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>