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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: iSCSI: Nailing down CRC-32CAll, Based on the finalization of the parameters of CRC-32C per following parameters, I obtained a check of 0xE3069283 for the nine-byte string of "123456789" (9 bytes) that the Rocksoft CRC document refers to. Name : "CRC-32C" Width : 32 Poly : 1EDC6F41 (note that the leading "1" is implied) Init : FFFFFFFF RefIn : True RefOut : True XorOut : FFFFFFFF Check : E3069283 It would be nice if other independant checks can validate this. Venkat Rangan Rhapsody Networks Inc. http://www.rhapsodynetworks.com The table and code follows: /*****************************************************************/ /* */ /* CRC LOOKUP TABLE */ /* ================ */ /* The following CRC lookup table was generated automagically */ /* by the Rocksoft^tm Model CRC Algorithm Table Generation */ /* Program V1.0 using the following model parameters: */ /* */ /* Width : 4 bytes. */ /* Poly : 0x1EDC6F41L */ /* Reverse : TRUE. */ /* */ /* For more information on the Rocksoft^tm Model CRC Algorithm, */ /* see the document titled "A Painless Guide to CRC Error */ /* Detection Algorithms" by Ross Williams */ /* (ross@guest.adelaide.edu.au.). This document is likely to be */ /* in the FTP archive "ftp.adelaide.edu.au/pub/rocksoft". */ /* */ /*****************************************************************/ unsigned long crctable[256] = { 0x00000000L, 0xF26B8303L, 0xE13B70F7L, 0x1350F3F4L, 0xC79A971FL, 0x35F1141CL, 0x26A1E7E8L, 0xD4CA64EBL, 0x8AD958CFL, 0x78B2DBCCL, 0x6BE22838L, 0x9989AB3BL, 0x4D43CFD0L, 0xBF284CD3L, 0xAC78BF27L, 0x5E133C24L, 0x105EC76FL, 0xE235446CL, 0xF165B798L, 0x030E349BL, 0xD7C45070L, 0x25AFD373L, 0x36FF2087L, 0xC494A384L, 0x9A879FA0L, 0x68EC1CA3L, 0x7BBCEF57L, 0x89D76C54L, 0x5D1D08BFL, 0xAF768BBCL, 0xBC267848L, 0x4E4DFB4BL, 0x20BD8EDEL, 0xD2D60DDDL, 0xC186FE29L, 0x33ED7D2AL, 0xE72719C1L, 0x154C9AC2L, 0x061C6936L, 0xF477EA35L, 0xAA64D611L, 0x580F5512L, 0x4B5FA6E6L, 0xB93425E5L, 0x6DFE410EL, 0x9F95C20DL, 0x8CC531F9L, 0x7EAEB2FAL, 0x30E349B1L, 0xC288CAB2L, 0xD1D83946L, 0x23B3BA45L, 0xF779DEAEL, 0x05125DADL, 0x1642AE59L, 0xE4292D5AL, 0xBA3A117EL, 0x4851927DL, 0x5B016189L, 0xA96AE28AL, 0x7DA08661L, 0x8FCB0562L, 0x9C9BF696L, 0x6EF07595L, 0x417B1DBCL, 0xB3109EBFL, 0xA0406D4BL, 0x522BEE48L, 0x86E18AA3L, 0x748A09A0L, 0x67DAFA54L, 0x95B17957L, 0xCBA24573L, 0x39C9C670L, 0x2A993584L, 0xD8F2B687L, 0x0C38D26CL, 0xFE53516FL, 0xED03A29BL, 0x1F682198L, 0x5125DAD3L, 0xA34E59D0L, 0xB01EAA24L, 0x42752927L, 0x96BF4DCCL, 0x64D4CECFL, 0x77843D3BL, 0x85EFBE38L, 0xDBFC821CL, 0x2997011FL, 0x3AC7F2EBL, 0xC8AC71E8L, 0x1C661503L, 0xEE0D9600L, 0xFD5D65F4L, 0x0F36E6F7L, 0x61C69362L, 0x93AD1061L, 0x80FDE395L, 0x72966096L, 0xA65C047DL, 0x5437877EL, 0x4767748AL, 0xB50CF789L, 0xEB1FCBADL, 0x197448AEL, 0x0A24BB5AL, 0xF84F3859L, 0x2C855CB2L, 0xDEEEDFB1L, 0xCDBE2C45L, 0x3FD5AF46L, 0x7198540DL, 0x83F3D70EL, 0x90A324FAL, 0x62C8A7F9L, 0xB602C312L, 0x44694011L, 0x5739B3E5L, 0xA55230E6L, 0xFB410CC2L, 0x092A8FC1L, 0x1A7A7C35L, 0xE811FF36L, 0x3CDB9BDDL, 0xCEB018DEL, 0xDDE0EB2AL, 0x2F8B6829L, 0x82F63B78L, 0x709DB87BL, 0x63CD4B8FL, 0x91A6C88CL, 0x456CAC67L, 0xB7072F64L, 0xA457DC90L, 0x563C5F93L, 0x082F63B7L, 0xFA44E0B4L, 0xE9141340L, 0x1B7F9043L, 0xCFB5F4A8L, 0x3DDE77ABL, 0x2E8E845FL, 0xDCE5075CL, 0x92A8FC17L, 0x60C37F14L, 0x73938CE0L, 0x81F80FE3L, 0x55326B08L, 0xA759E80BL, 0xB4091BFFL, 0x466298FCL, 0x1871A4D8L, 0xEA1A27DBL, 0xF94AD42FL, 0x0B21572CL, 0xDFEB33C7L, 0x2D80B0C4L, 0x3ED04330L, 0xCCBBC033L, 0xA24BB5A6L, 0x502036A5L, 0x4370C551L, 0xB11B4652L, 0x65D122B9L, 0x97BAA1BAL, 0x84EA524EL, 0x7681D14DL, 0x2892ED69L, 0xDAF96E6AL, 0xC9A99D9EL, 0x3BC21E9DL, 0xEF087A76L, 0x1D63F975L, 0x0E330A81L, 0xFC588982L, 0xB21572C9L, 0x407EF1CAL, 0x532E023EL, 0xA145813DL, 0x758FE5D6L, 0x87E466D5L, 0x94B49521L, 0x66DF1622L, 0x38CC2A06L, 0xCAA7A905L, 0xD9F75AF1L, 0x2B9CD9F2L, 0xFF56BD19L, 0x0D3D3E1AL, 0x1E6DCDEEL, 0xEC064EEDL, 0xC38D26C4L, 0x31E6A5C7L, 0x22B65633L, 0xD0DDD530L, 0x0417B1DBL, 0xF67C32D8L, 0xE52CC12CL, 0x1747422FL, 0x49547E0BL, 0xBB3FFD08L, 0xA86F0EFCL, 0x5A048DFFL, 0x8ECEE914L, 0x7CA56A17L, 0x6FF599E3L, 0x9D9E1AE0L, 0xD3D3E1ABL, 0x21B862A8L, 0x32E8915CL, 0xC083125FL, 0x144976B4L, 0xE622F5B7L, 0xF5720643L, 0x07198540L, 0x590AB964L, 0xAB613A67L, 0xB831C993L, 0x4A5A4A90L, 0x9E902E7BL, 0x6CFBAD78L, 0x7FAB5E8CL, 0x8DC0DD8FL, 0xE330A81AL, 0x115B2B19L, 0x020BD8EDL, 0xF0605BEEL, 0x24AA3F05L, 0xD6C1BC06L, 0xC5914FF2L, 0x37FACCF1L, 0x69E9F0D5L, 0x9B8273D6L, 0x88D28022L, 0x7AB90321L, 0xAE7367CAL, 0x5C18E4C9L, 0x4F48173DL, 0xBD23943EL, 0xF36E6F75L, 0x0105EC76L, 0x12551F82L, 0xE03E9C81L, 0x34F4F86AL, 0xC69F7B69L, 0xD5CF889DL, 0x27A40B9EL, 0x79B737BAL, 0x8BDCB4B9L, 0x988C474DL, 0x6AE7C44EL, 0xBE2DA0A5L, 0x4C4623A6L, 0x5F16D052L, 0xAD7D5351L }; /*****************************************************************/ /* End of CRC Lookup Table */ /*****************************************************************/ /*****************************************************************/ /* ComputeCRC */ /*****************************************************************/ #include <stdio.h> #include <stdlib.h> #include "crctable.h" #define TB_INIT 0xFFFFFFFF #define TB_INIT_REFLECTED 0xFFFFFFFF #define TB_XOROT 0xFFFFFFFF unsigned long crc_reflected (); unsigned long crc_reflected (blk_adr,blk_len) unsigned char *blk_adr; unsigned long blk_len; { unsigned long crc = TB_INIT_REFLECTED; while (blk_len--) crc = crctable[(crc ^ *blk_adr++) & 0xFFL] ^ (crc >> 8); return crc ^ TB_XOROT; } -----Original Message----- From: julian_satran@il.ibm.com [mailto:julian_satran@il.ibm.com] Sent: Tuesday, May 08, 2001 7:38 AM To: ips@ece.cmu.edu Subject: Re: iSCSI: Nailing down CRC-32C Mark, My basic assumption was that everything is (as in all IP related standards) in network order. Regards, Julo Mark Bakke <mbakke@cisco.com> on 07-05-2001 23:00:28 Please respond to Mark Bakke <mbakke@cisco.com> To: Julian Satran/Haifa/IBM@IBMIL cc: ips@ece.cmu.edu Subject: Re: iSCSI: Nailing down CRC-32C Julian- That's great; it covers nearly everything. The only thing left is the byte order; are they taken in the same order Ethernet uses? If so, I can generate a few test patterns that our implementations can all check against. Thanks, -- Mark julian_satran@il.ibm.com wrote: > > The CRC part of the appendix (for 07) reads: > > The following table lists cyclic integrity checksums that can be > negotiated for the digests and MUST be implemented by every iSCSI > initiator and target. Note that these digest options have only error > detection significance. > > +---------------------------------------------+ > | Name | Description | > +---------------------------------------------+ > | crc-32C | 32 bit CRC | 11EDC6F41 | > +---------------------------------------------+ > | none | no digest | > +---------------------------------------------+ > > The generator polynomials for those digests are given in hex-notation, > for example 3a stands for 0011 1010 - the polynomial x**5+X**4+x**3+x+1. > > The generator polynomial selected is evaluated in [Castagnioli93]. > When using the CRC the CRC register must be initialized to all 1s > (0xFFFFFFFF) and the CRC bits must be complemented before transmission. > Padding bytes, when presents in a segment covered by a CRC, have to be > set to 0 and are included in the CRC. > > Regards, > Julo > > Mark Bakke <mbakke@cisco.com> on 05-05-2001 00:13:09 > > Please respond to Mark Bakke <mbakke@cisco.com> > > To: IPS <ips@ece.cmu.edu> > cc: > Subject: iSCSI: Nailing down CRC-32C > > At the interim meeting, it was stated that iSCSI has selected > the CRC-32C polynomial as its required iSCSI-level header and > data CRC. Now that we have it, it's time to move on and make > sure we can implement it. > > In the interest of interoperability, we need to not only specify > the polynomial, but also the initial values, bit and byte > ordering, etc. > > "A Painless Guide to CRC Error Detection Algorithms" > (http://www.ross.net/crc/crcpaper.html) specifies a > method to unambiguously characterize these parameters > (sections 15 and 16). Has anyone taken a shot at defining > these yet? Otherwise, here is what it might look like: > > Name : "CRC-32C" > Width : 32 > Poly : 1EDC6F41 (note that the leading "1" is implied) > Init : FFFFFFFF > RefIn : True > RefOut : True > XorOut : FFFFFFFF > Check : ? > > I haven't attempted to create check data based on these yet. As > soon as the other parameters are nailed down, we need to do this. > > Anyway, I am not a CRC expert, and can't make any statement about > the above values being the "best" way to do this, but instead just > copied them (except the polynomial itself) from the Ethernet CRC, > since that is likely the easiest for everyone implementing hardware > to deal with. > > If someone else is already doing this, let me know; I just wanted > to start this thread so we can get closure. > > Regards, > > Mark > > -- > Mark A. Bakke > Cisco Systems > mbakke@cisco.com > 763.398.1054 -- Mark A. Bakke Cisco Systems mbakke@cisco.com 763.398.1054
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