randyc@hpfcdc.HP.COM (Randy Campbell) (02/03/90)
I have partial, modified source of CRC calculation program written in 1986 by Gary S. Brown. The program uses a feedback table; in the comments is the statement, "code to generate the table is shown later...". My copy lacks this code, and the source from whom I acquired it doesn't know where to get it. (The version we have had in-line assembly added by Samuel H. Smith in 1989, if that helps anyone). I would like to: A. Get the table-generating code; B. Get a pointer to Gary Brown; or C. Receive any explanation from a knowledgeable source of how to generate a feedback table for a CRC based on a given polynomial. Email or posting here are equally suitable. Thanks in advance, Randy Campbell, HP UDL/Commands, Fort Collins randyc@hpfcla 1-229-6227
lbr@holos0.uucp (Len Reed) (02/05/90)
In article <5450005@hpfcdc.HP.COM> randyc@hpfcdc.HP.COM (Randy Campbell) writes: >I have partial, modified source of CRC calculation program written >in 1986 by Gary S. Brown. > >The program uses a feedback table; in the comments is the statement, >"code to generate the table is shown later...". A good explanation of CRCs can be found in _C Programmer's Guide to Serial Communications_ by Joe Campbell, Howard W. Sams & Co. This book can be found at your basic mall bookstore with a moderately sized computer section. The book gives an explanation of CRCs both using bit-shifting and tables. The CRC section focuses on the practical but treats the theory a little. (Campbell stops short of the abstract algebra required to prove the 99+% detection rates.) I would not recommend transcribing a table from a book: it takes longer than writing the table generator program and is error prone. Generate the table with a program and hand check a few of the entries. -- Len Reed Holos Software, Inc. Voice: (404) 496-1358 UUCP: ...!gatech!holos0!lbr