03F2,
	                0x5EB4691841135847, 0x1C4488F3E8F96ED4,
	                0x663D78FF90E185EF, 0x24CD9914390BB37C,
	                0xE3DCBB28C335E8C9, 0xA12C5AC36ADFDE5A,
	                0x2F0E1EBA9EA36930, 0x6DFEFF5137495FA3,
	                0xAAEFDD6DCD770416, 0xE81F3C86649D3285,
	                0xF45BB4758C645C51, 0xB6AB559E258E6AC2,
	                0x71BA77A2DFB03177, 0x334A9649765A07E4,
	                0xBD68D2308226B08E, 0xFF9833DB2BCC861D,
	                0x388911E7D1F2DDA8, 0x7A79F00C7818EB3B,
	                0xCC7AF1FF21C30BDE, 0x8E8A101488293D4D,
	                0x499B3228721766F8, 0x0B6BD3C3DBFD506B,
	                0x854997BA2F81E701, 0xC7B97651866BD192,
	                0x00A8546D7C558A27, 0x4258B586D5BFBCB4,
	                0x5E1C3D753D46D260, 0x1CECDC9E94ACE4F3,
	                0xDBFDFEA26E92BF46, 0x990D1F49C77889D5,
	                0x172F5B3033043EBF, 0x55DFBADB9AEE082C,
	                0x92CE98E760D05399, 0xD03E790CC93A650A,
	                0xAA478900B1228E31, 0xE8B768EB18C8B8A2,
	                0x2FA64AD7E2F6E317, 0x6D56AB3C4B1CD584,
	                0xE374EF45BF6062EE, 0xA1840EAE168A547D,
	                0x66952C92ECB40FC8, 0x2465CD79455E395B,
	                0x3821458AADA7578F, 0x7AD1A461044D611C,
	                0xBDC0865DFE733AA9, 0xFF3067B657990C3A,
	                0x711223CFA3E5BB50, 0x33E2C2240A0F8DC3,
	                0xF4F3E018F031D676, 0xB60301F359DBE0E5,
	                0xDA050215EA6C212F, 0x98F5E3FE438617BC,
	                0x5FE4C1C2B9B84C09, 0x1D14202910527A9A,
	                0x93366450E42ECDF0, 0xD1C685BB4DC4FB63,
	                0x16D7A787B7FAA0D6, 0x5427466C1E109645,
	                0x4863CE9FF6E9F891, 0x0A932F745F03CE02,
	                0xCD820D48A53D95B7, 0x8F72ECA30CD7A324,
	                0x0150A8DAF8AB144E, 0x43A04931514122DD,
	                0x84B16B0DAB7F7968, 0xC6418AE602954FFB,
	                0xBC387AEA7A8DA4C0, 0xFEC89B01D3679253,
	                0x39D9B93D2959C9E6, 0x7B2958D680B3FF75,
	                0xF50B1CAF74CF481F, 0xB7FBFD44DD257E8C,
	                0x70EADF78271B2539, 0x321A3E938EF113AA,
	                0x2E5EB66066087D7E, 0x6CAE578BCFE24BED,
	                0xABBF75B735DC1058, 0xE94F945C9C3626CB,
	                0x676DD025684A91A1, 0x259D31CEC1A0A732,
	                0xE28C13F23B9EFC87, 0xA07CF2199274CA14,
	                0x167FF3EACBAF2AF1, 0x548F120162451C62,
	                0x939E303D987B47D7, 0xD16ED1D631917144,
	                0x5F4C95AFC5EDC62E, 0x1DBC74446C07F0BD,
	                0xDAAD56789639AB08, 0x985DB7933FD39D9B,
	                0x84193F60D72AF34F, 0xC6E9DE8B7EC0C5DC,
	                0x01F8FCB784FE9E69, 0x43081D5C2D14A8FA,
	                0xCD2A5925D9681F90, 0x8FDAB8CE70822903,
	                0x48CB9AF28ABC72B6, 0x0A3B7B1923564425,
	                0x70428B155B4EAF1E, 0x32B26AFEF2A4998D,
	                0xF5A348C2089AC238, 0xB753A929A170F4AB,
	                0x3971ED50550C43C1, 0x7B810CBBFCE67552,
	                0xBC902E8706D82EE7, 0xFE60CF6CAF321874,
	                0xE224479F47CB76A0, 0xA0D4A674EE214033,
	                0x67C58448141F1B86, 0x253565A3BDF52D15,
	                0xAB1721DA49899A7F, 0xE9E7C031E063ACEC,
	                0x2EF6E20D1A5DF759, 0x6C0603E6B3B7C1CA,
	                0xF6FAE5C07D3274CD, 0xB40A042BD4D8425E,
	                0x731B26172EE619EB, 0x31EBC7FC870C2F78,
	                0xBFC9838573709812, 0xFD39626EDA9AAE81,
	                0x3A28405220A4F534, 0x78D8A1B9894EC3A7,
	                0x649C294A61B7AD73, 0x266CC8A1C85D9BE0,
	                0xE17DEA9D3263C055, 0xA38D0B769B89F6C6,
	                0x2DAF4F0F6FF541AC, 0x6F5FAEE4C61F773F,
	                0xA84E8CD83C212C8A, 0xEABE6D3395CB1A19,
	                0x90C79D3FEDD3F122, 0xD2377CD44439C7B1,
	                0x15265EE8BE079C04, 0x57D6BF0317EDAA97,
	                0xD9F4FB7AE3911DFD, 0x9B041A914A7B2B6E,
	                0x5C1538ADB04570DB, 0x1EE5D94619AF4648,
	                0x02A151B5F156289C, 0x4051B05E58BC1E0F,
	                0x87409262A28245BA, 0xC5B073890B687329,
	                0x4B9237F0FF14C443, 0x0962D61B56FEF2D0,
	                0xCE73F427ACC0A965, 0x8C8315CC052A9FF6,
	                0x3A80143F5CF17F13, 0x7870F5D4F51B4980,
	                0xBF61D7E80F251235, 0xFD913603A6CF24A6,
	                0x73B3727A52B393CC, 0x31439391FB59A55F,
	                0xF652B1AD0167FEEA, 0xB4A25046A88DC879,
	                0xA8E6D8B54074A6AD, 0xEA16395EE99E903E,
	                0x2D071B6213A0CB8B, 0x6FF7FA89BA4AFD18,
	                0xE1D5BEF04E364A72, 0xA3255F1BE7DC7CE1,
	                0x64347D271DE22754, 0x26C49CCCB40811C7,
	                0x5CBD6CC0CC10FAFC, 0x1E4D8D2B65FACC6F,
	                0xD95CAF179FC497DA, 0x9BAC4EFC362EA149,
	                0x158E0A85C2521623, 0x577EEB6E6BB820B0,
	                0x906FC95291867B05, 0xD29F28B9386C4D96,
	                0xCEDBA04AD0952342, 0x8C2B41A1797F15D1,
	                0x4B3A639D83414E64, 0x09CA82762AAB78F7,
	                0x87E8C60FDED7CF9D, 0xC51827E4773DF90E,
	                0x020905D88D03A2BB, 0x40F9E43324E99428,
	                0x2CFFE7D5975E55E2, 0x6E0F063E3EB46371,
	                0xA91E2402C48A38C4, 0xEBEEC5E96D600E57,
	                0x65CC8190991CB93D, 0x273C607B30F68FAE,
	                0xE02D4247CAC8D41B, 0xA2DDA3AC6322E288,
	                0xBE992B5F8BDB8C5C, 0xFC69CAB42231BACF,
	                0x3B78E888D80FE17A, 0x7988096371E5D7E9,
	                0xF7AA4D1A85996083, 0xB55AACF12C735610,
	                0x724B8ECDD64D0DA5, 0x30BB6F267FA73B36,
	                0x4AC29F2A07BFD00D, 0x08327EC1AE55E69E,
	                0xCF235CFD546BBD2B, 0x8DD3BD16FD818BB8,
	                0x03F1F96F09FD3CD2, 0x41011884A0170A41,
	                0x86103AB85A2951F4, 0xC4E0DB53F3C36767,
	                0xD8A453A01B3A09B3, 0x9A54B24BB2D03F20,
	                0x5D45907748EE6495, 0x1FB5719CE1045206,
	                0x919735E51578E56C, 0xD367D40EBC92D3FF,
	                0x1476F63246AC884A, 0x568617D9EF46BED9,
	                0xE085162AB69D5E3C, 0xA275F7C11F7768AF,
	                0x6564D5FDE549331A, 0x279434164CA30589,
	                0xA9B6706FB8DFB2E3, 0xEB46918411358470,
	                0x2C57B3B8EB0BDFC5, 0x6EA7525342E1E956,
	                0x72E3DAA0AA188782, 0x30133B4B03F2B111,
	                0xF7021977F9CCEAA4, 0xB5F2F89C5026DC37,
	                0x3BD0BCE5A45A6B5D, 0x79205D0E0DB05DCE,
	                0xBE317F32F78E067B, 0xFCC19ED95E6430E8,
	                0x86B86ED5267CDBD3, 0xC4488F3E8F96ED40,
	                0x0359AD0275A8B6F5, 0x41A94CE9DC428066,
	                0xCF8B0890283E370C, 0x8D7BE97B81D4019F,
	                0x4A6ACB477BEA5A2A, 0x089A2AACD2006CB9,
	                0x14DEA25F3AF9026D, 0x562E43B4931334FE,
	                0x913F6188692D6F4B, 0xD3CF8063C0C759D8,
	                0x5DEDC41A34BBEEB2, 0x1F1D25F19D51D821,
	                0xD80C07CD676F8394, 0x9AFCE626CE85B507
                };


        /* Initialize a CRC accumulator */
        public void Init_crc(ref UInt64 crc)
        {
	        crc = 0xffffffffffffffff;
        }

        /* Finish a CRC calculation */
        public void Fin_crc(ref UInt64 crc)
        {
	        crc ^= 0xffffffffffffffff;
        }

        
        /* Accumulate some (more) bytes into a CRC */
        public void Calc_crc(ref UInt64 crc, Byte[] pbData, uint len)
        {
	        /* Constant table for CRC calculation */
            uint __len = len;
            uint pos = 0;
            byte byteInput = 0;

	        while (__len-- > 0)
	        {
                        uint __tab_index = ((uint)(crc >> 56) ^ pbData[pos++]) & 0xFF;
		        crc = crc64_table[__tab_index] ^ (crc << 8);
	        }

        }

    }
}