I was given this Delphi code:
unit lib_CRC;
interface uses SysUtils;
function CalculateCRC(Text: String): String;
implementation{ CRC Code generation routines }
const{: @summary CRC Code generation array }
CRCTable : array [0..255] of Cardinal =
(
$00000000, $77073096, $ee0e612c, $990951ba,
$076dc419, $706af48f, $e963a535, $9e6495a3,
$0edb8832, $79dcb8a4, $e0d5e91e, $97d2d988,
$09b64c2b, $7eb17cbd, $e7b82d07, $90bf1d91,
$1db71064, $6ab020f2, $f3b97148, $84be41de,
$1adad47d, $6ddde4eb, $f4d4b551, $83d385c7,
$136c9856, $646ba8c0, $fd62f97a, $8a65c9ec,
$14015c4f, $63066cd9, $fa0f3d63, $8d080df5,
$3b6e20c8, $4c69105e, $d56041e4, $a2677172,
$3c03e4d1, $4b04d447, $d20d85fd, $a50ab56b,
$35b5a8fa, $42b2986c, $dbbbc9d6, $acbcf940,
$32d86ce3, $45df5c75, $dcd60dcf, $abd13d59,
$26d930ac, $51de003a, $c8d75180, $bfd06116,
$21b4f4b5, $56b3c423, $cfba9599, $b8bda50f,
$2802b89e, $5f058808, $c60cd9b2, $b10be924,
$2f6f7c87, $58684c11, $c1611dab, $b6662d3d,
$76dc4190, $01db7106, $98d220bc, $efd5102a,
$71b18589, $06b6b51f, $9fbfe4a5, $e8b8d433,
$7807c9a2, $0f00f934, $9609a88e, $e10e9818,
$7f6a0dbb, $086d3d2d, $91646c97, $e6635c01,
$6b6b51f4, $1c6c6162, $856530d8, $f262004e,
$6c0695ed, $1b01a57b, $8208f4c1, $f50fc457,
$65b0d9c6, $12b7e950, $8bbeb8ea, $fcb9887c,
$62dd1ddf, $15da2d49, $8cd37cf3, $fbd44c65,
$4db26158, $3ab551ce, $a3bc0074, $d4bb30e2,
$4adfa541, $3dd895d7, $a4d1c46d, $d3d6f4fb,
$4369e96a, $346ed9fc, $ad678846, $da60b8d0,
$44042d73, $33031de5, $aa0a4c5f, $dd0d7cc9,
$5005713c, $270241aa, $be0b1010, $c90c2086,
$5768b525, $206f85b3, $b966d409, $ce61e49f,
$5edef90e, $29d9c998, $b0d09822, $c7d7a8b4,
$59b33d17, $2eb40d81, $b7bd5c3b, $c0ba6cad,
$edb88320, $9abfb3b6, $03b6e20c, $74b1d29a,
$ead54739, $9dd277af, $04db2615, $73dc1683,
$e3630b12, $94643b84, $0d6d6a3e, $7a6a5aa8,
$e40ecf0b, $9309ff9d, $0a00ae27, $7d079eb1,
$f00f9344, $8708a3d2, $1e01f268, $6906c2fe,
$f762575d, $806567cb, $196c3671, $6e6b06e7,
$fed41b76, $89d32be0, $10da7a5a, $67dd4acc,
$f9b9df6f, $8ebeeff9, $17b7be43, $60b08ed5,
$d6d6a3e8, $a1d1937e, $38d8c2c4, $4fdff252,
$d1bb67f1, $a6bc5767, $3fb506dd, $48b2364b,
$d80d2bda, $af0a1b4c, $36034af6, $41047a60,
$df60efc3, $a867df55, $316e8eef, $4669be79,
$cb61b38c, $bc66831a, $256fd2a0, $5268e236,
$cc0c7795, $bb0b4703, $220216b9, $5505262f,
$c5ba3bbe, $b2bd0b28, $2bb45a92, $5cb36a04,
$c2d7ffa7, $b5d0cf31, $2cd99e8b, $5bdeae1d,
$9b64c2b0, $ec63f226, $756aa39c, $026d930a,
$9c0906a9, $eb0e363f, $72076785, $05005713,
$95bf4a82, $e2b87a14, $7bb12bae, $0cb61b38,
$92d28e9b, $e5d5be0d, $7cdcefb7, $0bdbdf21,
$86d3d2d4, $f1d4e242, $68ddb3f8, $1fda836e,
$81be16cd, $f6b9265b, $6fb077e1, $18b74777,
$88085ae6, $ff0f6a70, $66063bca, $11010b5c,
$8f659eff, $f862ae69, $616bffd3, $166ccf45,
$a00ae278, $d70dd2ee, $4e048354, $3903b3c2,
$a7672661, $d06016f7, $4969474d, $3e6e77db,
$aed16a4a, $d9d65adc, $40df0b66, $37d83bf0,
$a9bcae53, $debb9ec5, $47b2cf7f, $30b5ffe9,
$bdbdf21c, $cabac28a, $53b39330, $24b4a3a6,
$bad03605, $cdd70693, $54de5729, $23d967bf,
$b3667a2e, $c4614ab8, $5d681b02, $2a6f2b94,
$b40bbe37, $c30c8ea1, $5a05df1b, $2d02ef8d
);
{: @summary CRC Codegeneration routine }
function CalculateCRC(Text: String): String ;
var Index : Integer;
CRCVal : Cardinal;
begin
CRCVal:=0;
for Index:=1 to Length(Text)
do CRCVal:=CRCTable[Byte(CRCVal xor Ord(Text[Index]))] xor((CRCVal shr 8) and $00FFFFFF);
Result:=UpperCase(IntToHex(CRCVal, 8));
end;
end.
For which I have produced my correspondent Java code:
package com.noemalife.hal.communication.test.drivers;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
public class LyrasCRC {
private static final int[] CRC_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};
public static void main(String [] args) throws IOException {
byte[] bytes = Files.readAllBytes(new File("C:\\...").toPath());
System.out.println(calculateLyrasCRC(bytes));
}
public static String calculateLyrasCRC(byte[] text) {
int crcValue = 0;
for(int i = 0; i<text.length; i++) {
crcValue = CRC_TABLE[(crcValue ^ text[i])] ^ ((crcValue >> 8) & 0x00FFFFFF);
}
String crcValueStr = Integer.toHexString(crcValue).toUpperCase();
return crcValueStr;
}
}
The ouput of that CRC calculation must be appended at the end of the file before being sent.
Anyway, the procedure fails: after one or two iterations it seems to generate a big negative number used to access the CRC_TABLE for which I get a java.lang.ArrayIndexOutOfBoundsException.
I have seen these examples: Example in C Example in C#
but I cannot get the difference, except in the use of the final XOR. Do you have any ideas where I am making the mistake?
POSSIBLE SOLUTION As suggested by @g00se and @Matthias B a working solution may be
crcValue = CRC_TABLE[(crcValue ^ text[i]) & 0xFF] ^ ((crcValue >> 8) & 0x00FFFFFF);
I've said "may be" because actually I have no possibility nor feedback to verify if the calculated value is logically correct
The Java code is missing the type cast to Byte that the Delphi code has.
The type cast to Byte truncates the value so that it always stays in the 0-255 range, which fits what the array needs to be indexed by.
Note that in Delphi, Byte is an unsigned 8-bit number, while Java's byte data type is signed, so you cannot use Java's byte directly. I believe that the way to truncate an integer to an unsigned byte in Java is by taking (value & 0xFF).