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       gperf - generate a perfect hash function from a key set


       gperf [OPTION]... [INPUT-FILE]


       GNU ’gperf’ generates perfect hash functions.

       If  a  long option shows an argument as mandatory, then it is mandatory
       for the equivalent short option also.

   Output file location:
       --output-file=FILE Write output to specified file.

       The results are written  to  standard  output  if  no  output  file  is
       specified or if it is -.

   Input file interpretation:
       -e, --delimiters=DELIMITER-LIST
              Allow  user  to  provide  a string containing delimiters used to
              separate keywords from their attributes.  Default is ",".

       -t, --struct-type
              Allows the user to include a  structured  type  declaration  for
              generated  code.  Any  text  before %% is considered part of the
              type declaration. Key words and  additional  fields  may  follow
              this, one group of fields per line.

              Consider  upper  and  lower case ASCII characters as equivalent.
              Note that locale dependent case mappings are ignored.

   Language for the output code:
       -L, --language=LANGUAGE-NAME
              Generates code in the specified language. Languages handled  are
              currently C++, ANSI-C, C, and KR-C. The default is C.

   Details in the output code:
       -K, --slot-name=NAME
              Select name of the keyword component in the keyword structure.

       -F, --initializer-suffix=INITIALIZERS
              Initializers for additional components in the keyword structure.

       -H, --hash-function-name=NAME
              Specify name of generated hash function. Default is ’hash’.

       -N, --lookup-function-name=NAME
              Specify name of  generated  lookup  function.  Default  name  is

       -Z, --class-name=NAME
              Specify   name   of   generated   C++  class.  Default  name  is

       -7, --seven-bit
              Assume 7-bit characters.

       -l, --compare-lengths
              Compare key lengths before trying a string comparison.  This  is
              necessary  if  the keywords contain NUL bytes. It also helps cut
              down on the number of string comparisons made during the lookup.

       -c, --compare-strncmp
              Generate comparison code using strncmp rather than strcmp.

       -C, --readonly-tables
              Make  the  contents  of  generated lookup tables constant, i.e.,

       -E, --enum
              Define constant  values  using  an  enum  local  to  the  lookup
              function rather than with defines.

       -I, --includes
              Include  the  necessary  system  include  file <string.h> at the
              beginning of the code.

       -G, --global-table
              Generate the  static  table  of  keywords  as  a  static  global
              variable,  rather  than  hiding it inside of the lookup function
              (which is the default behavior).

       -P, --pic
              Optimize the generated table for inclusion in shared  libraries.
              This reduces the startup time of programs using a shared library
              containing the generated code.

       -Q, --string-pool-name=NAME
              Specify name of string pool generated by option --pic.   Default
              name is ’stringpool’.

              Use  NULL  strings  instead  of  empty strings for empty keyword
              table entries.

       -W, --word-array-name=NAME
              Specify name of word list array. Default name is ’wordlist’.

              Specify  name  of  length   table   array.   Default   name   is

       -S, --switch=COUNT
              Causes  the  generated  C code to use a switch statement scheme,
              rather than an array lookup table.  This can lead to a reduction
              in both time and space requirements for some keyfiles. The COUNT
              argument determines how many switch statements are generated.  A
              value  of  1  generates  1 switch containing all the elements, a
              value of 2 generates 2 tables with  1/2  the  elements  in  each
              table, etc. If COUNT is very large, say 1000000, the generated C
              code does a binary search.

       -T, --omit-struct-type
              Prevents the transfer of the  type  declaration  to  the  output
              file.  Use this option if the type is already defined elsewhere.

   Algorithm employed by gperf:
       -k, --key-positions=KEYS
              Select the  key  positions  used  in  the  hash  function.   The
              allowable choices range between 1-255, inclusive.  The positions
              are separated by commas, ranges may be used, and  key  positions
              may occur in any order.  Also, the meta-character ’*’ causes the
              generated hash function to consider ALL  key  positions,  and  $
              indicates the "final character" of a key, e.g., $,1,2,4,6-10.

       -D, --duplicates
              Handle  keywords  that  hash to duplicate values. This is useful
              for certain highly redundant keyword sets.

       -m, --multiple-iterations=ITERATIONS
              Perform multiple choices of the -i and -j values, and choose the
              best  results.  This  increases  the running time by a factor of
              ITERATIONS but does a good job minimizing  the  generated  table

       -i, --initial-asso=N
              Provide an initial value for the associate values array. Default
              is 0. Setting this value larger helps inflate the  size  of  the
              final table.

       -j, --jump=JUMP-VALUE
              Affects   the  "jump  value",  i.e.,  how  far  to  advance  the
              associated character value  upon  collisions.  Must  be  an  odd
              number, default is 5.

       -n, --no-strlen
              Do not include the length of the keyword when computing the hash

       -r, --random
              Utilizes randomness to initialize the associated values table.

       -s, --size-multiple=N
              Affects the size  of  the  generated  hash  table.  The  numeric
              argument  N  indicates  "how  many  times larger or smaller" the
              associated value range should be, in relationship to the  number
              of  keys,  e.g. a value of 3 means "allow the maximum associated
              value to be about 3 times larger than the number of input keys".
              Conversely,  a  value  of 1/3 means "make the maximum associated
              value about 3 times smaller than the number of  input  keys".  A
              larger   table   should   decrease  the  time  required  for  an
              unsuccessful search,  at  the  expense  of  extra  table  space.
              Default value is 1.

   Informative output:
       -h, --help
              Print this message.

       -v, --version
              Print the gperf version number.

       -d, --debug
              Enables  the  debugging  option  (produces verbose output to the
              standard error).


       Written by Douglas C. Schmidt and Bruno Haible.


       Report bugs to <>.


       Copyright © 1989-1998, 2000-2004, 2006-2007 Free  Software  Foundation,
       This is free software; see the source for copying conditions.  There is
       NO warranty; not even for MERCHANTABILITY or FITNESS FOR  A  PARTICULAR


       The full documentation for gperf is maintained as a Texinfo manual.  If
       the info and gperf programs are properly installed at  your  site,  the

              info gperf

       should give you access to the complete manual.