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.\" Copyright (c) 2008 Guillaume Ballet
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.\" $FreeBSD: src/share/man/man9/DB_COMMAND.9,v 1.6 2012/05/20 16:43:47 gjb Exp $
.\"
.Dd May 5, 2015
.Dt DB_COMMAND 9
.Os
.Sh NAME
.Nm DB_COMMAND ,
.Nm DB_COMMAND_FLAG ,
.Nm DB_SHOW_COMMAND
.Nd Extends the ddb command set
.Sh SYNOPSIS
.In ddb/ddb.h
.Fo DB_COMMAND
.Fa command_name
.Fa command_function
.Fc
.Fo DB_COMMAND_FLAG
.Fa command_name
.Fa command_function
.Fa flag
.Fc
.Fn DB_SHOW_COMMAND "command_name" "command_function"
.Sh DESCRIPTION
The
.Fn DB_COMMAND
macro adds
.Fa command_name
to the list of top-level commands.
Invoking
.Fa command_name
from ddb will call
.Fa command_function .
.Pp
The
.Fn DB_COMMAND_FLAG
macro is a variant of
.Fn DB_COMMAND
which allows for specifying an additional
.Fa flag .
.Pp
The
.Fn DB_SHOW_COMMAND
is roughly equivalent to
.Fn DB_COMMAND
but in this case,
.Fa command_name
is a sub-command of the ddb
.Sy show
command.
.Pp
The general command syntax:
.Cm command Ns Op Li \&/ Ns Ar modifier
.Ar address Ns Op , Ns Ar count ,
translates into the following parameters for
.Fa command_function :
.Bl -tag -width Fa -offset indent
.It Fa addr
The address passed to the command as an argument.
.It Fa have_addr
A boolean value that is true if the addr field is valid.
.It Fa count
The number of quad words starting at offset
.Fa addr
that the command must process.
.It Fa modif
A pointer to the string of modifiers.
That is, a series of symbols used to pass some options to the command.
For example, the
.Sy examine
command will display words in decimal form if it is passed the modifier "d".
.El
.Sh EXAMPLES
In your module, the command is declared as:
.Bd -literal
DB_COMMAND(mycmd, my_cmd_func)
{
	if (have_addr)
		db_printf("Calling my command with address %p\en", addr);
}
.Ed
.Pp
Then, when in ddb:
.Bd -literal
.Bf Sy
db> mycmd 0x1000
Calling my command with address 0x1000
db>
.Ef
.Ed
.Sh SEE ALSO
.Xr ddb 4
.Sh AUTHORS
This manual page was written by
.An Guillaume Ballet Aq Mt gballet@gmail.com .