.\" $NetBSD: ctod.9,v 1.4 2011/04/08 07:55:04 jruoho Exp $
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Jukka Ruohonen.
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.Dd April 8, 2011
.Dt CTOD 9
.Os
.Sh NAME
.Nm ctod
.Nd macros related to bytes, pages, and disk blocks
.Sh SYNOPSIS
.In sys/param.h
.Ft size
.Fn ctod "size x"
.Ft size
.Fn dtoc "size x"
.Ft size
.Fn ctob "size x"
.Ft size
.Fn btoc "size x"
.Ft size
.Fn dbtob "size x"
.Ft size
.Fn btodb "size x"
.Sh DESCRIPTION
The
.Nm
family of macros can be used to convert between bytes, pages
.Pq Dq clicks ,
and disk blocks.
.Pp
The following table lists the possible conversions:
.Bl -column -offset indent "disk blocks " "disk blocks " "disk blocks "
.It Sy Macro Ta Sy From Ta Sy To
.It Fn ctod Ta pages Ta disk blocks
.It Fn dtoc Ta disk blocks Ta pages
.It Fn ctob Ta pages Ta bytes
.It Fn btoc Ta bytes Ta pages
.It Fn dbtob Ta disk blocks Ta bytes
.It Fn btodb Ta bytes Ta disk blocks
.El
.Pp
These are typical macros that may appear
with different names in other operating systems.
Examples include
.Fn btop
and
.Fn btopr
in Solaris.
.Sh SEE ALSO
.Xr param 3
.Sh HISTORY
Some of these macros appeared in
.At v7 .
.Sh CAVEATS
The described macros make no assumptions
about the type of the input parameter.
A caller should ensure that neither
integer overflow nor integer underflow are possible.