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.\" Author: Archie Cobbs <archie@freebsd.org>
.\"
.\" $Id: structs_type_data.3,v 1.1.1.1 2012/02/21 23:25:53 misho Exp $
.\"
.Dd April 22, 2002
.Dt STRUCTS_TYPE_DATA 3
.Os
.Sh NAME
.Nm STRUCTS_DATA_TYPE ,
.Nm STRUCTS_FIXEDDATA_TYPE
.Nd structs types for binary data
.Sh LIBRARY
PDEL Library (libpdel, \-lpdel)
.Sh SYNOPSIS
.In sys/types.h
.In pdel/structs/structs.h
.In pdel/structs/type/data.h
.Fn STRUCTS_DATA_TYPE charset mtype
.Fn STRUCTS_FIXEDDATA_TYPE length
.Vt extern const struct structs_type structs_type_data ;
.Vt extern const struct structs_type structs_type_hexdata ;
.Sh DESCRIPTION
The
.Fn STRUCTS_DATA_TYPE
and
.Fn STRUCTS_FIXEDDATA_TYPE
macros define a
.Xr structs 3
type (i.e., a
.Dv "struct structs_type" )
for describing variable and fixed length binary data, respectively.
.Pp
For
.Fn STRUCTS_DATA_TYPE ,
the described data structure must be a
.Dv "struct structs_data" :
.Pp
.Bd -literal -offset 3n
    struct structs_data {
	u_int   length;       /* number of bytes */
	u_char  *data;        /* bytes */
    };
.Ed
.Pp
The
.Fa length
field contains the number of bytes in the sequence.
The data itself is pointed to by
.Fa data .
.Fa mtype
is the
.Xr typed_mem 3
type used to dynamically allocate the buffer pointed to by
.Fa data .
The ASCII form of the data is a base-64 encoding using the character
set specified by
.Fa charset ,
or the default charset if
.Fa charset
is
.Dv NULL .
See
.Xr base64 3
for the definition of a valid character set.
As a special case, if
.Fa charset
is the empty string, then a straight hex encoding will be used.
This results in a longer but more human readable encoding.
.Pp
.Fn STRUCTS_FIXEDDATA_TYPE
defines a structs type for a binary sequence having fixed length
.Fa length .
The described data structure is an array of
.Fa length
.Li "u_char" .
The ASCII form is a straight hexadecimal encoding.
.Pp
Two variable length types are predefined.
.Nm structs_type_data
uses the default RFC 2045 character set and
.Nm structs_type_hexdata
uses hexadecimal encoding for the ASCII expression.
Both of these types use the
.Xr typed_mem 3
type
.Dv STRUCTS_DATA_MEMTYPE ,
defined in the header file.
.Sh SEE ALSO
.Xr base64 3 ,
.Xr libpdel 3 ,
.Xr structs 3 ,
.Xr structs_type 3 ,
.Xr typed_mem 3
.Sh HISTORY
The PDEL library was developed at Packet Design, LLC.
.Dv "http://www.packetdesign.com/"
.Sh AUTHORS
.An Archie Cobbs Aq archie@freebsd.org