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-.\" nroff
-.ie t \{\
-. ds ss \s8\u
-. ds se \d\s0
-.\}
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-.\}
-.TH crc-mktab 1 "9 November 2003" "Straylight/Edgeware" "mLib utilities library"
-.SH NAME
-crc-mktab \- construct CRC tables for efficient computation
-.SH SYNOPSIS
-.B crc-mktab
-.RB [ \-cr ]
-.RB [ \-s
-.IR symbol ]
-.RB [ \-t
-.IR type ]
-.RB [ \-i
-.IR header ]
-.br
- \c
-.RB [ \-g
-.IR macro ]
-.RB [ \-b
-.IR bits ]
-.RB [ \-B
-.IR chunk ]
-.RB [ \-p
-.IR poly ]
-.br
- \c
-.RB [ \-o
-.IR filename ]
-.SH DESCRIPTION
-The
-.B crc-mktab
-program constructs tables for efficient computation of CRC (cyclic
-redundancy check) values. It will produce the table as either an array
-defined in a C source file or as an initializer macro defined in a C
-header file.
-.SS "Options"
-The program accepts no non-option arguments. At least one of
-.B \-b
-or
-.B \-p
-must be given. The options are as follows.
-.TP
-.B "\-h, \-\-help"
-Print a help message to standard output and exit successfully.
-.TP
-.B "\-v, \-\-version"
-Print the program's version number to standard output and exit
-successfully.
-.TP
-.B "\-u, \-\-usage"
-Print a one-line usage summary to standard output and exit successfully.
-.TP
-.B "\-c, \-\-c-source"
-Produce a C source file which exports a symbol naming the array, instead
-of a C header file.
-.TP
-.BI "\-s, \-\-symbol=" symbol
-Name the table
-.IR symbol .
-This is the name of the macro defined by a header file, or the array
-exported by a C source. The default macro name is
-.BR CRC_TAB ;
-the default array name is
-.BR crctab .
-.TP
-.BI "\-t, \-\-type=" type
-Specify the element type of the array defined by a C source output. The
-default is
-.B "unsigned short"
-if the polynomial has degree 16 or less, or
-.B "unsigned long"
-otherwise. This option does nothing without the
-.B \-c
-option.
-.TP
-.BI "\-i, \-\-include=" header
-Request that generated C source include the named
-.I header
-file. Inserts a
-line of the form
-.PP
-.nf
-.BI " #include """ header """"
-.fi
-.IP
-at the top of the generated C source. The default is not to include a
-header file. This option does nothing without the
-.B \-c
-option.
-.TP
-.BI "\-g, \-\-guard=" macro
-Use the named
-.I macro
-as a guard against multiple inclusion of the generated header file.
-Inserts a pair of lines of the form
-.PP
-.nf
-.BI " #ifndef " macro
-.BI " #define " macro
-.fi
-.IP
-at the top of the generated header, and a line
-.PP
-.nf
-.BI " #endif"
-.fi
-.IP
-at the end. The default guard macro name is built from the output file
-name specified with
-.B \-o
-by uppercasing all alphabetic characters in the name and replacing
-nonalphanumeric characters by underscores
-.RB ` _ '.
-This option does nothing with the
-.B \-c
-option.
-.TP
-.BI "\-b, \-\-bits=" bits
-Specifies the degree of the CRC polynomial or, equivalently, the length
-of the generated CRC. This must be an integer between 1 and 32
-inclusive. If it is not specified, the polynomial given by
-.B \-p
-is examined and an educated guess made. (Currently we choose the
-smallest multiple of 8 which is large enough.)
-.TP
-.BI "\-B, \-\-bit-chunk=" chunk
-Chunk size in which bits are taken from the input. The number of
-entries in the table is precisely
-.RI 2\*(ss chunk \*(se.
-The default chunk size is 8.
-.TP
-.BI "\-p, \-\-polynomial=" poly
-Specifies the CRC polynomial as an integer. The polynomial has a
-nonzero coefficient in its
-.IR x \*(ss i \*(se
-term if and only if bit
-.I i
-of
-.I poly
-is nonzero. Note that if you want to specify the polynomial in
-hexadecimal, you must prefix it with
-.BR 0x .
-Default polynomials of degree 16 and 32 are known.
-.TP
-.B "\-r, \-\-reverse"
-Construct the table to compensate for unusual bit-ordering. Without
-this option, you'd have to reverse the order of all input chunks and the
-output CRC.
-.SS "The table and how to use it"
-Describing in detail the contents of the table would take too long. For
-an example of use, see the header file
-.BR crc32.h .
-.SH "SEE ALSO"
-.BR crc32 (3).
-.PP
-.I A painless guide to CRC error detection algorithms
-by Ross N. Williams.
-.SH "AUTHOR"
-Mark Wooding, <mdw@distorted.org.uk>
-
~mdw / mLib / blobdiff