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d4file(4)             DragonFly Kernel Interfaces Manual             d4file(4)

NAME
       d4file - D4-format binary file

SYNOPSIS
       d4file

DESCRIPTION
       The universal file format for storing the list of 4-tuple data.  The
       file is called "D4-format file".  D4-format file consists of two parts.
       A header with 256byte data is put on the head of file; a magic number
       for recognizing file format, an attribute code, the number of data,
       lower- and higher-limit of data are held in the header.  Data part
       follows the header; list of 4-tuple data, the quadruple of
       2-byte-integers (short), are put in the data part.  Bit- and byte-order
       are MSB-first (big-endian).  The file header is defined by the
       following structure.

              struct d4file {
                   char    d4_magic[8];     /* = "DATA0004" */
                   int32   d4_attrb;        /* = 0 */
                   int32   d4_count;        /* = 0 */
                   short   d4_llimit[4];    /* lower  limit of each member */
                   short   d4_hlimit[4];    /* higher limit of each member */
                   short   d4_spc[48];      /* (filler) */
              };

       d4_magic field is always filled with string "DATA0004".

       d4_attrb holds the attribute code of file. The attribute code is always
       0.

       d4_count holds the number of 4-tuple data.  If this field is not used,
       constant 0 is set.

       d4_llimit and d4_hlimit arrays hold lower- and higher-limits of 4-tuple
       data respectively.

       d4_spc array is a dummy field, which is filled with zeros.

       Each 4-tuple data is defined by the following structure.

              struct d4pac {
                   short   d4_data[4];
              };

       The real value held in d4_data can be either signed 2byte-integer
       (short) and unsigned 2byte-integer (unsigned short).  The selection of
       the type depends on its application.

AUTHOR
       Copyright (C) 1995-1997 Hideaki Goto

       E-Mail: hgot@ecip.tohoku.ac.jp, hgot@aso.ecei.tohoku.ac.jp

                                   July 1997                         d4file(4)