.\" $NetBSD: humanize_number.3,v 1.4 2003/04/16 13:34:37 wiz Exp $
-.\" $FreeBSD: src/lib/libutil/humanize_number.3,v 1.8 2005/04/10 12:15:25 delphij Exp $
+.\" $FreeBSD$
.\"
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-.Dd May 25, 2004
+.Dd October 7, 2013
.Dt HUMANIZE_NUMBER 3
.Os
.Sh NAME
function formats the signed 64-bit quantity given in
.Fa number
into
-.Fa buffer .
+.Fa buf .
A space and then
.Fa suffix
is appended to the end.
The buffer pointed to by
-.Fa buffer
+.Fa buf
must be at least
.Fa len
bytes long.
If the formatted number (including
.Fa suffix )
would be too long to fit into
-.Fa buffer ,
+.Fa buf ,
then divide
.Fa number
by 1024 until it will.
In this case, prefix
.Fa suffix
-with the appropriate SI designator.
+with the appropriate designator.
+The
+.Fn humanize_number
+function follows the traditional computer science conventions by
+default, rather than the IEE/IEC (and now also SI) power of two
+convention or the power of ten notion.
+This behaviour however can be altered by specifying the
+.Dv HN_DIVISOR_1000
+and
+.Dv HN_IEC_PREFIXES
+flags.
+.Pp
+The traditional
+.Pq default
+prefixes are:
+.Bl -column "Prefix" "Description" "1000000000000000000" -offset indent
+.It Sy "Prefix" Ta Sy "Description" Ta Sy "Multiplier" Ta Sy "Multiplier 1000x"
+.It Li (note) 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
+Note:
+An uppercase K indicates a power of two, a lowercase k a power of ten.
.Pp
-The prefixes are:
-.Bl -column "Prefix" "Description" "Multiplier" -offset indent
+The IEE/IEC (and now also SI) power of two prefixes are:
+.Bl -column "Prefix" "Description" "1000000000000000000" -offset indent
.It Sy "Prefix" Ta Sy "Description" Ta Sy "Multiplier"
-.It Li k Ta No kilo Ta 1024
-.It Li M Ta No mega Ta 1048576
-.It Li G Ta No giga Ta 1073741824
-.It Li T Ta No tera Ta 1099511627776
-.It Li P Ta No peta Ta 1125899906842624
-.It Li E Ta No exa Ta 1152921504606846976
+.It Li Ki Ta No kibi Ta 1024
+.It Li Mi Ta No mebi Ta 1048576
+.It Li Gi Ta No gibi Ta 1073741824
+.It Li Ti Ta No tebi Ta 1099511627776
+.It Li Pi Ta No pebi Ta 1125899906842624
+.It Li Ei Ta No exbi Ta 1152921504606846976
.El
.Pp
The
argument must be at least 4 plus the length of
.Fa suffix ,
in order to ensure a useful result is generated into
-.Fa buffer .
+.Fa buf .
To use a specific prefix, specify this as
.Fa scale
-(multiplier = 1024 ^ scale).
+.Po multiplier = 1024 ^ scale;
+when
+.Dv HN_DIVISOR_1000
+is specified,
+multiplier = 1000 ^ scale
+.Pc .
This cannot be combined with any of the
.Fa scale
flags below.
.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.
+If the final result is less than 10, display it using one decimal place.
.It Dv HN_NOSPACE
Do not put a space between
.Fa number
Divide
.Fa number
with 1000 instead of 1024.
+.It Dv HN_IEC_PREFIXES
+Use the IEE/IEC notion of prefixes (Ki, Mi, Gi...).
+This flag has no effect when
+.Dv HN_DIVISOR_1000
+is also specified.
.El
.Sh RETURN VALUES
-The
-.Fn humanize_number
-function returns the number of characters stored in
-.Fa buffer
+Upon success, the
+.Nm
+function returns the number of characters that would have been stored in
+.Fa buf
(excluding the terminating
.Dv NUL )
-upon success, or \-1 upon failure.
+if
+.Fa buf
+was large enough, or \-1 upon failure.
+Even upon failure, the contents of
+.Fa buf
+may be modified.
If
.Dv HN_GETSCALE
is specified, the prefix index number will be returned instead.
+.\" .Sh SEE ALSO
+.\" .Xr expand_number 3
+.Sh STANDARDS
+The
+.Dv HN_DIVISOR_1000
+and
+.Dv HN_IEC_PREFIXES
+flags
+conform to
+.Tn ISO/IEC
+Std\~80000-13:2008
+and
+.Tn IEEE
+Std\~1541-2002.
.Sh HISTORY
The
.Fn humanize_number
function first appeared in
-.Nx 2.0 .
+.Nx 2.0
+and then in
+.Fx 5.3 .
+The
+.Dv HN_IEC_PREFIXES
+flag was introduced in
+.Fx 9.0 .
projects / apple / libutil.git / blobdiff