source: rtems-libbsd/freebsd-userspace/lib/libutil/humanize_number.3 @ b6ac989

.\"     $NetBSD: humanize_number.3,v 1.4 2003/04/16 13:34:37 wiz Exp $
.\" $FreeBSD$
.\"
.\" Copyright (c) 1999, 2002 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Luke Mewburn and by Tomas Svensson.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"        This product includes software developed by the NetBSD
.\"        Foundation, Inc. and its contributors.
.\" 4. Neither the name of The NetBSD Foundation nor the names of its
.\"    contributors may be used to endorse or promote products derived
.\"    from this software without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd May 25, 2004
.Dt HUMANIZE_NUMBER 3
.Os
.Sh NAME
.Nm humanize_number
.Nd format a number into a human readable form
.Sh LIBRARY
.Lb libutil
.Sh SYNOPSIS
.In libutil.h
.Ft int
.Fo humanize_number
.Fa "char *buf" "size_t len" "int64_t number" "const char *suffix"
.Fa "int scale" "int flags"
.Fc
.Sh DESCRIPTION
The
.Fn humanize_number
function formats the signed 64-bit quantity given in
.Fa number
into
.Fa buffer .
A space and then
.Fa suffix
is appended to the end.
The buffer pointed to by
.Fa buffer
must be at least
.Fa len
bytes long.
.Pp
If the formatted number (including
.Fa suffix )
would be too long to fit into
.Fa buffer ,
then divide
.Fa number
by 1024 until it will.
In this case, prefix
.Fa suffix
with the appropriate SI designator.
The
.Fn humanize_number
function
follows the traditional computer science conventions rather than the proposed
SI power of two convention.
.Pp
The prefixes are:
.Bl -column "Prefix" "Description" "1000000000000000000" -offset indent
.It Sy "Prefix" Ta Sy "Description" Ta Sy "Multiplier" Ta Sy "Multiplier 1000x"
.It Li k Ta No kilo Ta 1024 Ta 1000
.It Li M Ta No mega Ta 1048576 Ta 1000000
.It Li G Ta No giga Ta 1073741824 Ta 1000000000
.It Li T Ta No tera Ta 1099511627776 Ta 1000000000000
.It Li P Ta No peta Ta 1125899906842624 Ta 1000000000000000
.It Li E Ta No exa Ta 1152921504606846976 Ta 1000000000000000000
.El
.Pp
The
.Fa len
argument must be at least 4 plus the length of
.Fa suffix ,
in order to ensure a useful result is generated into
.Fa buffer .
To use a specific prefix, specify this as
.Fa scale
(multiplier = 1024 ^ scale).
This cannot be combined with any of the
.Fa scale
flags below.
.Pp
The following flags may be passed in
.Fa scale :
.Bl -tag -width ".Dv HN_DIVISOR_1000" -offset indent
.It Dv HN_AUTOSCALE
Format the buffer using the lowest multiplier possible.
.It Dv HN_GETSCALE
Return the prefix index number (the number of times
.Fa number
must be divided to fit) instead of formatting it to the buffer.
.El
.Pp
The following flags may be passed in
.Fa flags :
.Bl -tag -width ".Dv HN_DIVISOR_1000" -offset indent
.It Dv HN_DECIMAL
If the final result is less than 10, display it using one digit.
.It Dv HN_NOSPACE
Do not put a space between
.Fa number
and the prefix.
.It Dv HN_B
Use
.Ql B
(bytes) as prefix if the original result does not have a prefix.
.It Dv HN_DIVISOR_1000
Divide
.Fa number
with 1000 instead of 1024.
.El
.Sh RETURN VALUES
The
.Fn humanize_number
function returns the number of characters stored in
.Fa buffer
(excluding the terminating
.Dv NUL )
upon success, or \-1 upon failure.
If
.Dv HN_GETSCALE
is specified, the prefix index number will be returned instead.
.Sh SEE ALSO
.Xr expand_number 3
.Sh HISTORY
The
.Fn humanize_number
function first appeared in
.Nx 2.0
and then in
.Fx 5.3 .