CRC32

Bonjour tout le monde !!

Je suis un petit nouveau sur ce site, alors je vais tenter de bien m'intégrer ...

Dites moi, je cherche à faire une petite fonction VB toute bébête qui me retourne le CRC32 d'un input de type String.

Ex : =checkCRC32("HELLOWORLD") => devrait me retourner "f2743d92" (conformément aux implémentations disponibles sur http://www.fileformat.info/tool/hash.htm?text=HELLOWORLD ou encore http://www.zorc.breitbandkatze.de/crc.html ou encore bien d'autres sites.

J'ai trouvé cette petite implémentation sur le ouaib :

Public Function checkCRC32(str) As String

    Dim crc32Table(256) As Long
    crc32Table(0) = 0
    crc32Table(1) = 1996959894
    crc32Table(2) = -301047508
    crc32Table(3) = -1727442502
    crc32Table(4) = 124634137
    crc32Table(5) = 1886057615
    crc32Table(6) = -379345611
    crc32Table(7) = -1637575261
    crc32Table(8) = 249268274
    crc32Table(9) = 2044508324
    crc32Table(10) = -522852066
    crc32Table(11) = -1747789432
    crc32Table(12) = 162941995
    crc32Table(13) = 2125561021
    crc32Table(14) = -407360249
    crc32Table(15) = -1866523247
    crc32Table(16) = 498536548
    crc32Table(17) = 1789927666
    crc32Table(18) = -205950648
    crc32Table(19) = -2067906082
    crc32Table(20) = 450548861
    crc32Table(21) = 1843258603
    crc32Table(22) = -187386543
    crc32Table(23) = -2083289657
    crc32Table(24) = 325883990
    crc32Table(25) = 1684777152
    crc32Table(26) = -43845254
    crc32Table(27) = -1973040660
    crc32Table(28) = 335633487
    crc32Table(29) = 1661365465
    crc32Table(30) = -99664541
    crc32Table(31) = -1928851979
    crc32Table(32) = 997073096
    crc32Table(33) = 1281953886
    crc32Table(34) = -715111964
    crc32Table(35) = -1570279054
    crc32Table(36) = 1006888145
    crc32Table(37) = 1258607687
    crc32Table(38) = -770865667
    crc32Table(39) = -1526024853
    crc32Table(40) = 901097722
    crc32Table(41) = 1119000684
    crc32Table(42) = -608450090
    crc32Table(43) = -1396901568
    crc32Table(44) = 853044451
    crc32Table(45) = 1172266101
    crc32Table(46) = -589951537
    crc32Table(47) = -1412350631
    crc32Table(48) = 651767980
    crc32Table(49) = 1373503546
    crc32Table(50) = -925412992
    crc32Table(51) = -1076862698
    crc32Table(52) = 565507253
    crc32Table(53) = 1454621731
    crc32Table(54) = -809855591
    crc32Table(55) = -1195530993
    crc32Table(56) = 671266974
    crc32Table(57) = 1594198024
    crc32Table(58) = -972236366
    crc32Table(59) = -1324619484
    crc32Table(60) = 795835527
    crc32Table(61) = 1483230225
    crc32Table(62) = -1050600021
    crc32Table(63) = -1234817731
    crc32Table(64) = 1994146192
    crc32Table(65) = 31158534
    crc32Table(66) = -1731059524
    crc32Table(67) = -271249366
    crc32Table(68) = 1907459465
    crc32Table(69) = 112637215
    crc32Table(70) = -1614814043
    crc32Table(71) = -390540237
    crc32Table(72) = 2013776290
    crc32Table(73) = 251722036
    crc32Table(74) = -1777751922
    crc32Table(75) = -519137256
    crc32Table(76) = 2137656763
    crc32Table(77) = 141376813
    crc32Table(78) = -1855689577
    crc32Table(79) = -429695999
    crc32Table(80) = 1802195444
    crc32Table(81) = 476864866
    crc32Table(82) = -2056965928
    crc32Table(83) = -228458418
    crc32Table(84) = 1812370925
    crc32Table(85) = 453092731
    crc32Table(86) = -2113342271
    crc32Table(87) = -183516073
    crc32Table(88) = 1706088902
    crc32Table(89) = 314042704
    crc32Table(90) = -1950435094
    crc32Table(91) = -54949764
    crc32Table(92) = 1658658271
    crc32Table(93) = 366619977
    crc32Table(94) = -1932296973
    crc32Table(95) = -69972891
    crc32Table(96) = 1303535960
    crc32Table(97) = 984961486
    crc32Table(98) = -1547960204
    crc32Table(99) = -725929758
    crc32Table(100) = 1256170817
    crc32Table(101) = 1037604311
    crc32Table(102) = -1529756563
    crc32Table(103) = -740887301
    crc32Table(104) = 1131014506
    crc32Table(105) = 879679996
    crc32Table(106) = -1385723834
    crc32Table(107) = -631195440
    crc32Table(108) = 1141124467
    crc32Table(109) = 855842277
    crc32Table(110) = -1442165665
    crc32Table(111) = -586318647
    crc32Table(112) = 1342533948
    crc32Table(113) = 654459306
    crc32Table(114) = -1106571248
    crc32Table(115) = -921952122
    crc32Table(116) = 1466479909
    crc32Table(117) = 544179635
    crc32Table(118) = -1184443383
    crc32Table(119) = -832445281
    crc32Table(120) = 1591671054
    crc32Table(121) = 702138776
    crc32Table(122) = -1328506846
    crc32Table(123) = -942167884
    crc32Table(124) = 1504918807
    crc32Table(125) = 783551873
    crc32Table(126) = -1212326853
    crc32Table(127) = -1061524307
    crc32Table(128) = -306674912
    crc32Table(129) = -1698712650
    crc32Table(130) = 62317068
    crc32Table(131) = 1957810842
    crc32Table(132) = -355121351
    crc32Table(133) = -1647151185
    crc32Table(134) = 81470997
    crc32Table(135) = 1943803523
    crc32Table(136) = -480048366
    crc32Table(137) = -1805370492
    crc32Table(138) = 225274430
    crc32Table(139) = 2053790376
    crc32Table(140) = -468791541
    crc32Table(141) = -1828061283
    crc32Table(142) = 167816743
    crc32Table(143) = 2097651377
    crc32Table(144) = -267414716
    crc32Table(145) = -2029476910
    crc32Table(146) = 503444072
    crc32Table(147) = 1762050814
    crc32Table(148) = -144550051
    crc32Table(149) = -2140837941
    crc32Table(150) = 426522225
    crc32Table(151) = 1852507879
    crc32Table(152) = -19653770
    crc32Table(153) = -1982649376
    crc32Table(154) = 282753626
    crc32Table(155) = 1742555852
    crc32Table(156) = -105259153
    crc32Table(157) = -1900089351
    crc32Table(158) = 397917763
    crc32Table(159) = 1622183637
    crc32Table(160) = -690576408
    crc32Table(161) = -1580100738
    crc32Table(162) = 953729732
    crc32Table(163) = 1340076626
    crc32Table(164) = -776247311
    crc32Table(165) = -1497606297
    crc32Table(166) = 1068828381
    crc32Table(167) = 1219638859
    crc32Table(168) = -670225446
    crc32Table(169) = -1358292148
    crc32Table(170) = 906185462
    crc32Table(171) = 1090812512
    crc32Table(172) = -547295293
    crc32Table(173) = -1469587627
    crc32Table(174) = 829329135
    crc32Table(175) = 1181335161
    crc32Table(176) = -882789492
    crc32Table(177) = -1134132454
    crc32Table(178) = 628085408
    crc32Table(179) = 1382605366
    crc32Table(180) = -871598187
    crc32Table(181) = -1156888829
    crc32Table(182) = 570562233
    crc32Table(183) = 1426400815
    crc32Table(184) = -977650754
    crc32Table(185) = -1296233688
    crc32Table(186) = 733239954
    crc32Table(187) = 1555261956
    crc32Table(188) = -1026031705
    crc32Table(189) = -1244606671
    crc32Table(190) = 752459403
    crc32Table(191) = 1541320221
    crc32Table(192) = -1687895376
    crc32Table(193) = -328994266
    crc32Table(194) = 1969922972
    crc32Table(195) = 40735498
    crc32Table(196) = -1677130071
    crc32Table(197) = -351390145
    crc32Table(198) = 1913087877
    crc32Table(199) = 83908371
    crc32Table(200) = -1782625662
    crc32Table(201) = -491226604
    crc32Table(202) = 2075208622
    crc32Table(203) = 213261112
    crc32Table(204) = -1831694693
    crc32Table(205) = -438977011
    crc32Table(206) = 2094854071
    crc32Table(207) = 198958881
    crc32Table(208) = -2032938284
    crc32Table(209) = -237706686
    crc32Table(210) = 1759359992
    crc32Table(211) = 534414190
    crc32Table(212) = -2118248755
    crc32Table(213) = -155638181
    crc32Table(214) = 1873836001
    crc32Table(215) = 414664567
    crc32Table(216) = -2012718362
    crc32Table(217) = -15766928
    crc32Table(218) = 1711684554
    crc32Table(219) = 285281116
    crc32Table(220) = -1889165569
    crc32Table(221) = -127750551
    crc32Table(222) = 1634467795
    crc32Table(223) = 376229701
    crc32Table(224) = -1609899400
    crc32Table(225) = -686959890
    crc32Table(226) = 1308918612
    crc32Table(227) = 956543938
    crc32Table(228) = -1486412191
    crc32Table(229) = -799009033
    crc32Table(230) = 1231636301
    crc32Table(231) = 1047427035
    crc32Table(232) = -1362007478
    crc32Table(233) = -640263460
    crc32Table(234) = 1088359270
    crc32Table(235) = 936918000
    crc32Table(236) = -1447252397
    crc32Table(237) = -558129467
    crc32Table(238) = 1202900863
    crc32Table(239) = 817233897
    crc32Table(240) = -1111625188
    crc32Table(241) = -893730166
    crc32Table(242) = 1404277552
    crc32Table(243) = 615818150
    crc32Table(244) = -1160759803
    crc32Table(245) = -841546093
    crc32Table(246) = 1423857449
    crc32Table(247) = 601450431
    crc32Table(248) = -1285129682
    crc32Table(249) = -1000256840
    crc32Table(250) = 1567103746
    crc32Table(251) = 711928724
    crc32Table(252) = -1274298825
    crc32Table(253) = -1022587231
    crc32Table(254) = 1510334235
    crc32Table(255) = 755167117

   Dim crc32Result As Long
   crc32Result = &HFFFFFFFF

   Dim i As Integer
   Dim iLookup As Integer
   Dim buffer() As Byte
   buffer = StrConv(str, vbFromUnicode)

   For i = LBound(buffer) To UBound(buffer)
      iLookup = (crc32Result And &HFF) Xor buffer(i)
      crc32Result = ((crc32Result And &HFFFFFF00) \ &H100) And 16777215
      ' nasty shr 8 with vb :/
      crc32Result = crc32Result Xor crc32Table(iLookup)
   Next i

   checkCRC32 = Not (crc32Result)

End Function

Bon le gars avait l'air de s'y connaitre alors j'ai fait un petit copié collé, mais là je n'obtiens pas le bon résultat, j'obtiens : -227263086 ...

Quelqu'un s'y connait un peu en CRC32 ici ?? Quelqu'un peu m'aider svp ??

Merci par avance.

Bonne journée

Christophe

Bonjour

Modifies la formule

=DECHEX(checkCRC32("HELLOWORLD"))

Il y a FF en plus au début

Normal ou pas normal ?

Super !! Merci Banzai64 !!

Je ne sais pas d'où viennent ce "FF" du début, mais je vais les ignorer ! Merci beaucoup !!

Bonjour

Je ne sais pas trop non plus

Tout ce que j'ai pu trouver

DECHEX(nombre, [nb_car])

nombre Obligatoire. Représente le nombre entier décimal à convertir. Si nombre est négatif, nb_car n’est pas pris en compte, et DECHEX renvoie un nombre hexadécimal de 10 caractères (40 bits), dans lequel le bit de poids fort est le bit de signe. Les 39 autres bits sont des bits de grandeur. Les nombres négatifs sont représentés à l’aide de la notation de complément à 2.

Thanks !!