mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-22 11:17:19 +00:00
120 lines
6.7 KiB
Plaintext
120 lines
6.7 KiB
Plaintext
GNU `gperf' generates perfect hash functions.
|
|
|
|
Usage: ../src/gperf [OPTION]... [INPUT-FILE]
|
|
|
|
If a long option shows an argument as mandatory, then it is mandatory
|
|
for the equivalent short option also.
|
|
|
|
Input file interpretation:
|
|
-e, --delimiters=DELIMITER-LIST
|
|
Allow user to provide a string containing delimiters
|
|
used to separate keywords from their attributes.
|
|
Default is ",\n".
|
|
-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.
|
|
|
|
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.
|
|
-H, --hash-fn-name=NAME
|
|
Specify name of generated hash function. Default is
|
|
`hash'.
|
|
-N, --lookup-fn-name=NAME
|
|
Specify name of generated lookup function. Default
|
|
name is `in_word_set'.
|
|
-Z, --class-name=NAME Specify name of generated C++ class. Default name is
|
|
`Perfect_Hash'.
|
|
-7, --seven-bit Assume 7-bit characters.
|
|
-c, --compare-strncmp Generate comparison code using strncmp rather than
|
|
strcmp.
|
|
-C, --readonly-tables Make the contents of generated lookup tables
|
|
constant, i.e., readonly.
|
|
-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 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).
|
|
-W, --word-array-name=NAME
|
|
Specify name of word list array. Default name is
|
|
`wordlist'.
|
|
-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 1-126, 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.
|
|
-l, --compare-strlen Compare key lengths before trying a string
|
|
comparison. This helps cut down on the number of
|
|
string comparisons made during the lookup.
|
|
-D, --duplicates Handle keywords that hash to duplicate values. This
|
|
is useful for certain highly redundant keyword sets.
|
|
-f, --fast=ITERATIONS Generate the gen-perf.hash function ``fast''. This
|
|
decreases gperf's running time at the cost of
|
|
minimizing generated table size. The numeric
|
|
argument represents the number of times to iterate
|
|
when resolving a collision. `0' means ``iterate by
|
|
the number of keywords''.
|
|
-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 function.
|
|
-o, --occurrence-sort Reorders input keys by frequency of occurrence of
|
|
the key sets. This should decrease the search time
|
|
dramatically.
|
|
-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 -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).
|
|
|
|
Report bugs to <bug-gnu-utils@gnu.org>.
|