NAME

       triehash - Generate a perfect hash function derived from a trie.

SYNOPSIS

       triehash [option] [input file]

DESCRIPTION

       triehash takes a list of words in input file and generates a function and an enumeration
       to describe the word

INPUT FILE FORMAT

       The file consists of multiple lines of the form:

           [label ~ ] word [= value]

       This maps word to value, and generates an enumeration with entries of the form:

           label = value

       If label is undefined, the word will be used, the minus character will be replaced by an
       underscore. If value is undefined it is counted upwards from the last value.

       There may also be one line of the format

           [ label ~] = value

       Which defines the value to be used for non-existing keys. Note that this also changes
       default value for other keys, as for normal entries. So if you place

           = 0

       at the beginning of the file, unknown strings map to 0, and the other strings map to
       values starting with 1. If label is not specified, the default is Unknown.

OPTIONS

       -C.c file --code=.c file
           Generate code in the given file.

       -Hheader file --header=header file
           Generate a header in the given file, containing a declaration of the hash function and
           an enumeration.

       --enum-name=word
           The name of the enumeration.

       --function-name=word
           The name of the function.

       --label-prefix=word
           The prefix to use for labels.

       --label-uppercase
           Uppercase label names when normalizing them.

       --namespace=name
           Put the function and enum into a namespace (C++)

       --class=name
           Put the function and enum into a class (C++)

       --enum-class
           Generate an enum class instead of an enum (C++)

       --counter-name=name
           Use name for a counter that is set to the latest entry in the enumeration + 1. This
           can be useful for defining array sizes.

       --ignore-case
           Ignore case for words.

       --multi-byte=value
           Generate code reading multiple bytes at once. The value is a string of power of twos
           to enable. The default value is 320 meaning that 8, 4, and single byte reads are
           enabled. Specify 0 to disable multi-byte completely, or add 2 if you also want to
           allow 2-byte reads. 2-byte reads are disabled by default because they negatively
           affect performance on older Intel architectures.

           This generates code for both multiple bytes and single byte reads, but only enables
           the multiple byte reads of GNU C compatible compilers, as the following extensions are
           used:

           Byte-aligned integers
                   We must be able to generate integers that are aligned to a single byte using:

                       typedef uint64_t __attribute__((aligned (1))) triehash_uu64;

           Byte-order
                   The macros __BYTE_ORDER__ and __ORDER_LITTLE_ENDIAN__ must be defined.

           We forcefully disable multi-byte reads on platforms where the variable __ARM_ARCH is
           defined and __ARM_FEATURE_UNALIGNED is not defined, as there is a measurable overhead
           from emulating the unaligned reads on ARM.

       --language=language
           Generate a file in the specified language. Currently known are 'C' and 'tree', the
           latter generating a tree.

       --include=header
           Add the header to the include statements of the header file. The value must be
           surrounded by quotes or angle brackets for C code. May be specified multiple times.

LICENSE

       triehash is available under the MIT/Expat license, see the source code for more
       information.

AUTHOR

       Julian Andres Klode <jak@jak-linux.org>