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I have to translate partially one old and large application from Delphi to .NET (C#). Here is one strange (at least for me) implementation of CRC32:
function CRC32(CRC: LongWord; Data: Pointer; DataSize: LongWord): LongWord; assembler;
asm
AND EDX,EDX
JZ @Exit
AND ECX,ECX
JLE @Exit
PUSH EBX
PUSH EDI
XOR EBX,EBX
LEA EDI,CS:[OFFSET @CRC32]
@Start: MOV BL,AL
SHR EAX,8
XOR BL,[EDX]
XOR EAX,[EDI + EBX * 4]
INC EDX
DEC ECX
JNZ @Start
POP EDI
POP EBX
@Exit: RET
DB 0, 0, 0, 0, 0 // Align Table
@CRC32: DD 000000000h, 077073096h, 0EE0E612Ch, 0990951BAh
DD 0076DC419h, 0706AF48Fh, 0E963A535h, 09E6495A3h
DD 00EDB8832h, 079DCB8A4h, 0E0D5E91Eh, 097D2D988h
DD 009B64C2Bh, 07EB17CBDh, 0E7B82D07h, 090BF1D91h
DD 01DB71064h, 06AB020F2h, 0F3B97148h, 084BE41DEh
DD 01ADAD47Dh, 06DDDE4EBh, 0F4D4B551h, 083D385C7h
DD 0136C9856h, 0646BA8C0h, 0FD62F97Ah, 08A65C9ECh
DD 014015C4Fh, 063066CD9h, 0FA0F3D63h, 08D080DF5h
DD 03B6E20C8h, 04C69105Eh, 0D56041E4h, 0A2677172h
DD 03C03E4D1h, 04B04D447h, 0D20D85FDh, 0A50AB56Bh
DD 035B5A8FAh, 042B2986Ch, 0DBBBC9D6h, 0ACBCF940h
DD 032D86CE3h, 045DF5C75h, 0DCD60DCFh, 0ABD13D59h
DD 026D930ACh, 051DE003Ah, 0C8D75180h, 0BFD06116h
DD 021B4F4B5h, 056B3C423h, 0CFBA9599h, 0B8BDA50Fh
DD 02802B89Eh, 05F058808h, 0C60CD9B2h, 0B10BE924h
DD 02F6F7C87h, 058684C11h, 0C1611DABh, 0B6662D3Dh
DD 076DC4190h, 001DB7106h, 098D220BCh, 0EFD5102Ah
DD 071B18589h, 006B6B51Fh, 09FBFE4A5h, 0E8B8D433h
DD 07807C9A2h, 00F00F934h, 09609A88Eh, 0E10E9818h
DD 07F6A0DBBh, 0086D3D2Dh, 091646C97h, 0E6635C01h
DD 06B6B51F4h, 01C6C6162h, 0856530D8h, 0F262004Eh
DD 06C0695EDh, 01B01A57Bh, 08208F4C1h, 0F50FC457h
DD 065B0D9C6h, 012B7E950h, 08BBEB8EAh, 0FCB9887Ch
DD 062DD1DDFh, 015DA2D49h, 08CD37CF3h, 0FBD44C65h
DD 04DB26158h, 03AB551CEh, 0A3BC0074h, 0D4BB30E2h
DD 04ADFA541h, 03DD895D7h, 0A4D1C46Dh, 0D3D6F4FBh
DD 04369E96Ah, 0346ED9FCh, 0AD678846h, 0DA60B8D0h
DD 044042D73h, 033031DE5h, 0AA0A4C5Fh, 0DD0D7CC9h
DD 05005713Ch, 0270241AAh, 0BE0B1010h, 0C90C2086h
DD 05768B525h, 0206F85B3h, 0B966D409h, 0CE61E49Fh
DD 05EDEF90Eh, 029D9C998h, 0B0D09822h, 0C7D7A8B4h
DD 059B33D17h, 02EB40D81h, 0B7BD5C3Bh, 0C0BA6CADh
DD 0EDB88320h, 09ABFB3B6h, 003B6E20Ch, 074B1D29Ah
DD 0EAD54739h, 09DD277AFh, 004DB2615h, 073DC1683h
DD 0E3630B12h, 094643B84h, 00D6D6A3Eh, 07A6A5AA8h
DD 0E40ECF0Bh, 09309FF9Dh, 00A00AE27h, 07D079EB1h
DD 0F00F9344h, 08708A3D2h, 01E01F268h, 06906C2FEh
DD 0F762575Dh, 0806567CBh, 0196C3671h, 06E6B06E7h
DD 0FED41B76h, 089D32BE0h, 010DA7A5Ah, 067DD4ACCh
DD 0F9B9DF6Fh, 08EBEEFF9h, 017B7BE43h, 060B08ED5h
DD 0D6D6A3E8h, 0A1D1937Eh, 038D8C2C4h, 04FDFF252h
DD 0D1BB67F1h, 0A6BC5767h, 03FB506DDh, 048B2364Bh
DD 0D80D2BDAh, 0AF0A1B4Ch, 036034AF6h, 041047A60h
DD 0DF60EFC3h, 0A867DF55h, 0316E8EEFh, 04669BE79h
DD 0CB61B38Ch, 0BC66831Ah, 0256FD2A0h, 05268E236h
DD 0CC0C7795h, 0BB0B4703h, 0220216B9h, 05505262Fh
DD 0C5BA3BBEh, 0B2BD0B28h, 02BB45A92h, 05CB36A04h
DD 0C2D7FFA7h, 0B5D0CF31h, 02CD99E8Bh, 05BDEAE1Dh
DD 09B64C2B0h, 0EC63F226h, 0756AA39Ch, 0026D930Ah
DD 09C0906A9h, 0EB0E363Fh, 072076785h, 005005713h
DD 095BF4A82h, 0E2B87A14h, 07BB12BAEh, 00CB61B38h
DD 092D28E9Bh, 0E5D5BE0Dh, 07CDCEFB7h, 00BDBDF21h
DD 086D3D2D4h, 0F1D4E242h, 068DDB3F8h, 01FDA836Eh
DD 081BE16CDh, 0F6B9265Bh, 06FB077E1h, 018B74777h
DD 088085AE6h, 0FF0F6A70h, 066063BCAh, 011010B5Ch
DD 08F659EFFh, 0F862AE69h, 0616BFFD3h, 0166CCF45h
DD 0A00AE278h, 0D70DD2EEh, 04E048354h, 03903B3C2h
DD 0A7672661h, 0D06016F7h, 04969474Dh, 03E6E77DBh
DD 0AED16A4Ah, 0D9D65ADCh, 040DF0B66h, 037D83BF0h
DD 0A9BCAE53h, 0DEBB9EC5h, 047B2CF7Fh, 030B5FFE9h
DD 0BDBDF21Ch, 0CABAC28Ah, 053B39330h, 024B4A3A6h
DD 0BAD03605h, 0CDD70693h, 054DE5729h, 023D967BFh
DD 0B3667A2Eh, 0C4614AB8h, 05D681B02h, 02A6F2B94h
DD 0B40BBE37h, 0C30C8EA1h, 05A05DF1Bh, 02D02EF8Dh
DD 074726F50h, 0736E6F69h, 0706F4320h, 067697279h
DD 028207468h, 031202963h, 020393939h, 048207962h
DD 06E656761h, 064655220h, 06E616D64h, 06FBBA36Eh
end;
It's used now and it's somehow working, because data are sent through network and destination devices are processed them OK. I need to achieve the same result from C# function and for this reason i played with most recommended on StackOverflow solution related to CRC32 in C# by [)amien, link here: But I am getting different results:
//Old-Delphi
procedure TestCrc();
var
ret: LongWord;
const
lArr: array[0..2] of Byte = (49, 50, 51); //"123"
begin
ret := CRC32(0, @lArr, Length(lArr)); //1997126336
//print IntToStr(ret); //1997126336
end
and in C#
//New-C#
static void Main(string[] args)
{
Crc32 crc32 = new Crc32(); //Using Default ctor
String hash = String.Empty;
string testStr = "123"; //in bytes {49, 50, 51}
byte[] out_bytes = crc32.ComputeHash(Encoding.ASCII.GetBytes(testStr));
foreach (byte b in out_bytes) hash += b.ToString("x2").ToLower();
Console.WriteLine("CRC-32 is {0} ({1})", hash, BitConverter.ToUInt32(out_bytes, 0));
//Output is Uint32 value = 3529721992
}
I don't know where is the difference - maybe in tables and seed? Or maybe better solution to wrap old functionality in DLL and access it from new C# application via COM?
Please advice...
476
I have "emulated" the assembly code you posted. It gives the same result of your test (1997126336).
class Program
{
static void Main(string[] args)
{
byte[] test = { 49, 50, 51 };
Console.WriteLine(CRC32(0, test));
Console.ReadLine();
}
static uint CRC32(uint CRC, byte[] data)
{
if (data == null || data.Length == 0) return CRC;
uint eax = CRC, ebx = 0, ecx = (uint)data.Length, edx = 0;
Start:
ebx = (ebx & 0xFFFF0000) | (eax & 0x0000FFFF);
eax >>= 8;
ebx = (ebx & 0xFFFF0000) | (data[edx] ^ (ebx & 0x000000FF));
eax = eax ^ Table[ebx];
edx++;
ecx--;
if (ecx != 0) goto Start;
return eax;
}
static readonly uint[] Table = {
0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA,
0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3,
0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988,
0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91,
0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE,
0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC,
0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5,
0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172,
0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,
0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940,
0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116,
0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F,
0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,
0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D,
0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A,
0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818,
0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,
0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E,
0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457,
0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C,
0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2,
0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB,
0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0,
0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9,
0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086,
0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4,
0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD,
0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A,
0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683,
0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8,
0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE,
0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7,
0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC,
0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,
0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252,
0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60,
0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79,
0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,
0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F,
0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04,
0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A,
0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,
0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38,
0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21,
0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E,
0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C,
0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45,
0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2,
0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB,
0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0,
0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6,
0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF,
0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94,
0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D,
0x74726F50, 0x736E6F69, 0x706F4320, 0x67697279,
0x28207468, 0x31202963, 0x20393939, 0x48207962,
0x6E656761, 0x64655220, 0x6E616D64, 0x6FBBA36E };
}
Following @DavidHeffernan suggestions I achieved the same results in C# too:
using System;
using System.Text;
namespace CRC32_Tst
{
class Program
{
static void Main(string[] args)
{
UInt32[] MyTAB = new UInt32[] {
0x000000000, 0x077073096, 0x0EE0E612C, 0x0990951BA,
0x0076DC419, 0x0706AF48F, 0x0E963A535, 0x09E6495A3,
0x00EDB8832, 0x079DCB8A4, 0x0E0D5E91E, 0x097D2D988,
0x009B64C2B, 0x07EB17CBD, 0x0E7B82D07, 0x090BF1D91,
0x01DB71064, 0x06AB020F2, 0x0F3B97148, 0x084BE41DE,
0x01ADAD47D, 0x06DDDE4EB, 0x0F4D4B551, 0x083D385C7,
0x0136C9856, 0x0646BA8C0, 0x0FD62F97A, 0x08A65C9EC,
0x014015C4F, 0x063066CD9, 0x0FA0F3D63, 0x08D080DF5,
0x03B6E20C8, 0x04C69105E, 0x0D56041E4, 0x0A2677172,
0x03C03E4D1, 0x04B04D447, 0x0D20D85FD, 0x0A50AB56B,
0x035B5A8FA, 0x042B2986C, 0x0DBBBC9D6, 0x0ACBCF940,
0x032D86CE3, 0x045DF5C75, 0x0DCD60DCF, 0x0ABD13D59,
0x026D930AC, 0x051DE003A, 0x0C8D75180, 0x0BFD06116,
0x021B4F4B5, 0x056B3C423, 0x0CFBA9599, 0x0B8BDA50F,
0x02802B89E, 0x05F058808, 0x0C60CD9B2, 0x0B10BE924,
0x02F6F7C87, 0x058684C11, 0x0C1611DAB, 0x0B6662D3D,
0x076DC4190, 0x001DB7106, 0x098D220BC, 0x0EFD5102A,
0x071B18589, 0x006B6B51F, 0x09FBFE4A5, 0x0E8B8D433,
0x07807C9A2, 0x00F00F934, 0x09609A88E, 0x0E10E9818,
0x07F6A0DBB, 0x0086D3D2D, 0x091646C97, 0x0E6635C01,
0x06B6B51F4, 0x01C6C6162, 0x0856530D8, 0x0F262004E,
0x06C0695ED, 0x01B01A57B, 0x08208F4C1, 0x0F50FC457,
0x065B0D9C6, 0x012B7E950, 0x08BBEB8EA, 0x0FCB9887C,
0x062DD1DDF, 0x015DA2D49, 0x08CD37CF3, 0x0FBD44C65,
0x04DB26158, 0x03AB551CE, 0x0A3BC0074, 0x0D4BB30E2,
0x04ADFA541, 0x03DD895D7, 0x0A4D1C46D, 0x0D3D6F4FB,
0x04369E96A, 0x0346ED9FC, 0x0AD678846, 0x0DA60B8D0,
0x044042D73, 0x033031DE5, 0x0AA0A4C5F, 0x0DD0D7CC9,
0x05005713C, 0x0270241AA, 0x0BE0B1010, 0x0C90C2086,
0x05768B525, 0x0206F85B3, 0x0B966D409, 0x0CE61E49F,
0x05EDEF90E, 0x029D9C998, 0x0B0D09822, 0x0C7D7A8B4,
0x059B33D17, 0x02EB40D81, 0x0B7BD5C3B, 0x0C0BA6CAD,
0x0EDB88320, 0x09ABFB3B6, 0x003B6E20C, 0x074B1D29A,
0x0EAD54739, 0x09DD277AF, 0x004DB2615, 0x073DC1683,
0x0E3630B12, 0x094643B84, 0x00D6D6A3E, 0x07A6A5AA8,
0x0E40ECF0B, 0x09309FF9D, 0x00A00AE27, 0x07D079EB1,
0x0F00F9344, 0x08708A3D2, 0x01E01F268, 0x06906C2FE,
0x0F762575D, 0x0806567CB, 0x0196C3671, 0x06E6B06E7,
0x0FED41B76, 0x089D32BE0, 0x010DA7A5A, 0x067DD4ACC,
0x0F9B9DF6F, 0x08EBEEFF9, 0x017B7BE43, 0x060B08ED5,
0x0D6D6A3E8, 0x0A1D1937E, 0x038D8C2C4, 0x04FDFF252,
0x0D1BB67F1, 0x0A6BC5767, 0x03FB506DD, 0x048B2364B,
0x0D80D2BDA, 0x0AF0A1B4C, 0x036034AF6, 0x041047A60,
0x0DF60EFC3, 0x0A867DF55, 0x0316E8EEF, 0x04669BE79,
0x0CB61B38C, 0x0BC66831A, 0x0256FD2A0, 0x05268E236,
0x0CC0C7795, 0x0BB0B4703, 0x0220216B9, 0x05505262F,
0x0C5BA3BBE, 0x0B2BD0B28, 0x02BB45A92, 0x05CB36A04,
0x0C2D7FFA7, 0x0B5D0CF31, 0x02CD99E8B, 0x05BDEAE1D,
0x09B64C2B0, 0x0EC63F226, 0x0756AA39C, 0x0026D930A,
0x09C0906A9, 0x0EB0E363F, 0x072076785, 0x005005713,
0x095BF4A82, 0x0E2B87A14, 0x07BB12BAE, 0x00CB61B38,
0x092D28E9B, 0x0E5D5BE0D, 0x07CDCEFB7, 0x00BDBDF21,
0x086D3D2D4, 0x0F1D4E242, 0x068DDB3F8, 0x01FDA836E,
0x081BE16CD, 0x0F6B9265B, 0x06FB077E1, 0x018B74777,
0x088085AE6, 0x0FF0F6A70, 0x066063BCA, 0x011010B5C,
0x08F659EFF, 0x0F862AE69, 0x0616BFFD3, 0x0166CCF45,
0x0A00AE278, 0x0D70DD2EE, 0x04E048354, 0x03903B3C2,
0x0A7672661, 0x0D06016F7, 0x04969474D, 0x03E6E77DB,
0x0AED16A4A, 0x0D9D65ADC, 0x040DF0B66, 0x037D83BF0,
0x0A9BCAE53, 0x0DEBB9EC5, 0x047B2CF7F, 0x030B5FFE9,
0x0BDBDF21C, 0x0CABAC28A, 0x053B39330, 0x024B4A3A6,
0x0BAD03605, 0x0CDD70693, 0x054DE5729, 0x023D967BF,
0x0B3667A2E, 0x0C4614AB8, 0x05D681B02, 0x02A6F2B94,
0x0B40BBE37, 0x0C30C8EA1, 0x05A05DF1B, 0x02D02EF8D,
0x074726F50, 0x0736E6F69, 0x0706F4320, 0x067697279,
0x028207468, 0x031202963, 0x020393939, 0x048207962,
0x06E656761, 0x064655220, 0x06E616D64, 0x06FBBA36E
};
//UInt32 DefaultSeed = 0xffffffff;
UInt32 UsedSeed = 0x00000000;
string testStr = "123";
byte[] inBytes = Encoding.ASCII.GetBytes(testStr);
UInt32 ret_uint = CalculateHash(MyTAB, UsedSeed, inBytes, 0, inBytes.Length);
Console.WriteLine("CRC-32 is {0}", ret_uint); //1997126336
Console.ReadKey();
}
public static UInt32 CalculateHash(UInt32[] table, UInt32 seed, byte[] buffer, int start, int size)
{
UInt32 crc = seed;
for (int i = start; i < size; i++)
unchecked
{
crc = (crc >> 8) ^ table[buffer[i] ^ crc & 0xff];
}
return crc;
}
}
}
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